when boiler is not running pressure falls to below 0.5 bar within 30 mins. when i refill to 0.75 bar boiler ignites and pressure rises to 3 bar in around 10 mins. The iso valve is ok and no leaks on system.

tony o, November 2009

Had the same problem, the tech guy just re-pressurized my expansion vessel and everything looks fine so far!

Nikava, January 2010

Got the same problem. CH guy changed the Pressure relief valve ( which was leaking) first £ 10 parts and then changed the expansion vessel £42 parts, labour extra.

Apparently there is a rubber diaphragm in the expansion vessel that goes porous and leaks.Throw all the pressures haywire. Pressure builds up to 3 bar and then overflows, loses pressure after a couple of hours and can't reignite. Job easy to do 1.5 hours approx.

Just been fixed. Tell you tomorrow if it works. CH engineer is confident it will be OK.

Bob Wild, December 2009

check the pressure in the expansion vessel it wants to
be about 1 bar
you will need to drop the pressure in the rads first

b, November 2009