Hi everyone, I am having problem with my 6 year old Worcester 28cdi rsf. the gauge is reading 2.8 bar, and is causing the pressure relief valve to discharge, even when the boiler is not running. I have reset the pressure via the relief valve back to 1.5 bar,but it soon creeps back up again. I don't think it is the diverter valve, as the hot water and the central heating seem to be working normally. Could it be the grey-nob valve next to the bayonet filling key? Or a duff diaphragm in the diverter valve? Any advise would be much appretiated.regards Mike