Boiler going on/off independently of timer & no heating?
I have a Vaillant Combi-boiler VCW-GB 242E. It is continually switching on & off heating the water to boiling point, it seems, even when the timer is either off or on timed. We have no heating at all.
Most likely problem is the water section has leaked through the stuffing box, this 'gums' up the push rod above which (sounds like) is sticking the servo valve in the H/W demand position, this would indicate what you describe.
Solution: Replace the water section/stuffing box, clean the push rod above it, grease and replace. You will need to push the servo valve to one side to access the push rod.
Carefree
October 2010
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