can anyone tell me why when my heating is on the boiler pressure keeps rising from 1Bar all the way up past 2bar at this point i switch it off because it might blow if it rises any more

j helliwell, June 2007

assuming that the pressure vessel is ok

you are going from one to two bar because of water expansion when heated.

I would only expect 1 to 1.5 bar

it could be you have a lot of radiators or the vessel needs replacing or re-charging.
At 3 bar the pressure relief valve will operate and excess water will be shot out through the wall. This is not dangerous but not desirable.

dave broadbent, June 2007