Xylem MOH2 Multi zone mixing module (obsolete) - Manual (Page 20)

20
Installation and operation manual MOH2
www.lainginc.com
Troubleshooting
• If you use Laing controls, you’ll get error messages for typical errors.
You find the explanation of these error messages in the manual of the
control. In most cases, this will answer your question.
Step-down control doesn’t work:
• The sensors for boiler feed tempera-
ture and floor heating feed temperature
have not been connected properly.
Connect sensors according to the ap-
propriate instruction.
• The bypass valve is closed or opened
insufficiently. Open the bypass valve
according to the appropriate instruc-
tion.
The feed temperature is oscillating significantly:
• The presetting valve is opened too far,
therefore too much boiler water is en-
tering the floor heating loop. Adjust the
presetting valve according to the ap-
propriate instruction.
• If the heating load is very small, for
example, if only one short loop is open,
an oscillation of the feed temperature is
normal.
The pump is not running: • Possibly the over temperature protec-
tion has tripped and shut off the pump.
• If not, the pump may be clogged by dirt.
Remove the circulator to inspect it.
Heating performance is insufficient:
• The presetting knob is turned in too far
• The bypass valve is opened too far
• The system is just being put into
service, in which case it may take
longer to heat the floor for the first time.
As long as the floor heating return
temperature is still cold, the feed
temperature also cannot increase
independently since most of the feed
water comes from the floor heating
return and only a small portion is boiler
water.