13.2 General symptoms
Symptom 1: The unit is turned on but the unit is not heating or 
cooling as expected
When a safety device was activated, stop the unit and find out why 
the safety device was activated before resetting it. Under no 
circumstances can safety devices  be bridged or changed to a 
value other than the factory setting. If the cause of the problem 
cannot be found, call your local dealer.
If the pressure relief valve is not working correctly and is to be 
replaced, always reconnect the flexible hose attached to the 
pressure relief valve to avoid water dripping out of the unit!
For problems related to the optional solar kit for domestic 
water heating, refer to the troubleshooting in the Installation & 
Owner's manual for that kit.
When carrying out an inspection on the switch box of the 
unit, always make sure that the main switch of the unit is 
switched off.
POSSIBLE CAUSES CORRECTIVE ACTION
The temperature setting 
is not correct.
Check the controller set point.T4HMAX,
T4HMIN in heat mode.T4CMAX,T4CMIN 
in cool mode.T4DHWMAX,T4DHWMIN 
in DHW mode.
Symptom 2: The unit is turned on but the compressor is not 
starting (space heating or domestic water heating)
POSSIBLE CAUSES CORRECTIVE ACTION
The unit must start up 
out of its operation range 
(the water temperature 
is too low).
In case of low water temperature, the 
system utilizes the backup heater to 
reach the minimum water temperature 
first (12°C).
•  Check that the backup heater 
   power supply is correct.
•  Check that the backup heater 
   thermal fuse is closed.
•  Check that the backup heater 
   thermal protector is not activated.
•  Check that the backup heater 
   contactors are not broken.
Symptom 6: Space heating capacity shortage at low outdoor 
temperatures
POSSIBLE CAUSES CORRECTIVE ACTION
Backup heater operation 
is not activated.
Controls parts for backup 
heater(IBH) ” 
Too much heat pump 
capacity is used for 
heating domestic hot 
water (applies only to 
installations with a 
domestic hot water tank).
Symptom 5: The water pressure relief valve leaks
POSSIBLE CAUSES CORRECTIVE ACTION
Dirt is blocking the water 
pressure relief valve 
outlet.
Check for correct operation of the 
pressure relief valve by turning the 
red knob on the valve counter 
clockWise:
•  If you do not hear a clacking sound,
   contact your local dealer.
•  In case the water keeps running out 
   of the unit, close both the water inlet 
   and outlet shut-off valves first and
   then contact your local dealer.
The water flow is too 
low.
•  Check that all shut off valves of the 
    water circuit are completely open.
•  Check if the water filter needs cleaning.
•  Make sure there is no air in the system
   (purge air).
•  Check on the manometer that there is 
   sufficient water pressure. The water 
   pressure must be>1 bar (water is cold).
•  Make sure that the expansion vessel 
   is not broken.
•  Check that the resistance in the water 
   circuit is not too high for the pump 
POSSIBLE CAUSES CORRECTIVE ACTION
The expansion vessel is 
broken.
Replace the expansion vessel.
The filling water pressure
in the installation is 
higher than 0.3MPa.
Make sure that the filling water pressure
in the installation is about 
0.15~0.20MPa (refer to "9.3 water 
pipework/Checking the water volume 
and expansion vessel pre-pressure").
Symptom 3: Pump is making noise (cavitation)
POSSIBLE CAUSES CORRECTIVE ACTION
Purge air.
Water pressure at pump 
inlet is too low.
•  Check on the manometer that there 
   is sufficient water pressure. The water
   pressure must be > 1 bar (water is 
   cold).
•  Check that the manometer is not 
   broken.
•  Check that the expansion vessel is 
   not broken.
•  Check that the setting of the 
   pre- pressure of the expansion 
   vessel is correct  (refer to "9.3 water 
pipework/Checking the water volume 
and expansion vessel pre-pressure").
Symptom 4: The water pressure relief valve opens
The water volume in the 
installation is too low.
Make sure that the water volume in the 
installation is above the minimum 
required value (refer to "9.3 water 
pipework/Checking the water volume 
and expansion vessel pre-pressure").
WARNING
NOTE
50