ZONE CONTROLS WIRE GUIDE J8680 REV - Taco-Hvac

TACO ZONE CONTROLS WIRING GUIDE
Pages
Switching Relays – Single Zone Wiring 2 – 2
Switching Relays – Oil Boiler Wiring Safety Notice 2 3 – 4
Switching Relays – NON EXP Connected Together with Priority 5 – 11
Switching Relays – EXP Connected Together with Priority 12 – 14
Switching Relays – Multiple Indirect Hot Water Heaters 15 – 16
Switching Relays – EXP Connected To Reset Controls (PC700, 702 & 705) 17 – 28
Zone Valve Controls – NON EXP Connected Together with Priority 29 – 34
Zone Valve Controls – EXP Connected Together with Priority 35 – 38
Zone Valve Controls – Connected To Reset Controls (PC700, 702 & 705) 39 – 46
Hydro Air Fan Controls (HAFC 101 & 201) 47 – 51
Specialty Thermostat and Zone Valve Wiring 52 – 56
Radiant Mixing Block 57 – 58
X-Pump Block 59 – 61
iSeries Mixing Valves 62 – 63
Low Water Cutoffs and Electric Water Feeders 64 – 79
Aquastat Wiring 80 – 86
Instruction Sheets 87 – 97
Standard Terms and Definitions – 98
Cross Reference 99 – 100
Do it once.
Do it right.
© Taco Catalog No. 100-9.0 Effective Date: July 1, 2010
Supersedes Date: July 1, 2007

TACO Zone Control Product Information
Switching Relays
Product No.
SR501
SR501-845RP
SR502
SR503
SR504
SR506
Description
1 Zone Switching Relay
1 Zone Switching Relay Replacement PC Board for
Honeywell R845, RA89A, RA832 or Comparable Relay
2 Zone Switching Relay with Priority
3 Zone Switching Relay with Priority
4 Zone Switching Relay with Priority
6 Zone Switching Relay with Priority
Switching Relays with PowerPort Options and Expandable to 20 Zones
Product No.
Description
SR501-EXP
1 Zone Switching Relay
SR503-EXP
3 Zone Switching Relay with Priority and 3 PowerPorts
SR504-EXP
4 Zone Switching Relay with Priority and 3 PowerPorts
SR506-EXP
6 Zone Switching Relay with Priority and 3 PowerPorts
Zone Valve Controls
Product No.
ZVC403
ZVC404
ZVC405
ZVC406
Description
3 Zone Valve Control
4 Zone Valve Control with Priority
5 Zone Valve Control
6 Zone Valve Control with Priority
Zone Valve Controls with PowerPort Options and Expandable to 20 Zones
Product No.
Description
ZVC404-EXP
4 Zone Valve Control with Priority and 2 PowerPorts
ZVC406-EXP
6 Zone Valve Control with Priority and 2 PowerPorts
Plug-In PowerPort Cards (For use with all -EXP controls)
Product No.
Description
PC600
Post Purge Timer Plug-In Card
PC605
Priority Protection Plug-In Card
PC610
Universal Timer/Pump Exercise Plug-In Card
Add-On Power Controls (For use with all -EXP controls)
Product No.
Description
PC700
Boiler Reset Control
PC702
2-Stage Boiler Reset Control
PC705
Variable Speed Pump Injection Mixing Control
Fan Controls
Product No.
HAFC101
HAFC201
Description
Hydro Air Fan Control
Hydro Air Fan Control with Optional Time Delays
Do it once.
Do it right.

SR501 Switching Relay Wiring
ALTERNATIVE WIRING
(TANKLESS COIL)
THERMOST
AT
T
SR501
1 ZONE
SWITCHING RELAY
24
R W VAC
T T COM
POWER
T STAT
120 VAC
INPUT
N H 3 4 4 6 6 N/O N/C N/C N/O 5
TO: ZC
TO: ZR
TO: 120 VAC POWER
CIRCULATOR
Note: When using Alternative Wiring diagram, the boiler operating
control’s ZC terminal will see the load of the circulator(s).
Warning: When using Alternative Wiring diagram, wiring
instructions must be followed so power originates from the boiler
aquastat. Failure to follow these wiring instructions may result in
a secondary source of power being connected to the boiler that
may activate it under certain circumstances, causing injury or death.
ALTERNATIVE WIRING
(24 VAC POWERED INPUT SIGNAL)
24 VAC
SIGNAL
SR501
1 ZONE
SWITCHING RELAY
24
R W VAC
T T COM
POWER *
T STAT *
N H 3 4 4 6 6 N/O N/C N/C N/O 5
H
N
TO: TT ON BOILER
TO: 120 VAC POWER
CIRCULATOR
REMOVE JUMPER.
DO NOT CONNECT POWER
TO N AND H TERMINALS.
* T STAT LIGHT WILL GO
ON AND OFF WITH 24 VAC
SIGNAL. POWER LIGHT
WILL ALWAYS BE OFF.
2
TYPICAL WIRING
(COLD START)
AT
THERMOST
T
24
R W VAC
T T COM
SR501
1 ZONE
SWITCHING RELAY
POWER
T STAT
120 VAC
INPUT
N H 3 4 4 6 6 N/O N/C N/C N/O 5
JUMPER
TO: TT ON BOILER
CIRCULATOR
TO: 120 VAC
POWER

NOTE: No tankless coil priority.
3

(cont.)
(HOT)
L1
L2
(NEUTRAL)
THERMOSTATS
CIRCUIT
BREAKER
CUSTOMER
EMERGENCY
SWITCH
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
THERMOSTAT
L1 L2 T T
HONEYWELL L8124
OR EQUAL
THERMAL
FUSE
(FIROMATIC)
SERVICE
SWITCH
24 VAC
POWER
FUSE 1 AMP
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
ZONE 2
ZONE 3
ZONE 4
B2
C1
C2
CIRCULATOR
ON BOILER
(IF ATTACHED)
ZR
ZC
B1
LINE VOLTAGE
OIL BURNER RELAY
LOW
WATER
CUTOFF
120 VAC INPUT
NOTE: Tankless coil has priority.
(HOT)
L1
L2
(NEUTRAL)
THERMOSTAT
CIRCUIT
BREAKER
24 VAC
POWER
SR 503
THERMOSTAT
CUSTOMER
EMERGENCY
SWITCH
FUSE 1 AMP
ZONE 1 ZONE 2 ZONE 3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
POWER
ZONE 1
L1 L2 T T
HONEYWELL L8124
OR EQUAL
THERMAL
FUSE
(FIROMATIC)
ZONE 2
ZONE 3
B2
C1
C2
ZR
ZC
B1
SERVICE
SWITCH
N P ZC H
X1
X2
ZR
ZONE1 ZONE2 ZONE3
120 VOLT CIRCULATORS
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
LOW
WATER
CUTOFF
120 VAC INPUT
NOTE: The boiler operating control’s ZC terminal will see the load of the circulator(s).
4

SR502/503 Switching Relay Controlling Another SR502/503 Switching Relay
MASTER
AQUASTAT
ON DHW
HEATER
A
T
T
PRIORITY ON
VIA JUMPER
PLACEMENT
24 VAC
POWER
SR 503
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
ZONE 2
ZONE 3
N P ZC H
JUMPER
X 2
X 1 ZR
ZONE1 ZONE2 ZONE3
N
H
120 VAC POWER
DHW
HEATER
CIRCULATOR
120 VOLT
CIRCULATORS
SLAVE
T
T
T
PRIORITY OFF
VIA JUMPER
PLACEMENT
24 VAC
POWER
SR 503
FUSE 1 AMP
N P ZC H
JUMPER
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
X ZR 1
ZONE 1
ZONE 2
ZONE 3
X 2
ZONE1 ZONE2 ZONE3
POWER
BOILER
120 VOLT CIRCULATORS
TO: "TT" ON AQUASTAT CONTROL
5

SR502/503 Switching Relay Controlling Another SR504/506 Switching Relay
MASTER
AQUASTAT
ON DHW
HEATER
A
T
T
24 VAC
POWER
SR 503
ZONE1 ZONE2 ZONE3
FUSE 1 AMP
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
PRIORITY ON
VIA JUMPER
PLACEMENT
POWER
ZONE 1
ZONE 2
ZONE 3
N P ZC H
JUMPERS
X 2
X 1 ZR
ZONE1 ZONE2 ZONE3
120 VOLT
CIRCULATORS
24 VAC
POWER
SLAVE
SR 506
120V RELAY
X X
END
SWITCH
THERMOSTATS
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
T
POWER
INPUT
ZONE 6
PRIORITY
ON
OFF
PRIORITY
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
REMOVE
JUMPER
120 VAC INPUT
H
N
TO: "TT" ON BOILER
BOILER
6

Two SR504/506 Switching Relays Connected Together
A
AQUASTAT ON
DHW HEATER
T
T
T
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
PRIORITY
ON
24 VAC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
DHW
HEATER
CIRCULATOR
BOILER
T
T
T
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
PRIORITY
ON
24 VAC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
OUTPUT
NOT
USED
120 VAC INPUT
H
N
7

Priority Zoning Circulator Controlling SR504/506 Switching Relay
MASTER
PRIORITY ZONING CIRCULATOR
PRIORITY
ON
OFF
PRIORITY
ON
THERMOSTAT BOILER PRIORITY POWER IN
1 2 3 4 PR-IN PR-OUT LIVE NEUT
A
120 VAC INPUT
AQUASTAT ON
DHW HEATER
THERMOSTATS
SLAVE
T
PRIORITY
OFF
24 VAC
POWER
SR 506
120V RELAY
X X
END
SWITCH
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
POWER
INPUT
ZONE 6
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
REMOVE
JUMPER
120 VAC INPUT
H
N
TO: "TT" ON BOILER
BOILER
8

FUSE 1 AMP
BOILER
Priority Zoning Circulator Controlling 2 SR504/506 Switching Relays
SR 504
T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4
T
ZONE 4
PRIORITY
ON
OFF
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
120V RELAY
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
120V RELAY
24 VAC
POWER
SLAVE
MASTER
PRIORITY ZONING CIRCULATOR
OFF
PRIORITY
ON
PRIORITY
ON
THERMOSTAT BOILER PRIORITY POWER IN
1 2 3 4 PR-IN PR-OUT LIVE NEUT
AQUASTAT ON
DHW HEATER
A
120 VAC INPUT
T T T T T
PRIORITY
OFF
SLAVE
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
FUSE 1 AMP
REMOVE
REMOVE
JUMPER
JUMPER
TO: "TT" ON BOILER
PRIORITY
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
120 VAC INPUT
H
N
24 VAC
POWER
9

FUSE 1 AMP
BOILER
SR502/503 Switching Relay Controlling 2 SR504/506 Switching Relays
SR 504
T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4
T
ZONE 4
PRIORITY
ON
OFF
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
120V RELAY
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
120V RELAY
24 VAC
POWER
SLAVE
MASTER
AQUASTAT ON
DHW HEATER
A
T T
24 VAC
POWER
SR 503 ZONE1 ZONE2 ZONE3
PRIORITY
ON
TWO ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
ZONE 2
ZONE 3
X 2
N P ZC H X ZR
1
ZONE1 ZONE2 ZONE3
JUMPER
T T T T T
PRIORITY
OFF
SLAVE
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
FUSE 1 AMP
REMOVE
REMOVE
JUMPER
JUMPER
TO: "TT" ON BOILER
120 VAC INPUT
PRIORITY
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
H
N
24 VAC
POWER
10

SLAVE
24 VAC
POWER
FUSE 1 AMP
BOILER
SR 504
120V RELAY
X X
END
SWITCH
ZC ZR
REMOVE
JUMPER
TO: "TT" ON BOILER
SR501 Switching Relay Controlling 2 SR504/506 Switching Relays
MASTER
A
AQUASTAT ON
DHW HEATER
SR501
24
R W VAC
T T COM
1 ZONE SWITCHING RELAY
POWER
T STAT
N H 3 4 4 6 6
N/O N/C N/C N/O 5
JUMPER
120 VAC INPUT
DHW
CIRCULATOR
T T T T
SLAVE
T T T T
PRIORITY OFF PRIORITY OFF
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
24 VAC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
REMOVE
JUMPER
120 VAC
INPUT
H
N
11

SR501-EXP Switching Relay Controlling Another SR504/506 Switching Relay
AQUASTAT ON
DHW HEATER
TO: "TT" ON BOILER
A
TO: OPTIONAL ZONE VALVE
OR iSeries MIXING VALVE
MASTER
POWER
CONTROLS
MODE
RESET
FUSE
1 AMP
NORMAL
SLAVE
MASTER
END
SWITCH
X
EXPANSION
ZONE
THERMOSTAT
VALVE
X 1 3 4 T/R T/W COM 1
2 2
SR 501-EXP
FUSE
5 AMP
POWER
T STAT
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
120VAC CIRC
OUTPUT OUTPUT
PRIORITY
OUTPUT
JUMPER
DHW CIRCULATOR
24 VAC
POWER
SLAVE
SR 506
120V RELAY
X X
END
SWITCH
THERMOSTATS
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
T
POWER
INPUT
ZONE 6
PRIORITY
ON
OFF
PRIORITY
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
REMOVE
JUMPER
120 VAC INPUT
H
N
TO: "TT" ON BOILER
BOILER
12

SR501-EXP Switching Relay Controlling a ZVC404/406 Zone Valve Control
AQUASTAT ON
DHW HEATER
A
TO: OPTIONAL ZONE VALVE
OR iSeries MIXING VALVE
ZONE
VALVE
X 1 2 1 2
END
EXPANSION THERMOSTAT
SWITCH
X 3 4 T/R T/W COM
SR 501-EXP
POWER
T STAT
FUSE
5 AMP
N H ZC ZR H H
PRIORITY
OUTPUT
CIRC
OUTPUT
120VAC
OUTPUT
120VAC
INPUT
POWER
INPUT
THERMOSTAT THERMOSTAT THERMOSTAT
T T T
DHW
HEATER
CIRCULATOR
JUMPER
24 VAC
SLAVE
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
POWER IN
120 VAC
INPUT
BLACK
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 6
1 2 3 4
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
MAIN N/C
N/O COM
ZONE 6 RELAY
EXTRA
END
SWITCH
END
SWITCH
TO BOILER AQUASTAT RELAY
SEE NOTE
JUMPER
3 & 4
JUMPER
3 & 4
PRIORITY
ZONE
MOTOR END
SWITCH
SYSTEM
PUMP
1
2
3
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
BOILER TURNS ON WHEN ANY ZONE VALVE OPENS.
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
SYSTEM PUMP TURNS ON WHEN ANY ZONE VALVE OPENS
EXCEPT WHEN THE DHW HEATER (SR501-EXP) CALLS.
MASTER
TO BOILER AQUASTAT RELAY
MODE
POWER
CONTROLS RESET
NORMAL
SLAVE
FUSE
1 AMP
MASTER
N
120 VAC
INPUT
H
BOILER
13

2 Expandable Switching Relays Connected Together
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T
THERMOSTATS
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
SR 504-EXP
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
MASTER
THERMOSTATS
T
A
AQUASTAT
ON DHW
HEATER
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
X X
END
SWITCH
PLUG-IN CARDS
RESET
NORMAL
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SR 506-EXP
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
POWER
INPUT
ZONE 6
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
120 VAC INPUT
H
N
BOILER
DHW
CIRCULATOR
14

2 Indirect Water Heaters with Priority Connected to Standard Switching Relays
AQUASTATS ON
DHW HEATERS
A
A
MASTER
24 VAC
POWER
SR 502 ZONE1 ZONE2 ZONE3
PRIORITY
OFF
TWO ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
N P ZC H X ZR
1
ZONE1 ZONE2 ZONE3
JUMPERS
SR 504
T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4
T
SLAVE SLAVE
ZONE 4
PRIORITY
ON
OFF
PRIORITY
ON
SR 504
T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4
T
ZONE 4
PRIORITY
ON
OFF
24 VAC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
24 V AC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
FUSE 1 AMP
FUSE 1 AMP
JUMPER
ZONE
NOT
USED
JUMPER
ZONE
NOT
USED
BOILER
TO: "TT" ON BOILER
120 VAC INPUT
PRIORITY
ON
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
H
N
X 2
ZONE 2
15

2 Indirect Water Heaters with Priority Connected to EXP Switching Relays
A
A
AQUASTATS ON
DHW HEATERS
24 VAC
POWER
SR 502 ZONE1 ZONE2 ZONE3
PRIORITY
OFF
TWO ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
N P ZC H X ZR
1
ZONE1 ZONE2 ZONE3
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
T
JUMPERS
DHW
CIRCULATORS
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
MASTER SLAVE
T
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
SR 504-EXP
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
SR 504-EXP
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
FUSE 1 AMP
FUSE 1 AMP
JUMPER
JUMPER
BOILER
TO: "TT" ON BOILER
ZONE
NOT
USED
120 VAC INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
H
N
X 2
ZONE 2
16

PC700 Boiler Reset Control Connected to SR501-EXP Switching Relay
OUTDOOR
SENSOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
PC700
THERMOSTAT
BOIL OUT
SEN SEN
ZONE
CONTROL
TO: "TT" ON BOILER
T
TO: OPTIONAL ZONE VALVE
OR iSeries MIXING VALVE
BOILER SENSOR
POWER
CONTROLS
MODE
RESET
FUSE
1 AMP
NORMAL
SLAVE
MASTER
END
ZONE
EXPANSION THERMOSTAT
SWITCH
VALVE
X 1 3 4 T/R T/W COM 1
X
2 2
SR 501-EXP
FUSE
5 AMP
POWER
T STAT
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
120VAC CIRC
OUTPUT OUTPUT
PRIORITY
OUTPUT
BOILER
JUMPER
120 VAC INPUT
H
N
SYSTEM
CIRCULATOR
17

SR501-EXP and PC700 Boiler Reset Control Connected to an Existing Switching Relay
OUTDOOR
SENSOR
TO: "TT" ON BOILER
Note: If Zone Control comes on without a call for heat,
reverse Reset Override input (1 & 2) wires on SR501-EXP.
A
AQUASTAT ON
DHW HEATER
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
FUSE
1 AMP
POWER
CONTROLS
END
RESET
EXPANSION THERMOSTAT
SWITCH
OVERRIDE
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SLAVE
FUSE
5 AMP
SR 501-EXP
K1 K2
MODE
RESET
NORMAL
POWER
T STAT
EXISTING
ZONE
CONTROL
THERMOSTATS
SR 504
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
120V RELAY
T
ZONE1 ZONE2 ZONE3 ZONE4
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
120VAC
OUTPUT
K1-B K2-A K2-A
CIRC
OUTPUT
PRIORITY
OUTPUT
24 VAC
POWER
FUSE 1 AMP
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4
120 VOLT CIRCULATORS
POWER
INPUT
JUMPER
MASTER
JUMPER
BOILER
PRIMARY
SYSTEM
CIRCULATOR
(Optional)
DHW
HEATER
CIRCULATOR
120 VAC
INPUT
H
N
OUTDOOR
SENSOR
Connecting a DHW Heater to an Existing Heating Only Switching Relay
Using an SR501-EXP and PC700 Boiler Reset Control
TO: "TT" ON BOILER
A
AQUASTAT ON
DHW HEATER
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
MASTER
FUSE
1 AMP
POWER
CONTROLS
END
RESET
EXPANSION THERMOSTAT
SWITCH
OVERRIDE
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SLAVE
FUSE
5 AMP
SR 501-EXP
K1 K2
MODE
RESET
NORMAL
POWER
T STAT
EXISTING
ZONE
CONTROL
SLAVE
SR 504
120V RELAY
T
ZONE1 ZONE2 ZONE3 ZONE4
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
THERMOSTATS
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
120VAC
OUTPUT
K1-B K2-A K2-A
CIRC
OUTPUT
PRIORITY
OUTPUT
24 VAC
POWER
FUSE 1 AMP
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4
120 VOLT CIRCULATORS
POWER
INPUT
BOILER
JUMPER
DHW
HEATER
CIRCULATOR
REMOVE
JUMPER
120 VAC
INPUT
H
N
18

