sorry space the gas already tried your suggestions could not find blockageand ive aready replaced pressure release valve so i assumed it was a fault with the expansion tank .what do you think?
thanks to space the heat for confirming my suspicions on the expansion tank front, i just wanted a second opinion before the boiler was removed from the wall,will keep you posted thanks again
problem with the boiler is its keeps building pressure on the central heating until the saftey pressure release blows could any one help with this problem, as too which component needs replacing to rectify it .many thanks lee621