I have a condensing fanned boiler the CSI 85T. The problem I have is with the central heating side in that whether it is on full time or timmer it does not work. It initially fires up the cuts out aftre about 20 seconds and that is that. Have tried to reset but to no avail. (The hot water is fine). Going through the fault finding sequence it indicates one of 2 possible causes the ignition control board or the diverter valve. My question here is is there anyway to test more positively which one is causing the problem?

Paul Mackenzie, January 2009

It's your fan control PCB capacitors... replace them

Use 1uF 400V or 275V metalised polyester

any electrical/tv repair shop can replace them for you.

The fan control PCB is the small one on the left hand side.

videoVandal, February 2009

hi paul haven't got the same boiler as you so not sure about your set up but to cheek my diverter valve there is a pipe on the heating system with a actuator on top should be labeled (a box with a motor with a switch on) this thing controls where the heat is going either to the water or heating or booth its return position is set to water (this is why you might be getting hot water) so check the actuator switch before you put the heating on now put the heating on and oviously the switch should of moved position's if it has not changed or keeps moving every 30 secounds approx you have found your problem and will have to replace the actuator which should cost £30-£40 for the part

:), January 2009