Combi Boiler Problem

[gerry-k]

I have a Vokera Compact boiler and the pressure keeps rising to over 3 bar and the release valve opens taking pressure back down to 1 This has been happening for a few weeks and recently happens even when heating is off and boiler itself is switched off. Also have disconnected top up valve so no water is getting in Any suggestions?

[jam79]

could be the expansion vessel that has gone or needs recharging