Glow Worm Fuel Saver 40 mkll flue gas temperature

Anyone know the flue gas temperature of a Glow Worm Fuel Saver 40 mkll? Odd question I know, but I have had two quotes for a new flue liner and they differ on the type of liner required. When I questioned the fitters, one stated a class one liner was required because of high temperature and the other said a class two liner was OK because the flue gas temperature would not exceed 250c. When pressed both admitted they has never worked on this model before.
I contacted the manufacturer of Glow Worm twice but they have no knowledge of the boiler. I believe it to be a least twenty-two years old and is working perfectly apart from being full of soot caused by a hole in the existing flue liner. Please don't recommend I change it for a new one. A new liner will cost £423 and a new boiler £1900+.

hastings38 said:

.. I believe it to be a least twenty-two years old and is working perfectly apart from being full of soot caused by a hole in the existing flue liner.

Click to expand...

Who says a hole in the flue liner would cause the boiler to be full of soot? And what is the reasoning behind this?

Hello chrishutt

I don't know this for sure, but small bits of corrugated metal dropped through the bottom of the boiler case. I showed these to a heating engineer at work and he suggested this was causing the soot (full of soot was a slight exaggeration. The combustion chamber was covered with soot when the case was opened). unfortunately he was not interested in private work so I called in the (domestic heating) profesionals. They both agreed the liner was to blame. Normally I would ask more questions but I'm out of my depth with gas. That's why I'm looking for info. It worries me that I use gas and electric heating, both potentially fatal, and know so little about them.

I think you or someone is making a lot of assumptions about the cause of the soot. You need a proper heating engineer to check the boiler using a Flue Gas Analyser. This will indicate the level of CO (associated with soot), excess air, efficiency, etc. I doubt if the boiler is burning properly if soot is being produced.

Also a smoke test is required on the flue to see if it's working properly and whether any flue gases are escaping, although a hole in a flue liner wouldn't usually have a significant effect on combustion. Don't waste any more time and money on so-called heating engineers who don't know how to carry out such basic checks.

Quite frankly, 22 years is very old for a boiler and you ought to be thinking in terms of replacing it anyway. That's another can of worms on which advice is often given here. But at least a new boiler (condensing) should be much more efficient resulting in lower fuel bills.

To answer the question, the flue pipe must be to BS567 and in accordance with BS5440 part 1 subclause 20.1.

BS 715 could be used but you would need an adaptor to the appliance spigot.