Controls, Start-Up, Operation, Service and ... - Climayoreo

Whenever the outdoor ambient temperature (OAT), is
above 70 F, the maximum stage will always be on when the
compressors are on.
On the initial start-up of a circuit, the condenser fans will
start 5 seconds prior to the compressor starting in order to ensure
proper head pressure of the compressor immediately at
start-up. After the compressor starts, the normal head pressure
routine is followed. What stage fans starts depends on the outdoor
ambient temperature. The three situations are:
OAT < 50 F
50 F < OAT < 70 F
OAT > 70 F
See Fig. 7 for what stage of fans starts for each scenario.
ECONOMIZER INTEGRATION WITH MECHANICAL
COOLING — When the economizer is able to provide free
cooling (Run StatusECONACTV = YES), mechanical
cooling may be delayed or even held off indefinitely.
NOTE: Once mechanical cooling has started, this delay logic
is no longer relevant.
Multi-Stage Cooling Economizer Mechanical Cooling
Delay — This type of mechanical cooling delay is relevant to
the following machine control types:
C.TYP = 1 VAV-RAT
C.TYP = 2 VAV-SPT
C.TYP = 3 TSTAT-MULTI
C.TYP = 4 SPT-MULTI
If the economizer is able to provide free cooling at the start
of a cooling session, the mechanical cooling algorithm
(SumZ), checks the economizer’s current position (Run Status
ECONECN.P) and compares it to the economizer’s
maximum position (ConfigurationECONEC.MX) – 5%.
Once the economizer has opened beyond this point a 150 second
timer starts. If the economizer stays beyond this point for
2.5 minutes continuously, the mechanical cooling algorithm is
allowed to start computing demand and stage compressors and
unloaders.
Heating Control — The P Series ComfortLink controls
offers control for four different types of heating systems to
satisfy general space heating requirements: 2-stage gas heat,
2-stage electric heat, multiple-stage gas heat and hydronic heat.
Heating control also provides tempering and reheat functions.
These functions are discussed in separate sections. Reheat is discussed
under Dehumidification function on page 79.
Variable air volume (VAV) type applications (C.TYP = 1 or
2) require that the space terminal positions be commanded to
open to minimum heating positions when gas or electric heat
systems are active, to provide for the unit heating system’s
Minimum Heating Airflow rate.
Also, for VAV applications, the heat interlock relay (HIR)
function provides the switching of a control signal intended for
use by the VAV terminals. This signal must be used to command
the terminals to open to their Heating Open positions.
The HIR is energized whenever the Heating mode is active, an
IAQ pre-occupied force is active, or if fire smoke modes, pressurization,
or smoke purge modes are active.
Table 39 — Demand Limit Configuration
ITEM EXPANSION RANGE UNITS CCN POINT DEFAULT
DMD.L DEMAND LIMIT CONFIG.
DM.L.S Demand Limit Select 0 - 3 DMD_CTRL 0
D.L.20 Demand Limit at 20 ma 0 - 100 % DMT20MA 100
SH.NM Loadshed Group Number 0 - 99 SHED_NUM 0
SH.DL Loadshed Demand Delta 0 - 60 % SHED_DEL 0
SH.TM Maximum Loadshed Time 0 - 120 min SHED_TIM 60
D.L.S1 Demand Limit Sw.1 Setpt. 0 - 100 % DLSWSP1 80
D.L.S2 Demand Limit Sw.2 Setpt. 0 - 100 % DLSWSP2 50
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Hydronic heating applications that use the unit’s control
require the installation of a communicating actuator on the hydronic
heating coil’s control valve. This actuator (with or without
matching control valve) may be separately shipped for field
installation.
All heating systems are available as factory-installed
options. The hydronic heating coil may also be field-supplied
and field-installed; the actuator is still required if unit control
will be used to manage this heating sequence.
SETTING UP THE SYSTEM — The essential heating configurations
located at the local display under Configuration
HEAT. See Table 40.
Heating Control Type (HT.CF) — The heating control types
available are selected/configured with this variable.
0 = No Heat
1 = Electric Heat
2 = 2 Stage Gas Heat
3 = Staged Gas Heat
4 = Hydronic Heat
Heating Supply Air Set Point (HT.SP) — In a low heat mode
for either staged gas or hydronic heat, this is the supply air set
point for heating.
Occupied Heating Enable (OC.EN) — This configuration
only applies when the unit’s control type (Configuration
UNITC.TYP) is configured for 1 (VAV-RAT) or 2 (VAV-
SPT). If the user wants to have the capability of performing
heating throughout the entire occupied period, then this
configuration needs to be set to “YES”. Most installations do
not require this capability, and if heating is installed, it is used
to heat the building up in the morning. In this case set OC.EN
to “NO”.
NOTE: This unit des not support simultaneous heating and
cooling. If significant simultaneous heating and cooling
demand is expected, it may be necessary to provide additional
heating or cooling equipment and a control system to provide
occupants with proper comfort.
MBB Sensor Heat Relocate (LAT.M) — This option allows
the user additional performance benefit when under CCN
Linkage for the 2-stage electric and gas heating types. As twostage
heating types do not “modulate” to a supply air set point,
no leaving air thermistor is required and none is provided. The
evaporator discharge thermistor, which is initially installed upstream
of the heater, can be repositioned downstream and the
control can expect to sense this heat. While the control does not
need this to energize stages of heat, the control can wait for a
sufficient temperature rise before announcing a heating mode
to a CCN Linkage system (ComfortID).
If the sensor is relocated, the user will now have the
capability to view the leaving-air temperature at all times at
TemperaturesAIR.TCTRLLAT.
NOTE: If the user does not relocate this sensor for the 2-stage
electric or gas heating types and is under CCN Linkage, then
the control will send a heating mode (if present)
unconditionally to the linkage coordinator in the CCN zoning
system regardless of the leaving-air temperature.