Underfloor heating air-water heat pump. House too warm when the sun shines

You have to do a bit of reading. But you have to do that with every type of heating device. Of course, you can just run it on factory settings, but then it usually runs suboptimally. You also adjust a TV to your needs and not to what the manufacturer has programmed in.

The hydraulic balancing, etc. has nothing per se to do with the heat pump. This always has to be done (or have it done) no matter how the heating is done.

So I was indeed just as shocked about a year ago that you basically have to do everything yourself. I spent hours, days, and nights on it and racked my brains, it was ultra hot in the house, then too cold, the heating very inefficient. But by now it’s really running well I would say – after I closed the [Ü-Stromventil] again.

and all thanks to the great team here in the forum, I have received so much help here, incredible. A big thank you once again

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A technician from the manufacturer Novelan came along.
He basically checked all my settings and adjusted the bypass valve from almost closed to almost fully open. According to him, this was completely fine and only excess would flow out anyway. The valve had to be opened that far.

Interestingly, I had exactly the same. In summer, someone from Stiebel came several times because my heat pump wouldn't produce hot water properly anymore, and now that I've switched back to heating mode, the unit started cycling like crazy.
The technician also turned the bypass valve fully open.. I even told him that I had disabled the ERR and all circuits were always on... well..

Theoretically, the settings are correct, but it costs the compressor's lifespan and electricity, which the technician simply couldn't care less about.

If a client is reading who is still choosing their service providers: Choose those who love their profession and the installed technology. This may cost extra – but it apparently pays off especially when it comes to the topic of [Wärmepumpe].

You do have to read a little. But you have to do that with every type of heating device. Of course, you can just run it at the factory settings, but then it usually runs suboptimally. You also set a TV to your needs and not to what the manufacturer has programmed in. By the way, the hydraulic balancing has nothing per se to do with the heat pump. You always have to do (or have done) this regardless of how it is heated.

That's true. But a heating system is much more complicated than a TV. I consciously choose an energy-efficient device with a certain annual performance factor. I have now also played around with the heating curve so that it is 22.5° Celsius for me. All thermostats/valves are open. However, I don't know if the settings are correct. My heat pump is also short cycling like crazy.