Troubleshooting He - Danfoss Termix VX Operating Manual

Operating Guide Termix VX with complete insulation

7.2 Troubleshooting HE

Problem
Too little or no heat.
Uneven heat distribution.
DH supply temperature too high.
DH supply temperature too low.
20 | © Danfoss | 2022.11
Possible cause
Strainer clogged in DH or HE circuit
(radiator circuit).
The filter in the energy meter on DH circuit
clogged.
Defective or wrongly adjusted differential
pressure controller.
Sensor defective – or possibly dirt in the
valve housing.
Automatic controls, if any, wrongly set or
defective - possibly power failure.
Pump out of operation.
The pump is set at too low speed of
rotation.
Pressure drop – the pressure drop on
the radiator circuit shows lower than
recommended operating pressure.
Air pockets in the system.
Limiting of the return temperature adjusted
too low.
Defective radiator valves.
Uneven heat distribution in building
because of incorrectly set balancing valves,
or because there are no balancing valves.
Diameter of pipe to substation too small or
branch pipe too long.
Air pockets in the system.
Wrong setting of thermostat or of
automatic controls, if any.
Defective controller. The controller does
not react as it should according to the
instructions.
Defective sensor on self-acting thermostat.
Wrong setting of automatic controls, if any.
Defective controller. The controller does
not react as it should according to the
instructions.
Defective sensor on self-acting thermostat.
Wrong placement/fitting of outdoor
temperature sensor.
Strainer clogged.
Solution
Clean gate/strainer(s).
Clean the filter (after consulting the DH
plant operator).
Check the operation of the differential
pressure controller – clean the valve seat if
required.
Check the operation of the thermostat –
clean the valve seat if required.
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.
Check if the pump is receiving power and
that it turns. Check if there is air trapped in
the pump housing – see pump manual.
Set the pump at higher speed of rotation.
Fill water on the system and check the
functioning of the pressure expansion
vessel if required.
Vent the installation thoroughly.
Adjust according to instructions.
Check – replace.
Adjust/install balancing valves.
Check pipe dimensions.
Vent the installation thoroughly.
Adjust automatic controls, – see
instructions for automatic controls.
Call automatic controls manufacturer or
replace the regulator.
Replace thermostat – or sensor only.
Adjust automatic controls – see instructions
for automatic controls.
Call in automatic controls manufacturer or
replace controller.
Replace thermostat – or sensor only.
Adjust location of outdoor temperature
sensor.
Clean gate/strainer.
AQ221686472754en–010401 / LUK4030601