SR501-EXP and PC700 Boiler Reset Control Connected to an Existing Zone Valve Control
OUTDOOR
SENSOR
TO: "TT" ON BOILER
Note: If Zone Control comes on without a call for heat,
reverse Reset Override input (1 & 2) wires on SR501-EXP.
THERMOSTATS
A
AQUASTAT ON
DHW HEATER
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
POWER
CONTROLS
FUSE
1 AMP
END
RESET MODE
EXPANSION THERMOSTAT
SWITCH
OVERRIDE RESET
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SR 501-EXP NORMAL
SLAVE
FUSE
5 AMP
K1
K2
POWER
T STAT
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24
VAC
POWER IN
MAIN EXTRA
END END
SWITCH SWITCH
EXISTING
ZONE
CONTROL
MODE
NORMAL RESET
FUSE
(3 AMP MAX)
T
24 VAC
T
T T T T T T T T
ZONE 1
ZONE 2 ZONE 3 ZONE 4
ZONE 1 ZONE 2
N/O COM N/C
ZONE 4 RELAY 1 2 3 4 1 2 3 4
ZVC 404
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 4
PRIORITY
OFF
ON
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
POWER
K1-B K2-A K2-A
N H ZC ZR H H
POWER 120VAC 120VAC CIRC
INPUT INPUT OUTPUT OUTPUT
PRIORITY
OUTPUT
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
JUMPER
2 WIRE ZONE VALVE TACO
(NO END SWITCH) 3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN,
SELF CLOSING)
BOILER
PRIMARY
SYSTEM
CIRCULATOR
(Optional)
DHW HEATER
CIRCULATOR
ZONE VALVE SYSTEM
CIRCULATOR
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
H
N
120 VAC
INPUT
Connecting a DHW Heater to an Existing Heating Only Zone Valve Control
Using an SR501-EXP and PC700 Boiler Reset Control
OUTDOOR
SENSOR
A
AQUASTAT ON
DHW HEATER
TO: "TT" ON BOILER
THERMOSTATS
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
MASTER
POWER
CONTROLS
FUSE
1 AMP
END
RESET MODE
EXPANSION THERMOSTAT
SWITCH
OVERRIDE RESET
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SR 501-EXP NORMAL
SLAVE
FUSE
5 AMP
K1
K2
POWER
T STAT
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24
VAC
POWER IN
MAIN EXTRA
END END
SWITCH SWITCH
EXISTING
ZONE
CONTROL
MODE
NORMAL RESET
FUSE
(3 AMP MAX)
T
24 VAC
T
ZONE 1 ZONE 2
N/O COM N/C
ZONE 4 RELAY 1 2 3 4 1 2 3 4
ZONE 4
PRIORITY
OFF
T T T T T T T T
ON
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZVC 404
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
SLAVE
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
POWER
K1-B K2-A K2-A
N H ZC ZR H H
POWER 120VAC 120VAC CIRC
INPUT INPUT OUTPUT OUTPUT
PRIORITY
OUTPUT
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
JUMPER
2 WIRE ZONE VALVE TACO
(NO END SWITCH) 3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN,
SELF CLOSING)
BOILER
DHW HEATER
CIRCULATOR
ZONE VALVE SYSTEM
CIRCULATOR
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
H
N
120 VAC
INPUT
19

SR501-EXP and PC700 Boiler Reset Control Connected to an Existing
Tankless Coil Boiler – Zoning with Circulators
OUTDOOR
SENSOR
T
THERMOSTATS
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
FUSE
1 AMP
POWER
CONTROLS
END
RESET
EXPANSION THERMOSTAT
SWITCH
OVERRIDE
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SLAVE
FUSE
5 AMP
SR 501-EXP
K1 K2
MODE
RESET
NORMAL
POWER
T STAT
EXISTING
ZONE
CONTROL
SR 504
120V RELAY
ZONE1 ZONE2 ZONE3 ZONE4
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
120VAC
OUTPUT
K1-B K2-A K2-A
CIRC
OUTPUT
PRIORITY
OUTPUT
24 VAC
POWER
FUSE 1 AMP
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4
120 VOLT CIRCULATORS
POWER
INPUT
JUMPER
BOILER
TO: "ZR" ON BOILER CONTROL
TO: "ZC" ON BOILER CONTROL
PRIMARY
SYSTEM
CIRCULATOR
(Optional)
REMOVE
JUMPER
120 VAC
INPUT
H
N
Boiler and Zone Control(s) need to be on same power supply (same circuit breaker).
OUTDOOR
SENSOR
SR501-EXP and PC700 Boiler Reset Control Connected to an Existing
Tankless Coil Boiler – Zoning with Zone Valves
THERMOSTATS
PC700
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
MASTER
FUSE
1 AMP
POWER
CONTROLS
END
RESET MODE
EXPANSION THERMOSTAT
SWITCH
OVERRIDE RESET
X X 1 2 3 4 T/R T/W COM 1 2
K1-A
MASTER
SR 501-EXP NORMAL
SLAVE
FUSE
5 AMP
K1
K2
POWER
T STAT
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24
VAC
POWER IN
MAIN EXTRA
END END
SWITCH SWITCH
EXISTING
ZONE
CONTROL
MODE
NORMAL RESET
FUSE
(3 AMP MAX)
T
24 VAC
T
ZONE 1 ZONE 2
N/O COM N/C
ZONE 4 RELAY 1 2 3 4 1 2 3 4
ZONE 4
PRIORITY
OFF
T T T T T T T T
ON
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZVC 404
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
SLAVE
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
POWER
K1-B K2-A K2-A
N H ZC ZR H H
POWER 120VAC 120VAC CIRC
INPUT INPUT OUTPUT OUTPUT
PRIORITY
OUTPUT
JUMPER
3 & 4
1
2
3
MOTOR END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
TO: "ZR" ON BOILER CONTROL
TO: "ZC" ON BOILER CONTROL
JUMPER
PRIMARY
SYSTEM
CIRCULATOR
(Optional)
2 WIRE ZONE VALVE
(NO END SWITCH)
ZONE VALVE SYSTEM
CIRCULATOR
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN,
SELF CLOSING)
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
BOILER
H
N
120 VAC
INPUT
Boiler and Zone Control(s) need to be on same power supply (same circuit breaker).
20

OUTDOOR
SENSOR
BOIL
SEN
PC700
OUT
SEN
ZONE
CONTROL
BOILER SENSOR
BOILER
PC700 Boiler Reset Control Connected to EXP Switching Relay
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
T
THERMOSTATS
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1234 PLUG-IN CARDS
RESET NORMAL
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
TO: "TT" ON BOILER
H
N
21

STAGE
1
PC702 2–Stage Boiler Reset Control Connected to EXP Switching Relay
OUTDOOR
SENSOR
DHW
DEMAND
SWITCH SETTINGS
PC702
STAGE
2
BOIL
SEN
OUT
SEN
ZONE
CONTROL
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
T
THERMOSTATS
BOILER
#1
BOILER SENSOR
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1234 PLUG-IN CARDS
RESET NORMAL
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
H
N
BOILER
#2
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
SYSTEM
CIRCULATOR
(OPTIONAL)
22

OUTDOOR
SENSOR
PC705-2
BOIL
SEN
SUP
SEN
OUT
SEN
ZONE
CONTROL
SUPPLY SENSOR
BOILER SENSOR
BOILER
PC705 Variable Speed Pump Injection Control Connected to EXP Switching Relay
GREEN/GROUND
(SEE NOTE B)
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
T
THERMOSTATS
RED
BLUE
BLACK
SYSTEM
CIRCULATOR
AND/OR BOILER
INJECTION
CIRCULATOR
24 VAC
POWER
SLAVE
MASTER
1234 PLUG-IN CARDS
RESET NORMAL
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
SYSTEM
CIRCULATOR
AND/OR BOILER
(SEE NOTE A)
120 VAC INPUT
N
H
NOTE A: WHEN SYSTEM CIRCULATOR IS CONNECTED TO ZR TERMINAL ON SWITCHING RELAY, THE MODE SWITCH MUST BE SET TO NORMAL.
THE PC705-2 WILL NOT RESET THE BOILER WHEN IN THE NORMAL MODE.
NOTE B: WHEN SYSTEM CIRCULATOR IS CONNECTED TO RED WIRE ON PC705-2, THE CIRCULATOR WILL OPERATE ONLY WHEN THERMOSTAT CALLS FOR HEAT
AND THE OUTDOOR TEMPERATURE IS BELOW THE WARM WEATHER SHUT DOWN (WWSD) TEMPERATURE. THE WWSD CAN BE ADJUSTED OR TURNED
OFF SO THAT THE CIRCULATOR IS NOT AFFECTED BY OUTDOOR TEMPERATURE.
23

PC700 Boiler Reset Control Connected to 2 EXP Switching Relays
OUTDOOR
SENSOR
SWITCH SETTINGS
BOIL OUT
SEN SEN
PC700
ZONE
CONTROL
BOILER SENSOR
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
MASTER
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
BOILER
TO: "TT" ON BOILER
JUMPER
120 VAC
INPUT
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: No Priority
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
SLAVE
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
H
N
SYSTEM
CIRCULATOR
(OPTIONAL)
24

PC702 2–Stage Boiler Reset Control Connected to 2 EXP Switching Relays
STAGE
1
PC702
STAGE
2
BOIL OUT ZONE
SEN SEN CONTROL
BOILER
#1
BOILER SENSOR
DHW
DEMAND
OUTDOOR
SENSOR
POWER
CONTROL
INTERFACE
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
MASTER
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
120 VAC INPUT
BOILER
#2
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: No Priority
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
SLAVE
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
SYSTEM
CIRCULATOR
(OPTIONAL)
JUMPER
H
N
120 VAC INPUT
25

PC705 Variable Speed Pump Injection Control Connected to 2 EXP Switching Relays
SWITCH SETTINGS
OUTDOOR
SENSOR
GREEN/GROUND
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
T
THERMOSTATS
MASTER
BOIL
SEN
PC705-2
SUP OUT
SEN SEN
ZONE
CONTROL
SUPPLY SENSOR
BOILER SENSOR
RED
BLUE
BLACK
(SEE NOTE B
ON PAGE 23)
SYSTEM
CIRCULATOR
INJECTION
CIRCULATOR
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
120 VAC
INPUT
BOILER
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: No Priority
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
SLAVE
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
H
N
SYSTEM
CIRCULATOR
(OPTIONAL)
(SEE NOTE A ON PAGE 23)
120 VAC INPUT
26

PC700 and PC705 Controls Connected to 2 EXP Switching Relays
OUTDOOR
SENSOR
SWITCH SETTINGS
BOIL OUT
SEN SEN
PC700
ZONE
CONTROL
BOILER SENSOR
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
MASTER
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
120 VAC INPUT
BOILER
OUTDOOR
SENSOR
BOIL
SEN
PC705-2
SUP OUT
SEN SEN
ZONE
CONTROL
SUPPLY SENSOR
BOILER SENSOR
GREEN/GROUND
RED
BLUE
BLACK
(SEE NOTE B
ON PAGE 23)
SYSTEM
CIRCULATOR
INJECTION
CIRCULATOR
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: No Priority
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END
SWITCH
ZC ZR
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
SLAVE
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
SYSTEM CIRCULATOR
(OPTIONAL LOCATION)
(SEE NOTE A ON PAGE 23)
H
N
120 VAC INPUT
27

PC702 and PC705 Controls Connected to 2 EXP Switching Relays
STAGE
1
PC702
STAGE
2
BOIL OUT ZONE
SEN SEN CONTROL
BOILER
#1
BOILER SENSOR
DHW
DEMAND
OUTDOOR
SENSOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
POWER
CONTROL
INTERFACE
24 VAC
POWER
SLAVE
MASTER
FUSE 1 AMP
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
MASTER
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
JUMPER
120 VAC INPUT
BOILER
#2
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
OUTDOOR
SENSOR
BOIL
SEN
PC705-2
SUP OUT
SEN SEN
ZONE
CONTROL
SUPPLY SENSOR
BOILER SENSOR
GREEN/GROUND
RED
BLUE
BLACK
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: No Priority
(SEE NOTE B
ON PAGE 23)
SYSTEM
CIRCULATOR
INJECTION
CIRCULATOR
24 VAC
POWER
SLAVE
MASTER
1 2 3 4
EXPANSION
120V RELAY
PLUG-IN CARDS
RESET NORMAL
X X
END ZC ZR
SWITCH
T
THERMOSTATS
ZONE 1 ZONE 2 ZONE 3 ZONE 4
SR 504-EXP
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
SLAVE
ZONE 4
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
FUSE 1 AMP
JUMPER
28
SYSTEM CIRCULATOR
(OPTIONAL LOCATION)
(SEE NOTE A ON PAGE 23)
120 VAC INPUT
H
N

THERMOSTAT THERMOSTAT THERMOSTAT
24 VAC
T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
ZVC 405
T STAT 1
VALVE 1
T STAT 2
ZVC403/405 with System Pump
VALVE 2
T STAT 3
VALVE 3
T STAT 4
T T T
VALVE 4
T STAT 5
VALVE 5
POWER
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
POWER IN
FIVE ZONE ZONE VALVE CONTROL
FUSE (5 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
N/O COM N/C
BOILER
END
SWITCH
JUMPER
3 & 4
TO BOILER AQUASTAT RELAY
MOTOR END
SWITCH
1
2
3
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
SYSTEM
PUMP
N
H
SYSTEM PUMP AND BOILER TURN ON
WHEN ANY ZONE VALVE OPENS.
29

ZVC404/406 with System Pump
THERMOSTAT THERMOSTAT THERMOSTAT
AQUASTAT ON
DHW HEATER
A
T T T
24 VAC
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
POWER IN
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 6
1 2 3 4
N
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
H
MAIN N/C
N/O COM
ZONE 6 RELAY
EXTRA
END
SWITCH
END
SWITCH
SEE NOTE
JUMPER
3 & 4
TO BOILER AQUASTAT RELAY
MOTOR END
SWITCH
DRY
CONTACTS
1
2
3
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
BOILER
JUMPER
3 & 4
PRIORITY
ZONE
SYSTEM
PUMP
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SYSTEM PUMP AND BOILER TURN ON
WHEN ANY ZONE VALVE OPENS.
30

ZVC404/406 with Domestic Hot Water (DHW) Pump
THERMOSTAT THERMOSTAT THERMOSTAT
AQUASTAT ON
DHW HEATER
A
T T T
24 VAC
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
POWER IN
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 6
1 2 3 4
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
MAIN N/C
N/O COM
ZONE 6 RELAY
N
EXTRA
END
SWITCH
END
SWITCH
SEE NOTE
JUMPER
3 & 4
JUMPER
3 & 4
PRIORITY
ZONE
TO BOILER AQUASTAT RELAY
MOTOR END
SWITCH
1
2
3
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
H
BOILER
DHW
PUMP
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
BOILER TURNS ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
31

ZVC404/406 with System and DHW Pumps
THERMOSTAT THERMOSTAT THERMOSTAT
AQUASTAT ON
DHW HEATER
A
T T T
24 VAC
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
POWER IN
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 6
1 2 3 4
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
MAIN N/C
N
JUMPER
3 & 4
H
N/O COM
ZONE 6 RELAY
EXTRA
END
SWITCH
END
SWITCH
SEE NOTE
JUMPER
3 & 4
PRIORITY
ZONE
TO BOILER AQUASTAT RELAY
MOTOR END
SWITCH
1
2
3
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
BOILER
SYSTEM
PUMP
DHW
PUMP
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SYSTEM PUMP AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
32

ZVC404/406 with System, DHW and Secondary Pumps
THERMOSTAT THERMOSTAT THERMOSTAT
AQUASTAT ON
DHW HEATER
A
T T T
24 VAC
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
POWER IN
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 6
1 2 3 4
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
N
MAIN N/C
H
N/O COM
ZONE 6 RELAY
EXTRA
END
SWITCH
END
SWITCH
SEE NOTE
JUMPER
3 & 4
TO BOILER AQUASTAT RELAY
JUMPER
3 & 4
PRIORITY
ZONE
MOTOR END
SWITCH
1
2
3
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
TACO
3 WIRE ZONE VALVE
2 WIRE ZONE VALVE
(NO END SWITCH)
BOILER
SYSTEM
PUMP
DHW
PUMP
SECONDARY
PUMP
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SYSTEM PUMP AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
SECONDARY PUMP COMES ON WHEN ANY ZONE CALLS EXCEPT PRIORITY ZONE.
33

2 ZVC404/406 Connected Together with Priority
THERMOSTAT THERMOSTAT THERMOSTAT
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
T T T
24 VAC
N
H
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24
VAC
POWER IN
MAIN
END
SWITCH
EXTRA
END
SWITCH
MODE
NORMAL RESET
N/O COM N/C
ZONE 4 RELAY
FUSE (3 AMP MAX)
ZONE 4 PRIORITY
OFF
ON
T T T T T T T T
ZONE 1
ZONE 2 ZONE 3 ZONE 4
ZONE 1 ZONE 2
1 2 3 4 1 2 3 4
ZVC 404
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
PRIORITY
ON
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
POWER
TO BOILER
AQUASTAT RELAY
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN,
SELF CLOSING)
THERMOSTAT THERMOSTAT THERMOSTAT
T T T
A
AQUASTAT ON
DHW HEATER
24 VAC
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24
VAC
POWER IN
MAIN
END
SWITCH
EXTRA
END
SWITCH
MODE
NORMAL RESET
N/O COM N/C
ZONE 4 RELAY
FUSE (3 AMP MAX)
ZONE 4 PRIORITY
OFF
ON
T T T T T T T T
ZONE 1
ZONE 2 ZONE 3 ZONE 4
ZONE 1 ZONE 2
1 2 3 4 1 2 3 4
ZVC 404
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
PRIORITY
ON
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
POWER
BOILER
TO BOILER AQUASTAT RELAY
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN,
SELF CLOSING)
34

2 EXP Zone Valve Controls Connected Together with System Pump
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
MASTER
T
24 VAC
T
T
A
AQUASTAT ON
DHW HEATER
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER AQUASTAT RELAY
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
SYSTEM
PUMP
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
SYSTEM PUMP AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
N
H
120 VAC
INPUT
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T T T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE
ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE
ZONE VALVE
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
35

2 EXP Zone Valve Controls Connected Together with DHW Pump
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
MASTER
T
24 VAC
T
T
A
AQUASTAT ON
DHW HEATER
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
DHW
PUMP
2 WIRE ZONE VALVE
(NO END SWITCH)
BOILER TURNS ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
N
H
120 VAC
INPUT
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T T T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE
ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE
ZONE VALVE
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
36

