Technical comparison of air-to-water heat pump

It is always about the design temperature, i.e. Nat. If the heating is calculated at 30 degrees flow temperature, the rooms must be laid out accordingly. This means in most cases that more area is covered than at 35 degrees; as a result, the flow temperature naturally decreases correspondingly in real operation. I just spoke today with a craftsman who can run his Nibe heat pump at 23/24 degrees flow temperature.

It is always about the design temperature, i.e., Nat.
If the heating is calculated at 30 degrees supply temperature, the rooms must be laid out accordingly.
This usually means that more area is covered than at 35 degrees; as a result, the supply temperature naturally also drops accordingly in real operation.
I just spoke today with a craftsman who can run his Nibe heat pump with a 23/24 degree supply temperature.

Sounds logical: the tighter the underfloor heating pipes, the larger the area, the lower the supply temperature. But: try explaining that as a layperson to a craftsman. One who is fixed in position because the general contractor hired him.

Sure: you can exclude the heating from the GC package. Consequences: no warranty, no support for the overall package (own energy consultant necessary for KfW), risk of even getting a craftsman in a timely manner, etc.

Just happened to me. The (only!!!) heating and sanitary subcontractor of my general contractor dropped out because I wanted an efficient design and installation plan. I was even willing to provide a new one from the building services engineer myself, then I received the information without comment that he will not carry out my project. See also here:
https://www.hausbau-forum.de/threads/heizlastberechnung-verlegeplan-din-neue-berechnung-notwendig.36961/post-445657
https://www.hausbau-forum.de/threads/lage-stadtvilla-oder-efh-auf-500-m2-rechteck.33505/post-446544

As Tolentino already writes, it depends on the Gu and the HB.

My HB probably also hinted that he is a bit of a "difficult customer" to the GU, but still did everything the way I wanted, although he was already well positioned beforehand.

Since I have a direct contractual relationship, although everything is organized and scheduled through the GU, it was easier for me.

The price was just adjusted according to the additional work and then it went smoothly.

For the heat pump, I would inquire 9 KW is a lot and minimum power 5 kw is also a lot

Can run 23/24 degrees flow temperature.

I think the also runs 24.5 with 1 hysteresis. As far as I have read. I myself run with my on-off heat pump 27/22