When the boiler fires up and heats the system, the pressure gauge rises quickly and i have to drain the system twice a day.
Do you know what could be wrong with it?

Ian, September 2008

Oh.. durrr. My fault.

If you have your pressure set normally at 1.5 bar, and when you put your heating on it flies up to 3 or 4 (and then will drop like a stone when the prv blows), then it could be an expansion vessel problem as well.

Sorry.

BunSlinger, September 2008

The pressure gauge is supposed to rise when the heating is on. It'll usually go up by about half to a whole bar.

You should have your system pressure at about 1 and a quarter when the boiler is cold.

If it's much higher than this, you might be causing yourself problems - the pressure relief valve in the boiler is set to blow at 3 bar, so if your pressure is normally at 2 to 2 and a half, then it will rise to 3 when your heating is on and the prv will blow.

Check your pressure when cold, make sure it's not too high.

BunSlinger, September 2008