A cavity wall insulation installer was to install today but said I
required a vent for the gas fire. The fire is on the chimney breast
and vent up the chimney. I will happily pay the £50 extra if
absolutely necessary but I'm not convinced. I know Health and safety
deem it no be necessary if the fire is 7kw or over. I cannot, nor can
the manufacturers of the fire tell me whether this is the case as the
fire is 30 years old. It came with the house. It hasn't been used for
a few years but still works fine and has been tested. I do not want to
pay £50 as this is 1/3 the cost of the cavity wall insulation. I do
not want a hole in the front of my property either. The draught will
get in which negates the insulation. The fire is a firedance made by
and measuring the gas usage via your gas meter. Use the volume to kWhr
conversion figures, measurement time and a bit of maths to get the input
rate. If it comes out at over 7kW then tell the chap that the fire is
obsolete and you are replacing it with a more efficient model (with an
input rate of less than 7kW).
FIVE TV's superbright logo - not the DOG's, it's bollocks
tacky brass flame effect fires weren't so common 30 years ago so looked
a bit further.
Turns out the older one was a grannies favourite 4 radiant gas fire but
I couldn't find the rating and didn't want to guess that it would be
under 7kW, hence my suggestion to measure with the meter.
For the o/p, forgot to mention in my reply that the conversion rate
between volume and kWhr will be on your gas bill. It depends on whether
you have a cubic feet or cubic meter volume meter but the bill should
know what you have and will give the right conversion.
FIVE TV's superbright logo - not the DOG's, it's bollocks
If the fire is sound and not dangerous -- why do you suggest that course of
action when a new fire will cost far more than £50 - and will need to be
fitted by a qualified gas engineer (in this over-zealous health and safety
age) and the [un]necessary certification filed away in a safe place just to
And that's not including any redecoration that may be needed.
I probably have far hire "standards" than you, but I don't let them cloud my
judgement and throw something useful away just because of its looks - unless
I am *NAGGED* into doing so by a far greater being than any supreme power -
and *SHE* is unstoppable when she fully winds-up into an "I want this done
this way mode" and about a subtle as a brick thrown through a window. :-)
A year or two ago I reluctantly changed (at the insistence of SWMBO ) a
35 year old "ugly" (and to your standards "inefficient" gas fire that
actually heated the room) for a brand spanking, up to date all singing and
dancing model - and it was rather pointless!
Yes, the bloody thing looked pretty (and that is what SWMBO wanted) - but
its as useful as a "chocolate fireguard" with regards to heating the room,
and when used (rarely) costs a damn site more to run than the old one.
In reality, the "old, ugly one" wall mounted, three radiant one was a damn
site more efficient at heating the room, and did it for far less cost than
the new, bright and beautiful coal fired effect built in one.
 Who I warned would not chuck out the same heat as the old one, and
unlike the old piezzo ignited one, could *NOT* be used in the event of a
power cut, which would leave us without any form of alternative heating.
To resolve that, after we has a power cut for a few hours in the middle of a
snowstorm - I had to go and buy two calor gas heaters (piezzo ignited of
course) to keep the 'other half' warm. Poetic justice I called it at the
New is not always the best or most reliable - but telling that to someone
you've been married too for 40 plus years is like King Canute trying to stop
the tide, in the end, I just surrender, its easier now!! LOL
Gas fires come in several types, outset & inset, decorative flame
An inset decorative flame effect draws far more than 7kW (input) and
shoves the bulk of that straight up the chimney, along with a good
chunk of room air. Efficiency can be as little as 32%.
An outset radiant fire usually draws 5.2-5.8-6.2-6.7kW (input) by
design, but outputs about 72-85% if modern or about 46-55-58% if old.
That a fire is 30yrs old may or may not be material.
Some old fires had a problem whereby run on max the pressed metal heat
exchanger could crack - permitting products of combustion to mix with
convected room air (CO hazard). Some however were well built, probably
better built then current units.
Conversely modern units have flame supervision device (hold the dial
down until flame limit), useful if the gas pressure is lost and then
restored such as an idiot driving down a manhole with a gas main at
the bottom of it (exactly that happened a few years back, I heard an
FSD-less gas fire go out because it was on low and then hiss). Some
modern units also have oxygen depletion units and can therefore be
fitted to a bedroom (although most gas fitters will not through
ignorance, pig ignorance or liability).
The Radiant elements may be cracked, but if complete that is usually
ok - if there are bits missing then it is beyond use and should be
replaced. You can get cheap fires at £199 and a gas fitter should be
able to fit one reasonably cheaply. No a new gas fire does not always
need a chimney single-layer lining, a good class-1 chimney is often
fine if 50-60yrs old and refractory lined, fire cemented, built like a
brick-tank (and a bad concrete lash up recent build can be much worse
re mortar ingress).
If you are not happy with a gas fitter, tell them where to go.
If any gas fitter demands to disconnect any appliance as unsafe and
you suspect of talking complete bollocks *always* call Transco /
National Grid. If the fitter panics and screams then call the police,
there are plenty idiots out there who have atrocious history and are
very difficult for NG to track down and get rid of. They are happy to
attend, check what inspection & test procedure has been done - and do
the same on the gas fitter too.
