Underfloor heating and solar thermal

No competent help can be offered to you as long as no one knows your entire system. Do you have a single buffer tank that is also used to produce hot water, or one with a fresh water station? Or perhaps a small adjacent tank? Does the solar thermal system also support heating, or does it only produce hot water? How is the entire system connected? And what primary heat generator do you have, and how is it set?

You cannot be offered competent help as long as no one knows your entire system.

I see it similarly.

Last night I set the value Temp.-Adjustment from originally 1.0 to -1.0. Due to this change, the loss has dropped to 9.0 degrees (instead of about 30) per night. Let's see how this now affects the room temperature?

That is also not very helpful if you don’t know what it causes.