Three-way valves - Merx AS

merx.ee

Three-way valves - Merx AS

Three-way valves

as mixing or flowshare valves

• Size DN 15 and DN 20

(Presettable in DN 15)

• Constant pressure

loss through heat load

and bypass

• T-piece available as

accessory for use with

four-pipe systems


Method of operation and applications

The MNG three-way mixer valve is suitable for use

in heating, ventilating and air-conditioning systems.

In conjunction with the “eltherm” actuator, the valve

serves as a changeover valve, for example for boiler

priority or for demand-switched control of drinking

water vessels or heating circuits. In conjunction with

a constant actuator, for example the Centra type

M 7410 C 1007, it functions as a mixer valve for the

control of air-conditioning equipment, fanned convectors,

two-pipe systems with a heat exchanger or

for the control of heating zones, for example in apartments

or individual rooms etc.

The particular feature of this valve is that the kvs value

through the bypass is reduced by 30 % in comparison

with the kvs values of the load branch being controlled.

In this way the pressure loss through the heat load is

compensated for and the total flow rate remains almost

constant. This ensures that a system operates quietly

and reliably.

The three way mixer valve is available in DN 15 and

DN 20 sizes. There is also a T-piece which fits the bypass,

thus providing a compact solution for four way

circuits with flow and return to central heating plus

flow and return to hot water load.

Example:

Water side control of hot water storage units

Example:

Flow switching between heat loads, for example

hot water heaters and central heating circuits

By pressing in the spindle the control branch A – AB

is opened and the mixing branch is closed. The valve

then has spring return back to the starting position.

100

Total quantity

100

The pressure loss and therefore the total flow rate

remain almost constant throughout the control cycle.

The flow resistance of the water storage unit is allowed

for by reducing the kvs value of the bypass by approximately

30 %.

Control load A – AB

Bypass B – AB

Kv

(%) 0

0

Stroke (%)

100

0

2


Specification

Three-way mixer valve

MNG three-way mixer valve 2°C to 130°C, PN 16, maximum

differential pressure 0.8 bar for good performance.

Valve stroke 2.9 mm. Matt nickel plated red bronze

Rg 5 valve body to DIN 1705, suitable for MNG actuators.

Letby rate ports A – AB, approximately 0.05 % of Kvs

(full flow) value, letby rate bypass B – AB approximately

0.02 % of kvs (full flow) value.

With union nuts and seals. See “Accessories” for suitable

union connectors.

Nominal Connection Kvs values Part No.

size size (full flow)

DN 15 1/2" 2.5* 2.27 60 49.015

DN 20 3/4" 4.0 2.27 60 49.020

*With fine adjustment

T-piece

T-piece for screwing onto the bypass of the MNG

three-way mixer valve. With union nuts and seals.

See “Accessories” for suitable union connectors.

Nominal size Connection size

Part No.

DN 15 1/2" 2.41 20 02.015

DN 20 3/4" 2.41 20 02.020

3


Accessories

Eltherm actuator for zone control

MNG-“eltherm” electric thermal actuator for zone control

with all MNG thermostatic valves, totally quiet.

White RAL 9010 housing of self-extinguishing plastics,

to protection Class II. Operating voltage 230 V or 24 V

depending on type, current consumption: Changeover:

58 VA (230 V) or 6 VA (24 V) – Holding: 2.5W (230 V) or

3.0 W (24 V). Protection type IP 43, Protection Class D.

Cable length 1.2 metres. Opening (or closing) time:

Approximately 3 minutes. Maximum operating temperature:

100°C. Maximum ambient temperature: 50°C.

Differential pressure: 0.3 bar to 1.0 bar depending on

valve body used. Suitable for all MNG thermostatic

valves. Supplied for normally-closed operation but can

be adapted during installation for normally-open use.

Item Type Part No.

“eltherm” 230 V, 50 – 60 Hz 20 90 13

24 V, 50 – 60 Hz 20 90 15

Welded union connector

for connection of hot water load, bypass and heating

circuit

Item Size Type Part No.

Welded union DN 15 for DIN 15 valves 40 35 02.015

connector DN 20 for DIN 20 valves 40 35 02.020

Soldered union connector

for connection of hot water load and heating circuit

Item Size Type Part No.

Soldered union 15 mm for DIN 15 valves 20 53 03.015

connector 22 mm for DIN 20 valves 20 53 03.020

Threaded union connector

for connection of hot water load, bypass and heating

circuit

Item Size Type Part No.

Threaded union 1/2" for DIN 15 valves 20 35 01.015

connector 3/4" for DIN 20 valves 20 35 01.020

4


Flow diagram

DN 15 DN 20

0,6

K v -values

0,63

1,0

1,6

2,5

4,0

6

0,5

5

0,4

4

0,3

3

Pressure drop (bar)

0,2

0,1

0,08

0,07

0,06

0,05

0,04

0,03

2

10000

8

7

6

5

4

3

Pressure drop (Pascal)

(10 Pascal ~ 1 mm water column ~ 0.1 mbar)

0,02

2

0,01

50 6 7 8 9100 2 3 4 5 6 7 8 9 1000 2 3

1000

Flow rate (kg/h)

Pressure losses, Kv values

Example:

Given:

Flow rate 400 kg/h

DN 15 three-way mixer valve, Kv = 2.5

Required: Pressure drop

The pressure drop is found at the point

where the flow line and the line for the

chosen valve Kv intersect.

Answer:

25 mbar

The Kvs values (full flow) in the diagram

are without hot water loads connected.

To establish the value for the system, the

pressure loss across the hot water load

must also be taken into account.

5


Dimensions

Connector accessories

Soldered union connector A, AB

l5

l6

S l2

h

d4

Welded union connector A, B, AB

l4

d1

d1

d3

Threaded union connector A, B, AB

l3

S

d1

l1

S

d2

DN d 1 h l 1 l 2 l 3 l 4 l 5 l 6 d 2 d 3 d 4 s

DIN ISO 228/1 mm mm mm mm mm mm mm DIN2999 mm mm mm

15 G 3/4 A 32 58 28 28 28 18 12 R 1/2 20,5 15 2

20 G 1 A 26,5 60 34 30 33 23 17 R 3/4 26 22 2

6


Dimensions

Connector accessories

Soldered union connector

l5

l6

d1

l2

d1

d1

d1

d3

h

d4

Welded union connector

l4

Threaded union connector

l3

d2

S

l1

S

DN d 1 h l 1 l 2 l 3 l 4 l 5 l 6 d 2 d 3 d 4 s

DIN ISO 228/1 mm mm mm mm mm mm mm DIN2999 mm mm mm

15 G 3/4 A 32 58 40 28 28 18 12 R 1/2 20,5 15 2

20 G 1 A 26,5 60 60 30 33 23 17 R 3/4 26 22 2

7


Metallwerke Neheim Goeke & Co. GmbH

Postfach 20 40 • D-59710 Arnsberg

Telefon (++49) 29 32 9 88-0

Telefax (++49) 29 32 9 88-239

DIN ISO 9001

Subject to change – EN3H - OO8GE25

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