2 EXP Zone Valve Controls Connected Together with System and DHW Pumps
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
MASTER
T
24 VAC
T
T
A
AQUASTAT ON
DHW HEATER
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
DHW
PUMP
SYSTEM
PUMP
JUMPER
3 & 4
2 WIRE ZONE VALVE
(NO END SWITCH)
1
2
3
TACO
3 WIRE ZONE VALVE
MOTOR
END
SWITCH
PRIORITY
ZONE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
JUMPER
3 & 4
SEE NOTE
SYSTEM PUMP AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
N
H
120 VAC
INPUT
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T T T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE
ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE
ZONE VALVE
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
37

2 EXP Zone Valve Controls Connected Together with System, DHW and Secondary Pumps
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On
MASTER
T
24 VAC
T
T
A
AQUASTAT ON
DHW HEATER
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
DHW
PUMP
SYSTEM
PUMP
SECONDARY
PUMP
JUMPER
3 & 4
2 WIRE ZONE VALVE
(NO END SWITCH)
1
2
3
TACO
3 WIRE ZONE VALVE
MOTOR
END
SWITCH
PRIORITY
ZONE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
JUMPER
3 & 4
SEE NOTE
SYSTEM PUMP AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW PUMP TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
SECONDARY PUMP TURNS ON WHEN ANY ZONE CALLS, EXCEPT PRIORITY ZONE.
N
H
120 VAC
INPUT
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T T T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE
ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE
ZONE VALVE
4 WIRE
ZONE VALVE
(POWER OPEN, SELF CLOSING)
38

PC700 Boiler Reset Control Connected To EXP Zone Valve Control
THERMOSTAT THERMOSTAT THERMOSTAT
24 VAC
POWER
CONTROLS
RESET
MODE
SLAVE
NORMAL
MASTER
1 2 3 4
EXPANSION
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
JUMPER
3 & 4
2 WIRE ZONE VALVE
(NO END SWITCH)
1
2
3
TACO
3 WIRE ZONE VALVE
MOTOR END
SWITCH
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
JUMPER
3 & 4
PRIORITY
ZONE
INDIRECT
WATER HEATER
AQUASTAT
OR THERMOSTAT
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SEE NOTE
TACO, INC ZVC406-EXP
POWER IN
24 VAC
FACTORY
INSTALLED
TRANSFORMER
BOILER
OUTDOOR
SENSOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
PC700
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
BOIL
SEN
OUT
SEN
ZONE
CONTROL
BOILER SENSOR
T T T
WHITE
120 VAC
INPUT
BLACK
24 VAC
END
SWITCH
B
PUMP
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
TO BOILER
AQUASTAT RELAY
DRY
CONTACTS
SYSTEM
CIRCULATOR
H
N
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
39

PC702 2–Stage Boiler Reset Control Connected To EXP Zone Valve Control
THERMOSTAT THERMOSTAT THERMOSTAT
24 VAC
POWER
CONTROLS
RESET
MODE
SLAVE
NORMAL
MASTER
1 2 3 4
EXPANSION
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
JUMPER
3 & 4
1
2
3
MOTOR END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
INDIRECT
WATER HEATER
AQUASTAT
OR THERMOSTAT
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SEE NOTE
FACTORY
INSTALLED
TRANSFORMER
24 VAC
TACO, INC ZVC406-EXP
POWER IN
STAGE
1
OUTDOOR
SENSOR
DHW
DEMAND
PC702
STAGE
2
BOIL
SEN
OUT
SEN
ZONE
CONTROL
BOILER SENSOR
BOILER
#1
BOILER
#2
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
T T T
WHITE
120 VAC
INPUT
BLACK
24 VAC
END
SWITCH
B
PUMP
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
SYSTEM
CIRCULATOR
H
N
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
DHW
CIRCULATOR
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW CIRCULATOR TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
40

PC705 Variable Speed Pump Injection Control Connected To EXP Zone Valve Control
THERMOSTAT THERMOSTAT THERMOSTAT
24 VAC
POWER
CONTROLS
RESET
MODE
SLAVE
NORMAL
MASTER
1 2 3 4
EXPANSION
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
JUMPER
3 & 4
1
2
3
MOTOR END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
INDIRECT
WATER HEATER
AQUASTAT
OR THERMOSTAT
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SEE NOTE
TACO, INC ZVC406-EXP
POWER IN
24 VAC
FACTORY
INSTALLED
TRANSFORMER
BOILER
WHITE
120 VAC
INPUT
BLACK
24 VAC
END
SWITCH
B
PUMP
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
TO BOILER
AQUASTAT RELAY
DRY
CONTACTS
H
N
FACTORY
INSTALLED
TRANSFORMER
OUTDOOR
SENSOR
BOIL
SEN
GREEN/GROUND
PC705-2
SUP
SEN
OUT
SEN
ZONE
CONTROL
RED
BLUE
BLACK
SYSTEM
CIRCULATOR
(SEE NOTE B ON PAGE 23)
INJECTION
CIRCULATOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
T T T
SUPPLY SENSOR
BOILER SENSOR
WHITE
120 VAC
INPUT
BLACK
SYSTEM CIRCULATOR
(OPTIONAL LOCATION)
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
41

PC700 Boiler Reset Control Connected To 2 EXP Zone Valve Controls
OUTDOOR
SENSOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
PC700
INDIRECT WATER HEATER
AQUASTAT OR THERMOSTAT
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
MASTER
T
24 VAC
T
T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
SYSTEM
CIRCULATOR
DHW
CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW CIRCULATOR TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
H
N
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
T
24 VAC
T
T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
42

PC702 2–Stage Boiler Reset Control Connected To 2 EXP Zone Valve Controls
OUTDOOR
SENSOR
DHW
DEMAND
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
PC702
STAGE STAGE BOIL OUT ZONE
1 2 SEN SEN CONTROL
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
INDIRECT WATER HEATER
AQUASTAT OR THERMOSTAT
BOILER SENSOR
MASTER
T
24 VAC
T
T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
#1
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
SYSTEM
CIRCULATOR
DHW
CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW CIRCULATOR TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
H
N
BOILER
#2
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
SLAVE
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
T
24 VAC
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
T
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
43

PC705 Variable Speed Pump Injection Control Connected To 2 EXP Zone Valve Controls
OUTDOOR
SENSOR
GREEN/GROUND
RED
(SEE NOTE B ON PAGE 23)
SYSTEM
CIRCULATOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
PC705-2
BOIL SUP OUT ZONE
SEN SEN SEN CONTROL
BLUE
BLACK
INJECTION
CIRCULATOR
INDIRECT WATER HEATER
AQUASTAT OR THERMOSTAT
SUPPLY SENSOR
BOILER SENSOR
WHITE
120 VAC
INPUT
BLACK
WHITE
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
MASTER
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
T
24 VAC
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
T
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
DRY
CONTACTS
SYSTEM CIRCULATOR
(OPTIONAL LOCATION)
JUMPER
3 & 4
2 WIRE ZONE VALVE
(NO END SWITCH)
1
2
3
TACO
3 WIRE ZONE VALVE
MOTOR
END
SWITCH
PRIORITY
ZONE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
JUMPER
3 & 4
SEE NOTE
H
N
WHITE
120 VAC
INPUT
BLACK
WHITE
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
SLAVE
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
T
24 VAC
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
T
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
44

PC700 and PC705 Connected To 2 EXP Zone Valve Controls
OUTDOOR
SENSOR
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Reset
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
PC700
INDIRECT WATER HEATER
AQUASTAT OR THERMOSTAT
BOIL OUT
ZONE
SEN SEN CONTROL
BOILER SENSOR
MASTER
T
24 VAC
T
T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
TO BOILER
AQUASTAT RELAY
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
SYSTEM
CIRCULATOR
DHW
CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
H
OUTDOOR
SENSOR
GREEN/GROUND
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW CIRCULATOR TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
N
RED
(SEE NOTE B ON PAGE 23)
SYSTEM
CIRCULATOR
PC705-2
BLUE
INJECTION
CIRCULATOR
BOIL SUP OUT
SEN SEN SEN
ZONE
CONTROL
BLACK
SUPPLY SENSOR
BOILER SENSOR
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
SLAVE
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
T
24 VAC
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
T
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
T
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
45

PC702 and PC705 Connected To 2 EXP Zone Valve Controls
OUTDOOR
SENSOR
DHW
DEMAND
SWITCH SETTINGS
Master/Slave: Master
Reset/Normal: Normal
Priority Zone: On or Off
Note: When a circulator is used on the
priority zone instead of a zone valve,
jumper 3 and 4 of the priority zone.
PC702
STAGE STAGE BOIL OUT ZONE
1 2 SEN SEN CONTROL
WIRING NEEDED ONLY IF
PRIORITY ZONE IS DHW
INDIRECT WATER HEATER
AQUASTAT OR THERMOSTAT
BOILER SENSOR
MASTER
T
24 VAC
T
T
BOILER
#1
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
BOILER
#2
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
SYSTEM
CIRCULATOR
DHW
CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
H
OUTDOOR
SENSOR
GREEN/GROUND
SYSTEM CIRCULATOR AND BOILER TURN ON WHEN ANY ZONE VALVE OPENS.
DHW CIRCULATOR TURNS ON ONLY WHEN PRIORITY ZONE CALLS.
N
RED
(SEE NOTE B ON PAGE 23)
SYSTEM
CIRCULATOR
PC705-2
BLUE
BLACK
INJECTION
CIRCULATOR
BOIL SUP OUT
SEN SEN SEN
ZONE
CONTROL
SUPPLY SENSOR
BOILER SENSOR
SLAVE
T
24 VAC
T
T
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
MODE
RESET NORMAL
END
SWITCH
B
PUMP
SLAVE 1 2 3 4
EXPANSION
MASTER
N/O COM N/C
ZONE 6 RELAY
END
SWITCH
A
BOILER
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SWITCH SETTINGS
Master/Slave: Slave
Reset/Normal: Normal
Priority Zone: Off
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
46

HAFC101 with 1 Speed Air Handler
THERMOSTAT
Optional Power Wire
to Thermostat
that Requires 24VAC
T
To: Aquastat on
Return Line of
Hydro Coil
C R W Y
THERMOSTAT
G
T T
AQUASTAT
HAFC101
HYDRO AIR FAN CONTROL
Power On
Call for Heat
Fan, Cooling
Fan, Heating
BOILER
AIR HANDLER
X X C R Y
G G
LOW HIGH
Jumper
Dry Contacts To:
“T T” on Boiler
or Switching Relay
Line 24 VAC
Fan
Relay
M
Outdoor
Condenser
Unit
HAFC 101 WITH 1 SPEED AIR HANDLER
(Both HFC 101 and HAFC 201 are
capable of 1 and 2 speed applications.)
47

HAFC101 with 2 Speed Air Handler
THERMOSTAT
Optional Power Wire
to Thermostat
that Requires 24VAC
T
To: Aquastat on
Return Line of
Hydro Coil
C R W Y
THERMOSTAT
G
T T
AQUASTAT
HAFC101
HYDRO AIR FAN CONTROL
Power On
Call for Heat
Fan, Cooling
Fan, Heating
BOILER
AIR HANDLER
X X C R Y
G G
LOW HIGH
Dry Contacts To:
“T T” on Boiler
or Switching Relay
Line 24 VAC
Low
High
M
Fan Relays
Outdoor
Condenser
Unit
HAFC 101 WITH 2 SPEED AIR HANDLER
(Both HFC 101 and HAFC 201 are
capable of 1 and 2 speed applications.)
48

HAFC201 with 1 Speed Air Handler
Optional Power Wire
to Thermostat
that Requires 24VAC
THERMOSTAT
T
To: Optional
Aquastat on
Return Line of
Hydro Coil
To: Optional Aquastat
or Thermostat to sense
low ambient
temperature
C R W Y
THERMOSTAT
G
T
T
T
T
WATER COIL FREEZE PR
AQUASTATS
NOTE: For 4 minute
on delay of Heating Fan,
switch 1 and 3 MIN ON
DELAY to ON position.
OFF ON
1 MIN ON DELAY - FAN
3 MIN ON DELAY - FAN
2 MIN @ 24 HR - PUMP
30 SEC @ 2 WK - PUMP
HAFC201
HYDRO AIR FAN CONTROL
DRY CONTACTS
5 AMP 1/6 HP RATED
PUMP
X
X
BOILER
AIR HANDLER
XXCRY
G G
LOW HIGH
Power On
Call for Heat
Fan, Cooling
Fan, Heating
Jumper
Hot
Neutral
(or to “T T” on
switching relay)
Circulator
Dry Contacts To:
“T T” on Boiler
or Switching
Relay
Line 24 VAC
Fan
Relay
M
Outdoor
Condenser
Unit
HAFC 201 WITH 1 SPEED AIR HANDLER
(Both HFC 101 and HAFC 201 are
capable of 1 and 2 speed applications.)
49

HAFC201 with 2 Speed Air Handler
Optional Power Wire
to Thermostat
that Requires 24VAC
THERMOSTAT
T
To: Optional
Aquastat on
Return Line of
Hydro Coil
To: Optional Aquastat
or Thermostat to sense
low ambient
temperature
C R W Y
THERMOSTAT
G
T
T
T
T
WATER COIL FREEZE PR
AQUASTATS
NOTE: For 4 minute
on delay of Heating Fan,
switch 1 and 3 MIN ON
DELAY to ON position.
OFF ON
1 MIN ON DELAY - FAN
3 MIN ON DELAY - FAN
2 MIN @ 24 HR - PUMP
30 SEC @ 2 WK - PUMP
HAFC201
HYDRO AIR FAN CONTROL
DRY CONTACTS
5 AMP 1/6 HP RATED
PUMP
X
X
BOILER
AIR HANDLER
XXCRY
G G
LOW HIGH
Power On
Call for Heat
Fan, Cooling
Fan, Heating
Hot
Neutral
(or to “T T” on
switching relay)
Circulator
“T T” on Boiler
or Switching
Relay
Line 24 VAC
Low
High
M
Fan Relays
Outdoor
Condenser
Unit
HAFC 201 WITH 2 SPEED AIR HANDLER
(Both HFC 101 and HAFC 201 are
capable of 1 and 2 speed applications.)
50

Multiple HAFC’s and Switching Relay
THERMOSTAT
THERMOSTAT
THERMOSTAT
C R W Y G T T
THERMOSTAT AQUASTAT
C R W Y G T T
THERMOSTAT AQUASTAT
C R W Y G T T
THERMOSTAT AQUASTAT
HAFC101
HYDRO AIR FAN CONTROL
POWER PM
CALL FOR HEAT
FAN, COOLING
FAN, HEATING
HAFC101
HYDRO AIR FAN CONTROL
HAFC101
HYDRO AIR FAN CONTROL
BOILER AIR HANDLER
X X C R Y G G
LOW HIGH
BOILER AIR HANDLER
X X C R Y G G
LOW HIGH
BOILER AIR HANDLER
X X C R Y G G
M
OUTDOOR
CONDENSER
UNIT
Line 24 VAC
Low
High
Fan Relays
M
Line 24 VAC
Low
High
Fan Relays
M
Line 24 VAC
Low
High
Fan Relays
OPTIONAL POWER WIRE
TO THERMOSTAT
THAT REQUIRES 24VAC
T T T
TO: AQUASTAT ON
RETURN LINE OF
HYDRO COIL
OPTIONAL POWER WIRE
TO THERMOSTAT
THAT REQUIRES 24VAC
TO: AQUASTAT ON
RETURN LINE OF
HYDRO COIL
OPTIONAL POWER WIRE
TO THERMOSTAT
THAT REQUIRES 24VAC
TO: AQUASTAT ON
RETURN LINE OF
HYDRO COIL
POWER PM
CALL FOR HEAT
FAN, COOLING
FAN, HEATING
POWER PM
CALL FOR HEAT
FAN, COOLING
FAN, HEATING
LOW HIGH
OUTDOOR
CONDENSER
UNIT
OUTDOOR
CONDENSER
UNIT
2 SPEED AIR HANDLER
2 SPEED AIR HANDLER
2 SPEED AIR HANDLER
SR 504
ZONE 1 ZONE 2 ZONE 3 ZONE 4
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE 4
PRIORITY
ON
OFF
24 VAC
POWER
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
DHW
HEATER
AQUASTAT
FUSE 1 AMP
JUMPER
120 VAC INPUT
TO: "TT" ON BOILER
BOILER
H
N
51

3 Wire Thermostat Connected to TACO Switching Relay
3 WIRE
THERMOSTAT
SR 504
COM T
T T T
W R
ZONE 1 ZONE 2 ZONE 3 ZONE 4
ZONE 4
PRIORITY
ON
OFF
24 VAC
POWER
120V RELAY
FOUR ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
X X
END ZC ZR
SWITCH
ZONE1 ZONE2 ZONE3 ZONE4 POWER
120 VOLT CIRCULATORS INPUT
FUSE 1 AMP
JUMPER
120 VAC INPUT
H
N
TO: "TT" ON BOILER
BOILER
3 Wire Thermostat Connected to TACO Zone Valve Control
THERMOSTAT THERMOSTAT THERMOSTAT
T T T
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24 VAC
C
W R
WH
RED
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24 VAC
END
SWITCH
POWER IN
COMMON
T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
ZVC 405
FIVE ZONE ZONE VALVE CONTROL
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
POWER
T
T
TO T&T ON BOILER
OR PUMP RELAY
JUMPER
3 & 4
1
2
3
BLACK
BLACK
RED
RED
MOTOR
END
SWITCH
2 WIRE ZONE VALVE
(NO END SWITCH)
3 WIRE ZONE VALVE
(TACO TYPE)
4 WIRE ZONE VALVE
(HONEYWELL TYPE)
52

White-Rogers 1361 Hydronic Zone Valve with TACO Zone Valve Control
NOTE: WHEN USING ZVC 404 OR ZVC 406,
CONNECT WIRE #2 OF ZONE VALVE
TO PRIORITY ZONE RIGHT TT SCREW
THERMOSTAT THERMOSTAT THERMOSTAT
T T T
24 VAC
T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
ZVC 405
FIVE ZONE ZONE VALVE CONTROL
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
3
1
2
3
MOTOR END
SWITCH
WHITE-ROGERS 1361
HYDRONIC ZONE VALVE
3 WIRE ZONE VALVE
(TACO TYPE)
4 WIRE ZONE VALVE
(HONEYWELL TYPE)
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
POWER
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
RIGHT TT
SCREW
(SEE NOTE)
POWER IN
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
END
SWITCH
BLACK
BLACK
RED
RED
T
T
TO T&T ON BOILER
OR PUMP RELAY
2
1
4
TERMINAL ASSIGNMENT
ZONE VALVE CONTROL
1 1
2
TT (Rt)
3
3
4 2
53

Honeywell VC 40 & 80 (spdt) Hydronic Zone Valve with TACO Zone Valve Control
24 VAC
THERMOSTAT THERMOSTAT THERMOSTAT
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
NOTE: WHEN USING ZVC 404 OR ZVC 406,
CONNECT WIRE #3 OF ZONE VALVE
TO PRIORITY ZONE RIGHT TT SCREW
T T T
RIGHT TT
SCREW
(SEE NOTE)
TERMINAL ASSIGNMENT
ZONE VALVE CONTROL
ORANGE 1 3
BLUE 2 1
BROWN 3 TT (Rt)
GRAY 4 4
BLACK 6 2
END
SWITCH
T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
ZVC 405
FIVE ZONE ZONE VALVE CONTROL
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
T STAT 1
VALVE 1
T STAT 2
POWER IN
24 VAC
VALVE 2
T STAT 3
VALVE 3
T STAT 4
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
POWER
BLACK
BLACK
RED
RED
T
T
TO T&T ON BOILER
OR PUMP RELAY
3
2
6
4
1
1
2
3
MOTOR END
SWITCH
HONEYWELL VC (SPST)
HYDRONIC ZONE VALVE
SERIES 40 & 80
3 WIRE ZONE VALVE
(TACO TYPE)
4 WIRE ZONE VALVE
(HONEYWELL TYPE)
54

