how can i fix it ?

Declan, January 2012

the expansion tank in your boiler needs to be replaced it all depends the make and model of your boiler how difficult it is as some have to be taken off the wall

annon, January 2012

It will only go to 3, An overpressure release valve will then open, if it is going up that much, water getting into system, check fill loop valve, make sure it is turned off fully. Normal pressure cold system, usualy 1 bar, above that it could go to 3 on heating, depending on system size, If it has just started doing it, drain boiler down, make sure that expansion vessel is empty, refill system, If water filsl expansion vessle, no buffer for water expansion, so pressure will go up high

SD, January 2012