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Posted by Nick (GDC registered!) on August 26, 2004 at 10:35:30:
In Reply to: Worcester 240 pilot solenoid valve problem posted by David on August 10, 2004 at 09:33:36:
I'm not a service engineer, just a dentist who's pretty experienced with electromechanical equipment, so take what I say with a small pinch of salt!
I've got a Worcester 280, which may be similar to yours - but maybe not!
The 280 has gas valve with 2 coils: one seems to be the main on/off one, the other adjusts the gas flow rate (and hence the flame size).
The former has a resistance of 1.5K Ohms, and is presumably mains-energised.
The resistance of the latter is about 120 Ohms, and should have a DC voltage of about 5-25 volts across it when the boiler's running.
Get hold of the "Installation and Servicing Instructions" booklet - it's superb, and tells you loads about how the boiler works, how to replace parts, and fault finding flow diagrams.
This suggests that you need to replace the whole valve if the coil is o/c, but presumably only because the coil isn't sold separately. If you bought a new valve, you could possibly transplant the coil from the new to the old, thereby saving yourself some messing about with gas connections. If you have to undo the gas connections (not too difficult), then you MUST check for gas soundness - at the very least, buy an aerosol of leak detector spray.
You can get the gas valve mail-order from internet retailers. Do a Google search, ideally with the "GC Number" from the parts list in the above pamphlet.
The only faults I've had with my Worcester to date were: (1)The Expansion Vessel's rubber diaphragm perished, leading to air in the radiators and falling system pressure, and (2) The Fan's bearings dried out and stopped it turning, which meant the boiler wouldn't light because the Air Pressure Switch detected that the fan wasn't creating a draught. I got it going with some WD40, but then replaced it for long-term peace of mind.
Don't forget that gas can be deadly, so get a pro in if you get out of your depth. But as you've found, not all pros know their stuff, esp. where electronics are concerned!
Good luck and let everyone know how you get on.
Nick.