570 Zone Valve to Switching Relay
T
THERMOSTAT
24 VAC
TRANSFORMER
1
2
3
24 VAC
POWER
SR 503
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
ZONE 2
ZONE 3
N P ZC H
JUMPERS
X 2
X 1 ZR
ZONE1 ZONE2 ZONE3
120 VOLT
CIRCULATORS
TO: 120 VAC POWER (NEUTRAL)
TO: 120 VAC POWER (HOT)
TO: "TT" ON AQUASTAT CONTROL
TO: "TT" ON AQUASTAT CONTROL
55

Zone Valve Control with 1 Low Temperature Zone Using Priority Zoning Circulator
THERMOSTAT THERMOSTAT THERMOSTAT
AQUASTAT ON
DHW HEATER
A
T T T
24 VAC
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
N
120 VAC
INPUT
BLACK
H
ZONE 6 PRIORITY
OFF
ON
MODE
NORMAL RESET
T STAT 1
VALVE 1
T STAT 2
POWER IN
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
VALVE 2
T STAT 3
VALVE 3
T STAT 4
ZVC 406
FUSE (7 AMP MAX)
24 VAC
FACTORY
INSTALLED
TRANSFORMER
WHITE
120 VAC
INPUT
BLACK
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 6
1 2 3 4
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
MAIN N/C
N/O COM
ZONE 6 RELAY
EXTRA
END
SWITCH
END
SWITCH
JUMPER
3 & 4
SEE NOTE
JUMPER
3 & 4
PRIORITY
ZONE
TO BOILER AQUASTAT RELAY
END
SWITCH
MOTOR
MOTOR END
SWITCH
DRY
CONTACTS
Note: When a circulator is
used on the priority zone
instead of a zone valve,
jumper 3 and 4 of the
priority zone.
BOILER
1
2
3
4 WIRE
ZONE VALVE
(POWER OPEN,
SELF CLOSING)
TACO
3 WIRE
ZONE VALVE
4 WIRE
ZONE VALVE
(POWER OPEN,
SELF CLOSING)
SYSTEM
PUMP
PRIORITY
ON
PRIORITY ZONING CIRCULATOR
PRIORITY
ON
OFF
THERMOSTAT BOILER PRIORITY POWER IN
1 2 3 4 PR-IN PR-OUT LIVE NEUT
SYSTEM PUMP AND BOILER TURN ON
WHEN ANY ZONE VALVE OPENS.
120 VAC INPUT
56

Radiant Mixing Block (RMB)
Back of
Control
Front of
Control
R
Power: 120 V + 10%
C US 50/60 Hz, 750 VA
158033 Var. Speed: 120 V
(ac) 1 A
Pmp Relay: 120 V
(ac) 5 A, 1/6 hp
Use copper
conductors only
Com SupSys
ComBoil Out ComHeat
Ret
Dem
Boiler
MENU ITEM
RADIANT MIXING BLOCK
PATENT PENDING
U L RMB-1
Boiler
Meets Class B:
Canadian ICES
FCC Part 15
Sys
Y R B
Var
Boiler Operation
Off-Enable On-Control
Fuse
Pump
Man
H
N
Line Cord
Supply
Sensor
Boiler
Sensor
Outdoor
Sensor
To
Zone
Control
End
Switch
or
Thermostat
Injection
Circulator
Radiant
Circulator
Radiant Mixing Block, Single Zone
Boiler
RMB
Back of Control
Boiler Operation
Off-Enable On-Control
T
Thermostat
(Dry Contact)
Pump
ComSupSysComBoil Out ComHeat
Ret
Dem
H
N
H
N
Power
Input
Outdoor
Sensor
N
Boiler
Sensor
Supply
Sensor
High Mass Boiler
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard
57

Radiant Mixing Block Connected to Zone Valve Control with System Pump Wired off the RMB
Outdoor
Sensor
Power
Input
H
N
Factory
Installed
Transformer
T
T
Thermostats
Boiler
RMB
Back of Control
Boiler Operation
Off-Enable On-Control
POWER IN
FUSE
(5 AMP MAX)
T T
ZONE 1
T T
ZONE 2
ZVC 403
T T
ZONE 3
THREE ZONE ZONE VALVE CONTROL
Pump
END
SWITCH
N/O COM N/C
ZONE 1
1 2 3 4
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
Com Sup Sys Com Boil Out Com Heat
Ret
Dem
H
N
N
Motor
M
End Switch
Motor
M
End Switch
Boiler
Sensor
Supply
Sensor
Radiant Mixing Block Connected to 2 EXP Switching Relays with DHW Pump
SLAVE
MASTER
POWER CONTROL
INTERFACE
1 2 3 4
EXPANSION
RESET
Thermostats
T
PLUG-IN CARDS
NORMAL
ZONE1
T
ZONE2
A
ZONE3
DHW
Aquastat
ZONE 3
PRIORITY
ON
OFF
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY SR503-EXP
Outdoor
Sensor
Boiler
RMB
Back of Control
Boiler Operation
Off-Enable On-Control
Power Cord
SLAVE
MASTER
POWER CONTROL
INTERFACE
1 2 3 4
EXPANSION
PLUG-IN CARDS
RESET NORMAL
T
T
Thermostats
ZONE 3
PRIORITY
ON
ZONE1 ZONE2 ZONE3
OFF
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
SR503-EXP
24 VAC
POWER
FUSE 1 AMP
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3
120 VOLT CIRCULATORS
POWER
INPUT
Sys Com
ComSup Boil Out ComHeat
Ret
Dem
Pump
H
N
24 VAC
POWER
FUSE 1 AMP
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3
120 VOLT CIRCULATORS
POWER
INPUT
H
N
Power
Input
DHW
Circ.
N
Boiler
Sensor
Supply
Sensor
58
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard

X - Pump Block (XPB)
Back of
Control
Front of
Control
R
Power: 120 V + 10%
C US 50/60 Hz, 750 VA
158033 Var. Speed: 120 V
(ac) 1 A
Pmp Relay: 120 V
(ac) 5 A, 1/6 hp
Use copper
conductors only
MENU ITEM
Com Sup SysCom
Boil Out Com Heat
Ret
Dem
Heat Source
X – PUMP BLOCK
PATENT PENDING
U L XPB-1
System
Supply
Sensor
Heat
Source
Sensor
Outdoor
Sensor
Boiler
To
Zone
Control
End Switch
or
Thermostat
(Relay or
Mechanical
Type)
Meets Class B:
Canadian ICES
FCC Part 15
Sys
Y R B
Var
Boiler Operation
Off-Enable On-Control
Fuse
Pump
Man
H
N
Manual
Operation
Switch
Line Cord
Variable Speed Circulator
Heating: Heat Source Circulator
Snowmelt: System Circulator
Constant Speed Circulator
Heating: System Circulator
Snowmelt: Heat Source Circulator
X - Pump Block, Single Zone
Outdoor
Sensor
Boiler
XPB
Back of Control
Boiler Operation
Off-Enable On-Control
Power
Cord
Pump
Thermostat
(Relay or Mechanical Type)
ComSupSysComBoil Out Com Heat
Ret
Dem
H
N
T
Pressure
Relief
HEAT
SOURCE
Input from
Heat Source
Exp
Tank
Output to
System
Supply
Sensor
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard
59

X - Pump Block Connected to Zone Valve Control
Outdoor
Sensor
Power
Cord
Power
Input
H
N
Factory
Installed
Transformer
T
T
T
Boiler
Boiler Operation
XPB Off-Enable On-Control
Back of Control
NORMAL
POWER IN
T T
ZONE 1
T T
ZONE 2
T T
ZONE 3
ZONE 4 PRIORITY
OFF
T T
ON
ZONE 4
ComSupSysComBoil Out Com Heat
Ret
Dem
H
Pump
MAIN EXTRA
END END
SWITCH SWITCH
FUSE
(3 AMP MAX)
N/O COMN/C
ZONE 4 RELAY
MODE
RESET
ZVC 404
ZONE 1
1 2 3 4
FOUR ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
N
Pressure
Relief
HEAT
SOURCE
Input from
Heat Source
Exp
Tank
Output to
System
Supply
Sensor
Radiant Manifold - Return
Radiant Manifold - Supply
X - Pump Block Connected to 2 SR502/503 Switching Relays
T
Power
Input
24 VAC
POWER
H
N
SR 502 ZONE1 ZONE2
TWO ZONE SWITCHING RELAY
FUSE 1 AMP
X2
N P ZC H X1 ZR
T
ZONE1
ZONE2
Outdoor
Sensor
Boiler
ComSupSysComBoil Out Com Heat
Ret
Dem
H
N
Power
Cord
Boiler Operation
Off-Enable On-Control
XPB
Back of Control
Pump
Power
Input
24 VAC
POWER
H
N
SR 502 ZONE1 ZONE2
TWO ZONE SWITCHING RELAY
FUSE 1 AMP
T
X2
N P ZC H X1 ZR
T
ZONE1
ZONE2
Pressure
Relief
Return
Sensor
Input from
Heat Source
Exp
Tank
Output to
System
Supply
Sensor
60
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard

Typical Radiant Floor to Water Heater Installation
ASSE 1017
Tempering
Valve
Domestic
Hot
Supply
C
MIX
H
Hot
Cold
Cold
Supply
Check
Valve
X-PUMP
BLOCK
Air
Separator
Exp.
Tank
Supply
Relief
Valve
Return
RADIANT
SYSTEM
(Secondary Side
of the System)
WATER
HEATER
WARNING! A pressure relief valve and expansion tank must be installed on the secondary
side in addition to any pressure relief valve and expansion tank which is installed on primary
side of system. Use dedicated supply and return piping to the X-Pump Block from the water
heater so as not to add heated water into the house’s cold water piping.
Typical Snow Melt Installation
Separator
(Tb)
Exp.
Tank
Note 3
{
Note 1 Note 2
{
Note 3
{
{
X-PUMP
BLOCK
SYSTEM
RETURN
SENSOR
Note 2
{
}
Note 1
(Ts)
Air
Separator
Exp.
Tank
SYSTEM
SUPPLY
SENSOR
Relief
Valve
Return
(ΔTs)
HEAT
SOURCE
HEAT SOURCE
RETURN SENSOR
(OPTIONAL)
FIXED SPEED
CIRCULATOR
(4 PIN PLUG)
VARIABLE SPEED
CIRCULATOR
(3 PIN PLUG)
Supply
SNOW MELT
SYSTEM
Tb = Boiler Supply Temperature
Ts = System Supply Temperature
ΔTs = System Temperature Drop
(typically 20°F for convectors
and 10°F for radiant floor heating)
Note 1: There must be no more than 4 pipe diameters between the tees in the boiler and
system loops in order to prevent ghost flow when the variable speed injection
pump is off and either the boiler pump or system pump is on.
Note 2: There must be at least 6 pipe diameters of straight pipe on either side of the tees in
order to prevent the momentum of water in the boiler and system loops from pushing
flow through the injection loop.
Note 3: There should be a minimum 1 foot drop to create a thermal trap in order to prevent
convective heat transfer through the injection loop.
61

iSeries Mixing Valve
Boiler
Return
Sensor
(optional)
System
Supply
Sensor
Back of
Control
Boiler
Return
Sensor
System
Supply
Sensor
Back of
Control
BOILER
SUPPLY
SETBACK
POWER
GREEN
SENSOR
ERROR
RED
C
R
24 VAC
POWER INPUT
BOILER
SUPPLY
OUTDOOR
POWER
GREEN
SENSOR
ERROR
RED
C
R
24 VAC
POWER INPUT
SENSOR COMMON
SENSOR COMMON
Setback
Input
24 V (ac)
Transformer
or
End
Switch
Outdoor
Sensor
24 V (ac)
Transformer
or
End
Switch
iValve-S
iValve-R
iValve, 2-Way Injection, Single Zone
Outdoor
Sensor
T
Thermostat
BACK OF iVALVE-R MIXING VALVE ACTUATOR
BOILER
POWER
SUPPLY GREEN
OUTDOOR
SENSOR
ERROR
RED
SENSOR
COMMON
24 VAC
POWER INPUT
C R
SR501
1 Z ONE
SWITCHING RELAY
R
T
W
T
120 VAC
INPUT
N 4 N/O N/C
6 N/C
24
VAC
COM
H 3 4 6 5
N/O
24 Volt
Transformer
H
N
Power
Input
iSeries-R
Supply
Sensor
A
B
Boiler
Sensor
62
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard

iValve, 3-Way Mixing Working with SR502/503 Switching Relay with DHW Priority
T
Thermostats
Outdoor
Sensor
BACK OF iVALVE-R MIXING VALVE ACTUATOR
Power
Input
H N
24 VAC
POWER
DHW Aquastat
SR 503
FUSE 1 AMP
A
T
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
BOILER
POWER
SUPPLY GREEN
OUTDOOR
SENSOR
COMMON
24 VAC
POWER INPUT
C R
Transformer
24 Volt
X2
N P ZC H X1 ZR
ZONE1 ZONE2 ZONE3
SENSOR
ERROR
RED
DHW
Circ.
Supply
Sensor
B
C
A
C
A
iSeries-R
Boiler
Sensor
iValve, 4-Way Mixing Working with Zone Valve Control
Outdoor
Sensor
BACK OF iVALVE-R MIXING VALVE ACTUATOR
T
T
Thermostats
BOILER
SUPPLY
OUTDOOR
POWER
GREEN
SENSOR
ERROR
RED
SENSOR 24 VAC
COMMON POWER INPUT
C R
24 Volt
Transformer
Power
Input
H
N
Factory
Installed
Transformer
POWER IN
FUSE
(5 AMP MAX)
END N/O COM N/C
SWITCH
TT
ZONE 1
ZVC 403
THREE ZONE ZONE VALVE CONTROL
ZONE 1
1234
TT
ZONE 2
ZONE 2
1234
TT
ZONE 3
ZONE 3
1234
Motor
M
End Switch
Motor
M
End
Switch
Supply
Sensor
iSeries-R
Boiler
Sensor
FOR ADDITIONAL WIRING DIAGRAMS, PLEASE SEE www.taco-hvac.com/wiringwizard
63

Wiring for Boilers with Honeywell Control Center Model R8285 or Equivalent
TACO LTR0243T-1
FEMALE
CONNECTOR
FACTORY
WIRING
WH
RED
YEL
GRN
YEL
MALE
CONNECTOR
GROUND
CONNECTION
Alternate
Wiring
TACO LTR0243T-1
WH RED YEL GRN
YEL
24 VAC
CLASS 2
TRANSFORMER
HOT
LIMIT
CONTROLS
120
VAC
24 VAC
GAS
VALVE
COMMON
64

Wiring Boilers with a United Technologies Integrated Control Module and a Taco LTR0243U-1
INTEGRATED BOILER
CONTROL
MALE
CONNECTOR
FACTORY WIRING
FEMALE
CONNECTOR
BOILER MODULE
WIRING HARNESS
Wiring Boilers with a United Technologies Ucontrol or other Integrated Control Modules
which accept a 4-pin harness and a Taco LTR0243L-1
4-PIN CONNECTOR (#1)
4-PIN CONNECTOR (#2)
WIRING HARNESS
INTEGRATED
CONTROL
MODULE
Wiring Instructions
1. Plug the 4-pin connector on the wiring harness (#1 as
shown) into the integrated control module.
2. Plug the 4-pin connector on the wiring harness (#2 as
shown) into the LTR.
65

Wiring Taco LN and LTA-2 Series Low Water Cutoffs
Using Burner Circuit Power Source
*
*Factory Installed
NOTE: For 24 VAC models, LNA024xx and LTA0243S-2, 24 VAC to
be supplied by an EXTERNAL Class 2 power source to terminals
H and N. For 120 VAC models, LNA120xx and LTA1203S-2, 120 VAC
is supplied by an external circuit to terminals H and N.
Wiring Taco LN and LTA-2 Series Low Water Cutoffs
Using Power Source Other Than Burner Circuit
NOTE: For 24 VAC models, LNA024xx and LTA0243S-2, 24 VAC to
be supplied by an EXTERNAL Class 2 power source to terminals
H and N. For 120 VAC models, LNA120xx and LTA1203S-2, 120 VAC
is supplied by an external circuit to terminals H and N.
66

Wiring Taco LT Series (1st generation, -1) Low Water Cutoffs
Using Burner Circuit Power Source
*
*Factory Installed
NOTE: For 24 VAC models, LTx024xx-1, 24 VAC to be supplied
by an EXTERNAL Class 2 power source to terminals H and N.
For 120 VAC models, LTx120xx-1, 120 VAC is supplied by an
external circuit to terminals H and N.
Wiring Taco LT Series (1st generation, -1) Low Water Cutoffs
Using Power Source Other Than Burner Circuit
NOTE: For 24 VAC models, LTx024xx-1, 24 VAC to be supplied
by an EXTERNAL Class 2 power source to terminals H and N.
For 120 VAC models, LTx120xx-1, 120 VAC is supplied by an
external circuit to terminals H and N.
67

Wiring Taco LF Series Low Water Cutoffs Using Burner Circuit Power Source
NOTE: Remote probe available on remote probe models only.
NOTE: For 24 VAC models, LFx024xx, 24 VAC to be supplied by an EXTERNAL Class 2 power source to terminals H and N.
For 120 VAC models, LFx120xx, 120 VAC is supplied by an external circuit to terminals H and N.
Wiring Taco LF Series Low Water Cutoffs Using Power Source Other Than Burner Circuit
NOTE: For 24 VAC models, LFx024xx, 24 VAC to be supplied by an EXTERNAL Class 2 power source to terminals H and N.
For 120 VAC models, LFx120xx, 120 VAC is supplied by an external circuit to terminals H and N.
68

