boiler pressure goes to high and comes out pressure relief valve

Joe Hughes, January 2008

I lose pressure when i have the central heating on ie water starts to leak from the overflow pipe then the boiler pressure drops below 1 bar can you tell me what causes this

cihan, May 2012

Sounds like the diaphram on the expansion chamber may have gone. You can tell if there is water at the air valve. I drained a small unused rad and reconnected it without bleeding. The air trapped inside will act as an expansion cushion. You will need a new exp. chamber, but this does not have to be fitted to the boiler. If it is, the boiler has to come off the wall.

John Dickens, October 2010

got the same problem

Liviu, February 2008

Refill expansion tank

bendan, February 2008