Cooling with heat pump via underfloor heating?

Well, there are no problems with air conditioning systems. System on = cold... end of story. So I can’t understand the objection. On the other hand, there are problems with cooling via underfloor heating since it is rather homeopathic in nature, so the contributions in such a thread should always prevail.

Huh? The point is that this thread is not the right place to discuss the design and dimensioning of the air conditioning system.
I have absolutely nothing against negative EXPERIENCE reports prevailing in a thread.

But I also don’t go into a Dacia forum and write in every thread that people should please buy a Mercedes. Because I have one and am satisfied. "I have never sat in a Dacia, but whatever! It can only be rubbish. And now let’s please only talk about Mercedes here in the forum!"

Exactly, no one here is discussing the design and sizing of air conditioning systems anyway, so all is good.

I am not going to bother to look up all the posts from this thread for you in which the question was answered about which air conditioning unit was installed. How one could then best do it with the Open-Door solution. Whether an outdoor unit makes more sense and where the unit could be positioned. And last but not least, how best to manage the ceiling outlet for the air conditioning. To lower the ceiling or not? It's actually impossible to miss.

We have also had a ground source heat pump with passive cooling in operation for 1 year and think it’s great. I can confirm the mentioned 3°C difference, of course shading is still necessary, otherwise the heat input is simply too high. The cool floor does not bother us at all; on the contrary, it is even very pleasant during extreme summer heat. With tiled floors it is naturally more noticeable, with rooms with laminate flooring the difference between cooling on/off can hardly be reliably felt on the perceived floor temperature.

The biggest advantage is also the low electricity consumption, since only 2 circulation pumps have to run.

We are still looking for a solution to one problem. Since the heating circuits are set according to thermal balancing, the required flow rate reverses during cooling. The bedroom has the lowest heating water demand but the highest cooling demand. That means adjusting the flow rates twice a year. Are there actually control valves that can hold intermediate positions? KNX is installed in the house.

We have also been operating a brine heat pump with passive cooling for 1 year and find it great. I can confirm the mentioned 3°C difference,

how deep? how many pipes?

(sorry if it's a bit off-topic)

130m on one borehole (heated area 228m², of which 39m² in the basement only as needed).