22
Instructions for installation and use
TD & S substations
DKDHR
VI.GP.U2.02
Danfoss District Energy
19 Troubleshooting
Problem
Cause
Solution
Heat,
no heat
Dirt strainer in the district heating or
heating return line clogged.
The filter in the district heating meter – if
any – may be blocked.
Defective or incorrectly set differential
pressure controller.
Air pockets in the system.
Clean the filter/dirt strainer.
Clean (in consultation with the district
heating plant).
Check the function of the differential
pressure controller – if necessary, clean
the valve seat and capillary tube.
Vent the system thoroughly – see the
instructions.
Uneven distribution of heat
Air pockets in the system.
Vent the system thoroughly – see the
instructions.
Poor cooling
Insufficient heating surface / radiators
too small.
Poor utilisation of the existing heating
surface.
Non-return valve in mixing circuit doe
not close tightly or is defective.
Increase the total heating surface.
Turn on all the radiators and prevent the
radiators in the system from becoming
warm at the bottom.
Clean or replace the non-return valve.
No heat
(S-Units only)
Defective thermostat – or possibly dirt in
the valve housing.
Defective motor valve – or possibly dirt
in the valve housing.
Automatic components/controller
incorrectly adjusted or defective – or
possibly a power outage.
The pump is not working.
The pump is set at a “step” that is too low
(not all system types).
Air pockets in the system.
Check that the thermostat is functioning
correctly – clean the valve seat if necessary.
Check that the motor valve is functioning
correctly – clean the valve seat if necessary.
Check that the controller setting is cor-
rect – see the separate instructions for
the controller.
Check the power supply.
Temporarily set the motor to “manual”
control – see the instructions for the
heating system.
Check that there is a power supply for the
pump, and that it is operating.
Make sure that there is no air in the pump
housing – see the pump manual.
Set the pump to a higher step – see the
instructions for the heating system.
Vent the system thoroughly – see the
instructions.
Noise from unit
Non-return valve in mixing circuit defective
Replace non-return valve.
Fundamental
In the event of disruptions to operation, you should fundamentally
– before commencing the actual troubleshooting – check
whether:
•
the system is correctly connected
•
the district heating supply temperature is at its normal level
•
the differential pressure is at its normal level – ask your district
heating supplier if necessary
•
there is a power supply to the system pump and automatics
•
the dirt strainer in the district heating supply pipe is clean
•
there is air in the system