Taco Low Water Cutoff Replacement Guide
Taco McDonnell & Miller Hydrolevel Honeywell
LFA1203S-1
LTA1203N-1
LTA1203S-1
LFM1203S-1
LTM1203N-1
LTM1203S-1
LFA0243S-1
LTA0243N-1
LTA0243S-1
LFM0243S-1
LTM0243N-1
LTM0243S-1
LFA1203R-1
LTA1203R-1
LFM1203R-1
LTM1203R-1
LFA1202R-1
LTA1202R-1
LFM1202R-1
LTM1202R-1
LFA0242R-1
LTA0242R-1
LTA0243S-2
LNA0243S-1
LTA1203S-2
LNA1203S-1
LTR0243T-1
P3R-1
EWF120
EWF024
PS-801-120
PSE-801-120
PS-800-120
PS-850-120
900
900C
PS-801-M-120
PS-851-M-120
PS-851-SP-M-120
PS-850-M-120
900M
901M
902M
PS-802-24
PSE-802-24
PS-800-24
PS-850-24
PS-802-M-24
PS-852-M-24
PS-852-SP-M-24
PS-850-M-24
750-T-120
750-120
750-MT-120
750-M-120
PS-851-RX2-120
PS-851-M-RX2-120
PS-802-RX2-24
PS-852-24
PS-852-SP-24
750-MT-SP-24
750P-MT-24
750P-MT-U-24
RB-120
RB-122E
PS-851-120
PS-851-SP-120
750P-MT-120
750P-MT-SP-120
750P-MT-U-120
901
RB-120II
RB-122
RB-24E
RB-24
RS-1-BR-1
RS-1-LP
RS-1-LP-S
WFE-120
WF2-U-120V
WF-2-120
WF-4-120
WFE-24
WF2-U-24V
WF-2-24
WF-4-24
Bold / Italics Indicates Discontinued Part Number
450
CG450
CGT450
OEM170TD
550
550SV
750
OEM170MC
OEM170M
400
CG400
OEM24TD
500
500SV
700
OEM24MC
650R
550R
650R
550R
400R
24
24SV
600
600SV
OEM24C
170
170SV
1150
650
650SV
OEM170C
OEM170
1100
EL1214-R
VRTX-120
V-120-1&2
VRTX-24
V-24-1&2
RW700A1031
RW700A1056
RW700A1080
RW700B1054
RW700B1039
RW700B1021
RW700A1098
RW700A1007
RW700A1006
VW400A1004
VW800A1004
69

Taco LF Series 120 Volt LWCO Competitive Wiring Cross Reference
120 VAC Models with 120 VAC Burner Circuits
NC
TACO LFx120x
NO COM H N GND P
McDONNELL & MILLER
PS-801/851-120
w/Red & Amber LEDs
Series 750
1 2 3 4 5
BURNER
CIRCUIT
FACTORY
INSTALLED
JUMPER
120 VAC
CIRCUIT
HOT
NEUTRAL
HOT
NEUTRAL
120 VAC
CIRCUIT
BURNER
CIRCUIT
HYDROLEVEL
450, 550, 650 & 750
McDONNELL & MILLER
PS-801/851-120
w/Red & Green LEDs
2 1 P1 P2 A
N H C W B
HOT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
120 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
NEUTRAL
120 VAC Models with 24 VAC Burner Circuits
NC
TACO LFx120x
NO COM H N GND P
McDONNELL & MILLER
PS-801/851-120
w/Red & Amber LEDs
Series 750
1 2 3 4 5
BURNER
CIRCUIT
120 VAC
CIRCUIT
HOT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
24 VAC
TRANSFORMER
NEUTRAL
NEUTRAL
24 VAC
TRANSFORMER
HYDROLEVEL
450, 550, 650 & 750
McDONNELL & MILLER
PS-801/851-120
w/Red & Green LEDs
2 1 P1 P2 A
N H C W B
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
24 VAC
TRANSFORMER
NEUTRAL
24 VAC
TRANSFORMER
70

Taco LF Series 24 Volt LWCO Competitive Wiring Cross Reference
24 VAC Models with 24 VAC Burner Circuits
TACO LFx024x
NC
NO COM H N GND P
BURNER
CIRCUIT
FACTORY
INSTALLED
JUMPER
24 VAC
CIRCUIT
HOT
NEUTRAL
HYDROLEVEL
400, 500, 600 & 700
McDONNELL & MILLER
PS-802/852-24
2 1 P1 P2 A
N H C W B
HOT
HOT
24 VAC
CIRCUIT
BURNER
CIRCUIT
24 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
NEUTRAL
24 VAC Models with 120 VAC Burner Circuits
TACO LFx024x
NC
NO COM H N GND P
BURNER
CIRCUIT
24 VAC
TRANSFORMER
HOT
120 VAC
CIRCUIT
NEUTRAL
HYDROLEVEL
400, 500, 600 & 700
2 1 P1 P2 A
McDONNELL & MILLER
PS-802/852-24
N H C W B
HOT
HOT
120 VAC
CIRCUIT
NEUTRAL
24 VAC
TRANSFORMER
BURNER
CIRCUIT
120 VAC
CIRCUIT
NEUTRAL
24 VAC
TRANSFORMER
BURNER
CIRCUIT
71

Taco LTA-2 Series 120 Volt LWCO Competitive Wiring Cross Reference
120 VAC Models with 120 VAC Burner Circuits
TACO LTA1203S-2
N H COM NC NO
McDONNELL & MILLER
RB-120
1 2 3 4 5
HOT
HOT
NEUTRAL
120 VAC
CIRCUIT
FACTORY
INSTALLED
JUMPER
BURNER
CIRCUIT
NEUTRAL
120 VAC
CIRCUIT
BURNER
CIRCUIT
McDONNELL & MILLER
RB-122E
N H B C
HYDROLEVEL 1150
CUT-OFF
H N
HYDROLEVEL 170
GN H P1 P2 A
HOT
HOT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
120 VAC
CIRCUIT
BURNER
CIRCUIT
120 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
NEUTRAL
NEUTRAL
120 VAC Models with 24 VAC Burner Circuits
TACO LTA1203S-2
McDONNELL & MILLER
RB-120
N H COM NC NO
1 2 3 4 5
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
24 VAC
TRANSFORMER
NEUTRAL
24 VAC
TRANSFORMER
McDONNELL & MILLER
RB-122E
HYDROLEVEL 1150
HYDROLEVEL 170SV
N H B C H N
CUT-OFF
GN H P1 P2 A
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
120 VAC
CIRCUIT
BURNER
CIRCUIT
NEUTRAL
24 VAC
TRANSFORMER
NEUTRAL
24 VAC
TRANSFORMER
NEUTRAL
24 VAC
TRANSFORMER
72

Taco LTR and LTA-2 Series 24 Volt LWCO Competitive Wiring Cross Reference
24 VAC Models with 24 VAC Burner Circuits
TACO LTA0243S-2
N H COM NC NO
McDONNELL & MILLER
RB-24E
Red
Wire
White
Wire
Yellow
Wire
Yellow
Wire
HOT
HOT
NEUTRAL
24 VAC
CIRCUIT
FACTORY
INSTALLED
JUMPER
BURNER
CIRCUIT
NEUTRAL
24 VAC
CIRCUIT
BURNER
CIRCUIT
Red
Wire
TACO LTR0243T-1
White
Wire
Yellow
Wire
Yellow
Wire
HYDROLEVEL 1100
Red
Wire
White
Wire
Yellow
Wire
Yellow
Wire
HYDROLEVEL 24
2 1 P1 P2 A
HOT
24 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
24 VAC
CIRCUIT
BURNER
CIRCUIT
HOT
24 VAC
CIRCUIT
JUMPER
BURNER
CIRCUIT
NEUTRAL
NEUTRAL
NEUTRAL
24 VAC Models with 120 VAC Burner Circuits
TACO LTA0243S-2
HYDROLEVEL 24
N H COM NC NO
2 1 P1 P2 A
HOT
HOT
120 VAC
CIRCUIT
NEUTRAL
BURNER
CIRCUIT
120 VAC
CIRCUIT
NEUTRAL
BURNER
CIRCUIT
24 VAC
TRANSFORMER
24 VAC
TRANSFORMER
73

Wiring Taco LF Series Low Water Cutoffs
to Taco Electric Water Feeder with the Same Voltages
EWF Standard Wiring
Taco LFx120x / LFx024x
NC NO COM H N
GND
P
HOT
BURNER
CIRCUIT
FACTORY
INSTALLED
JUMPER
120 V AC / 24 V AC
CIRCUIT
NEUTRAL
LW
N
H
Taco E W F120 / E W F024
Wiring Taco LF Series Low Water Cutoffs
to Taco Electric Water Feeder with Different Burner Voltages
EWF Alternate Wiring
Taco LFx120x
Taco LFx024x
NC NO COM H N
GND
P
NC
NO COM H N GND P
BURNER
CIRCUIT
HOT
* *
BURNER
120 VAC
CIRCUIT
CIRCUIT
NEUTRAL
HOT
24 V AC
CIRCUIT
NEUTRAL
HOT
HOT
H
N
LW
24 V AC
CIRCUIT
H
N
LW
120 VAC
CIRCUIT
Taco EW F024
NEUTRAL
Taco EW F120
NEUTRAL
* NOTE: Remove factory installed
jumper between H and COM terminals
74

Wiring Taco 24VAC Electric Water Feeder to Taco LF Series 24VAC Low Water Cutoff
or 24VAC McDonnell & Miller or Hydrolevel Low Water Cutoffs
McDonnell & Miller
PS-802/852-24
B
W
C
H
N
Hydrolevel
400, 500, 600, & 700
P2
A
P1
1
2
Taco LFx024x
NC NO COM H N GND P
BURNER
CIRCUIT
INSTALLED
JUMPER **
HOT
24 V AC
CIRCUIT
** May be factory installed on
some LW COs
LW
N
Taco EWF024
H
NEUTRAL
NOTE: Wiring shown only for control
and burner circuits of the same
voltage. Some terminal designations
are not in their actual order on the
LW COs.
Wiring Taco 120VAC Electric Water Feeder to Taco LF Series 120VAC Low Water Cutoff
or 120VAC McDonnell & Miller or Hydrolevel Low Water Cutoffs
McDonnell & Miller
PS-801/851-120 w/Red &
Am ber LE Ds, Series 750
5
4
3
1 2
McDonnell & Miller
PS-801/851-120
w/Red & Green LEDs
B
W
C
H
N
Hydrolevel
450, 550, 650, & 750
P2
A
P1
1
2
Taco LFx120x
NC NO COM H N GND P
HOT
** May be factory installed on
some LW COs
BURNER
CIRCUIT
INSTALLED
JUMPER **
120 V AC
CIRCUIT
NEUTRAL
NOTE: Wiring shown only for control
and burner circuits of the same
voltage. Some terminal designations
are not in their actual order on the
LW COs.
LW
N
H
Taco EWF120
75

Wiring TACO LTA-2 or LF Series 24VAC Low Water Cutoff to
McDonnell & Miller Series WF2 Uni-Match Electric Water Feeder
UNI-MATCH
WATER FEEDER
MODEL WF2-U-24
1 2 3
0R
W N H
SWITCH POSITION #2
M&M
2
3
24VAC
SUPPLY
50/60 Hz
N
H
BURNER
Note on switch position:
Switch setting 1 (M&M), the feed cycle repeats
indefinitely. Position 2 and 3 gives one feed cycle.
N H COM NC NO
AC POWER OUTPUT CONTACTS
24 VAC LWCO Using Burner Circuit Power Source
Remove jumper between H and COM if using power source
other than burner circuit or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
If using the LTA-2 series, choose whichever position
best matches the application:
WF-2 switch to position 1
- 60 sec. delay, 90 sec. feed, repeats
WF-2 switch to position 2
- 90 sec. delay, 90 sec. feed
WF-2 switch to position 3
- 100 sec. delay, 90 sec. feed
Wiring TACO LTA-2 or LF Series 120VAC Low Water Cutoff to
McDonnell & Miller Series WF2 Uni-Match Electric Water Feeder
UNI-MATCH
WATER FEEDER
MODEL WF2-U-120
1 2 3
0R
W N H
SWITCH POSITION #2
M&M
2
3
120VAC N
SUPPLY
50/60 Hz H
BURNER
Note on switch position:
Switch setting 1 (M&M), the feed cycle repeats
indefinitely. Position 2 and 3 gives one feed cycle.
76
N H COM NC NO
AC POWER OUTPUT CONTACTS
120 VAC LWCO Using Burner Circuit Power Source
Remove jumper between H and COM if using power source
other than burner circuit or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
If using the LTA-2 series, choose whichever position
best matches the application:
WF-2 switch to position 1
- 60 sec. delay, 90 sec. feed, repeats
WF-2 switch to position 2
- 90 sec. delay, 90 sec. feed
WF-2 switch to position 3
- 100 sec. delay, 90 sec. feed

Wiring TACO LF Series 24VAC Low Water Cutoff to
Hydrolevel VXT-24 Water Feeder (Non-Display Model)
SAFGARD VXT-24
WATER FEEDER
Set Safgard as desired.
WHITE
BLACK
24VAC N
SUPPLY
50/60 Hz H
BURNER
Remove jumper between H and COM if using
power source other than burner circuit
or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
N H COM NC NO
AC POWER OUTPUT CONTACTS
24 VAC LWCO Using Burner Circuit Power Source
Wiring TACO LF Series 120VAC Low Water Cutoff to
Hydrolevel VXT-120 Water Feeder (Non-Display Model)
SAFGARD VXT-120
WATER FEEDER
Set Safgard as desired.
WHITE
BLACK
120VAC N
SUPPLY
50/60 Hz H
BURNER
Remove jumper between H and COM if using
power source other than burner circuit
or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
N H COM NC NO
AC POWER OUTPUT CONTACTS
120 VAC LWCO Using Burner Circuit Power Source
77

Wiring TACO LTA-2 or LF Series 24VAC Low Water Cutoff to
Hydrolevel VXT-24 Programmable Water Feeder (Model with Display)
SAFGARD VRTX-24
WATER FEEDER
Set Safgard as desired.
WHITE
BLACK
RED
24VAC N
SUPPLY
50/60 Hz H
BURNER
Remove jumper between H and COM if using
power source other than burner circuit
or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
N H COM NC NO
AC POWER OUTPUT CONTACTS
24 VAC LWCO Using Burner Circuit Power Source
Wiring TACO LTA-2 or LF Series 120VAC Low Water Cutoff to
Hydrolevel VXT-120 Programmable Water Feeder (Model with Display)
SAFGARD VRTX-120
WATER FEEDER
Set Safgard as desired.
WHITE
BLACK
RED
120VAC N
SUPPLY
50/60 Hz H
BURNER
Remove jumper between H and COM if using
power source other than burner circuit
or when using mixed voltages.
Do not connect feeder to a manual reset LWCO.
N H COM NC NO
AC POWER OUTPUT CONTACTS
120 VAC LWCO Using Burner Circuit Power Source
78

Taco LTR, LN, LT-1, LTA-2 & LF Series Low Water Cutoff and Taco Electric Water Feeder Wiring Cross Reference
Power Connections Output Contacts Remote Probes
Probe
Preference
To EWF’s LW
Terminal/Alarm
To Burner
Circuit
Manufacturer Device or Series
Probe
Hot Neutral Common
Taco LF & LT-1 Series H N COM NC NO P GND
Taco LTA-2 & LN Series H N COM NC NO — —
Taco LTR Series Red Wire White Wire Yellow Wire Yellow Wire — — —
PS-801/851 (Older Models
w/Red & Amber LEDs)
1 2 3 5 4 P or J2 Chassis GND
PS-801/851 (New Models
w/Red & Green LEDs)
H N C B W J2 Chassis GND
PS-802/852 (Older Models
w/Red & Amber LEDs)
H N C B W J7 Chassis GND
PS-802/852 (Older Models
w/Red & Green LEDs)
H N C B W J3 Chassis GND
McDonnell & Miller
McDonnell & Miller
McDonnell & Miller
McDonnell & Miller
McDonnell & Miller Series 750 1 2 3 5 4 P Chassis GND
— — —
B
(Yellow Wire)
C
(Yellow Wire)
N
(White Wire)
H
(Black Wire)
McDonnell & Miller RB-122
McDonnell & Miller RB-120 1 2 3 4 5 — —
McDonnell & Miller RB-24 Red Wire White Wire Yellow Wire Yellow Wire — — —
Hydrolevel 24 1 2 P1 P2 A — —
Hydrolevel 170 H GN P1 P2 A — —
Hydrolevel 1100 Red Wire White Wire Yellow Wire Yellow Wire — — —
— — —
CUT-OFF
(Yellow Wire)
CUT-OFF
(Yellow Wire)
N
(White Wire)
H
(Black Wire)
Hydrolevel 1150
1 2 P1 P2 A H3 Chassis GND
400, 500, 600, 700, 450,
550, 650, 750
RW700 Series
(Except RW700A1098)
Hydrolevel
Green Wire
2 Red Wires,
White Wire
L1 L2 — B A
Hydrolevel
Green Wire
2 Red Wires,
White Wire
Hydrolevel RW700A1098 T1 T2 — B A
79

Aquastat Wiring
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1 L2 T T
END SWITCH
TACO
ZONE
CONTROL
C1
ZC
B2 C2 ZR B1
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8124A & C OR EQUAL
MILLI-VOLTAGE
GAS VALVE
B1 B2 T T
END SWITCH
TACO
ZONE
CONTROL
C
L1
L2
C2
CIRCULATOR
ON BOILER
(IF ATTACHED)
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
HONEYWELL L8124B OR EQUAL
TV T Z
CIRCULATOR
ON BOILER
(IF ATTACHED)
END SWITCH
TACO
ZONE
CONTROL
C1
C2
B1
B2
L1
L2
LOW VOLTAGE
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
HONEYWELL L8124E OR EQUAL
80

Aquastat Wiring
TV T Z
END SWITCH
TACO
ZONE
CONTROL
L1
ZC
L2
ZR
B2
C2
B1
C1
LINE
VOLTAGE
OIL BURNER
RELAY OR
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
CIRCULATOR
ON BOILER
(IF ATTACHED)
HONEYWELL L8124G & L OR EQUAL
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1 L2 T T
END SWITCH
TACO
ZONE
CONTROL
C1
ZC
B2
C2
ZR
B1
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8124M OR EQUAL
L1
(HOT)
L1 L2 T T
3
120 VAC
INPUT
L2
(NEUTRAL)
END SWITCH
TACO
ZONE
CONTROL
C1
C2
B1
B2
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8148A OR EQUAL
81

Aquastat Wiring
TV W T
Z
CIRCULATOR
ON BOILER
(IF ATTACHED)
END SWITCH
TACO
ZONE
CONTROL
C1
C2
B1
B2
L1
L2
LOW VOLTAGE
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
HONEYWELL L8148E OR EQUAL
TV W T
TP
Z
CIRCULATOR
ON BOILER
(IF ATTACHED)
END SWITCH
TACO
ZONE
CONTROL
MILLI-
VOLTAGE
GAS
VALVE
B1
B2
B3
C1
L1
C2
L2
OR
LOW VOLTAGE
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
HONEYWELL L8148J OR EQUAL
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1
L2
B1
B2
C2
C1
OIL BURNER
AND
IGNITION
END SWITCH
TACO
ZONE
CONTROL
ZC
ZR
CIRCULATOR
ON BOILER
(IF ATTACHED)
T
T
F
F
CAD CELL
HONEYWELL L8182D OR EQUAL
82

Aquastat Wiring
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1 L2 T T
T
THERMOSTAT
(IF INDEPENDENT ZONE)
END SWITCH
X X
TACO
SWITCHING
RELAY
ZC ZR N H
C1
ZC
B2 C2 ZR B1
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8124A & C OR EQUAL
T
THERMOSTAT
(IF INDEPENDENT ZONE)
TV T Z
END SWITCH
X X
TACO
SWITCHING
RELAY
ZC ZR N H
ZC
ZR
B1
L1
(HOT)
L1
120 VAC
INPUT
L2
(NEUTRAL)
L2
B2
C2
C1
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE
VOLTAGE
OIL BURNER
RELAY OR
GAS VALVE
HONEYWELL L8124G & L OR EQUAL
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1 L2 T T
T
THERMOSTAT
(IF INDEPENDENT ZONE)
END SWITCH
X X
TACO
SWITCHING
RELAY
ZC ZR N H
C1
ZC
B2 C2 ZR B1
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8124M OR EQUAL
83

