LW Heat Pump Alpha Innotec LWDV with 12KW

Make sure to design the underfloor heating for 30 degrees supply and 23 degrees return.

Depending on the standard temperature, you will achieve an annual performance factor of 4.5 and qualify for Bafa.

You can calculate this using the annual performance factor calculator online.

with the above-mentioned LW heat pump, I also achieve a seasonal performance factor of 4.5 at -14 NormAT and standard flow/return temperature. With 30/23, the heating engineer told me that this is not realistic.

With such a good building envelope, this should presumably not be a problem. Look for an Excel file from HFrink. With it, you can also quite easily calculate the room-by-room heating load yourself and design the underfloor heating accordingly. I did it that way and presented it to my heating engineer. The journeyman then adhered to my calculation. I can now run all circuits completely open (except for the bedroom) and have the desired temperature in every room. Then you see what is actually possible. After that, you can classify the heating engineer's rough estimate.

Great idea, I'll do that. Thank you and everyone else for the great support.

So yesterday the heating engineer got in touch. He will not install the [LW-Wärmepumpe] because my heating load calculation is not realistic. His calculation with the high H'T value of 0.22 is realistic, and the 0.16 from the energy consultant is just theory. On the other hand, his hot water heat pump is also not eligible for funding because the tank is poorly insulated. I give up.

Best example of how it is currently being discussed in another thread.

The heating engineer does not have enough competence...

30/25 definitely works
With the Alpha possibly even 30/27 depending on the coolant

Another idea: With a shower pipe (heat recovery) you can reduce the hot water portion of the heat pump by a few percent and may still get funding.