There are very very good honest gas fitters, and very very poor idiots
who seem to have passed little more than a multiple choice and whose
workmanship is utterly frightening. As one Transco Inspector put it
"all that holds their pipework together is the flux plastered all over
it". Frankly Tracpipe should be mandatory, but I suspect some would
uck that up.
Google groups does not maintain threading.
Preach, well you are entitled to your opinion, I am mine.
That an insulation fitter wants a vent and a gas fitter did not
require one does not mean much.
Gas fitters vary between those who do the job to textbook excellence,
others just walk around with blinkers on, others miss the important
fault and want to sell something else - be it independent, housing
association & national grid min bid outsourcing. Insulation fitters
are most likely to be box tickers, if there is nothing to remove their
liability then they will not tick the box.
Cavity wall insulation requires obstruction of all vents which are not
ducted to the outside. It may appear that some vents are ducted (by
brick return) to the outside, but in reality the mortar has failed
which results in them being filled by insulation removing house
ventilation that was once present. This obstruction problem is also
true of suspended floor vents not properly ducted and whose
obstruction by insulation eliminates ventilation for underfloor areas
and gas fires directly via designated floor plates or distributed
around skirting boards, floorboards.
One solution is to have a gas fitter present, perform the spillage
tests etc with doors shut, all extractors & tumble dryer on after
cavity wall insulation has been performed. That may still not be
acceptable to the insulation fitter.
Another solution is to choose a more suitable vent than an insulation
fitter offers. For example a Stadium "black hole" vent which requires
a 127mm core drill (125mm hole) and uses an S-shape airpath and outer
blast cowl to eliminate gusts, eliminate light ingress & reduce
draughts along with maintaining a tested free air area. There are
other makes and they all have a chart or similar to identify what free
area is required in selecting a suitable vent.
If a gas fire is just over 7kW input, it is possible to do a per-kW
over calculation and thus the required free air area vent required.
Sorry to be pedantic, but having just had a look at free.uk.diy.home on
google groups, it would appear that the 'threading' has been maintained in
this group - and I will admit that was a only visual observation rather than
practical (I last used Google groups quite a long time ago and have lost the
details of my account there).
I see that you are with BT - have you tried using their Giganews offering as
your News Client? Very good retention there when I was with BT.
From your previous posts you clearly have a lot of knowledge that would
be useful to enquiring posters.
As a subjective observer however it is often difficult to separate the
pertinent facts from the perhaps less relevant content.
Previous posters have commented on your tendency to verbose extension in
answers and you have replied that you are providing a more complete
answer for the benefit of those who may search on the subject in the
That is all well and good (and I am one who always tries to give a
complete answer) but page long answers where a sentence of explanation
would suffice help no-one as readers will switch off after the second
paragraph of barely relevant text.
Again, as a subjective opinion, both you and others may gain more if you
keep your responses succinct and on topic.
FIVE TV's superbright logo - not the DOG's, it's bollocks
If the fire has been tested and passed as 'serviceable and properly
installed' by a [presumably] qualified gas engineer - then the lack of a
wall vent  is not detrimental to the safety of the appliance or users,
and there is no valid reason for the cavity insulation installers to insist
on a vent - they may well be 'trying it on' to get a bit of extra cash out
of a [presumably] subsidised job.
 This would [should] form part of the 'official' report and if a vent
was needed, the engineer would have issued a prohibition notice to prevent
the use of the fire until one was fitted.
The rules may have been changed since I retired from such activities as
this, but that was the situation some 10 years or so ago.
Thanks for your help. I did consider after I posted the message about
running the fire and reading the gas meter to get the KW reading using
the gas bill converter. The 7Kw limit is a HSE requirement and unless
I can prove its less, the installer wont budge (probably for fear of a
fine for contravening regulations). The installer was talking about a
6i inch vent (presumably through the outside wall) which would let the
draught in anyway - negating the effect of keeping the room warm with
cavity wall insulation. Although the fire is old, It still works on
the very few occasions we use it so I don't feel like buying a new one
In addition, The house is a semi and chalet style so the end wall
could be filled but front and rear are tiles about the ground floor
window so that would be uninsulated as there is no cavity. In that
event maybe the saving on fuel would not be worth the expense. I am
coming to the conclusion that its more trouble than its worth having
A few years ago we had a fancy new gas fire installed (A Brilliant 'Slab
22' - http://www.brilliantfires.co.uk /) and the installer insisted on a vent
being fitted into our suspended floor behind the TV. It was dreadful - a
howling gale blew into the room from the vent grille and completed negated
the pitiful heat thrown out by the 'decorative' fire. I tried various
measures to reduce the draught - including attaching a long length of ribbed
plastic vent pipe (similar to what you would use for a tumble drier vent)
and feeding that under the floor in an 'S' shape - but it made little
difference - there was still a freezing blast coming into the room when it
was windy outside.
We very rarely put the fire on because it's largely redundant with our
efficient central heating - and I've since laid laminate flooring over the
top of the vent! On the rare occasions when we *do* put the fire on - we
just leave the lounge door open.
The fire is a nice focal point - even when not lit however!
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