Aquastat Wiring
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
R
W
B
L1 L2 T T
3
B2
B
T
THERMOSTAT
(IF INDEPENDENT ZONE)
END SWITCH
X X
TACO
SWITCHING
RELAY
ZC ZR N H
L6006
LOW
LIMIT
CONTROLER
C1
C2
R
B1
B2
CIRCULATOR
ON BOILER
(IF ATTACHED)
LINE VOLTAGE
OIL BURNER RELAY
OR GAS VALVE
HONEYWELL L8148A OR EQUAL
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
L1
L2
B1
B2
C2
C1
ZC
OIL BURNER
AND
IGNITION
CIRCULATOR
ON BOILER
(IF ATTACHED)
END SWITCH
X X
TACO
SWITCHING
RELAY
ZC ZR N H
ZR
T
T
F
F
T
THERMOSTAT
(IF INDEPENDENT
ZONE)
CAD CELL
HONEYWELL L8182D OR EQUAL
84

Wiring for Boilers with Honeywell Aquastat Model L8124E or Equivalent
FACTORY WIRING
(unplug from B1 terminal)
TACO LTR0243T-1
WH RED YEL GRN YEL
TV T Z
HONEYWELL
L8124E
C1
C2
CIRCULATOR
ON BOILER
(IF ATTACHED)
MALE
CONNECTOR
B1
G
B2
L1
L2
FEMALE
CONNECTOR
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
NOTE: The green wire must be connected to a ground source
electrically common to the boiler ground.
Wiring for Boilers with Honeywell Aquastat Model L8148E or Equivalent
FACTORY WIRING
(unplug from B1 terminal)
TACO LTR0243T-1
WH RED YEL GRN
YEL
TV W T
Z
HONEYWELL
L8148E
CIRCULATOR
ON BOILER
(IF ATTACHED)
MALE
CONNECTOR
B1
B2
C1
C2
G
L1
L2
FEMALE
CONNECTOR
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
NOTE: The green wire must be connected to a ground source
electrically common to the boiler ground.
85

Aquastat Wiring to 24VAC Low Water Cutoff
TO
THERMOSTAT
TACO LNA024 or LTA024-2
N H COM NC NO
TV W T
HONEYWELL
L8148E
Z
B
R
C1
C2
CIRCULATOR
ON BOILER
(IF ATTACHED)
B1
B2
L1
L2
G
SPILL
SWITCH
LOW VOLTAGE
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)
Aquastat Wiring to 120VAC Low Water Cutoff
TO
THERMOSTAT
TACO LNA120 OR LTA120-2
N H COM NC NO
TV W T
Z
B
HONEYWELL
L8148E
CIRCULATOR
ON BOILER
(IF ATTACHED)
R
C1
C2
B1
B2
L1
L2
G
SPILL
SWITCH
86
LOW VOLTAGE
GAS VALVE
L1
(HOT)
120 VAC
INPUT
L2
(NEUTRAL)

Instruction Sheet
SR501 Switching Relay
Features:
External Indicator Lights
Universal Replaceability
Snap-in PC Board
Simplified Wiring
Fully Enclosed Snap-Out Relays
100% Factory Tested
Contractor Friendly PC Board Layout
Universal Thermostat Compatibility
UL Approved
Extended 3 Year Warranty
Made in the USA
Typical
Wiring
SR501
1 ZONE SWITCHING RELAY
THERMOSTAT
24
R W VAC
T T COM
POWER
T STAT
Alternative
Wiring
SR501
1 ZONE SWITCHING RELAY
THERMOSTAT
24
R W VAC
T T COM
POWER
T STAT
Operation:
Connect a thermostat to the “T T” terminals on
the switching relay. When the thermostat calls for
heat, the relay is energized and power is given to the
circulator.
120 VAC
INPUT
N H 3 4 4 6 6 N/O N/C N/C N/O 5
JUMPER
120 VAC
INPUT
N H 3 4 4 6 6 N/O N/C N/C N/O 5
Power Input:
Connect 120 volt ac power to terminals N and H.
TO: 120 VAC POWER
TO: TT ON BOILER
CIRCULATOR
TO: ZC
TO: ZR
TO: 120 VAC POWER
CIRCULATOR
Jumper Placement:
The jumper is factory installed between terminals H
and 3 to switch power on terminals 4 n/o and 4 n/c.
External Diagnostics:
The External lights show full functionality of the
switching relay. The green light should always be on,
indicating that power is connected. When the thermostat
calls for heat, both the appropriate circulator
and red indicating light is energized.
The Taco Connection:
Combine the reliability of the Taco Zone Valves,
Priority Zoning Circulators, Thermostats, and the “00”
family of circulators with the advanced features of the
Taco Zone Controls to achieve total system integration.
No matter the application, Taco now provides
the products to maximize system performance while
simplifying both installation and service.
Note: When using Alternative Wiring diagram, the boiler operating control’s
ZC terminal will see the load of the circulator(s).
Warning: When using Alternative Wiring diagram, wiring instructions
must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power
being connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Terminal Description:
T & T Thermostat Connection
COM Common side of transformer, to power some setback thermostats
N Neutral wire of power input
H Hot wire of power input
3 Common terminal for 4 n/o and 4 n/c
4 n/o Normally open terminal
4 n/c Normally closed terminal
6 n/c Normally closed terminal
6 n/o Normally open terminal
5 Common terminal for 6 n/o and 6 n/c
Specifications:
PRODUCT NUMBER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR501 1 Zone 120 VAC Input 7.2 amps 4 1/4" 5 1/4" 2 3/4"
All Switching Relays are relay type DPDT, have a thermostat current of .18, and have a single
phase motor rating per zone of 1/3 hp (7.2A) @ 120 VAC.
Warning: Wiring connections must be made in accordance with all applicable electrical
codes and these instructions. Use copper wire only. Failure to follow this
instruction can result in personal injury or death and/or property damage. 10-18
gauge wire recommended for 120 VAC connections with 9 in.lbs. max torque, 12-22
gauge wire for thermostat connections with 9 in.lbs. max torque, and 12-22 gauge
wire for 24 VAC source with 5 in.lbs. max torque.
TACO SR501 REPLACEMNENT CROSS-REFERENCE
MANUFACTURER MODEL CONNECTIONS
Taco SR501 H N 3 4 NO 4 NC 5 6 NO 6 NC R/T W/T C
Argo AR821 1 2 3 4 5 6 T
AR822 L1 L2 3 4 NO 4 NC 5 6 NO 6 NC R/T G/T C
Colombus MR10 L1 L2 3 4 NO 4 NC 5 6 NO 6 NC R/T G/T C
Erie SR100 L1 L2 3 4 NO 4 NC 5 6 NO 6 NC R/T G/T C
Honeywell RA89A 1 2 3 4 T T
RA832A 1 2 3 4 X X T T
R845A 1 2 3 4 5 6 T T
White-Rogers 889-189 1 2 3 4 T T
829-845 1 2 3 4 5 6 T T
Do it Once. Do it Right. ®
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2005
TACO, Inc.
87

Instruction Sheet
SR501-845RP Universal Replacement Relay
Features:
Universal Replaceability
Indicator Lights
Snap-in PC Board to Existing Enclosure
Simplified Wiring
Fully Enclosed Snap-Out Relay
100% Factory Tested
Universal Thermostat Compatibility
UL Approved
Extended 3 Year Warranty
Made in the USA
Operation:
Connect a thermostat to the “T T” terminals on
the switching relay. When the thermostat calls for
heat, the relay is energized and power is given to
the circulator.
Power Input:
Connect 120 volt ac power to terminals L1 and L2.
Typical
Wiring
REPLACES HONEYWELL
R845, RA89A & RA832
OR COMPARABLE RELAY
TO: 120 VAC POWER
JUMPER
R W
T T
UNIVERSAL REPLACEMENT RELAY
MODEL: SR501-845RP
120 VAC
INPUT
L2 L1 3 4 5 6
CIRCULATOR
THERMOSTAT
POWER
T STAT
TO: TT ON BOILER
Alternative
Wiring
REPLACES HONEYWELL
R845, RA89A & RA832
OR COMPARABLE RELAY
TO: ZC
TO: ZR
TO: 120 VAC POWER
120 VAC
INPUT
R W
T T
UNIVERSAL REPLACEMENT RELAY
MODEL: SR501-845RP
L2 L1 3 4 5 6
THERMOSTAT
POWER
T STAT
CIRCULATOR
Jumper Placement:
The jumper is factory installed between terminals
L1 and 3 to switch power on terminal 4.
Diagnostics:
The Indicator lights show full functionality of the
switching relay. The green light should always be
on, indicating that power is connected. When the
thermostat calls for heat, both the appropriate circulator
and red indicating light is energized.
The Taco Connection:
Combine the reliability of the Taco Zone Valves,
Priority Zoning Circulators, Thermostats, and the
“00” family of circulators with the advanced features
of the Taco Zone Controls to achieve total system
integration. No matter the application, Taco now provides
the products to maximize system performance
while simplifying both installation and service.
Terminal Description:
T & T Thermostat Connection
L2 Neutral wire of power input
L1 Hot wire of power input
3 Common terminal for 4
4 Normally open terminal
6 Normally open terminal
5 Common terminal for 6
Note: When using Alternative Wiring diagram, the boiler operating control’s
ZC terminal will see the load of the circulator(s).
Warning: When using Alternative Wiring diagram, wiring instructions must
be followed so power originates from the boiler aquastat. Failure to follow
these wiring instructions may result in a secondary source of power being
connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Specifications:
PRODUCT NUMBER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR501-845RP 1 Zone 120 VAC Input 7.2 amps 4 1/4" 5 1/4" 2 3/4"
All Switching Relays are relay type DPDT, have a thermostat current of .18, and have a single phase
motor rating per zone of 1/3 hp (7.2A) @ 120 VAC.
TACO SR501-845RP REPLACEMENT CROSS-REFERENCE
MANUFACTURER MODEL CONNECTIONS
Taco SR501-845RP L1 L2 3 4 5 6 R/T W/T
Argo AR821 1 2 3 4 5 6 T
AR822 L1 L2 3 4 NO 5 6 NO R/T G/T
Colombus MR10 L1 L2 3 4 NO 5 6 NO R/T G/T
Erie SR100 L1 L2 3 4 NO 5 6 NO R/T G/T
Honeywell RA89A 1 2 3 4 T T
RA832A 1 2 3 4 X X T T
R845A 1 2 3 4 5 6 T T
White-Rogers 889-189 1 2 3 4 T T
829-845 1 2 3 4 5 6 T T
Warning: Wiring connections must be made in accordance with all applicable electrical
codes and these instructions. Use copper wire only. Failure to follow this
instruction can result in personal injury or death and/or property damage. 10-18
gauge wire recommended for 120 VAC connections with 9 in.lbs. max torque, 12-22
gauge wire for thermostat connections with 9 in.lbs. max torque, and 12-22 gauge
wire for 24 VAC source with 5 in.lbs. max torque.
88
Do it Once. Do it Right. ®
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2005
TACO, Inc.

Instruction Sheet
SR502 & SR503 Switching Relay
Cold Start Boiler
Application
THERMOSTATS
Tankless Coil Boiler
Application
THERMOSTATS
24 VAC
POWER
24 VAC
POWER
SR 503
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
SR 503
FUSE 1 AMP
N P ZC H
JUMPERS
POWER
ZONE 1
ZONE 2
ZONE 3
X 2
X 1 ZR ZONE1 ZONE2 ZONE3
X
ZONE1 ZONE2 ZONE3
THREE ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
FUSE 1 AMP
POWER
ZONE 1
ZONE 2
ZONE 3
2
N P ZC H X 1 ZR ZONE1 ZONE2 ZONE3
JUMPERS
TO: 120 VAC POWER (NEUTRAL)
TO: 120 VAC POWER (NEUTRAL)
TO: 120 VAC POWER (HOT)
TO: "TT" ON AQUASTAT CONTROL
120 VOLT
CIRCULATORS
TO: 120 VAC POWER (HOT)
TO: "ZC" ON AQUASTAT CONTROL
120 VOLT
CIRCULATORS
TO: "TT" ON AQUASTAT CONTROL
TO: "ZR" ON AQUASTAT CONTROL
Note: When using Alternative Wiring diagram, the boiler operating control’s ZC terminal will see the load of the circulator(s).
Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Operation: When the thermostat calls for heat, the appropriate circulator
is energized and the isolated end switch (X 1 and X 2 ) will start the
boiler.
Jumper Placement: The jumper should be placed between terminals
ZC and H. Connect the isolated end switch, X 1 and X 2 to the boiler
aquastat control. For zone 1 priority, remove jumper between
terminals P and ZC.
Power Input: Connect 120 volt ac power input to terminals N and H.
Neutral wire to terminal N. Hot wire to terminal H.
Operation: When any thermostat calls for heat, the boiler and appropriate
circulator are energized when the boiler temperature is above the
set low limit.
Jumper Placement: A jumper should be placed between terminals ZC
and X 1 . Connect terminal ZC to ZC terminal on the aquastat control.
Connect terminal ZR to ZR terminal on the aquastat control. Confirm
polarity is consistent between boiler aquastat and switching relay. For
zone 1 priority, remove jumper between terminals
P and ZC.
Power Input: Connect 120 volt ac power input to terminals N and H.
Neutral wire to terminal N. Hot wire to terminal H.
The Taco Connection:
Combine the reliability of the Taco Zone Valves, Priority Zoning
Circulators, Thermostats, and the “00” family of circulators with the
advanced features of the Taco Zone Controls to achieve total system
integration. No matter the application, Taco now provides the products
to maximize system performance while simplifying both installation
and service.
External Diagnostics:
Externally visible lights show full functionality of the switching relay.
The green light should always be on, indicating that power is connected.
When the thermostat calls for heat, both the appropriate circulator
and red indicating light is energized.
Specifications:
PRODUCT NUMBER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR502 2 with Priority 120 VAC Input 15 amps 10 1/4" 6 3/4" 2 3/4"
SR503 3 with Priority 120 VAC Input 15 amps 10 1/4" 6 3/4" 2 3/4"
All Switching Relays are relay type DPST, have a thermostat current of .18, and have a single phase
motor rating per zone of 1/3 hp (7.2A) @ 120 VAC.
Do it Once. Do it Right. ®
Features:
External Indicator Lights
Priority
Simplified Wiring
Fully Enclosed Snap-Out Relays
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Contractor Friendly PC Board Layout
Universal Thermostat Compatibility
UL Approved
24 volt Power Input or Output Terminal
Extended 3 Year Warranty
Made in the USA
Warning: Wiring connections must be made in accordance with all applicable electrical codes and these
instructions. Use copper wire only. Failure to follow this instruction can result in personal injury or
death and/or property damage. 10-18 gauge wire recommended for 120 VAC connections with 9 in.lbs.
max torque, 12-22 gauge wire for thermostat connections with 9 in.lbs. max torque, and 12-22 gauge
wire for 24 VAC source with 5 in.lbs. max torque.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2005
TACO, Inc.
89

Instruction Sheet
SR504 & SR506 Switching Relay
Cold Start Boiler
Application
THERMOSTATS
Tankless Coil Boiler
Application
THERMOSTATS
24 VAC
POWER
SR 506
120V RELAY
X X
END
SWITCH
ZC ZR
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6 POWER
120 VOLT CIRCULATORS INPUT
ZONE 6
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
24 VAC
POWER
SR 506
120V RELAY
X X
END
SWITCH
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
POWER
INPUT
ZONE 6
PRIORITY
ON
OFF
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
FUSE 1 AMP
TO: "ZR" ON AQUASTAT
TO: "TT" ON BOILER
JUMPER
120 VAC INPUT
TO: "ZC" ON AQUASTAT
JUMPER
120 VAC INPUT
Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Operation: When any thermostat calls for heat, the appropriate circulator
is energized and the isolated end switch (X and X) will start the
boiler.
Priority Operation: When zone 6 is switched to the priority setting
and is actuated, all other zones will stop operation until zone 6 is satisfied.
When zone 6 is not switched to priority, all zones will operate
independently.
Jumper Placement: The jumper should be placed between terminals
ZC and ZR. Connect the isolated end switch to the aquastat control on
the boiler.
Power Input: Connect 120 volt ac power input to terminals N and H.
Neutral wire to terminal N. Hot wire to terminal H.
Operation: When any thermostat calls for heat, the boiler and appropriate
circulator are energized when the boiler temperature is above the
set low limit.
Priority Operation: When zone 6 is switched to the priority setting
and is actuated, all other zones will stop operation until zone 6 is satisfied.
When zone 6 is not switched to priority, all zones will operate
independently.
Jumper Placement: MOVE the jumper between terminals ZC and ZR
to end switch X and ZC. Connect terminal ZC to ZC terminal on the
aquastat control. Connect the other end switch X to ZR terminal on the
aquastat control. Confirm polarity is consistent between boiler aquastat
and switching relay.
Power Input: Connect 120 volt ac power input to terminals N and H.
Neutral wire to terminal N. Hot wire to terminal H.
The Taco Connection:
Combine the reliability of the Taco Zone Valves, Priority Zoning
Circulators, Thermostats, and the “00” family of circulators with the
advanced features of the Taco Zone Controls to achieve total system
integration. No matter the application, Taco now provides the products
to maximize system performance while simplifying both installation
and service.
External Diagnostics:
Externally visible lights show full functionality of the switching relay.
The green light should always be on, indicating that power is connected.
When the thermostat calls for heat, both the appropriate circulator and
red indicating light is energized.
Specifications:
PRODUCT NUMBER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR504 4 with Priority 120 VAC Input 20 amps 10 1/4" 6 3/4" 2 3/4"
SR506 6 with Priority 120 VAC Input 20 amps 11 3/4" 7 1/2" 3"
All Switching Relays are relay type DPST, have a thermostat current of .18, and have a single phase
motor rating per zone of 1/3 hp (7.2A) @ 120 VAC.
Do it Once. Do it Right. ®
Visit our web site at: http://www.taco-hvac.com
90
Features:
External Indicator Lights
Switchable Priority
Simplified Wiring
Fully Enclosed Snap-Out Relays
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Contractor Friendly PC Board Layout
Universal Thermostat Compatibility
UL Approved
24 volt Power Input or Output Terminal
Extended 3 Year Warranty
Made in the USA
Warning: Wiring connections must be made in accordance with all applicable electrical codes
and these instructions. Use copper wire only. Failure to follow this instruction can result in personal
injury or death and/or property damage. 10-18 gauge wire recommended for 120 VAC connections
with 9 in.lbs. max torque, 12-22 gauge wire for thermostat connections with 9 in.lbs.
max torque, and 12-22 gauge wire for 24 VAC source with 5 in.lbs. max torque.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Printed in USA
Copyright 2005
TACO, Inc.

