How do I fix my worcester bosch Heating Boiler?

if your system pressure is rising when heating is on it is likely you have a prob with the expansion vessel. if the pressure rises from "0" to 3 bar when heating etc is off then your boiler is leaking through the heat exchanger. Either the plate or gas to water depending on which boiler you own.
best of luck

boilerdoktor
May 2009

re-pressurize expantion vessel

b
May 2009