Xylem MOH2 User Manual
Installation and operation manual
for multi zone
mixing module
MOH2
Installation and operation manual MOH2
Design MOH2 base module Schematics
Control
11
10
16
12
19
2
7
1
14
5
4
6
9
8
3
15
13
18
17
1 Circulator pump
2 Floor heating loop feed side
3 Floor heating loop return side
4 Control valve
5 Presetting knob for control valve
6 Bypass valve
7 Check valve for filling of floor hea-
ting loops
8 Boiler loop feed side
9 Boiler loop return side
10 Ball valve boiler loop feed side
11 Ball valve boiler loop return side
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12 Fill valve
13 Drain valve
14 Sensor position for floor heating
loop feed temperature
15 Sensor position for floor heating
loop return temperature
16 Sensor position for safety tempe-
rature
17 Sensor position for boiler feed
temperature
18 Plug for calorimeter dip tube
19 Automatic air purger
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Installation and operation manual MOH2
Table of contents
Design MOH2 base module .................................................................. 2
Application of the MOH2 mixing module ............................................... 4
Construction .......................................................................................... 4
Function ................................................................................................ 4
Attaching a manifold to the MOH2 to base module ............................... 6
Attaching other kinds of manifolds ........................................................ 7
Changing the number of loops of the segmented plastic manifold ........ 7
Installation of the MOH2 station ............................................................ 8
Hydraulic connection ........................................................................... 10
Connection of calorimeter sensor........................................................ 10
Connection of the controls ...................................................................11
Bypass valve 6 .....................................................................................11
Presetting knob for control valve 5 ...................................................... 13
Filling the system................................................................................. 14
Pressure test ....................................................................................... 14
Start-up ................................................................................................ 15
Technical data ..................................................................................... 16
Dimensions ......................................................................................... 18
Changing out the circulator ................................................................. 19
Troubleshooting................................................................................... 20
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Installation and operation manual MOH2
Application of the MOH2 mixing module
Connection of low temperature heating systems to the boiler loop,
for example
• Floor heating systems
• Wall heating systems
Installation of the MOH2 is possible in the manifold cabinet, because
• It is very compact
• It operates very quietly
• In multifamily dwellings, the feed temperature for the low temperature
loop can be selected individually for each apartment.
Construction
The Laing mixing module MOH2 consist of a bronze cast main body, which
contains [see schematics on page 2]
• Connections for feed and return of the boiler loop
• Connections for feed and return of the low temperature loop
• Circulator
• Control valve
• Presetting knob for control valve
• Air purger as well as fill and drain valves
• Connections for all necessary sensors
• Bypass valve
Function
Floor heating loop
• The circulator 1 circulates the water through the floor heating feed connection and the floor heating loops to the floor heating return connection.
Mixing
• When the mixing valve 4 opens, boiler loop feed water 8 is mixed to the
floor heating loop feed side and the same amount of water is returned
from the floor heating return side 3 to the boiler loop return side 9.
• The mixing valve adjusts the quantity of water coming from the boiler
loop to control the desired floor heating feed temperature.
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Installation and operation manual MOH2
Control
18 16
17
8 10 14 2
5 4 7
1
12
6
15
9 11 3
13
1 Circulator
2 Feed for floor heating circuit
3 Return for floor heating circuit
4 Control valve
5 Presetting knob for control valve
6 Adjustable bypass valve
7 Check valve for filling of floor heating loops
8 Boiler feed connection
9 Boiler return connection
10 Ball valve of boiler feed connection
11 Ball valve of boiler return con-nection
12 Fill valve
13 Drain valve
14 Sensor for floor heating feed temperature
15 Sensor for floor heating return temperature
16 Sensor for safety temperature
17 Sensor for boiler feed temperature
18 Space for calorimeter dip tube
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Installation and operation manual MOH2
Presetting knob for control valve
• The control valve is equipped with a presetting knob 5, with which the
maximum amount of water from the boiler loop can be reduced. The
unit is shipped with the presetting knob completely open.
Bypass for step-down control
• If the bypass valve 6 is opened, a small quantity of boiler feed water will
run constantly through the mixing module. This is necessary for a stepdown control, which derives its outside temperature information from
the boiler feed temperature. The unit is shipped with the bypass valve
opened 1/2 turn.
Fill and drain valves
• If you fill the system from the fill valve 12, the check valve 7 will close.
In this way, the water will flow through the floor heating loops and not
through the mixing module. Excess water drains through the drain valve
13.
Sensor positions integrated in the base module
• Floor heating feed temperature 14
• Floor heating return temperature 15
• Safety temperature 16
• Boiler feed temperature 17
• Dip tube for calorimeter sensor 18
Attaching a manifold to the MOH2 to base module
Attaching a Laing segmented plastic manifold
• Attach the manifolds before mounting the module.
• Attach manifolds directly to the flanges of the MOH2
• Adjusts the length of the threaded rods according to the number of zones
• Screw the threaded rods into the MOH2
• If the manifolds should be offset, use one or two 20 mm spacers on the
feed or return side
• Insert the red segments on the feed side [top], the blue segments on
the return side (bottom) onto the threaded rods. Caution: make sure
that the seal surfaces and seal rings are free of dirt.
• Close manifolds with end plate (caution: plastic cover must face the
water) and tighten the nuts evenly.
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Installation and operation manual MOH2
Attaching other kinds of manifolds
• The flanges contain a 1" female thread to enable connection of other
kinds of manifolds. Attach the manifolds here using a proper pipe thread
sealant
• If the manifolds should be offset, use a spacer or a longer insert.
• We recommend to use a union connection between the manifolds and
the base module. This facilitates disassembly in case of repairs.
Changing the number of loops
of the segmented plastic manifold
• Make sure to adjust the number of loops before installing the module in
a manifold cabinet, since it may be impossible to remove the threaded
rods with the unit mounted in a cabinet.
Reduce number of loops, disassembly
• Remove both nuts at the end plate
• Remove end plate and unneeded manifold segments
• Cut the threaded rods to proper length [55 mm for every segment
removed]. Caution: take care not to damage the thread or the seal
surface of the last segment.
• If the threaded rods cannot be cut in place, remove them and shorten
them elsewhere. Caution: take care not to damage threads.
Increase number of loops, disassembly
• Remove both nuts at the end plate
• Remove the end plate
• Remove both threaded rods
• Install new threaded rods with the appropriate length [additional 55 mm
for every segment]. Caution: take care not to damage the thread.
• Install additional segments
Reassembly of manifold
• Caution: if manifolds have been in operation, it is necessary to clean
carefully the seal rings and the seal surfaces of each segment as well
as the end plates.
• Reinstall the end plates and tighten the nuts equally.
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