Heating (Heat Pump) Incorrect, heat output too high?

Good day,

my newly built semi-detached house (approx. 150 sqm without basement KfW55) is now almost 10 months old. The air-to-water heat pump is also working well. However, what has now become apparent is that a couple of friends also built a new semi-detached house (same developer, without basement KfW55) and have the same heating system but with 50% less heating capacity, even though their house is 250 sqm!

I would prefer not to operate my heating system inefficiently in terms of energy, and besides that, I also paid more for the heating system!

Who should I contact? The developer says nothing about it.

There is a heating load calculation for that. You have it handed to you. Then you know if it fits.

I already asked about that - no response.

Didn't you look into the things you buy before building the house? Every crappy phone for 300€ is compared online for hours, but none of this happens when building a house (at least for so many). Or do you also complain later when buying a car that the V8 consumes more than the same car of your neighbors who drive a diesel?

Well, take it slow. Who, please, builds with a [Bauträger] and gets a heating load calculation in advance? Sorry, that's nonsense. That's exactly why you use a [Bauträger].

Maintenance-free regards

Well, slow down. Who, please, builds with a property developer and has a heat load calculation done in advance? Sorry, that’s nonsense. That’s exactly why you use a property developer.

Maintenance-free greetings

Well, I would at least want to know what is being installed in my house ;-)
For that, I would also have the construction service description checked – at the latest, such inconsistencies should become apparent there. A heat load calculation is not necessary for that. A 20kW heat pump for a small house, for example, should be noticeable immediately.