PRVs?

[MickyP10]

Hi

Losing pressure (mostly) when cold, about 10 psi overnight. Have changed rad TRV gland seals, a weeping motorised valve, pressure vessel, fitted two new AAVs, tried leak sealer and it's still as bad. Although the overflow outlet is bone dry, could it be the PRV? No visible water leaks anywhere.

Boiler's a Firebird S 90

Any ideas on the next step welcome.

 

[oilman]

If the overflow's dry, then it's unlikely to be the PRV. Do you have pipes buried in concrete floors?

 

[MickyP10]

Sadly, yes...

 

[MickyP10]

Is there a dye which I can insert which will help make leak detection easier?