The boiler only ignites when I give the case a thump. It the runs for a minute or two and then switches off. Another thump and it ignites again.I have checked all the electrical connetions to it and within the control box situated at the base of the boiler.I have also checked the tank thermostat and all the heating controls and I can find nothing.The fan on top runs free. the only other symptom is the central heating warming up more than the hot water. Any ideas

hans, December 2008

Have you checked the three port valve as this has the switch that flicks from heating to hot water and will always give priority to hot water, if the valve has stuck in the central heating position this could explain why your central heating is getting priority, plus if the valve is stuck this may be preventing your boiler from firing up and it is not getting the message to fire up iyswim. Just a suggestion I'm no expert.

cb, January 2009

Update about problem.... changed air pressure switch ( cost £40 ) and now working perfectly ; was told it can be a common problem with this type of pressure switch . ..

leighton, January 2009

I have exactly the same problem on my ideal classic ff260 boiler , A gas fitter looked at it a week ago and took the red pipe off the top of the fan casing and blew down it - you could hear the air pressure switch operate . He then put the pipe back on and the outer case .... and it now lit ok , . It has been fine for a week , but now it has began to do the same .

leighton, January 2009

http://www.howtomendit.com/answers.php?id=198090

Peccavi, December 2008