When turning on the Central Heating and leaving it for approx. 30mins, the pressure keeps going over the blue zone onto 3 bars. I have bled all rads so no air in the system.

Can anyone please advise? Thanks.

Sohail, November 2008

sounds like the expansion vessel is broken , easy way to test it is to find valve on expansion vessel , its a small tyre valve on top of vessel . remove valve cap and depress pin in valve , if water comes out diaphragm in vessel has failed and vessel must be replaced . hope this helps

christian boiler man, November 2008