when i start my my Glow-worm combi boiler the pressure rises from 1.8 bar to 3 bar setting the prv off then it dumps the water out the overflow

john m, November 2009

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