Heat pump for KfW55 house 148 sqm

Our project: 2 full floors No basement 148 sqm KFW55

based on this data something around 4 kW....(unless it is built on the Zugspitze...)

In our energy demand calculation a 6kW air-to-water heat pump is proposed.

This paper is practically useless...

But in the heating load calculation there is an 8kW air-to-air heat pump in the plan.

And in a "proper" heating load calculation there is no heat pump at all, but only the heating load of the individual rooms and of course the total heating load. I would definitely stay away from that. Just out of interest: How many heating circuits does the "hut" have?

That's right, there are two documents, the "solution" is still attached to the heating load calculation, a printout from the heating solution navigator. The Daikin 8kW is suggested there.

We have 13 heating circuits. One for each room, the hallway (downstairs) and corridor (upstairs) each have one as well. The open space with kitchen, dining, living has 3 heating circuits. The bathrooms also have only one each, but positioned a bit tighter and extending into the shower.

What exactly would you steer clear of?

Open space with kitchen, dining, living has 3 heating circuits

it's probably 50-60 sqm, so 3 heating circuits are "very manageable"...

Maybe you do need a bigger heat pump because the pipe spacing is "relatively" large.
How big is the VA in the individual rooms?
What target/designed temperature did you specify?
What wall construction?

What exactly would you avoid?

Taking care of the heat pump...

The installation spacing is 15 cm, in the bathrooms 5-10 cm. This is estimated based on photos; we do not have a document in which the installation spacing is specified. Our open-plan room is 42 sqm, that is kitchen, dining, living. A target temperature of 20°C was calculated, in the bathrooms 24°C. There we also have electric heaters as supplementary heating. Wall construction lightweight expanded clay concrete elements exterior wall and load-bearing interior walls 15 cm, non-load-bearing interior walls 12 cm. Outside mineral wool plaster carrier boards, 16 cm, WLG 35. In the heating load calculation, a standard heating load is calculated for each room, plus a surcharge for the heating-up power. All added together, the standard heating load is 6233 W. Interestingly, the heating load for the hallway and corridor is even negative, so it is heated by the adjacent rooms? Outdoor temperature reference location -12°C

The laying distance can be estimated relatively easily. When taking pictures, you will have "jumped in" there at some point.
I wear size 46 shoes; with a 10cm laying distance, you have to "aim" very precisely to step between the pipes. At 15cm, you have plenty of room to walk around.

With the planned provision of the heat pump or even the entire installation done on your own, you can turn it any way you want. If you do it completely yourself through your own installer, you bear sole responsibility for everything that follows. The general contractor will always assume in case of damage that he installed everything correctly and that your installer messed up.
The same applies if you procure the heat pump yourself, i.e., provide it to the general contractor. How is he supposed to guarantee that?

Either way, you lose all claims under a construction time guarantee.

And the project is not particularly realistic. Because where else do you want to get a heat pump faster in the current situation than your general contractor or his installer?
If you knew an installer so well that he could get it for you, you would be asking him these questions here ;)

So. Let the general contractor do it. You won't get it done faster on your own either.

And if things go really badly, you might even end up arguing with your GU over change orders because you delayed the construction process with your "own work".