boiler pressure

[mjack]

I have a Sime Halstead combi-boiler (with no instructions). Boiler pressure reaches 4 bar when in heating mode, but the pressure release valve leaks at just under 2 bar, thus requiring constant top up to reach standard 1.5 bar pressure.
Can anybody offer a suggestion to this problem?
mjack

 

[oilman]

Sounds like the expansion vessel has failed. Stop trying to keep the pressure at 1.5 bar and have it as low as you can until the boiler won't work, then raise it a bit.

First though let all of the pressure off, and let some air INTO one of the upstairs radiators, this will act as a temporary expansion vessel, though not really big enough.

Then you need to get an engineer in unless you fancy changing the vessel yourself, and fairly soon IMO..

 

[mjack]

Many thanks for the information. Will give it a whirl. Appreciate your advice. Merry Christmas! and best wishes for the New Year.