Glow worm not firing when requested

I have a customer with a glow worm hideaway boiler that won't fire  when the stat is turned up. sometimes it's 30 seconds & sometimes it takes forever.

I checked the stat and it appeared to work okay. there is a Rothman's (I forget the name) timer that is just set to on all the time.

all this stuff is about 30 years old.

customers husband just had a stroke and she cannot afford to replace the boiler is there anything that might help? 

Is it actually getting a demand signal??

I belive so, It fired once while I was there and I turned the stat up but it wouldn't do it again after  :yawn

I just ducked in on my way home to see if it was anything obvious. didnt have much poking about time so will have to go back..

Could it not be a sticking valve? I'd take the valve head off and check operation is free moving. The fact that it takes some 30secs to kick in I'd say the valve may need replacing. ??

Does the stat go click when you turn it up and down? 

Does the system have motorised valves? 

Blue Duck said:

I belive so, It fired once while I was there and I turned the stat up but it wouldn't do it again after  :yawn

I just ducked in on my way home to see if it was anything obvious. didnt have much poking about time so will have to go back..

Click to expand...

That proves nothing though.... needs much more time testing

More testing needed.

You need to determine if the boiler is actually getting a call for heat. Of not a dicky motorised valve is the likely culprit.

If the boiler is getting a call for heat then it's probably time for a gas safe man to investigate further?

Thanks for the input guys

only had a chance to have a quick look

 I will try to book more time to give it a proper once over.

Normally our "heating engineer" would deal with such matters but he is off on long term sick leave so they have chucked me in to see what can be done.

what thew me is that this isn't a conventional boiler set up. it's only for the heating and the boiler is an ancient piece of carp.

Also I didn't notice any valves anywhere but this may be hidden in a cupboard or in the loft.

The customer was in a bit of a state which also put me off  a bit.

I will come back with some better info when I get the chance! 

Thanks again!