New underfloor heating system with heat pump is losing pressure

hello everyone, today (after 6 months) the pressure is back at 1.4 bar. I have to refill water again today. This time I only filled it up to 2 bar. That means, every month my underfloor heating loses 0.1 bar. The heating engineer said that this is normal. About 4 liters of water have flowed out in total through safety valves (from the tank, underfloor heating...). Question: - is this normal? - how often do you have to refill water in your underfloor heating? THANK YOU for your answers and I wish you a nice weekend.

About safety valves (from the tank, underfloor heating...) a total of approximately 4 liters of water has flowed out

What?

Please specify. Where exactly is something leaking?

In 7 years I have refilled once.. and that only because a valve was leaking in the [khv].

About safety valves (from the tank, underfloor heating...) a total of about 4 liters of water have leaked out

These are supposed to be SAFETY valves for emergencies. Regular dripping = incorrect planning / execution / botching

How often do you have to refill water in your underfloor heating?

Once in the last 10 months - but that was because after commissioning I had to vent 2 more times. Otherwise no refilling. Pressure stable at 1.5 bar.

I have never refilled.

Remember to send it by registered mail with a deadline. Nobody came to us either regarding the electricity. Kind regards Gabriele