Hi. Recently the pressure in my boiler constantly drops to practically zero. To turn the heating on I release water into the boiler to bring the pressure back up to 1 bar. After the heating being on for about 15 minutes the pressure shoots up to over 3 bar at which stage I turn off the heating so it doesn't explode. The pressure quickly drops to below 1 bar again. Does anyone know what could be causing this?

Gerty, March 2010

the expansion vessel is kaput

ian, March 2010

your boiler expansion vessel is possibly EMPTY and needs a recharge of AIR via a car foot pump,find the valve on expansion vessel, remove the cap,test pressure then inflate via the car valve to about 1 bar, or approx 15 psi. then re pressurize the waterside backup to 1 to 1.5 bar

wirecutterman, March 2010