Heat pump for KfW55 house 148 sqm

An oversized heating system simply consumes more electricity than necessary. You are building an energy-efficient house and the heating system is inefficient. That’s just rubbish. Can’t you talk to the general contractor so that you can speak with the executing company? You handle the daily business with the site manager, but when it comes to details, the individual trades are addressed directly. This approach is working very well for us at the moment :)

A larger modulating heat pump does not run at 100% continuously 24/7, but rather runs the compressor at a correspondingly low level. If it exceeds the supply temperature, it will cycle accordingly.

Our current coefficient of performance for heating is 5.6-6.1 despite oversizing... you can definitely get that running :)

An oversized heating system simply consumes more electricity than necessary. You are building an energy-efficient house and the heating system is inefficient. That is nonsense. Can't you talk to the general contractor so that you can speak directly with the executing company? You handle the daily business with the site manager, but when it comes to details, the individual trades are addressed directly. This approach is working very well for us at the moment :)

Good idea! I've been doing that for months, and I personally get along better with the heating technician than with the site manager or general contractor representative. But what's the use? He can't get the heating system to work...
And since he has a cooperation with the general contractor, of course, he will get me the heating system faster and cheaper because I bring him many follow-up orders... oh no, wait... my recommendation doesn't help the installer at all, he lives off the general contractor...

And where exactly does an oversized heating system consume more electricity than necessary???
Especially with air-to-water heat pumps, it is recommended to choose a size a bit larger rather than too small.

Our coefficient of performance for heating is currently 5.6-6.1 despite oversizing... you can definitely get that running :)

But that is geothermal energy in an extremely mild winter...

Especially with air-to-water heat pumps, it is advised to choose a size slightly larger rather than one that is too small.

Yep - that’s what a clueless and uninformed heating engineer would do ;) .

Anyone who really knows their stuff sizes appropriately (and first calculates correctly) or prefers something a bit smaller.

Search for "Bosch Planungstool Wärmepumpe" and enter your data. At the end, a performance curve will appear. If you now look at the minimum output the heat pump can provide and then overlay it with the building curve, the heat pump is too large wherever it is above the building curve and cycles.

A larger heat pump cannot modulate down as far as a big one. Therefore, you should always plan and select appropriately.

Regarding cycling: It is not bad at all if the heat pump starts 15 times during the transition period. The only important thing is the minimum run time due to oil return, lubrication, etc.

Even if it cycles 15 times per day throughout the entire heating season, it has an expected lifespan of over 50 years!