my boiler fires up for about 20 seconds then goes out and lockout light comes on, reset and just does the same over again.if i operate the air pressure switch manually and hold the air tube so the switch stays made the boiler works.its had new air pressure switch,new fan and i have checked the casing and flue for any holes or blockages where i could lose the air pressure found none, any ideas please i have had enough of it

dave derbyshire, January 2011

have done that brian still not working just want to hit it with a big hammer, hate ravenheat any other ideas please

dave derbyshire, January 2011

clean venturi tube on flue one of the rubber tubes goes to a spigot on the flue just above the fan remove and thoroughly clean the spigot hopefully this will cure the problem

brian, January 2011