Halstead ace high boiler has just had its fan replaced, but when new fan installed boiler will not ignite unless combustion chamber door is open! when its closed and screwed up it will not go into ignition process! although the fan and pump are both running! thought it might be the air pressure swithch but with new one installed same problem! flue is clear both internal and external!! halstead engineers juat keep asking me to change parts!! can some one please help!!!

alstewart, April 2010

Your boiler has air flow problem through flue terminal
it has to create air flow to active air switch to fire boiler and this is not happening.

k, April 2010

Yes, exactly as described. Boiler about 4 year old. You can get hot water providing the heating is on as well I'm not changing the diaphragm until the weather gets a bit warmer.

Peter McVea, April 2010