The ignitor of my old glow worm space saver BF50 seems to work well on initial ignition. but the boiler switches itself off after 10-30 minutes. What could be the problem?

Alec, November 2006

Same problem with Space Saver 40B Mk11.

I have replaced..thermocouple, thermocouple connecter lead, pilot burner, and gas valve. All worked well after replacing gas valve, but only for six weeks.

I have since replaced the thermostat and pump and power flushed the complete system.

All the above work was done by myself at a total cost of...£408!!!

Today I took out the flue and cleared a few leaves etc from it..but it made no difference.

However, if the seal between the wall sleeve and the outer flue has the slightest bit of a gap between them, this may cause oxygen deficiency.

I have this evening re-sealed the 'gap' with some fire cement and believe it or not...all is well!

Although I only have the thermostat on its lowest setting, I am now sitting here monitoring the system and all appears to be spot on!

I have requested advice from this forum on numerous occasions, but eventually sorted it out MYSELF!!

RSD, November 2006

Try replacing the thermocouple, or check that the thermocouple is in the flame, if the thermocouple doesn't sense or respond to heat it will cut the gas, it is a safety device designed to cut gas if the flame goes out. B&Q & Homebase sell universal thermocouples.

Pete., November 2006