Glow worm boiler not firing up...update now fixed.

13 Dec 2006
Reaction score
United Kingdom
Hi all, I have a Glow worm economy plus 50b bolier that is not firing up. The pilot light is continuously lit and the pump is running ok. It is controlled via an electronic ACL Drayton type timer with a wall mounted thermostat.
If I switch the heating (or hot water) to on and the thermostat is set correctly then I can hear the pump kick in but no heating (or hot water) appears. The pilot light is lit at this point but the boiler does not fire up at all.
Adjusting the thermostat or boiler water temp has no effect at all (apart from starting / stopping the pump)although whilst 'messing' with it all last night the boiler did fire up even though I hadn't really done anything. it is now back to the position of not firing up.
Any help / guidance or places to start would be gratefully received.
Sponsored Links
No, its a different(fan flued boiler). Yhe only thing you can do is to check all controls are calling for heat and that you have a 240v supply to your boilers gas valve.You really need a multimeter to test correctly.After that you should really get a registered gas engineer to repair it for you.From your description of what you did you may have a failed gas valve.If you describe your system controls ie 2 or 3 port valves we may be able to narrow it down.
Thanks for the reply, was just about to edit the original post to say that when calling for the boiler to be lit I do not have 240v at the gas valve, which suggests to me that it is on the controls side of it.

Does the fact it does not light for either water or heating point to anything?

Any pointers on what to look at, or assuming it is going to be the pcb board are these spares still available?

Re: the 2 or 3 port how can I tell? (I am not at the boilers location so will have to look later).
Sponsored Links
That boiler has no pcb or fan so if you get 240 at the gas valve and it does not open then gas valve solenoid has failed.If you are capable you can disc the gas valve wires and check the solenoid coil for continuity.Isolate boiler during this test.
So the fact that I am not getting a supply to the gas valve suggests what?

I can hear the pump kicking in when the controls call for water / heating. Would the same supply from the controls go to the pump and gas valve or would they be seperate?
Check that you have 240v to the boilers terminal strip when the system is on ie pump running etc.The 2 or 3 port valves can usually be found in the a/c near the cylinder.
The same signal that starts the pump also starts the boiler.Has the boiler got an overheat that has tripped?
You must determine if there is any supply to the boiler when the pump etc is running b4 continuing.Do you have the boilers manual?
Ok I will check the supply to the boiler incoming supply when I get home. No I do not have a manual fo rthe boiler.
Well that was a weird outcome, when I returned home the pilot light had gone out which was the first time that had happened. I got it lit again and managed to fire the boiler up going through the restart procedure. After 5 minutes though it went out. Thinking this must now be a thermocouple issue I fitted a new one and hey presto we have had hot water and heating since late last night (both manually and automatically turning on and off inbetween).
What's weird is how the thermocouple seems to have being giving enough return to let the pilot light stay lit in the original problem but not enough to let the main gas valve be operated.
Thought I'd update in case anyone else has a similar problem.

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Sponsored Links