All works fine then after 5 - 6 hrs cuts out on temperature then will only reset by turning mains power off then on again.
Tested APS and sensors all seem ok.

Dave Carter, April 2005

Definitely the ignition box, the solder joints crack around the realy pins and HT pins due the board sucessively heating up and cooling.
Use a jeweller's eye glass to inspect for the cracks, these are easily fixed by a soldering iron.

Very poor bit of PCB design for this to happen, shame on you Mr Sime!

Richard Blackman, April 2009

Hi thanks Joe, i have tried a new air pressure switch, but what your saying makes sense. this is one of the few boilers that i don't normally work on so i am in the dark on this. Many thanks for answer i will give it a go.

Regards.

Dave

Dave Carter, April 2005

hi dave it sounds very much like the problem is with the blue ignition box attatched to the side of the gas valve ,ihave found dry joints on relay which forms the latching circuit for the air pressure switch. as the pcb gets hot the relay remains in its closed position after the boiler reaches temperature preventing the boiler refiring until the electric has been removed and the reset button used to reclose the relay.the only other possibility is the air pressure switch being faulty but it is unusual for a fault like this.

joe waldron, April 2005