Xylem MOH2 Multi zone mixing module (obsolete) - Manual (Page 12)

12
Installation and operation manual MOH2
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With the help of this bypass, the boiler feed temperature can be sensed at
the boiler feed connection even when the control valve is closed.
Setting [only in conjunction with a step down control]
• Open the bypass valve sufficiently to allow correct sensing of the boiler
feed temperature even when the control valve is closed. The setting
depends on the length of the boiler feed pipe, the insulation and the
differential pressure of the boiler loop.
• For short boiler feed pipe lengths, is usually sufficient to open the bypass
valve 1/2 turn counter clockwise.
• For long pipe runs between the boiler and the MOH2, the bypass needs
to be opened further. When the control valve is closed, enough water
has to circulate through the bypass so that the correct boiler feed
temperature can be sensed at the boiler feed connection of the MOH2.
• Use the following diagram to set the valve correctly. It shows the flow
rate through the bypass valve depending on various differential pressures
in the boiler loop.
• To set the valve correctly, close it completely and then turn it counter
clockwise the indicated number of turns
Flow rate bypass valve