Combi Boiler

[discobobby]

I have a Worcester combi boiler, every other day the gauge keeps going down, I cant find any leaks, why does this happen.
Any good heating guys out there who can help?

many thanks
Bob

[ABlonde]

Hi, I know nothing about heating or plumbing but I had the same problem a month ago. The plumber who came round looked at the obvious (nothing) , and then checked outside where the vent and pipework comes out of the wall, and there was a little drip. He said it was likely that there was a defect in the rubber washer from the expansion vessel. When he opened it up, there was some scale/calcification all round the inner side of the joint where the washer sat. (Live in a very hard water area.) He said in his experience just that little bit of grit can stop the washer making a seal, there's a slow drip outside that you don't notice, but the system loses pressure.
He cleaned all the scale off, put new washer in, and hey presto, no problems since.