Ive had fitted a brand ne Vaillant Ecotec combi, hot water works fine heating doesnt, it cycles on and off for 2 seconds, but when the cold supply is turned off to the boiler and the boiler reset, heating works ......and no hot water as supply closed

any ideas before i call in Vaillant

Raj, February 2007

sound like your divertor valve sticking

gasmanuk, February 2007