Looking for underfloor heating - ceiling heating?

Hello everyone, we bought an old two-family mining house in which we live in the ground floor apartment of 60 sqm. We completely renovated the ground floor and since I didn’t like the wooden floor, we decided on screed. We installed underfloor heating from the company Selfio. Since we have district heating, we had to buy an additional control element. However, it turned out that we have direct district heating. And now a complete box with a heat exchanger has to be purchased. This is offered directly via the district heating Moers or Dinslaken and costs €1200 plus installation. Now my question: I would like to keep the district heating system for the upstairs apartment and look for an alternative for the ground floor. I practically need a new heating system only for the underfloor heating on the ground floor. I’ve done a bit of research and keep coming across that heat pumps are the best for underfloor heating. But no idea which one and how big the buffer tank should be. Can you even heat with a heat pump all year round, because I read they work down to minus 15 degrees. Can someone help me with tips and more info? Regards from Moers

With heat pumps, the underfloor heating serves as the buffer tank. An additional storage tank is inefficient (that's how it was explained to me). The problem will be finding a device with the appropriate suitable power; also, the investment for one floor is proportionally higher than for both, since fixed costs remain the same (installation, for example). Why have a separate heating system for the ground floor?

Regarding the underfloor heating: did you pressure test it? We also want to buy from Selfio, but we don't dare to do the pressure testing ourselves – there is nothing about it in the installation manual. They do install it as well, but only from 100 sqm upwards. It will be difficult for us to clear that many square meters at once. How did you manage that?

Underfloor heating is available in different installation methods. Normally, the underfloor heating is installed based on the temperature that will flow through later and the required load. So, if you calculated with 50 degrees and now connect a heat pump, your apartment will not get warm. If you calculated with 35 degrees, then a heat pump can handle this. Do you want to produce hot water in addition to heating? Or do you obtain it differently?