Set Square wrote:
In an earlier contribution to this discussion,
wrote:

I'm told the boiler heat exchanger is partly blocked, laeding to the
flame coming out sideways, licking round the edges of the the
combustion chamber. Is there any way to confirm/deny this, as visually
I cant see anything? The exchanger itself is not visible.

Last time I saw it alight through the viewing window, it looked fine,
with rows of neat upright blue flames.


thank you,
NT

What colour are the flames - are they still blue - or are they yellow? If
the latter, there could be some crud in the burner rail, interfering with
the proper gas/air mixture.

blue thankfully. There is a 3mm tide mark of what looks like well burnt
paint round the outside near the bottom of the combustion cavity, which
he says shows its burning, and the metal cover on the pilot light is
discoloured. Also theres a light scattering of white ash on the base of
the thing. Thats the evidence. I cant help being less than 100%
convinced, and I do need to know whats what on this and act on it
quickly.


Otherwise, it sounds as if either the heat exchanger is sooted up, or
there's a problem with the flue. What boiler is it?

Balanced flue glow worm fuel saver, quite an old one, may well be
1970s. Looks very basic, no protection mechanisms of any kind as far as
I could see, just a gas solenoid, pilot light with ignition and
thermocouple, and a knob to adjust heat output.

And I gather it may be not sealed, I had assumed it was. It looks like
a sealed box, but the cover just presses on, and could be better.

If its nothing more than soot in the exchanger, can it just be poked
clean?


Thanks!

NT