I've had to top up my Alpha HE CB33 combi boiler (which is, I think, about 6-7 years old) every day this week, and prior to turning up the CH temperature, it was every few days. Obviously this shouldn't be needed.
Today I finally had time in daylight to check the pressure relief exit (which is in an old coalshed), and sure enough, it's dripping very slightly when the boiler is running. Each time the boiler has failed to start I've topped the pressure up to the middle of the green area on the indicator- about 1 bar. When running, it's hitting around 2.5 bar when fully hot, which seems a bit high to me, but I have to admit I cannot remember what is normal, and the manual is no help, apart from stating that all pipework etc should be able to handle 3.0 bar.
Can anyone suggest if this is normal, or has perhaps the expansion vessel failed? If it makes any difference, it's a 7-radiator system on microbore in a 2 storey house.
If that's normal, seemingly the relief valve must be knackered. I'll be getting my friendly local boiler chap to do it, but it'd be nice to be able to be clued up beforehand. It's no emergency, as it's working, but obviously I don't want to introduce too much water, diluting the inhibitor.