First troubleshooting steps

These tips help you to take the first troubleshooting steps:

  • any fault can be acknowledged. To do this, please keep the adjustment button of the heat pump control unit pressed for 10 seconds.
  • If the measures described here do not help to correct the fault, please contact your local accredited installer.

First troubleshooting steps

Establishing emergency operation via integrated electric heating element

All units except brine/water compact (23 kW and 33kW) and water/water compact (28 kW and 44 kW) Here you must check whether an additional heat generetar is installed.

Heating mode changeover




Hot water mode changeover




4. Checking the heating element

Undo the quick-release screws of the front or side panel (depending on the unit model). Please ensure that the fuses (of the control and load current) are switched off before opening the housing.


The work is to be carried out by qualified personnel only.

5. Safety temperature limiter

A safety temperature limiter is installed in the electric heating element. In the event of a heat pump failure or air in the system, please check whether the reset button has tripped.

Please always press the Reset button first.

The Reset button can only be pushed in if it has tripped. In case of doubt, please have it checked by an accredited installer!

Error code 715/716: High-pressure faults

1. Checking the setpoints of the heat pump

Check that the setpoints (hot water setpoint and heating curve settings) that have been set are not outside the heat pump's use limits. The use limits of the unit are noted on the nameplate.

2. Are all shut-off valves necessary for operation of the heat pump open?

Check all the necessary shut-off valves are open. Otherwise there is no flow and the unit registers a fault and switches off. In this case, if necessary, contact your accredited installer for advice.

3. Is the heating system vented?

If "gurgling" can be heard while the circulation pump is running, the heating system may need venting. The heat pump controller can be used to activate the circulation pumps individually to check their function.

To do this, go to  Service > Settings > Vent system and set a tick next to the respective pump. The selected pump runs immediately following the confirmation.

ATTENTION: Refer to the operating manual for the individual pump designations.

Error code 701/702: Low-pressure faults in air/water heat pumps

1. Are the intake and discharge ducts/openings covered, blocked or grown over?

The intake and discharge openings of the heat pump must be clear so that the heat pump can "breathe" properly. Increased running costs (efficiency of the heating pump worsens) and faults can be avoided in this way.

2. Is the fan running?

If the fan is not running the heat pump cannot remove the cold air produced and the air heat exchanger (evaporator) freezes. The result is a low-pressure fault. The fan can be activated via the heat pump controller to check its function.

To do this, go to Service > Settings > Vent system and set a tick next to BOSUP fan. The fan runs immediately following the confirmation. It runs for the duration of the set time or can be ended manually by removing the tick next to BOSUP fan.

ATTENTION: During the power company off-time it is possible that the fan does not run because the power supply has been switched off.

3. Does the outdoor temperature sensor display the correct temperature?

Check the plausibility of the displayed value. This should correspond to the current outdoor temperature and be roughly the same as the heat source inlet temperature.
You will find these values under Service > Information > Temperatures.

ATTENTION: The outdoor temperature sensor must be fitted on the northern external wall of the building and must be protected against direct sunlight!