There is an electrical device that produces power from the heat of the flame and this power is taken to the gas valve through a mineral insulated cable that looks like a small pipe and is glanded into the valve. There are Universal replacements sold at places like Wickes with no instructions as it says it must be fitted by a plumber which is a little strange as it is electrical. These do fail from time to time and when they do cause the problem you talk about. As to the fitting that is all dependent on your boiler. Some are really easy other are **** and some times the boiler needs parts removing to get them in which is maybe why Wickes think it is a plumbers job. With lead free solder maybe that's wrong name! Heating and ventilating fitter? I think they may be called corgi's? I think that may be name to look for in yellow pages? When I was a kid they were little toy car's! I am sure one will pop up and tell you what to look for. I am an electrical guy I have fitted them many times but I am industrial not sure if domestic electrician would do it.
Could be the Thermocouple or the Gas Valve. Both should be fitted by a CORGI registered installer as you probably have to break a gas connection to replace. And if the gas valve is changed - gas pressures must be checked and adjusted and a gas tightness test performed.
Depending on the boiler make and model - it could also be a faulty over heat thermostat.
Thermocouple is the correct name, and undoubtly the part that is required. I would STRONGLY suggest that you get a Corgi Registered Gas Engineer to repair you appliace, as it a GAS CRITICAL part, and is very unsafe to DIY.
Mr EricMark, I am afraid to tell you that you are breaking the law. To install this part is a breach of gas safety, it is classed as a gas componant, NOT an electrical, as the current is so minute, it actually acts against a Electromagnet witin the gas valve, and there is live gas sorrounding the area that you are tampering with.
Have a look in the Gas and Gas Fitting Forum, Condemned Gas Cooker posts. There's a few people on here that think DIY gas work is fine and that CORGI registration is not essential - it is just a way of making money.
[quote="david boocock"]Dear DIY doctor I have a centrel heating boiler, the problem is when i ignite the pilot light and release the button the flame goes out can you help? Regards D.Boocock.[/b][/quote]
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