UFH loss pressure 0 when off

[Rospetal1]

Just recently installed UFH .When all radiators and Ufh are on pressure normal floors are warm radiates are warm .When anything is turned off pressure drops to 0 with Worcester boiler flashing
I have isloated it to the UFH and not boiler or radiatets could this be anything other than a leak as all flooring on but when all systems are on pressure is stable and I have tested this several times.ask stressed any advice would be helpful

 

[ShaunCorbs]

Need to find where the waters going can you install a pressure guage on the ufh and leave it at 2.5 bar over a week ?

 

[Rospetal1]

I was told to isolate and do a test to see if it’s UFH that is the issue with pressure loss and it was found that it was that and not the boiler or central heating . sorry I’m a complete beginner no plumbing or diy experience will this mean all my tiled flooring will need to be removed to determine a leak?

 

[ShaunCorbs]

I was told to isolate and do a test to see if it’s UFH that is the issue with pressure loss and it was found that it was that and not the boiler or central heating . sorry I’m a complete beginner no plumbing or diy experience will this mean all my tiled flooring will need to be removed to determine a leak?

It might be or it could be an expansion issue need to put a guage on the ufh when it’s isolated