Air-water heat pump very loud

Some manufacturers specify the COP at -7 degrees: It is around 2.8 to 3.3. Far from electric heating. This might be the case at -20 degrees, for a few hours every few years.

from -5 C it will run anyway only as an electric heater

There are indeed air-to-water heat pumps that operate without an electric heater down to -15°C.

what should freeze there???? The refrigerant???

Since I have not read anywhere what kind of heat pump it is, it could also be an outdoor heat pump where the supply and return water runs outside and not the refrigerant. But these pipes should be very well insulated and are also kept warm by the heat from the house.

But it is difficult to narrow down the problem here.

Yup, mathematically that’s even correct, the reciprocal of the Carnot efficiency is indeed in such ranges for performance numbers around 0.5. But why the hell do they then all install heating rods...? ;)

Back to the topic: to the OP: what supply temperature is your heating running at? If it is as low as possible, the efficiency improves significantly. Then maybe the heating doesn’t have to "work" as hard.

Best regards,

Andreas

There are indeed air-to-water heat pumps that operate without an electric heating element down to -15°C.

There are, that's true. There are also good air-to-water heat pumps that do not torment their neighbors with completely unreasonable noise.

However, these are somewhat more complex and cost a bit more.

If the neighbors are already complaining, it is probably unfortunately not one of those…

Best regards,

Andreas

But why the hell do they all install heating rods then...? ;)

For the mind that is filled with fear. Why do heater manufacturers put 20kW gas burners in single-family homes? So that in the most unlikely disaster scenarios, half the village can be called for a hot shower without running out of warm water. Anything else would be too unsafe.

I think 26 degrees?