Boiler won't stay lit. Please help...

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Hi,

I have a 30(?) year old Glow-Worm Space Saver 38 boiler which, for the last 10 months (when I moved in) has been totally fine. With all the strong wind recently I've noticed that the pilot light has gone out a lot but I've always been able to relight it and carry on as normal.

Last Thursday I got home from work to notice that it had gone out again. I tried to relight it and it wouldn't. When I eventually did and turned the gas flow upto full (On) the whole lot just went out after about 10 seconds. I thought it was the wind again so I tried a couple more times without success and left it for the evening.

Over the weekend the wind was a lot more settled so I tried it again but still had issues. It doesn't seem to like a sudden burst of gas (i.e. turning it upto full quickly) - turning it from pilot to full will almost guarantee it going out. The only was I can get it to light is the following:

1. Hold down the gas flow dial and light the pilot.
2. After about 30 seconds I SLOWLY release the gas flow dial and pilot light seems to stay lit.
3. I turn the gas flow upto about a third, just to get the main burner to kick in.
4. Leave it for five minutes (which seems to warm it up and make it stable) and then turn it upto about two thirds.
5. Leave it for another five minutes and then turn it upto full (On).

This method seems to work but after I turn the heating off the boiler obviously cools down and then the pilot light will eventually go out (within 20-30 mins). This means I cannot set the heating to come on with the timer.

It's almost like the boiler doesn't like being cool? When hot, the flame seems stable even when cutting out between main burner bursts.

I do intend on getting a gas man out asap to take a look at it, but I just wanted a "second opinion" from you guys just so I know what to expect to be told. Could it be the thermocouple, or something more drastic? (the thermocouple also seems to lead up behind the boiler making it hard to change - is it a boiler off-the-wall jobby?)

Cheers guys,
Paul.
 
Could be thermocpl or gas valve, T/C would be the first on the list....you should not need to take it off the wall to replace a Thermocpl.
 
Cheers mate.

When I look at my boiler controls I have the thermostat on the left, the ignition next to it, then the gas valve. Just to the right of the gas valve is what I think is the thermocouple (piccie from internet-> http://www.boilerpart.gbr.cc/images/cust/boilerpart.gbr.cc/GLOK9049l.jpg - just above the right contact in the blue plastic part) - something that looks screwed into gas valve housing - with a copper pipe coming out of it, going under the boiler and then goes into the back of the boiler. Am I correct? If so, how do I disconnect/connect the back part as there doesn't look to be enough room (couple of centimetres).

Is it a DIY job - am I a competent DIYer but I won't mess with what experts and professionals get trained to do!

Cheers,
Paul.
 
Many DIYers do successfully replace thermocouples but it is rather better left to a CORGI who can better judge if there are any other issues with the pilot light for example.

Tony
 
Duly noted. Will leave it to the experts. How much do you reckon the pros charge on average for service and replacing the thermocouple? Am I looking in excess of £100? Is it advisable to take out British Gas's cheapest HomeCare package for £12 a month?
 
An independent will usually do a more through service than BG.

Done as a routine service and t/c change then about £65 if he can choose when to come to fit it in and NOT as an urgent repair.

Tony
 
Quote from a little old gas man who used to do our last home's boiler a couple of years ago - £70 (service & t/c). Cheers Tony - almost spot on!

Not worth getting my hands burnt for that price!
 

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