38 | © Danfoss | Produced by Danfoss Redan A/S | 2022.03
145X2068
AQ40514397064001-000101
16. TROUBLESHOOTING HE
Problem
Possible cause
Solution
Too little or no heat.
Strainer clogged in DH or HE circuit
(radiator circuit).
Clean gate/strainer(s).
The filter in the energy meter on DH
circuit clogged.
Clean the filter (after consulting the DH
plant operator).
Defective or improperly adjusted diffe-
rential pressure controller
Check the operation of the differential
pressure controller – clean the valve seat
if required.
Sensor defective.
Check the operation of the thermostat –
clean the valve seat if required.
Automatic controls wrongly set or
defective - possibly power failure.
Check if the setting of the controller
is correct – see separate instructions.
Check the power supply. Temporary
setting of motor to “manual” control –
see instructions on automatic controls.
Pump out of operation.
Check if the pump is receiving power
and that it turns. Check if there is air
trapped in the pump housing – see
pump manual.
The pump is set at too low speed of
rotation.
Set the pump at higher speed of rotation.
Air pockets in the system.
Vent the installation thoroughly.
Limiting of the return temperature
adjusted too low.
Adjust according to instructions.
Defective radiator valves.
Check – replace.
Uneven heat distribution in building
because of incorrectly set balancing
valves, or because there are no balan-
cing valves.
Adjust/install balancing valves.
Diameter of pipe to flat station too small
or branch pipe too long.
Check pipe dimensions.
Uneven heat distribution.
Air pockets in the system.
Vent the installation thoroughly.
DH supply temperature too high.
Defective controller. The controller does
not react as it should according to the
instructions.
Set the automatic controls according to
the instructions.
Defective control valve.
Replace control valve .
DH supply temperature too low.
Defective controller. The controller does
not react as it should according to the
instructions.
Set the automatic controls according to
the instructions.
Strainer clogged.
Clean gate/strainer.
Montage- und Betriebsanleitung / User manual
VXe SLS
