All in all, it doesn't seem super bad to me...?!
I didn't say it was great either, but it's definitely not great for a new building.
You and the heating installers don't seem that convinced either if they are planning high-temperature heat pumps for old buildings.
What is still unclear to me is why the Daikin heat pump in the BAFA list shows different COPs for three different sizes but lists both the same heat and nominal heat outputs. In online shops, the nominal heating capacity is the same, but the maximum heating capacities differ depending on the size:
Despite the somewhat critical sentences above, the conclusion should be that this simply is not the right heat pump for your new building.
If it is supposed to be Daikin, then Altherma 3 R and not H.
What is still unclear to me is why the Daikin heat pump in the BAFA list shows different COPs for three different sizes but lists both the same heat and nominal heat outputs. In online shops, the nominal heating capacity is the same, but the maximum heating capacities differ depending on the size:
I would guess that the devices are almost identical.
They only differ in details like the amount of refrigerant, a slightly different valve.
Therefore, one is slightly more efficient, the other delivers a bit more peak output...
But what do I have to pay attention to when designing? Which power rating can I use if I initially trust the heat load calculator from , which came out to about 7kW?
There are different approaches. Some design for monovalent operation, meaning the heat pump should be able to cover the heating capacity even at outside design temperature (NAT).
It is also often recommended to undersize, for example design for -5/-7 degrees and cover the small remaining demand with the electric heater.
Overall, you should not select the heat pump without considering the design of the heating circuits.
Because not only the heating capacity but also pump performance, flow rate, delta T, etc., play a role.