I recently changed the expansion vessel on a worcester 240 combi. The pilot light wont stay lit when I try to relight it. I have checked the thermocouple and am getting 12 millivolts . . .
check pilot is clean and playing on t/c lead.if it is then could be faulty t/c lead. or interupter (easily wired out )or gas valve. look for poss reset button on boiler .
