We've added a bit of extra pressure to the boiler as it dropped below .5 but now it is reading nearly 3 we have let some pressure out of the radiator's and it dropped but it now keeps re-pressurising itself. The boiler is a Worcester 240 and is about 14 years old. TIA

Kaz x, November 2008

Also is the pressure rising with the c/heating on. If it is it could be a faulty expansion vessel-which is designed to keep system pressure level as the c/heating system water expands when its temperature rises.

daz71, November 2008

sounds like u have not shut off the filling tap properly

matt, November 2008

When you pressurized did you leave filling loop open. If you didn't then it sounds like you have mains pressure from the domestic hot water side of the boiler getting into c/heating side maybe through water to water heat exchanger. But only speculation as i don't have enough facts. p.s. Don't add pressure with c/heating on.

daz71, November 2008