Heat pumps require a lot of energy and make noise

There must be some value somewhere where the then says, okay, I've reached the target and can now switch off for a while. Otherwise, the thing runs continuously, right?

That's right. In winter, the heat pump runs 24/7 (as it does currently). And that's a good thing. Controlled "only" by the planned supply/return temperatures. For me currently 30/25 for 21 degrees indoor temperature and current sub-zero temperatures. If it gets warmer outside, the heat pump lowers the temperatures according to the stored heating curve (+5 degrees maybe to 28/23). If it gets colder, then the opposite. The temperature inside the rooms always remains approximately the same.

On the one hand, continuous operation at a consistent output is desirable for a heat pump. However, the heat pump switches off if the water returns too warm because the heating circuits are no longer absorbing heat. The whole system is designed so that the energy supplied by the heater corresponds to the energy lost through the exterior walls, and with open valves, the temperature is correct.

Okay, and how does it behave in summer then? Should you still leave the pump running, or does it switch off anyway at a certain outside temperature? Do you only adjust the temperature via the heating curve then? I always thought that if the pump runs continuously, it also consumes electricity continuously.

That's right. In winter, the heat pump runs 24/7 (as it is currently). And that's a good thing.

Controlled "only" by the planned supply and return temperatures. Currently, for me it's 30/25 for 21 degrees indoor temperature and current sub-zero temperatures. When it gets warmer outside, the heat pump reduces the temperatures according to the stored heating curve (+5 degrees maybe to 28/23). When it gets colder, the opposite happens. The temperature in the rooms always remains approximately the same.

Okay, and how do you control the individual rooms then? Or do you have 21 degrees throughout the entire house?

Okei und wie verhält es sich dann im Sommer, sollte man die Pumpe dann trotzdem so anlassen oder schaltet sich diese sowieso bei einer bestimmten Außentemperatur ab?

You set the temperature at which it switches from heating mode to summer mode (= hot water only). Depending on the manufacturer, different methods are used (average of the last 24 hours + actual temperature or however it is calculated).

Okey, and how do you then control the individual rooms? Or do you have 21 degrees everywhere in the house?

Not at all. I also don’t have ERR. I had the heating planned according to my wishes. 20-22 degrees was planned. But for that, I would have to keep the doors in the house closed all the time, which I don’t like. So everything is on, and the temperatures are +/- 1 degree the same everywhere.

Okei and how does it behave in summer then, should you still leave the pump on like that or does it switch off anyway at a certain outside temperature? Do you only set the temperature via the heating curve then? I always thought if the pump runs continuously, it also consumes electricity continuously.

The amount of electricity consumed essentially depends on the required amount of heat and thus on what you lose through the walls. Whether it produces it by running for one hour at 1k and then pausing for one hour, or running for 2 hours at 0.5kW, is relatively irrelevant. Compressors don't like starting and stopping, so it's best if the heat pump runs continuously, as this results in the least wear. The heating engineer has certainly set a temperature at which the heat pump automatically switches off the heating. However, you can also turn it off manually. I do this because due to our large window surfaces, in spring we relatively quickly reach the point where the heating demand becomes too low and otherwise the heat pump cycles, even if the outside temperature is not yet that warm.