LW Heat Pump Alpha Innotec LWDV with 12KW

So yesterday the heating engineer got in touch. He will not install the air-to-water heat pump 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 domestic hot water heat pump is also not eligible for funding because the storage tank is too poorly insulated. I give up.

Then he should install another eligible domestic hot water storage tank....!!

He definitely wants to install the 12KW air pump because he’s afraid that the smaller one won’t be sufficient and then you’ll come to him for compensation.

May I ask what the insulation of your house looks like so that you come to Ht 0.16?

In addition, the hot water storage subsidy is only 500€. It is a checkbox on the Bafa application and is called the "Efficiency Bonus". If the hot water storage is too poor, there is still the 4000€ basic subsidy for the water heat pump! Your heating engineer really has deficits here!!!!

Also, I don't understand why he simply doesn't offer an eligible storage tank....?

Regarding the eligible storage: it must of course be compatible with the heat pump. He doesn’t know whether it is as good as the poorly insulated storage tank.

About the insulation: actually a wooden house with 42 cm walls (cellulose and wood fiberboard) with the floor slab that has 18 cm insulation. Everything else basically standard.

Regarding the heating technician: I have no idea according to which criteria the calculations are made. Actually, I have to look for alternatives and I am an amateur. Other heating technicians don’t even get back to me. Maybe I’m thinking too complicated. If someone in my region knows a good and honest heating engineer/plumber, please send me a private message.

Sh-Tec Schweitenkirchen, Schmidhuber Attenkirchen

How many liters of hot water should the storage tank have? The above-mentioned storage tank was recommended to me in the Haus technikdialog forum because of the particularly thick insulation as well as the enormously large internal heat exchanger surface (better efficiency).

Currently, 300l domestic hot water and 200l buffer storage are offered. Efficiency class C. : Which storage do you mean?

What buffer? How installed? Why a buffer? You are building with underfloor heating! The storage capacity of 200l of water compared to the storage capacity of the screed of such a huge house is like a flyspeck on the floor. If there is no truly rational reason for the storage, cancel it! Why does the heating engineer simply calculate with an HT of 0.22 when the energy consultant calculated 0.16? That is quite a big difference. This all screams for outsourcing the calculation or doing it yourself.