2-family house KFW70 heating with air heat pump ventilation and exhaust ventilation

... Because very few systems are properly planned/dimensioned.

Who is responsible for this?
By the way, this is not limited to air heat pump systems, but applies to all heat generators! "Hope" is neither enforceable, a contractual component, nor a reasonable reason for a significant investment decision!

...So I am of the opinion that an air heat pump is a very expensive heating option nowadays, because as I said, it is mostly built according to a fixed pattern...

Neither the manufacturer nor the seller is responsible for this if the builder does not take his own responsibility into account!
How many air heat pump systems have you professionally planned, dimensioned, and supervised in practical operation exactly?

...A geothermal or groundwater heat pump is of course a completely different chapter...

Not at all! All heat generators fundamentally have market authorization. Whether they are actually suitable for the respective demand case is a completely different ball game!

......because hardly anyone can comply with the ventilation intervals...

Which ones?

.....Well, but the moisture must get out, and assuming one is employed, and I think that is the case when building a house...then one simply cannot ventilate 3-4 times a day because one simply is not there...

Why must one ventilate 3-4 times? Who believes this generalized sales myth?

....I have not regretted my decision and had a central controlled residential ventilation installed during the construction 2 years ago...everyone should have the extra 5-6 thousand EUR,...

Possible, but economically quite borderline! How much "ventilation loss energy" can I permanently buy with 5..6 thousand EUR? Completely aside from interest, depreciation, inflation rate, and current operating costs such as energy, filter changes, etc.
The comfort of controlled residential ventilation is undisputed, but absolutely necessary only in some cases and economically rather a pipe dream!
I understand if someone defends their own decision afterwards by all means.
However, a generally applicable "non-plus-ultra solution" cannot be derived from this!

Regards

yes, but how is a layperson supposed to find out if everything is properly dimensioned? In sales talks, they always calculate and show you that everything is precisely planned and dimensioned, but there is no guarantee.

yes, but how is a layperson supposed to find out if everything is properly sized? In sales talks, they always calculate and show you that everything is precisely planned and sized, but there is no guarantee.

You can gladly send me these calculations for formal verification. It takes me only a few minutes to recognize serious, formal errors, as I usually recognize the schemers relatively quickly! Aside from that, if someone actually offers no guarantee or warranty for their service, it is downright criminal to enter into a contractual relationship here without verification! regards

yes, no, so there is indeed a warranty. 10 years on the entire construction. only whether the HW pump also provides ENOUGH power to properly heat the apartment in winter, or the internal ventilation is SUFFICIENT to maintain the climate and achieve good air circulation, that is not commented on.

yes, no, well there is indeed a warranty. 10 years on the entire building. only whether the air-water heat pump provides ENOUGH power to properly heat the apartment in winter, or whether the internal ventilation is SUFFICIENT to maintain the climate and achieve good air circulation, that is not commented on.

This can certainly mean a major mistake in terms of consumption costs, depending on the intended period of use.
Moreover, it is not only the capacity of the air heat pump in the design case that is decisive, but over the entire accounting period!

With a short usage time, financial pain due to miscalculation is more likely to be temporary than with long-term use!
So check thoroughly before committing contractually on a permanent basis!
best regards

I have a detailed planning meeting on Wednesday. There I will receive all the data about the construction and the [anlagen]. I can then post them here again.