worcester 240 combi boiler pressure goes down all the time water going out the overflow pipe is it a core plug that has blown or a diaphragm thats sticking

paul, March 2006

true what craig answered, but could just be safety valve/ pressure relief valve letting by.(if you followed his instuctions then prv probably requires replacing now anyway!)

mm, March 2006

your expansion vessel is flat - easy to sort. open the pressure relief valve in the boiler and attatch a foot pump to the big red vessel in the boiler and pressurise to 1 bar. if you are doin it right, water will keep comin out the 'overflow' and eventually stop. close pressure relief valve (the one with the red top) and re-pressurise boiler. if this doesnt cure it, the expansion vessel needs replacing.

Craig, Plymouth, March 2006