Glowworm Ultimate 50FF & pilot light

raden said:

doesn't make any difference, the spark is derived from the HT transformer (which is totally insulated from the mains) and powered by the energy stored in a capacitor. If you conneceted the spark output directly to earth, it still wouldn't blow a fuse

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sorry I did not read the bit about the fuse blowing

of course you are right, what about the gasvalve could one of the solenoids cause this?

The question is "What is taking 10 seconds to blow the fuse?"

I can only think that it's a coil (pump, fan or GV) overheating and the insulation breaking down

Hi Guys, apologies for not posting earlier but I eventually got it fixed after changing half the parts

I changed the PCB and then the Electrode myself - no joy. A Heating Engineer (and Glowworm tech) suggested it was the gas valve so I arranged to get that replaced but that didn't fix it either.

I then got an Engineer who knew what he was doing and it turned out the pilot injector was partially blocked and not enough flame was getting through to turn off the ignition. He removed the blockage using a single strand of wire within a multi core cable. Chris looks like you were spot on.

I'm about £250 poorer but a little bit wiser.

Thanks for the advice guys.

So what was blowing the fuse? GV?

The fuse blowing got a bit weird. After I changed the electrode it stopped blowing the fuse. Then Engineer #1 unbolted the ignition head assembly from the boiler, switched on and the fuse blew again. Once Engineer #2 changed the GV, the fuse didn't blow whether the ignition head was bolted down or not. This possibly suggests the GV had a marginal problem and may have been about to pack in completely ??

I'm sure if the injector was unblocked first, the fuse wouldn't have blown as the boiler comes to life within a couple of ignition clicks.