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Instructions for installation and use
TD & S substations
Danfoss District Energy
VI.GP.U2.02
DKDHR
Problem
Possible cause
Solution
Domestic hot water,
Fluctuating temperature
Non-return valve in the circulation pipe
defective (leads to mixing – the circula-
tion water pipes become cold during
tapping).
Replace the non-return valve.
Low temperature/Different tempera-
tures at different tapping points
Non-return valve in thermostatic mixer in
the bathroom defective – results in hot
and cold water mixing. Please note that
fluctuating temperatures may occur at
other tapping points in the system!
NB Check all mixers in the house for
faults/defects!
Replace the mixer or perhaps only the
non-return valve.
No enough pressure on the hot water
Strainer in the cold water meter or in the
cold water supply line clogged.
Clean the strainer (cold water meter, in con-
sultation with the water supply company).
Long wait for hot water
Circulation pump out of order (outside
the unit – not part of the delivery).
Check whether the pump is running –
and whether there is a power supply to
the pump. Make sure that there is no air
in the pump housing.
No hot water
Dirt strainer in the district heating sup-
ply line clogged.
Clean the filter/dirt strainer.
Hot water temperature too low
As above.
Non-return valve in the circulation pipe
defective (results in mixing – the circula-
tion water pipes become cold during
tapping).
As above.
Replace the non-return valve.
Hot water temperature too high
Defective domestic hot water controller.
Check the functionality of the controller –
replace if defective.
Temperature falls during tapping
Air in the capillary tube.
Vent the capillary tube.
Temperature falls during tapping
Calified plate heat exchanger.
Plate heat exchanger short-circuited/
defective.
Clean with acid or replace the plate heat
exchanger.
Replace the plate heat exchanger.
Poor cooling
Calified plate heat exchanger.
Replace the plate heat xchanger or clean it
with acid.
Discoloured water
(during a protracted period)
Plate heat exchanger short-circuited.
Replace the plate heat exchanger.
Lack of hot water pressure
Calified plate heat exchanger.
Replace the plate heat exchanger or clean
it with acid.
