Heat pump for KfW55 house 148 sqm

I actually fully agree with you, but
this here

which, by the way, is integrated in the heat pump and not in the storage, maybe that's your mistake

is not always true. In Vaillant Arotherm, it is located in the Unitower. However, it must be said that the Unitower is not only storage but also partly control for the actual monoblock heat pump, which, by the way, can be operated both monovalent and bivalent.
In this respect, ’s description is misleading anyway. There are not exclusively monovalent or bivalent heat pumps. Maybe there are some, but there are definitely many that can do both. I would even go so far as to say that among the heat pumps sized for single-family homes, those prevail that can do both, and it is all just a matter of settings. So it is more an operating mode and not a type of heat pump.

Daniel-Sp no problem, you probably won't be doing any TGA calculations either,...


Techn_FAQ point 2.03
For a KfW efficiency house 55 according to reference values, there is a requirement to install a ventilation system in the building. This also applies, for example, to the installation of centralized residential systems in a multi-family house, which must therefore be installed in at least all apartments.

In the Vaillant arotherm, it is located in the Unitower. However, it should be noted that the Unitower is not only a storage unit but also partly controls the actual monobloc heat pump, which can be operated both monovalently and bivalently.

Yes, it was not fully formulated by me. Of course, this is model-specific. I meant to express that this is not a separately installed heating element used to always heat the water with it, but rather that it is a backup and usually part of the system.

The monovalent systems are designed differently, see the operating limit temperature specifications.
Or the other way around, you cannot operate a bivalent heat pump like a monovalent one.
Not least because of the inferior refrigerants.

For a KfW Efficiency House 55 according to reference values ....

This is the alternative proof. You have to calculate less and it is sufficient to meet the reference values.

With the calculated proof of meeting the requirement, no ventilation system is needed.

...I give up because I have no more desire. Maybe someone else wants to...

Just want to note for everyone following the thread or digging it up later that in my opinion writes completely incorrect content-wise things

In the calculation verification, you must arrive at the same values and compare them against the reference house.
You already have problems today if you leave out the heat recovery.