Air-water heat pump very loud

Our air-to-water heat pump manages without the electric heating element; I have switched it off. Even at -21°C, it was no problem. It needs the heating element for hot water. There is also a mode for noise reduction, in which the heating element runs and the compressor's power is reduced. But it does not cool down as a result.

That it is comparable to an electric heater is of course nonsense and sounds like half-knowledge from village gossip ;). The efficiency even partly increases again because the heat pump has to defrost more often near the freezing point. With colder, drier air, it increases slightly again.

Much has already been written here, but little of it is technically sound. Therefore:

[*]No single system is nowadays allowed to exclusively exhaust the guideline values of the TA Lärm. Because in this case, any additional system would lead to an exceedance of the guideline values.
[*]A single system should (technically correctly here: must) undershoot the nighttime guideline values by at least 3, preferably 6 dB.
[*]Building regulation offices and lower emission control authorities have completely overlooked the air-water heat pump noise problem in recent years and sometimes still do. According to current legal situation, after the authorities’ sleeping beauty slumber, there is a rude awakening for many current and future air-water heat pump operators.
[*] ~35 dB in front of bedroom windows in 400 m² new development lots, of which > 60% are heated using air-water heat pumps, is partially utopian.

oh man ... complex

Who does the neighbor turn to when it gets too loud for them? The building authority? Or the owner?

There is no fixed process here. Common sense would initially approach the operator - that is, the neighbor. But directly involving the building regulation office / police or filing an injunction has also sometimes been the first course of action. Basically, as the "disturbed" party of an existing installation, you are initially obliged to provide evidence. That means §29 measuring station, and not a mobile app.

A lot has already been written here, but very little of it is technically sound. Therefore:

[*]No single system is allowed nowadays to fully exploit the guideline values of TA Lärm alone. Because in this case, each additional system would lead to an exceeding of the guideline values.
[*]A single system should (technically correct here: must) fall below the nighttime guideline values by at least 3, preferably 6 dB.
[*]Building authorities and lower immission control authorities have completely missed the air-water heat pump noise problem in recent years and partly still do. According to the current legal situation, after the authorities’ deep sleep, many current and future air-water heat pump operators will experience an abrupt awakening.
[*]~35 dB in front of bedroom windows in 400 m² new development plots, of which > 60% are heated by air-water heat pumps, is partly utopian.

A Rotex HPSU Compact with 8 kW output generally falls below the guideline values in a general residential area at a distance of 5.80 m by 6 dB both during the protected quiet period in the day and also at night operation.

If the system is 3 m away from the neighbor and the neighbor complies with the 3 m clearance area, then the above is already fulfilled. Even the smallest play streets in residential areas are about 6 meters wide. If the heat pump is placed in front of the house and everyone only observes the clearance areas, we are at least about 12 meters distance to the opposite side.

I wouldn’t exaggerate here. Of course, poorly, incorrectly or not at all adjusted systems are certainly problematic. It should be installed by a competent company, with the base plate acoustically decoupled, etc.

A Rotex HPSU Compact with 8 kW output already falls short of the guidelines in a general residential area at a distance of 5.80m by 6 dB

Where do you know that from? Measured?