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gas fire / oxy sensor failure |
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| message from Colin Wilson on 12 May 2004 |
How hard are these damn things to replace ? - I had it replaced under
warranty at about 3 years old from new, and its gone again.
There is definitely no shortage of oxygen, but I believe they can be
blocked by dust or airborne crud - something our house seems to suffer an
excess of due to two large muddy dogs :-} (re: shortage of oxygen - the
damn doors are never shut as they have free run of the house and garden,
which is why we were so sodding desperate to get central heating
installed...)
Is it possible to remove and clean up the component in question ?
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| Bob Smith replied to Colin Wilson on 12 May 2004 |
A friend at work had his fixed under warranty. It was indeed fluff blocking
the air inlet.
The sensor works by usually having a blue flame blowing horizontally, and
when there is no oxygen (or or it gets blocked with fluff / muddy dog / low
flying pigeons) it changes to a yellow flame that goes straight up, and
heats a sensor directly above it.
Bob
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| John replied to Bob Smith on 12 May 2004 |
SNIP
Strange that your method of operation does not agree with that generally
accepted by the industry!
For the record on generic oxygen depletion sensing pilots there is indeed a
horizontal side flame which may either envelop the tip of a precision
thermocouple or impinge on a flame rectification probe. Reduction of oxygen
level in the atmosphere causes this flame to lift off the thermocouple or
sensing probe. It may be accompanied by a change of colour in the flame but
it does NOT rely on a sensor being heated to effect a recognition of a
problem.
The lack of flame contact is fail-safe rather than hoping a change is
recognised by an active system
HTH
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| Bob Smith replied to John on 13 May 2004 |
That's probably it - I remembered the blue / yellow flame mechanism, but
didn't think of the "failsafe" of having the thermocouple in the blue
flame... Just testing you...
Bob
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| John replied to Colin Wilson on 12 May 2004 |
What gas fire is it? As a general comment though it depends on what is
blocked. If your blockage is in the "gas hole" i.e. the injector then no its
not generally serviceable. If you have simply picked up fluff or dog hair in
the air inlet (think air hole of a Bunsen burner) or crud around the air/gas
mixture outlet then cleaning with a vacuum and a brush will generally solve
the problem.
You must be absolutely certain that the depletion device is not cutting off
the supply because its doing its job. Having lots of air inlet to the room
is not going to stop spillage of fumes into the room if the flue has a birds
nest in it or some other blockage, or there is an air leak into the flue
which effectively kills the "draw" of the flue.
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| Colin Wilson replied to John on 12 May 2004 |
Its a Crosslee Royal Chichester 6.6Kw real flame effect
I haven`t had chance to have a good look at it yet, but the pilot
assembly isn`t that easy to get to at first glance - it might become
obvious when the fake coals etc are removed.
It did have quite a hard winter though, and was on constantly from about
September last year to the end of March when we had gas c/h installed :-}
As above - i`m not sure whether its readily accessible :-(
I think its fair to say there`s no carbon monoxide spillage - we`ve got a
battery powered sensor in the same room, and that hasn`t gone into an
alarm state.
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Archived message: gas fire / oxy sensor failure (UK DIY House Improvement)
