164
Troubleshooting
The unit is switched on but the compressor does not start (for room heating or domestic hot water heating)
Possible causes Corrective action
The unit should start outside
its operating range (the
water temperature is too
low)
If the water temperature is low, the system first uses the backup heater to
reach the minimum required temperature (12°C).
• Check that the power supply to the backup heater is correct.
• Check that the backup heater's thermal fuse is closed.
• Check that the backup heater's thermal protection has not tripped.
• Check that the backup heater’s contactors are intact.
• Be prepared with a backup heater if you think that cold starts may be
frequent in these conditions (in case of long winter system shutdowns).
The pump is noisy (cavitation)
Possible causes Corrective action
The system contains air. Vent the air
Insucient pressure of water
entering the pump
• Check that the water pressure is sucient on the pressure gauge. The
water pressure must be >1 bar (cold water).
• Check that the pressure gauge is working properly.
• Check that the expansion tank is intact.
• Check that the expansion tank precharge is set correctly. See chapter “6.
Water connections” on page 36. Checking the volume of water and
precharge of the expansion tank
The water pressure relief valve opens
Possible causes Corrective action
Expansion tank is faulty Replace the expansion tank.
The water filling pressure
in the installation is greater
than 0.30 MPa.
Check that the water filling pressure in the installation is approx. 0.15 - 0.18
MPa. See chapter “6. Water connections” on page 36.
Checking the volume of water and precharge of the expansion tank.
If the pressure is higher, partially empty the circuit until the optimum range
is reached.
The water pressure relief valve is leaking
Possible causes Corrective action
The water pressure relief
valve outlet is obstructed.
Check that the pressure relief valve is working properly by turning the red
knob on the valve anticlockwise:
• you do not hear a click, contact your local dealer.
• if water continues to leak out of the unit, close the shut-o valves at the
water inlet and outlet and contact your local dealer.
The heat pump in DHW mode stops working but the setpoint is not reached, the room heating requires
heat but the unit remains in DHW mode
Possible causes Corrective action
Coil surface in the tank not
large enough
• Set dT1s5 to 20 and set t_DHWHP_RESTRICT to the minimum value.
• Set dT1SH to 2.
• Enable TBH, TBH must be controlled by the unit.
• If AHS (boiler) is available, enable it from the dip-switch also for DHW
production.
• If TBH and AHS are not available, try changing the position of the T5
probe.
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