Glow Worm 38cxi Combi. Expansion Vessel fault??

[jui]

Hi guys, I have an extremely annoying problem. The pressure on the boiler is dropping by 1.0bar every 4 hours. The problem has been going on for about 4 weeks now. It is a Glow Worm 38cxi. I called glow worm out who told me that it must be a leak in the system and not the boiler at fault. So I called a thermal imaging company out who checked over the whole house and did not find a single leak. Then I personally checked under all the floorboards to check, but nothing.
I called Glow Worm again and they came out and replaced the PRV Valve, which at first slowed down the dropping of pressure, but now the pressure is dropping like it was before.

Could the problem be with the expansion vessel or some other part of the boiler?

Please could any other members on this forum give me some confirmation on this before the boiler engineer comes out agai on wednesday.

Any help/advice would be much appreciated.

 

[ferret]

what pressure are you putting in to start with jui ?

 

[jui]

I put in 1.1bar, that drops down to 0.4 within 2 to 3 hours.

 

[ferret]

definitely sounds like a leak somewhere , a vessel problem usually results in pressure rising then the prv blowing and pressure dropping