Hi i have a Ferroli F24 Combi boiler and the pressure keeps dropping, there seems to be no leak on the system altho the prssure release valves seems to have started dripping, everytime i put more pressure into the system it starts escaping thru the external pipe for the PRV. what is the cause for this? I have been told it may be the expansion vessel? Any suggestions?

Tony, December 2008

I believe most pressure relief valves open at about 3 bar and I've read that once they've been actuated they often fail to reseat fully resulting in a gradual leak. You could try manually opening it a couple of times (when the system is cold) to try and wash away any debris in the hope it will then seat properly. I think you may have to twist/push or pull it to make it open. It wont do any harm and may cure it. If that fails you will probably have to replace the valve. You need to think about why the valve opned in the first place - ie why did the system pressure get so high? Is the pressure vessel properly charged?

Richard, December 2008