On Mon, 24 Nov 2003 07:49:47 +0000, Stuart wrote:
Hi All,
I'm having some concerns about our gas fire. Since we moved in 2 years
ago it's always been fine, but lately it cuts out after around 5
minutes with a little popping noise.
I'm not using it until I know it's safe, and after trawling numerous
old posts I'm wondering if it could be any of the following:
1. Not enough oxygen in the room, ODS activating and cutting out - I
don't think the fire has an ODS, it doesn't look particularly
sophisticated, but then why else would it cut out? Someone mentioned
in an old post about the gas pressure had changed and his pilot kept
cutting out - all I know is that the whole street's mains were
replaced in August and September, could this have any bearing?
2. Faulty thermocouple - not sure again, it might be where the pilot
light is, it has two flames coming out, one faces inwards towards the
gas tray and another flame comes out to the right, and a little to the
right of that flame is a vertical 'pole' but it doesn't touch the
flame. ??
OK we definately have an oxy-pilot aka ODS aka VSD (vitiation sensing
device)
The next question is it dropping out because the thermocouple is dud or
because it is doing its job.
Since it only takes a few minutes before it drops out all you have to do
is to see whether the flame is blue or has bent upwards and become yellow.
Frankly I think it very unlikely that the fire could use up most of the
oxygen in a few minutes much more likely is that the themrocouple is dodgy
or for some reason the flame is not hitting the 'pole' properly as the
fire warms up.
The flame should just touch the tip of the pole, perhaps the pilot
injector is partially blocked; crud on the bits; very poor running inlet
gas pressure.
3. Flue is blocked - I think I should get this sweeped anyway as I
know it hasn't been done since I've been here, and I doubt it was done
in the 5 years prior to us moving in (when the fire was installed).
It is a very good idea for someone to check the flue every year.
Normal practice is too check with a smoke match that there is a 'draw' on
the flue under worst case conditions (windows & doors closed - extractor
fans on).
If there is a 'draw' then proceed to a smoke pellet.
Checking that the smoke goes all up the right flue/chimney an not into
other rooms chimneys or lofts.
Finally check for spillage of combustion gases into the room with a smoke
match when the fire is running as laid down by the manufacturers.
4. Not enough airflow? Probably linked to 3 - My combi boiler is due
for a service, and last year when British Gas gave it it's initial
inspection (for their central heating cover) I showed him the gas fire
and asked if they'd cover it. Before he even looked at it in detail he
said "no way, there's no air vents in the room"... it was my
understanding that no air bricks were required because the gas fire is
sitting in a class 1 flue (previously solid fuel fire, it's an old
house)?
Most gas fires with a heat input of less than 7kW (Gross) do not need any
purpose provided ventilation PROVIDED IT WORKS CORRECTLY.
I believe class 1 flue's are 16" minimum,
1 brick length square = 225mm sq. nominal
and looking at the width of
the flue above the fire it does look suitable, so I shouldn't need an
air brick installing should I? The thought of having to knock through
a wall making the place even colder doesn't really impress me much
(and despite their inefficiencies our living flame fire kicks out
plenty of heat). It surprised me when the boiler engineer said that,
because a CORGI installer must have installed the fire in the first
place, so why the need for an air brick now?
See above.
HTH
--
Ed Sirett - Property maintainer and registered gas fitter.
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