when my heating is set on a timer for the morning it turns its self on but when i go to use the hot water first thing it turns the boiler off and will not re start for about 10 minutes later. it will give hot water but no heating for this time.

EMYR ADAMS, October 2008

which vaillant cmbi is it? if its vcw 242e then you have problem with yous servo valve or micro pipes to servo valves are blockrd.

universal heating ltd, October 2008