Cavity wall installer wants to install a vent for an old gas fire - cannot determine the fire output

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Hi
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 robinson willey
help please
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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 If it comes out at over 7kW then tell the chap that the fire is obsolete and you are replacing it with a more efficient model (with an input rate of less than 7kW).
--
fred
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MD wrote:

google!!
So tell the installer to foxtrot oscar as he is just trying to make a bit extra on the side.
Bob
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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.
--
fred
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30 years old 'eh? Chuck it on the tip and buy a new one ffs.
Mr Pounder

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Mr Pounder wrote:

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 prove that?
And that's not including any redecoration that may be needed.
Cash
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We seem to have different standards. You might like to keep warm by an ugly 30 year old inefficient gas fire. I sure as hell don't.
Mr Pounder

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Mr Pounder wrote:

Mr Pounder,
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. :-)
See below.
A year or two ago I reluctantly changed (at the insistence of SWMBO [1]) 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.
[1] 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 time!
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
Cash
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Cash wrote:

Error correction.
The above should have read:
I probably have far *higher* "standards" than .......
Ah well, it was one of those silly mistake days ROLFL
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Cash wrote:

OK I give up - I'm off to bed *ROTFL*
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Gas fires come in several types, outset & inset, decorative flame effect.
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.
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js.b1 wrote:

js.b1,
Just out of interest, who are you replying to?
Your snipping, along with your reply structure makes it difficult to follow the line of the thread.
Cash
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content from that contributor.
--
fred
FIVE TV's superbright logo - not the DOG's, it's bollocks
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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.
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js.b1 wrote:

js.b1,
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.
Cash
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In article

<snip loads>
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 future.
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.
--
fred
FIVE TV's superbright logo - not the DOG's, it's bollocks
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MD wrote:

MD
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 [1] 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.
[1] 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.
Cash
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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 it done.
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What would the "expert" accept as proof?
--
fred
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MD wrote:

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!
--
Kev


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