My Vaillant VCW 242 EH cuts out when upto temperature. When its fires first time it stays on for 2-3 minutes, then nocks off (doesn't trip), when it fires back up it stays on for 20seconds then nocks off again. This process then repeats itself. I've replaced the flame supervision PCB, also the NTC resistor. I've got a Flame sensor electrode on order. Does anybody what it could be if its not the electrode?????????

Simon Richardson, November 2006

This is not an electrical problem. Sounds to me like it is modulating from high gas to low gas then off, when it's cooled down a little it repeats this. This is due to a circulation problem, mucked up system/sludge/blockage/slow running pump etc.... These boilers are very relyable but most engineer don't know much about them so instead of attempting to repair them they quote for a new appliance. Best advice is to get someone that has experience with this boiler. Hope that helps!

Andy, heating engineer., December 2006

Might be filter on return pipe at boiler is partially blocked. Had same problem with Baxi and this fixed problem.

Houston, November 2006