Experiences with IDM salt heat pump?

Now seriously??? It only modulates down to 6 kW... and why do you need 17 kW? Are you trying to tell me that with your 1300m³ (I assume you mean cubic meters ;) ) you come to a heating load of 17 kW?

What heating load did your building physicist calculate??
The "smaller" model of the Terra can already do 3-13 kW. And that should not be enough??

The nominal power according to the device data sheet is 11.42 kW. We have a heating load of over 11 kW. That was initially the device that was offered to us. The appointment with the HLS person is still pending.

Ah ok. Still, 11kw heating load would be ultra much. Have you ever roughly calculated that with the crinktool? You can try using the search engine. You only need a few data points for that. Are you currently building according to the Energy Saving Ordinance? Without ventilation? Rated power means by the way at about half speed. It makes no sense to design it that way. I would urgently advise you to read up a bit more on the topic before the appointment...

Room-by-room heating load calculation according to DIN was done? 11 kW for a modern new building is unusually high

Thank you for the note. We had quickly replaced the heating load just before Christmas because we needed it for the drilling offer. Maybe an error occurred there as well. I have exactly all the data that the Crinktool queries. Here I come to 7,844 W including ventilation, hot water, and heating. We are building KFW 55 and with ventilation including heat recovery.

Now that sounds better. You really have to be careful because some people build in a bit too many "reserves." Additionally, you must not forget that this is all without solar gains and only a sizing based on NAT. So the few coldest days of the year. You can browse a bit through the neighboring threads here about that. We currently have/had the stress test. For that, you have to know with IDM that the nominal power is at half the speed or something like that. The smaller model would probably be more than enough for you. If you took the mentioned 6-13KW, just imagine what would happen around 0 degrees if your house maybe only has a 3kw heating load (randomly chosen number). It would be cycling. For that, no modulating is needed.