New underfloor heating system with heat pump is losing pressure

Hello everyone,
I've noticed for a few weeks that the underfloor heating is losing pressure. The first time the heat pump (HSPE Daikin) showed errors. Afterwards, I saw that the (water pressure) in the boiler dropped below 2 bar. After consulting with the heating technician, I refilled water and increased the pressure to 2.7 bar. After about 6 weeks, it's now about 2 bar again.
That means the underfloor heating loses about 0.1 bar every week.
Question:
Is this normal?

In summer, the underfloor heating probably does not run. Could it be related to that? Should I expect a leak?
THANKS for your answers.

Somewhere the pressure has to go. Have you checked the heating circuit distributor? Maybe a wrongly set or defective safety valve that releases pressure into a waste water pipe? But generally, that's quite a lot, something is wrong. Get the technician to come!

I suspect a defective (leaking) expansion vessel. But if the client doesn't even know (is sure) when the underfloor heating is on or off, I strongly recommend staying away from the system. Besides, this is a new building where the installer must please fix it free of charge.

Then I see that the (water pressure) in the boiler drops below 2 bar.

Which boiler? It is a heat pump, so why a boiler?

After consulting the heating engineer, I refilled water and increased the pressure to 2.7 bar.

Awesome! Normally, the heating system should operate at around +/- 1.5 bar.

Question:
Is that normal?

No!

In summer, the underfloor heating probably does not run. Could that have something to do with it? Should I expect a leak?

But the pressure is still present in the system. And hot water is also produced with it.

Should I expect a leak?

Either it is leaking, or water is escaping through the safety valve. Who knows what kind of safety valve was installed. After all, you are running a huge pressure of 2.7 bar.

sorry, I think: - it is only one tank (instead of boiler). - I mixed it up. It is 1.5 bar instead of 2.5 bar I don't see any dripping at the heating circuit distributor or at the tank. I have now reported it to the builder. He should check it. Let's see how it works.

That's exactly the MAG I meant. However, I would have rather suspected a plastic container…