Instruction Sheet
SR501-EXP Switching Relay
Cold Start Boiler
Application
TO: "TT" on Boiler Aquastat
THERMOSTAT
T
TO: DHW Aquastat if PC700
Boiler Reset is installed.
Tankless Coil Boiler
Application
THERMOSTAT
T
TO: DHW Aquastat if PC700
Boiler Reset is installed.
POWER
CONTROLS
POWER
CONTROLS
MODE
MODE
END
RESET
END
RESET
EXPANSION THERMOSTAT
EXPANSION THERMOSTAT
SWITCH
OVERRIDE RESET
SWITCH
OVERRIDE RESET
X X 1 2 3 4 T/R T/W COM 1 2
X X 1 2 3 4 T/R T/W COM 1 2
FUSE
K1-A
FUSE
K1-A
MASTER
1 AMP NORMAL
1 AMP MASTER
NORMAL
SLAVE
FUSE
5 AMP
K1
K2
POWER
T STAT
SLAVE
FUSE
5 AMP
K1
K2
POWER
T STAT
SR 501-EXP
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
K1-B K2-A K2-A
120VAC CIRC
OUTPUT OUTPUT
PRIORITY
OUTPUT
SR 501-EXP
N
POWER
INPUT
H ZC ZR H H
120VAC
INPUT
K1-B K2-A K2-A
120VAC CIRC
OUTPUT OUTPUT
PRIORITY
OUTPUT
JUMPER
TO: ZC on Boiler Control
TO: 120 VAC POWER
CIRCULATOR
TO: ZR on Boiler Control
TO: 120 VAC POWER
CIRCULATOR
Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Operation: When the thermostat calls for heat, the appropriate circulator is energized
and the isolated end switch (X and X) will start the boiler. Priority Output
has power all the time, except when the thermostat is calling.
Mode Operation: When the mode switch is set to NORMAL, the end switch
relay will be energized if any zone is in operation. When the switch is set to
RESET, the end switch relay will only be energized through the operation of a
plug-in reset control or closure of Priority Input.
Jumper Placement: The jumper should be placed between terminals ZC and H.
Connect the isolated end switch to the aquastat control on the boiler.
Power Input: Connect 120 volt ac power input to terminals N and H. Neutral
wire to terminal N. Hot wire to terminal H.
Expansion Connections: Set the expansion switch to MASTER on the switching
relay that has the designated priority zone or is utilizing the PowerPort options.
Set all other daisy chained controls to SLAVE. Connect thermostat wire (18-22
gauge) between terminals 1, 2, 3, 4 on the master control to the corresponding
1, 2, 3, 4 on the SLAVE control(s). Controls may be daisy chained up to 20 zones
using any combination of -EXP controls.
Operation: When the thermostat calls for heat, the appropriate circulator is energized
when the boiler’s aquastat is above the set low limit. The ZR (120VAC) output
will signal the boiler to start. Priority Output has power all the time, except
when the thermostat is calling.
Mode Operation: When the mode switch is set to NORMAL, the end switch
relay will be energized if any zone is in operation. When the switch is set to
RESET, the end switch relay will only be energized through the operation of a
plug-in reset control or closure of Priority Input.
Jumper Placement: REMOVE the jumper between terminals ZC and H. Connect
terminal ZC to ZC terminal on the aquastat control. Connect terminal ZR to ZR
terminal on the aquastat control. Confirm polarity is consistent between boiler
aquastat and switching relay.
Power Input: Connect 120 volt ac power input to terminals N and H. Neutral
wire to terminal N. Hot wire to terminal H.
Expansion Connections: Set the expansion switch to MASTER on the switching
relay that has the designated priority zone or is utilizing the PowerPort options.
Set all other daisy chained controls to SLAVE. Connect thermostat wire (18-22
gauge) between terminals 1, 2, 3, 4 on the master control to the corresponding
1, 2, 3, 4 on the SLAVE control(s). Controls may be daisy chained up to 20 zones
using any combination of -EXP controls.
Features: External Indicator Lights
Ideal for Retrofitting
Priority Output
Simplified Wiring
Add-On Power Controls
Sealed Relays
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Expandable to 20 Zones
Contractor Friendly PC Board
Layout
Universal Thermostat
Compatibility
UL Approved
24 volt Power Input or Output
Terminal
Extended 3 Year Warranty
Made in the USA
External Diagnostics: Externally visible lights show full functionality of the
switching relay. The green light should always be on, indicating that power is
connected. When the thermostat calls for heat, both the appropriate circulator
and red indicating light are energized.
Specifications:
PRODUCT NUMBER POWER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES CONTROLS VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR501-EXP 1 1 120 VAC Input 5.0 amps 4 1/4" 5 1/4" 2 3/4"
All Switching Relays are relay type DPDT, have a thermostat current of .18, and have a
single phase motor rating per zone of 1/3 hp (5.0A) @ 120 VAC.
Warning: Wiring connections must be made in accordance with all applicable electrical codes. Use copper wire only with a minimum temperature rating of 60/75°C. Failure to follow this instruction can
result in personal injury or death and/or property damage. 12-18 gauge wire recommended for 120 VAC connections, 14-22 gauge wire for thermostat connections, and 14-22 gauge wire for 24 VAC source
connections.
Do it Once. Do it Right. ®
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2005
TACO, Inc.
91

Instruction Sheet
SR503-EXP, SR504-EXP & SR506-EXP Switching Relay
Cold Start Boiler
Application
THERMOSTATS
Tankless Coil Boiler
Application
THERMOSTATS
EXPANSION
CONNECTIONS
EXPANSION
CONNECTIONS
POWER
CONTROL
INTERFACE
SLAVE
1234
MASTER
PLUG-IN CARDS
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZONE 6
PRIORITY
ON
OFF
POWER
CONTROL
INTERFACE
SLAVE
1234
MASTER
PLUG-IN CARDS
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZONE 6
PRIORITY
ON
OFF
24 VAC
POWER
120V RELAY
X X
END
SWITCH
RESET
NORMAL
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6
ZC ZR
120 VOLT CIRCULATORS
SR 506-EXP
POWER
INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
24 VAC
POWER
120V RELAY
X X
END
SWITCH
RESET
NORMAL
SIX ZONE SWITCHING RELAY
WITH OPTIONAL PRIORITY
SR 506-EXP
ZONE1 ZONE2 ZONE3 ZONE4 ZONE5 ZONE6 POWER
ZC ZR
120 VOLT CIRCULATORS
INPUT
POWER
ZONE 1
ZONE 2
ZONE 3
ZONE 4
ZONE 5
ZONE 6
FUSE 1 AMP
FUSE 1 AMP
TO: "TT" ON BOILER
JUMPER
120 VAC INPUT
TO: "ZR" ON AQUASTAT
TO: "ZC" ON AQUASTAT
JUMPER
120 VAC INPUT
Warning: When using Alternative Wiring diagram, wiring instructions must be followed so power originates from the boiler aquastat. Failure to
follow these wiring instructions may result in a secondary source of power being connected to the boiler that may activate it under certain circumstances,
causing injury or death.
Operation: When any thermostat calls for heat, the appropriate circulator is
energized and the isolated end switch (X and X) will start the boiler.
Priority Operation: When zone 6 is switched to the priority setting and is actuated,
all other zones will stop operation until zone 6 is satisfied. When zone 6 is
not switched to priority, all zones will operate independently.
Mode Operation: When the mode switch is set to NORMAL, the end switch
relay will be energized if any zone is in operation. When the switch is set to
RESET, the end switch relay will only be energized if priority zone is in operation,
or through the operation of a plug-in reset control.
Jumper Placement: The jumper should be placed between terminals ZC and ZR.
Connect the isolated end switch to the aquastat control on the boiler.
Power Input: Connect 120 volt ac power input to terminals N and H. Neutral
wire to terminal N. Hot wire to terminal H.
Expansion Connections: Set the expansion switch to MASTER on the switching
relay that has the designated priority zone or is utilizing the PowerPort options.
Set all other daisy chained controls to SLAVE. Connect thermostat wire (18-22
gauge) between terminals 1, 2, 3, 4 on the master control to the corresponding
1, 2, 3, 4 on the SLAVE control(s). Controls may be daisy chained up to 20 zones
using any combination of -EXP controls.
Operation: When any thermostat calls for heat, the boiler and appropriate circulator
are energized when the boiler temperature is above the set low limit.
Priority Operation: When zone 6 is switched to the priority setting and is actuated,
all other zones will stop operation until zone 6 is satisfied. When zone 6 is
not switched to priority, all zones will operate independently.
Mode Operation: When the mode switch is set to NORMAL, the end switch
relay will be energized if any zone is in operation. When the switch is set to
RESET, the end switch relay will only be energized if priority zone is in operation,
or through the operation of a plug-in reset control.
Jumper Placement: MOVE the jumper between terminals ZC and ZR to end
switch X and ZC. Connect terminal ZC to ZC terminal on the aquastat control.
Connect the other end switch X to ZR terminal on the aquastat control. Confirm
polarity is consistent between boiler aquastat and switching relay.
Power Input: Connect 120 volt ac power input to terminals N and H. Neutral
wire to terminal N. Hot wire to terminal H.
Expansion Connections: Set the expansion switch to MASTER on the switching
relay that has the designated priority zone or is utilizing the PowerPort options.
Set all other daisy chained controls to SLAVE. Connect thermostat wire (18-22
gauge) between terminals 1, 2, 3, 4 on the master control to the corresponding
1, 2, 3, 4 on the SLAVE control(s). Controls may be daisy chained up to 20 zones
using any combination of -EXP controls.
Features: External Indicator
Lights
Plug-In PowerPort Cards
Switchable Priority
Simplified Wiring
Add-On Power Controls
Fully Enclosed Snap-Out
Relays
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Expandable to 20 Zones
Contractor Friendly PC Board
Layout
Universal Thermostat
Compatibility
UL Approved
24 volt Power Input or Output
Terminal
Extended 3 Year Warranty
Made in the USA
External Diagnostics: Externally visible lights show full functionality of the
switching relay. The green light should always be on, indicating that power is
connected. When the thermostat calls for heat, both the appropriate circulator
and red indicating light is energized.
Specifications:
PRODUCT NUMBER POWER TRANSFORMER MAXIMUM DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES PORTS VOLTAGE COMBINED LOAD WIDTH HEIGHT DEPTH
SR503-EXP 3 with Priority 3 120 VAC Input 20 amps 10 1/4" 6 3/4" 2 3/4"
SR504-EXP 4 with Priority 3 120 VAC Input 20 amps 10 1/4" 6 3/4" 2 3/4"
SR506-EXP 6 with Priority 3 120 VAC Input 20 amps 11 3/4" 7 1/2" 3"
All Switching Relays are relay type DPST, have a thermostat current of .18, and have a single phase
motor rating per zone of 1/3 hp (7.2A) @ 120 VAC.
Warning: Wiring connections must be made in accordance with all applicable electrical codes and these instructions. Use copper wire only. Failure to follow this instruction can result in personal injury or
death and/or property damage. 10-18 gauge wire recommended for 120 VAC connections with 9 in.lbs. max torque, 12-22 gauge wire for thermostat connections with 9 in.lbs. max torque, and 12-22 gauge wire
for 24 VAC source with 5 in.lbs. max torque.
92
Do it Once. Do it Right. ®
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2005
TACO, Inc.

Instruction Sheet
ZVC403 & ZVC405 Zone Valve Control
Wiring
Diagram
THERMOSTAT THERMOSTAT THERMOSTAT
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
24 VAC
24 VAC
WHITE
120 VAC
INPUT
BLACK
Installation of
Optional System
Circulator
END
SWITCH
N/O COM N/C
FACTORY
INSTALLED
TRANSFORMER
24 VAC
T
T
END
SWITCH
TO CIRCULATOR
OR BOILER
AQUASTAT RELAY
POWER IN
N/O COM N/C
DRY
CONTACTS
FUSE (5 AMP MAX)
T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
ZVC 405
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
JUMPER
3 & 4
FIVE ZONE ZONE VALVE CONTROL
1
2
3
MOTOR END
SWITCH
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
POWER
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
T
T
BOILER
120 VAC
HOT
NEUTRAL
Operation/External Diagnostics: When any thermostat
calls for heat, the appropriate zone valve is energized and
the yellow light goes on. When the zone valve is fully
open, the red light goes on and energizes the end switch
relay. The green light should always be on, indicating that
power is connected.
Specifications:
PRODUCT NUMBER TRANSFORMER MAX OUTPUT DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE AT 24 VAC WIDTH HEIGHT DEPTH
ZVC403 3 Zone 120 VAC Input 40 VA 10 1 ⁄ 4" 6 3 ⁄ 4" 2 3 ⁄ 4"
ZVC405 5 Zone 120 VAC Input 80 VA 11 3 ⁄ 4" 7 1 ⁄ 2" 3"
All Zone Valve Controls are relay type DPDT and have a single phase motor rating per zone of
1 ⁄ 6 hp (5A) @ 120 VAC.
The Taco Connection: Combine the reliability of the Taco
Zone Valves, Priority Zoning Circulators, Thermostats, and
the “00” family of circulators with the advanced features of
the Taco Zone Controls to achieve total system integration.
No matter the application, Taco now provides the
products to maximize system performance while simplifying
both installation and service.
Warning: Wiring connections must be made in accordance with all applicable
electrical codes. Use copper wire only. Failure to follow this instruction can result
in personal injury or death and/or property damage. 10-18 gauge wire recommended
for 120 VAC connections with 9 in.lbs. max torque, 12-22 gauge wire for
thermostat connections with 9 in.lbs. max torque, and 12-22 gauge wire for 24
VAC source with 5 in.lbs. max torque.
Do it Once. Do it Right.
Features:
External Indicator
Lights
Simplified Wiring
Works with 2, 3, or 4-
Wire Zone Valves
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Extra Set of Dry Contacts
Contractor Friendly PC
Board Layout
Universal Thermostat
Compatibility
UL Approved
Sturdy Screw Connections
Extended 3 Year Warranty
Made in the USA
Printed in USA
Copyright 2000
TACO, Inc.
93

Instruction Sheet
ZVC404 & ZVC406 Zone Valve Control
Wiring
Diagram
THERMOSTAT THERMOSTAT THERMOSTAT
INDIRECT
WATER HEATER
AQUASTAT
OR THERMOSTAT
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
Installation of
Optional System
and/or DHW Circulator
24 VAC
24 VAC
MAIN
END
SWITCH
POWER IN
EXTRA
END
SWITCH
MODE
NORMAL RESET
FUSE (7 AMP MAX)
N/O COM N/C
ZONE 6 RELAY
24 VAC
ZONE 6 PRIORITY
OFF
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
ZVC 406
SIX ZONE ZONE VALVE CONTROL
WITH OPTIONAL PRIORITY
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
ZONE 6
1 2 3 4
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER
MAIN
END
SWITCH
EXTRA
END
SWITCH
N/O COM N/C
T
T
TO CIRCULATOR
OR BOILER
AQUASTAT RELAY
DRY
CONTACTS
JUMPER
3 & 4
1
2
3
MOTOR
END
SWITCH
JUMPER
3 & 4
PRIORITY
ZONE
SEE NOTE
T
T
BOILER
SYSTEM CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
DHW CIRCULATOR (See Note)
120 VAC
NEUTRAL
HOT
Operation/External Diagnostics: When any thermostat
calls for heat, the appropriate zone valve is energized and the
yellow light goes on. When the zone valve is fully open, the
red light goes on and energizes the end switch relay. The green
light should always be on, indicating that power is connected.
Priority Operation: When zone 6 is switched to the priority
setting and is actuated, all other zones will stop operation until
zone 6 is satisfied. When zone 6 is not switched to priority, all
zones will operate independently. Note: When a circulator is
used on the priority zone instead of a zone valve, jumper 3 and
4 of the priority zone.
Mode Operation: When the mode switch is set to NORMAL,
the end switch relay will be energized if any zone is in operation.
When the switch is set to RESET, the end switch relay
will only be energized if priority zone is in operation.
The Taco Connection: Combine the reliability of the Taco
Zone Valves, Priority Zoning Circulators, Thermostats, and the
“00” family of circulators with the advanced features of the
Taco Zone Controls to achieve total system integration. No
matter the application, Taco now provides the products to
maximize system performance while simplifying both installation
and service.
94
Do it Once. Do it Right.
Specifications:
PRODUCT NUMBER TRANSFORMER MAX OUTPUT DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE AT 24 VAC WIDTH HEIGHT DEPTH
ZVC404 4 with Priority 120 VAC Input 40 VA 10 1 ⁄ 4" 6 3 ⁄ 4" 2 3 ⁄ 4"
ZVC406 6 with Priority 120 VAC Input 80 VA 11 3 ⁄ 4" 7 1 ⁄ 2" 3"
All Zone Valve Controls are relay type DPDT and have a single phase motor rating per zone of
1 ⁄ 6 hp (5A) @ 120 VAC.
Features: External Indicator Lights
Switchable Priority
Simplified Wiring
Works with 2, 3, or 4-Wire Zone Valves
Compact Design
Fuse Protected
100% Factory Tested
Isolated End Switch
Extra Set of Dry Contacts
Contractor Friendly PC Board Layout
Universal Thermostat Compatibility
UL Approved
Sturdy Screw Connections
Extended 3 Year Warranty
Made in the USA
Warning: Wiring connections must be made in accordance with all applicable electrical codes. Use copper
wire only. Failure to follow this instruction can result in personal injury or death and/or property damage.
10-18 gauge wire recommended for 120 VAC connections with 9 in.lbs. max torque, 12-22 gauge wire for
thermostat connections with 9 in.lbs. max torque, and 12-22 gauge wire for 24 VAC source with 5 in.lbs.
max torque.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2000
TACO, Inc.

