my worcester heatslave 18/25 system-one of the radiators we frequently have to bleed, as it goes cold,and then the pressure drops, and we have to top that up .is this usual
Expansion vessel has a torn diaphragm. I replace 60-70 of these a year. It needs to be replaced and the system volume needs to be calculated to make sure there is enough expansion volume (manufacturer states this). If it was me, I'd get an engineer to put a half inch cap on the heat exchanger tapping and fit you an 18L vessel minimum before any valve on the central heating system (close to boiler). Reason being is the Worcester vessel is dear (part number 87161425050) but an 18L standard vessel is about one third the price and will last longer. I have just fitted an 18/25 heatslave for a friend with a total of 30L expansion. I'd do this job for £100 locally so don't pay much more.
