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

in post #686 your differential is just 2.8K.
Can you set that somewhere?
Return flow should be 26.6°C at AT=-3°C, that also seems very low to me.

The system is an air pump. I can't set the differential anywhere, right? It calculates the return flow setpoint based on the heating curve, which is low but absolutely within range according to comparisons.

I'll let the system run like this for at least 24 hours now and hope that I don't cause an error through the manual pump control or, even worse, completely ruin the system...

All clear. I stumbled over the source temperature. The RT can definitely be correct. Of course, it may be that the heating curve no longer fits with the current outside temperatures and little sun. Do you have a comparison to last year? Sorry but I don’t have the entire history in my head.

All right. I stumbled upon the source temperature. The room temperature (RT) can certainly be correct. Of course, it may be that the heating curve no longer fits with the current outdoor temperatures and little sun. Do you have a comparison to last year? Sorry but I don't have your entire history in my head.

That’s no problem, just ask. I am grateful for any help. I am very convinced that it's due to the flow rates. Normally, the heating runs at a maximum of 800 l/h. In my opinion, that is far too little for the house with 200 m2 of heated area. That’s why almost nothing arrives upstairs. Since I switched to manual today, the room temperatures have shot up. In the dining room it was 21 degrees in the morning, now already 21.8 degrees. I will observe it. Even though I believe that the pump on modulating systems should actually be set to automatic. But at the moment, I have no choice but to set it manually for testing.

my heat pump modulates the flow rate at -3°C AT also between 780-960L/h with a power of about 5kW for a 200sqm house. I can adjust both the compressor power and the heating curve in my system (however, in technician mode). It would be interesting to know if you can do that too and what power the compressor is currently set to.

Err are exceptions I assume?

The runtime should be on for several hours up to continuously.
If you have been operating the heat pump at a minimum performance of 60% the entire time, it is not surprising that the runtime is short.

Err are exceptions, I assume?

Runtime should be a few hours up to permanent.
If you have been running the heat pump at 60% minimum performance the whole time, it is not surprising that the runtime is short.

No, it has always been set to auto until now. I only have 2 compressor starts daily, I think that is very good.