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Danfoss District Energy
VI.GP.N2.02
DKDHR
Instructions Water
Heaters
15.0 Trouble shooting
If operating disturbances occur, the following basic features
should be checked before carrying out actual troubleshooting:
• there is pressure on the system. - see manometer on system
• the system is connected correctly,
• the system is connected to electricity - pump and automatic
• the strainer on the district heating supply is clean
• the district heating supply temperature is at normal level
• the differential pressure is higher than or equal to the normal /
local differential pressure on the district heating network. - If in
doubt, ask the district heating plant.
15.1 Troubleshooting - Domestic hot water
Problem
Possible cause
Solution
Variations in temperature
Non-return valve on the circulation line
defective (leads to mixing - and the
circulation water pipes become cold dur-
ing tapping).
Replace non-return valve.
Low temperature / variations in tem-
perature at the draining points
Non-return valve in thermostatic mixer
tap in the bathroom defective - leads to
mixing of cold and hot water-. Note that
variations in temperature may occur at
other draining points/water taps in the
household piping!
REMEMBER, to check all the mixer taps in
the house!
Replace mixer tap, or non-return valve
only.
Not enough pressure on the hot water
Strainer in cold water meter or in the
cold water supply line clogged .
Clean strainer (cold water meter possibly
in consulation with the water supply
company).
Long waiting time
Circulation pump out of operation - (not
part of the dly).
Check whether the pump is running -
whether the pump is receiving power.
control that there is no air in the pump
housing - see pump manual.
No domestic hot water
Defective or wrongly set differential
pressure controller (not part of the dly).
Strainer on DH supply clogged.
Check the functions of the differential
pressure controller - clean valve seat and
capillary tube if required.
Clean strainer.
DHW temperature too low
See above.
Non-return valve on the circulation line
defective (leads to mixing - and the
circulation water pipes become cold du-
ring tapping).
See above.
Replace non-return valve.
DHW temperature too high
Defective DHW controller.
Check the functions of the controller,
and replace if required.
Declining temperature during tapping
Defective or wrongly set differential
pressure controller (not part of the dly).
Air in capillary tubes
Check the functions of the differential
pressure controller - clean valve seat and
capillary tubes if required.
Air and rinse capillary tubes.
