Best options for finding a CH pressure leak

[dwaindigital]

I have a pressure leak on my CH system. Our piping is buried in the walls (maybe a mistake) and the room-to-room pipes are now covered by flooring making it difficult to detect any leaks if there is no yellowing happening on the ceilings below.
We have noticed that we need to top up the system every 2-3 weeks, as the pressure drops from 1.2 bar to 0.8 bar gradually, Then my Vaillant system flags it in the app (Ecotec 637 (37kw))
I have checked the expansion vessel no dripping or faulty to my knowledge, I have not been able to locate any leaks either from the exposed pipes in the loft.
Rads are only a year old and have been bled. I worried if I keep adding fresh water to the system that it will cause rusting.

I don't want to use leak sealer so what are my options?

Thanks in advance.

 

[king of pipes]

This may be of interest it's often difficult to find small leaks it really depends on how hands on you are ? Kop

 

[Chuck]

Use the search box on the top right of the page to search for 'losing pressure' and you'll find many good suggestions and useful insights.