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

For everyone who has been following the topic here, a final note about our heating: With the great help of all of you, especially Daniel, we have managed to reduce the impulses of the compressor from 100 per day to about five per day at our home. The heat pump now runs much more efficiently, really great. By closing the ÜV, our heating also no longer looks like a heart attack. The opendta program is really excellent; someone did a great job, and I now check the development daily, but it is really satisfactory. I will definitely continue to address the fact that the bathroom still does not get satisfactorily warm. 20.5 degrees is too cold, and that at 3l/min volume, the highest level. The new issue now is our water circulation; it does not circulate as I set it by timing. But we will somehow solve that too. Many thanks again to everyone who was and is so actively involved here – you are great!!!

But the return temperature would have to be measured for that. However, this is not done at all with my heating system, for example. Could it be that it makes a difference whether the heating is controlled on the return flow or the supply flow?

I can measure the return flow in our system, a few days ago during the heating cycle the supply was 34.5 and the return was 28.2. It is set to 3 l/min, the highest volume you can set. But it simply does not get warmer than 20.8° when the outside temperature is around 0°. So annoying. For comparison, the hallway is set to a volume of 0.25 l/min and it is 23° in the hallway every day.. Children's room 0.5 l/min and 22 degrees.

I can measure the return flow on our system; a few days ago during the heating cycle, the supply was 34.5 and the return was 28.2.
It is set to 3 l/min, the highest volume you can set. But it simply doesn’t get warmer than 20.8° when the outside temperature is around 0°. So annoying.
For comparison, the hallway is set to a volume of 0.25 l/min and it is 23° in the hallway every day.
Children’s room 0.5 l/min and 22 degrees.

Unfortunately, it was planned incorrectly; many more pipes should have been installed, e.g., with a 5cm spacing. Or an electric auxiliary heater was planned in advance like in our case. I wish I had dealt with that more back then... I left out the auxiliary heater because the door is always open anyway.

But for that, the return temperature would have to be measured. However, that is not done at all with my heating system, for example. Could it be that it makes a difference whether the heating is controlled by the return or the supply?

I don’t know, I’m still reading and learning myself.

Unfortunately, the planning was done incorrectly; there should have been many more pipes installed, for example with a 5cm laying distance. Or an electric preheater was planned in advance, like in our case. If only I had dealt with it more back then.... I left out the preheater because the door always stays open anyway. I don't know that myself, I'm just reading and learning.

Yes, more preparation should have been done in advance, but we really had zero knowledge about the subject. It really annoys me now... Especially that the expert apparently had no clue either... grrrrr

But the return temperature would have to be measured. However, this is not done at all with my heating system, for example. Could it be that it makes a difference whether the heating is controlled by the return flow or the supply flow?

Return-controlled seems more elegant to me, as the heating system measures based on the return temperature whether the screed has reached its temperature. Otherwise, you need some kind of room sensor that measures the room temperature and reports it to the heating system. That means additional wiring. Do you have something like that?

I can't tell you exactly according to which system the pump for the underfloor heating starts. I would have to check that myself again. The heat pump itself is supply-controlled and heats a combination tank for us. The system is from Lüumel with a DV heat pump from Sofath.