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

I am not familiar with DV-WP. Does such a system need a combination tank?

I don't know anything about DV-WP. Does such a system need a combined storage tank?

No idea if a storage tank is mandatory for a DV.

Lüumel developed a storage tank where the domestic hot water is heated in flow through the heating water. So there is no domestic hot water storage tank. It's called a stratified storage tank with different temperatures at the top than at the bottom.

Buy yourself an IR thermometer for 15 euros, I still found errors in the hydraulic balancing in my system. Some heating circuits throttled the heat pumps too early because the return flow increased too early.

And one of the 3 heating circuits in one room was throttled too much, which makes no sense since the others are heating more.
In the hallway exactly the other way around.

Etc.

Now wait another 24 hours and see if it made any difference.

Does every heat pump regulate when the return flow is too warm?

A technician regarding the hydraulic balancing is coming to me soon, what should I pay attention to? So what definitely should be done?

He will set the calculated values for the flow rate. Whether these are actually acceptable in practice, you will only find out when you live there.

A technician regarding the hydraulic balancing will be coming to me soon, what should I pay attention to? So what definitely should be done?

Have a detailed documentation of the underfloor heating handed over to you. Laying distances, actually installed circuit lengths (not just what was calculated beforehand), pipe diameters (also of the pipes to the hydraulic balancing valve), hydraulic diagram, installed components. Instruction in the functionality/operation of the flow measuring tubes, ask about any additional flow restrictors in the supply and return. Additional bypass valves and their operation. These are pieces of information you would otherwise be chasing in vain by phone. Ask Chewbacca123... You will have to do the thermal balancing yourself in the next proper winter anyway.