my Glow-worm combi boiler keeps over pressurizing when on?

I suspect this is the pressure vessel needs recharging it has no air in it or it could need replacing.Another common fault on this particular boiler is the chrome braided hose connecting the pressure vessel to the primary circut is blocked this will need removing and cleaning out probably a good exercise to do both.This will solve the problem.

Mark Heatline
January 2010