In article ,
"Zipadee Doodar" writes:

Alan Butler wrote in message
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Should conventional floor standing gas boilers with outside flue be
serviced each year? They seem to come each year and just hoover the
inside and clean it, check things over etc, never anything wrong with
it. Is this necessary? Or is it just a long check list of tick boxes
to make it a look like they are doing a lot. Bit like these 112 point
car checks etc

Yes, do it. I once failed to arrange an service, which meant the period
between services was actually 24 months. The build up of carbon was such
that the gas usage was very high, and flames were getting close to parts
they shouldnt. When the corgi opened it up, i was stunned at the build up. i
hate to think what a further 12 months could have produced.

In my experience, when they soot up, they do it quite suddenly.
Something (e.g. dust which hasn't been cleaned out) gets somewhere
where it causes part of the burner to burn badly and produce
perhaps only a tiny amount of soot. Some of this will fall off
and get sucked into the air intake making the situation worse.
The soot being laid down starts reducing the draft, causing further
incomplete burning and rapid sooting up.
I've seen this happen withing a few days.

So basically I see it as a random instantaneous event, whose
probablity of happening increases over time as dust builds up.
I don't think you can meaningfully say "my boiler takes x years
to soot up".

--
Andrew Gabriel