Having taken a radiator off the system and re-charging the water pressure to 1 bar I find my approx 5 year old Vaillant boiler (don't have model no) will not fire up and the lock out button keeps energising. This model has no digital code fault panel. Any ideas of what I can try as I cannot get it working?

Martin, October 2007

check air pressure switch if fan runs. top of boiler r/h side. if its black then these r cr*p so update to modified white one but observe blue and clear silicone hoses as these need to go on switch the right way. if boiler doesnt fire then switch hoses on switch and try again. dpmartin17@aol.com

paul, October 2007