Instruction Sheet
ZVC404-EXP & ZVC406-EXP Zone Valve Control
Wiring
Diagram
WHITE
120 VAC
INPUT
BLACK
WHITE
120 VAC
INPUT
BLACK
FACTORY
INSTALLED
TRANSFORMER
FACTORY
INSTALLED
TRANSFORMER
Installation of
Optional System
and/or DHW Circulator
END
SWITCH
B
PUMP
N/O COM N/C
24 VAC
24 VAC
END
SWITCH
A
BOILER
TACO, INC ZVC406-EXP
POWER IN
POWER
CONTROLS
RESET
END
SWITCH
B
PUMP
TO CIRCULATOR
OR BOILER
AQUASTAT RELAY
SLAVE 1 2 3 4
EXPANSION
MASTER
MODE
NORMAL
N/O COM N/C
ZONE 6 RELAY
DRY
CONTACTS
END
SWITCH
A
BOILER
TO CIRCULATOR
OR BOILER
AQUASTAT RELAY
PLUG-IN
ZONE 6
CARDS PRIORITY
ON
T T T T T T T T T T T T
ZONE 1 ZONE 2 ZONE 3 ZONE 4 ZONE 5 ZONE 6
OFF
FUSE 7 AMP MAX
ZONE 1
1 2 3 4
THERMOSTAT THERMOSTAT THERMOSTAT
JUMPER
3 & 4
24 VAC
ZVC 406-EXP
SIX ZONE ZONE VALVE CONTOL
WITH OPTIONAL PRIORITY
ZONE 2
1 2 3 4
1
2
3
ZONE 3
1 2 3 4
ZONE 4
1 2 3 4
ZONE 5
1 2 3 4
MOTOR
END
SWITCH
ZONE 6
1 2 3 4
JUMPER
3 & 4
PRIORITY
ZONE
INDIRECT
WATER HEATER
AQUASTAT
OR THERMOSTAT
T STAT 1
VALVE 1
T STAT 2
VALVE 2
T STAT 3
VALVE 3
T STAT 4
VALVE 4
T STAT 5
VALVE 5
T STAT 6
VALVE 6
POWER ON
SEE NOTE
SYSTEM
CIRCULATOR
2 WIRE ZONE VALVE
(NO END SWITCH)
TACO
3 WIRE ZONE VALVE
4 WIRE ZONE VALVE
(POWER OPEN, SELF CLOSING)
DHW
120 VAC
CIRCULATOR
(See Note)
NEUTRAL HOT
T T
BOILER
Operation/External Diagnostics: When any thermostat calls for
heat, the appropriate zone valve is energized and the yellow light goes
on. When the zone valve is fully open, the red light goes on and energizes
the end switch relays. The green light should always be on, indicating
that power is connected.
Priority Operation: When zone 6 is switched to the priority setting
and is actuated, all other zones will stop operation until zone 6 is satisfied.
When zone 6 is not switched to priority, all zones will operate
independently. Note: When a circulator is used on the priority zone
instead of a zone valve, jumper 3 and 4 of the priority zone.
Mode Operation: When the mode switch is set to NORMAL, both end
switch relays will be energized if any zone is in operation. When the
mode switch is set to RESET, the end switch relay “A” will only be energized
when the priority zone is in operation. The end switch relay “B”
will be energized when any zone is in operation
Power Input: Connect 120 volt ac power input to leads on transformer.
Neutral to white wire. Hot to black wire.
Expansion Connections: Set the expansion switch to MASTER on the
zone valve control that has the designated priority zone or is utilizing
the PowerPort options. Set all other daisy chained controls to SLAVE.
Connect thermostat wire (18-22 gauge) between terminals 1, 2, 3, 4 on
the master control to the corresponding 1, 2, 3, 4 on the SLAVE control(s).
Controls may be daisy chained up to 20 zones using any combination
of Switching Relay -EXP or Zone Valve -EXP controls.
The Taco Connection: Combine the reliability of the Taco Zone Valves,
Priority Zoning Circulators, Thermostats, and the “00” family of circulators
with the advanced features of the Taco Zone Controls to achieve
total system integration. No matter the application, Taco now provides
the products to maximize system performance while simplifying both
installation and service.
Specifications:
PRODUCT NUMBER TRANSFORMER MAX OUTPUT DIMENSIONS OF ENCLOSURE
NUMBER OF ZONES VOLTAGE AT 24 VAC WIDTH HEIGHT DEPTH
ZVC404-EXP 4 with Priority 120 VAC Input 80 VA 11 3 ⁄4" 7 1 ⁄2" 3"
ZVC406-EXP 6 with Priority 120 VAC Input 80 VA 11 3 ⁄4" 7 1 ⁄2" 3"
All Zone Valve Controls are relay type DPDT and have a single phase motor rating per zone
of 1 ⁄ 6 hp (5A) @ 120 VAC.
Features:
External Indicator Lights
Plug-In PowerPort Cards
Switchable Priority
Simplified Wiring
Add-On Power Controls
Works with 2, 3, or 4-Wire
Zone Valves
UL Approved
Fuse Protected
100% Factory Tested
Isolated End Switch
Expandable to 20 Zones
Extra Set of Dry Contacts
Contractor Friendly PC
Board Layout
Universal Thermostat
Compatibility
Sturdy Screw Connections
Extended 3 Year Warranty
Made in the USA
Warning: Wiring connections must be made in accordance with all applicable electrical codes. Use copper wire only. Failure to follow this instruction can result in personal injury or death and/or property
damage. 10-18 gauge wire recommended for 120 VAC connections with 9 in.lbs. max torque, 12-22 gauge wire for thermostat connections with 9 in.lbs. max torque, and 12-22 gauge wire for 24 VAC source with
5 in.lbs. max torque.
Do it Once. Do it Right.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2000
TACO, Inc.
95

Instruction Sheet
Hydro Air Fan Controls
Operation HAFC101 and 201:
The Hydro Air Fan Control is an interface
between the thermostat and air handler. It
also has an isolated end switch to start the
boiler and/or pump. When the thermostat
calls for heat, the Fan Control energizes the
end switch relay and allows the fan to operate
at low speed when the water is above the
optional aquastat setting. When the thermostat
calls for cooling, the Fan Control energizes
the condenser and operates on high speed.
Additional HAFC201 Operations:
Selectable one, three or four minute delay on
fan operation in heating mode. Selectable
pump exercise activates circulator but does
not enable boiler contacts. Two minutes every
24 hours minimizes the chance of bacteria
build-up in an open loop system. Thirty seconds
every two weeks minimizes seasonal
start-up problems generally associated with
harsh water conditions. Optional aquastat or
thermostat can be connected to Freeze
Protection TT terminals to reduce the chance
of pipes freezing by energizing the pump dry
contacts (boiler contacts not activated.)
Switch Settings (HAFC201):
1 1 minute on fan delay, in heating mode
2 3 minute on fan delay, in heating mode
1&2 4 minute on fan delay, in heating mode
3 Pump dry contact activated for 2 minutes
every 24 hours (boiler contacts not
activated)
4 Pump dry contacts activated for 30 seconds
every two weeks (boiler contacts
not activated)
External Diagnostics:
The external lights show full functionality of
the Hydro Air Fan Control. The green light
should always be on, indicating that power is
connected. Red lights indicate fan operation
for heating and cooling modes.
Warning:
Wiring connections must be made in accordance with
all applicable electrical codes. Use copper wire only.
Failure to follow this instruction can result in personal
injury or death and/or property damage. 10-18 gauge
wire recommended for 120 VAC connections with
9 in.lbs. max torque, 12-22 gauge wire for thermostat
connections with 9 in.lbs. max torque, and 12-22 gauge
wire for 24 VAC source with 5 in.lbs. max torque.
Optional Power Wire
to Thermostat
that Requires 24VAC
THERMOSTAT
C R W Y
1 MIN ON DELAY - FAN
3 MIN ON DELAY - FAN
2 MIN @ 24 HR - PUMP
30 SEC @ 2 WK - PUMP
OFF ON
THERMOSTAT
Hot
Neutral
(or to “T T” on
switching relay)
Circulator
Dry Contacts
To: “T T” on
Boiler or
Switching
Relay
G T
DRY CONTACTS
5 AMP 1/6 HP RATED
PUMP BOILER
Line 24 VAC
T T T
WATER COIL FREEZE PR
AQUASTATS
HAFC201
HYDRO AIR FAN CONTROL
X X XXCRY
To: Optional
Aquastat on
Return Line of
Hydro Coil
AIR HANDLER
G G
Fan
Relay
M
To: Optional Aquastat
or Thermostat to sense
low ambient
temperature
Power On
Call for Heat
Fan, Cooling
Fan, Heating
Jumper
Outdoor
Condenser
Unit
Optional Power Wire
to Thermostat
that Requires 24VAC
Dry Contacts
To: “T T” on Boiler
or Switching Relay
THERMOSTAT
C R W Y
THERMOSTAT
G T T
AQUASTAT
HAFC101
HYDRO AIR FAN CONTROL
BOILER AIR HANDLER
X X C R Y G G
To: Aquastat on
Return Line of
Hydro Coil
1 Speed Air Handler*
2 Speed Air Handler*
* Both HAFC101 and 201 capable of 1 and 2 speed applications
Terminal Description:
Thermostat:
C Optional: Common side of transformer W White - Heating signal
to power some styles of thermostats Y Yellow - Condenser signal
R Red - Hot side of transformer used to G Green - Fan signal
switch all functions
Water Coil Aquastat:
TT Connect to aquastat at air handler to control operation of the fan when
in the heating mode. Install a jumper if the aquastat is not used
Freeze Protection Aquastat:
TT Connect to aquastat or thermostat to sense low ambient temperature.
Reduces the chance of pipes freezing by energizing the pump dry contacts.
Pump Dry Contacts:
XX May switch pump directly by bringing in external line voltage or connect
to “T T” on a switching relay.
Boiler Dry Contacts:
XX Connect to the boiler or “T T” terminals on a switching relay.
Air Handler:
C Common side of transformer to power the Fan Control
R Red - Hot side of transformer used to switch all functions
Y Yellow - Condenser signal
One Speed Motor:
G low Connect the fan to the relay. Keep the jumper installed between G high and G low.
Two Speed Motor:
G high Remove jumper and connect G high to the high speed fan relay and
connect G low to the low speed fan relay.
Line 24 VAC
Low
High
M
Fan Relays
Power On
Call for Heat
Fan, Cooling
Fan, Heating
Outdoor
Condenser
Unit
Specifications:
** Model number changed from SR501-F
PRODUCT
NUMBER
NUMBER
OF ZONES
POWER INPUT
VOLTAGE
MAXIMUM
COMBINED LOAD
RELAY
TYPE
THERMOSTAT
CURRENT
SINGLE PHAZE MOTOR
RATING (RELAY)
DIMENSIONS OF ENCLOSURE
WIDTH HEIGHT DEPTH
HAFC101** 1 Zone 24 VAC Input 5 amps DPDT .18 1/6 HP(5A) @120VAC 4 1/4" 5 1/4" 2 3/4"
HAFC201•• 1 Zone 24 VAC Input 5 amps DPDT .18 1/6 HP(5A) @120VAC 4 1/4" 5 1/4" 2 3/4"
The Hydro Air Fan Controls are relay type DPDT, have a thermostat current of .18 and a single phase motor rating per zone of 1/6 HP (5A) @ 120 VAC.
Do it Once. Do it Right.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
96
Printed in USA
Copyright 1999
TACO, Inc.

Instruction Sheet
PC600 Post Purge Timer Plug-In PowerPort Card
102-094
SUPERSEDES: August 1, 1997 EFFECTIVE: May 1, 2000
Plant ID No. 9300-867
Operation:
Once the priority zone is satisfied, the PC600 maintains power to the circulator, but does not fire the boiler. The circulator purges excess heat into the priority zone,
minimizing standby loss during warm weather months and optimizing boiler operation when used with a boiler reset control. Power can be maintained to the circulator
from a minimum of 10 seconds to a maximum of 420 seconds. The power LED light is energized when the priority zone or the post purge card is in operation.
Installation:
The PC600 can be installed in any one of the PowerPort terminals located on the Taco Expandable (-EXP) Control(s). Remove the shunt/jumper between pins 9
& 10 on the PowerPort terminal before installing the PC600. Align the connector on the base of the post purge card with the PowerPort terminal on the Expandable
Control and push until the two mate.
XX Terminals (Optional):
The XX terminals on the post purge card can be wired to TT on the boiler to fire only when the priority zone is calling for heat. If using a boiler with an internal
reset control, wire the XX terminals in parallel with the TT connections of the internal reset control.
Do it Once. Do it Right.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Printed in USA
Copyright 2000
TACO, Inc.
Instruction Sheet
PC605 Priority Protection Plug-In PowerPort Card
102-095
SUPERSEDES: MAY 1, 1998 EFFECTIVE: MAY 1, 2000
PLANT ID NO. 9300-1012
Operation:
The PC605 Priority Protection Plug-In Card is a solid state control that helps prevent freeze-ups in the event of a priority zone failure. If the priority zone calls for heat
continuously for more than one hour, power is returned to the space heating (non-priority) zones, allowing all zones to function independently. Once the priority zone is
satisfied, the PC605’s auto-reset is activated and the priority zone is again allowed to have priority for up to one hour the next time it calls. The one hour time frame is
not adjustable. The red LED light is energized only when the Priority Protection Card is operating in priority override mode.
Installation:
The PC605 can be installed in any unoccupied PowerPort terminal located on the Taco Expandable (-EXP) Control(s). Do not remove the shunt between pins 9 &
10 on the Expandable Control unless a PC600 is also installed. Align the connector on the base of the priority protection card with the PowerPort terminal on the
Expandable Control and push until the two mate. The PC605 can be used in conjunction with any other Taco PC style PowerPort Cards or Add-on Controls.
Do it Once. Do it Right.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Printed in USA
Copyright 2000
TACO, Inc.
Instruction Sheet
PC610 Pump Exercise and Timer Plug-In PowerPort Card
102-096
SUPERSEDES: May 31, 1998 EFFECTIVE: May 1, 2000
Plant ID No. 9300-1025
Operation:
The PC610 Pump Exercise and Timer Plug-In Card is a solid state universal timer designed to cycle all the pumps that are attached to the Expandable Control(s)
at selected time intervals. This minimizes seasonal start-up problems generally associated with harsh water conditions. The control can be configured to reduce
the chance of freeze-ups by cycling the pumps more often during cold weather months. Bacteria can be minimized in heating systems that utilize domestic hot
water heaters as their heat source by systematically circulating the water.
Installation:
The PC610 can be installed in any unoccupied PowerPort terminal located on the Taco Expandable (-EXP) Control(s). Do not remove the shunt between pins 9 & 10 on
the Expandable Switching Relay unless a PC600 is also installed. Align the connector on the base of the priority protection card with the PowerPort terminal on the
Expandable Switching Relay and push until the two mate. The PC610 can be used in conjunction with any other Taco PC style PowerPort Cards or Add-on Controls.
Typical Settings:
Application On Time Off Time
Pump Exercise 30 sec. 2 weeks
Bacteria Minimization 4 min. 12 hours
Freeze Protection 4 min. 1 hour
Do it Once. Do it Right.
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 6180 Ordan Drive, Mississauga, Ontario L5T 2B3. Telephone: 905/564-9422. FAX: 905/564-9436.
Printed in USA
Copyright 2000
TACO, Inc.
97

Standard Terms and Definitions
Switching Relay: Transformer and relay in one box, which allows a low voltage thermostat to control a line voltage load (circulator),
with an isolated end switch that can energize the boiler.
Zone Valve Control: Transformer and relay in one box, which allows a low voltage thermostat to control a low voltage zone valve, with
an isolated end switch that can energize the boiler and/or circulators.
Dry Contacts: Set of relay contacts that make and beak, where no voltage is present. Usually can switch 24 or 120 VAC.
Isolated End Set Switch: Set of dry contacts that make when a zone calls for heat. Usually connected to a boiler’s aquastat TT.
Mode Switch: Switch set to NORMAL – When any zone calls for heat, the end switch will make and fire the boiler.
Switch set to RESET – When any zone calls for heat, a heat demand signal is given to external add-on reset control and it controls
boiler operation.Also when the priority zone calls for heat and is switched to priority, the end switch will override reset control and
fire boiler to high limit.
TT: Where thermostat or aquastat connects on a heating control.
XX: Denotes Isolated End Switch.
Low Voltage: 24 VAC for most HVAC systems.
Line Voltage: Normally 120 VAC relative to ground.
H or L1: Hot side of line voltage.
N or L2: Neutral side of line voltage.
ZR: 120 VAC (Hot) signal from switching relay to boiler’s operating aquastat to fire the burner to high limit when any zone calls for
heat. Also ideal for controlling primary circulator.
ZC: 120 VAC (Hot) signal from boiler’s operating aquastat to switching relay allowing circulator(s) to run when aquastat is above the
set low limit.
Cold Start: A boiler that fires only when there is a call for heat.
Tankless Coil: A method of heating domestic water utilizing a heat exchanger inside a boiler.The boiler also maintains heat year round
to deliver hot water on demand.
DHW Heater: A method of heating domestic water utilizing a heat exchanger and storage tank.
Transformer: A component for increasing or reducing AC voltage. Rated in VA (volts x amps).
OHMS Law: Example: A 24 volt, 40 VA transformer can produce how much current?
Current = VA / Voltage
40 / 24 = 1.6 Amps
I = E/R where I = Current in Amps
R = E/I
R = Resistance in Ohms
E = I x R
E = Volts
W = E x I
W = Watts or VA
I = W(VA)/E
RELAY CONTACTS:
N/C: Normally closed connection of a relay, when not energized.
N/O: Normally open connection of a relay, when not energized.
Com: The common terminal for normally open and normally closed.
Pole: The number of independent circuits of a switch or relay.
Throw: The number of settings which a switch or relay can have.
3 4 4 6 6 5
COM N/O N/C N/C N/O COM
DPDT = Double Pole Double Throw
98

TACO Zone Controls Cross-Reference
TACO ARGO ERIE HONEYWELL WHITE-ROGERS
SWITCHING RELAYS
1 Zone Switching Relay (DPDT) SR501 AR821 (1), AR822 SR100 RA89A (2), RA845A (1), RA832A (1) 889-189 (2), 829-845 (1)
1 Zone Switching Relay Replacement PC Board (DTSP) SR501-845RP
2 Zone Switching Relay with Priority SR502 AR-861-2 (3) SR201
3 Zone Switching Relay with Priority SR503 AR-861-3 (3) SR301 R8888A1007
4 Zone Switching Relay with Priority SR504 AR-842 SR601 R8888B1005
6 Zone Switching Relay with Priority SR506 AR-866 SR601 (4)
SWITCHING RELAYS
WITH POWERPORT OPTIONS
3 Zone Switching Relay with Priority and 3 Power Ports SR503-EXP ARM-861-DP (5,6),ARM-3P
4 Zone Switching Relay with Priority and 3 Power Ports SR504-EXP ARM-842-DP (5,6),ARM-4P
6 Zone Switching Relay with Priority and 3 Power Ports SR506-EXP ARM-866-DP (5,6),ARM-6P
ZONE VALVE CONTROLS
3 Zone Valve Control ZVC403 (7) AZ-3 R8889A1014
4 Zone Valve Control with Priority ZVC404 (7) AZ-4P R8889B1012
5 Zone Valve Control ZVC405 (7) AZ-5 VL500 (8)
6 Zone Valve Control with Priority ZVC406 (7) AZ-6P VL500 (8)
ZONE VALVE CONTROLS
WITH POWERPORT OPTIONS
4 Zone Valve Control with Priority and 2 Power Ports ZVC404-EXP
6 Zone Valve Control with Priority and 2 Power Ports ZVC406-EXP
PLUG IN POWERPORT CARDS
Post Purge Timer Plug-In Card PC600
Priority Protection Plug-In Card PC605 DPM-1
Universal Timer/Pump Exercize Plug-In Card PC610
99

TACO Zone Controls Cross-Reference (Continued)
100
TACO ARGO ERIE HONEYWELL WHITE-ROGERS
ADD-ON POWER CONTROLS
Boiler Reset Control PC700 DPM-2 BB1200
2-Stage Boiler Reset Control PC702
Variable Speed Pump Injection Mixing Control PC705 BB3000
FAN CONTROLS
1 Zone Hydro Air Fan Control (1 or 2 Speed) HAFC101 ARH-1,ARH-2,ARH-3 WA300
1 Zone Hydro Air Fan Control with Time Delays (1 or 2 Speed) HAFC201
REPLACEMENT PARTS
24 Volt Replacement Relay SR024-001RP R-35 EXP10
120 Volt Replacement Relay SR120-001RP R-49
NOTES:
1. Does not have both normally open and normally closed contacts.
2. Has only one set of normally open contacts (SPST).
3. Does not have optional priority.
4. Can be expanded to five and six zones with the addition of EXP10 relays.
5. Argo ARM units are expandable to 10 zones using special controls (ARM-1,ARM-4) with a phone jack.
TACO switching relays can be expanded up to 20 zones using any combination of -EXP models with no special connections.
6. Includes only one data port for adding data port modules.
7. All TACO zone valve controls include an extra set of dry contacts (N/O, Common, N/C).
8. VL500 is only 5 zones, 4 normal and 1 priority.

CONTROLS MADE EASY. ®
TACO, INC., 1160 Cranston Street, Cranston, RI 02920 Telephone: (401) 942-8000 FAX: (401) 942-2360.
TACO (Canada), Ltd., 8450 Lawson Road, Unit #3, Milton, Ontario L9T 0J8. Telephone: 905/564-9422. FAX: 905/564-9436.
Visit our web site at: http://www.taco-hvac.com
Printed in USA
Copyright 2010
TACO, Inc.