Troubleshooting Dhw - Danfoss Termix VMTD-F MIX-I Operating Manual

Operating Guide Termix VMTD-F MIX-I

7.2 Troubleshooting DHW

Problem
Too little or no DHW.
Hot water in some taps but not in all.
Tap temperature too high; DHW tap load
too high.
Temperature drop during tapping.
Thermostatic control valve does not close
Idle temperature too low (for stations
equipped with IHPT).
AQ110886479343en-010601 / LUK4025001
Possible cause
Strainer in supply or return line clogged.
DHW circulation pump out of order or with
too low setting.
Defective or clogged non-return valve.
No electricity.
Wrong setting of automatic controls, if any.
Scaling of the plate heat exchanger.
Defective motorized valve.
Defective temperature sensors.
Defective controller.
DCW is being mixed with the DHW, e.g. in a
defective thermostatic mixing valve.
Defective or clogged non-return valve on
circulation valve.
Thermostatic valve adjusted to a too high
level.
Scaling of the plate heat exchanger.
Larger DHW flow than the substation has
been designed for.
Temperature difference between DH
supply and DHW set point too low.
Set point too low.
Solution
Clean strainer(s).
Check circulation pump.
Replace – clean.
Check.
To adjust an electronic controller for
DHW, pls. note enclosed instructions for
electronic controller.
Replace – rinse out.
Check (use manual function) – replace.
Check – replace.
Check – replace.
Check – replace.
Replace – clean.
Check – set.
Replace – rinse out.
Reduce DHW flow.
Lower the set point temperature or increase
the DH supply temperature.
Turn thermostat in (+) direction.
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