i have a problem with my combi worcester cd35i ii the pressure of the unit is at just over 1 bar and when you either switch the hot water or the central heating on the relevant lights come on and the boiler kicks into action and the gas fires up, the pressure increases slowly to 1.5 bar then all of a sudden the pressure increases to just over 2bar and then the needle waves about and the boiler makes a banging noise as if there is an air lock and then switches reverting back to the standby mode and the pressure goes back to 1 bar, ive bled all the radiators, what else can i do or reset or change or is it an expensive plumber call out

andy, October 2010

the pump seams to be working from what i can hear but it does get hot to touch once you have started the boiler up a couple of times

andy, October 2010

the boiler is banging due to lack of circulation, it may be due to a siezed pump or a blocked heat exchanger, either way you will need the help of a good gas engineer in your area as you need to be Gas safe approved to work on gas.

andy the gas man, October 2010