won.t ignite newmainswitch . sensor .ingnitionsensor fitted

bert, October 2009

The PCB commonly fails often giving one of the following symptoms:
Fuse on PCB blown - boiler does nothing.
Pump runs but fan not running or erratic.
Pump and fan run but gas valve doesn't open (but check air pressure switch).
Pump, fan & gas valve operate but no spark ignition.
Boiler lights but shuts down after a few seconds because it doesn't detect flame (but check electrode leads and condensate trap if conncted).

PCBs are available on Ebay.

Phil T, June 2010

Change the air pressure switch if the fan runs and the boiler doesnt go to ignition. You can check this by turning on boiler and giving a sharp bang to top right hand side of casing,. if boiler fires then aps is faulty. remember however, to swap the aps requires removal of front combustion chamber cover for which you should be gas safe registered.

chris m - ravenheat specialist, November 2009

Do you hear the igniter click?
Its probably the fan about to fail, which does not create enough of a pressure drop inside the boiler to trigger the air pressure switch. This pressure switch initiates the igniter. Take care and only do the following if you are competant enough: If you take of the front cover remove the rubber tube from the flue inlet, turn on the boiler and gently blow in the tube, and the boiler ignites, then the fan is probably about to fail.

tre, October 2009