unvented gas fire

Probably not a DIY topic but I think there will be folks out there who have an opinion.
I need to move my gas fire to a new location as I'm rearranging the room layout. I'm limited as to where a balanced flue can go, and unless somebody has a good idea I don't think I will be able to use the existing chimney. The chimney is a line of hollow bricks going up the cavity wall ca 1980.
I've seen several models of flueless fires which claim to be 100% efficient and deliver up to 3.5 KW, which would be adequate. I find it hard to accept the idea of filling up the room with CO2 as being a good thing, though I guess they must be approved and considered safe.
Comments anyone?
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andyv wrote:

They are safe given that they are fitted with a catalytic(sp?) converter, similar to those in cars. That said, I still wouldn't have one in a room without good ventilation, and by good ventilation I mean an unobstructed 9 inch by 6 inch permanent vent (not a sliding louvre type), overkill yes, but I doubt if it would be noticable with the heat that flueless fires give out.
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andyv wrote:

The catalytic converters should deal with any CO that's produced - that's the real nasty stuff. I guess the CO2 would be no different to a gas hob running.....
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andyv wrote:

ventilation, i would be in agreement with phil on the overkill vent!, obviously you will have a window in the room that opens too.
out of interest i would like a look at the manufacturers installation instructions if you do go ahead and fit one of these, just to find out if there is yet a 'common' way of installing/venting/room size etc
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I'm still undecided, but it's an interesting comment about gas cookers as these usually vent straight into the kitchen. Not everybody has an extractor.
A regular gas fire, such as I now have also probably vents some of its exhaust into the room too.
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The news groups are fine for getting some ideas about this, but I'd be astounded if the installation notes for these appliances didn't exactly specify the minimum ventilation requirements, probably in relation to the size of the room they're installed in.
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On Sat, 08 Apr 2006 10:38:28 -0700, mark_yh wrote:

Yes they typically specify a huge amount of permanent purpose provided ventilation (100cm^2) and large minimum room size. (40m^3) The more powerful models may regire an even bigger room.
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andyv wrote:

yes, but only for limited time. Running one all day is not smart. I wouldnt install an unvented fire myself. They arent as safe as vented, but more to the point youre breathing in the fumes day in day out. I've been to a few places with old ones installed and cant say I liked the atmosphere too much. They will also deposit a fair amount of damp of course. I think you could do better.
NT
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OK I think I have a viable idea. See what you think.
The existing fire has a chimney which runs up the cavity wall into the loft. Here it runs in a concrete pipe and exhausts out through a vent in the apex of the roof.
What if I was to fit an extractor fan into the piped section in the loft? I could then have the room downstairs turning over the air and sucking out the excess CO2 just as if it was going out of the window or a conventional vent in the wall. I'd have a grating on the wall hidden behind furniture. I don't fancy an extractor fan in the room itself unless anybody can point me to an ultra quiet one.
Also it may even be possible to get a switch which operates when the gas is flowing so the fan is automatically turned on.
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andyv wrote:

If you install a vent in the living room wall, and leave the existing flue open, you can do away with the extractor fan altogether as the air will naturally flow up the chimney (it will even without a vent, hold a lit match in front of it if you don't believe me!) The manufacturers insist on their safety as do British standards and gods knows what other governing bodies, but when push comes to shove, the waste products from that fire are going to end up in that room at some stage in whatever form and over a long period of time, I can't see how this is going to be benificial to either the room or it's occupants. You'll find that a permanent vented room as mentioned above will make it a lot more comfortable, and dryer too considering the water produced by burning gas.
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OK I just found a government report on this at http://www.hse.gov.uk/research/rrpdf/rr023.pdf
Basically what it says is that when they had several of these fires tested, they ended up with CO2 in excess of permitted occupational exposure levels. These were admittedly tested at extreme conditions but it doesn't fill me with much confidence..
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andyv wrote:

CO2 isn't toxic. It's when there is no oxygen left in the room that the fire takes in the CO2 and produces CO - carbon monoxide. With good ventilation this can never happen, although breathing in CO2 isn't much fun, it won't kill you outright. As you say, the testing conditions would probably *never* occur in real life - how many rooms are completely sealed and air tight? A few vents, probably one in each side if it's possible for cross-flow ventilation, although not imperative would certainly make it more comfortable.
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wrote:
|andyv wrote: |> OK I just found a government report on this at |> http://www.hse.gov.uk/research/rrpdf/rr023.pdf |> |> Basically what it says is that when they had several of these fires |> tested, they ended up with CO2 in excess of permitted occupational |> exposure levels. These were admittedly tested at extreme conditions |> but it doesn't fill me with much confidence.. | |CO2 isn't toxic.
Not strictly true. http://en.wikipedia.org/wiki/Carbon_dioxide

When inhaled in high concentrations (about 5% by volume), it is toxic to humans and other animals. This is sometimes known as choke damp, an old mining industry term, and was the cause of death at Lake Nyos in Cameroon, where an upwelling of CO2-laden lake water in 1986 covered a wide area in a blanket of the gas, killing nearly 2000.. <<<
|It's when there is no oxygen left in the room that the fire takes in the CO2 |and produces CO - carbon monoxide.
See above:
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Dave Fawthrop wrote:

It is true, CO2 is non-toxic. To say it is toxic is like saying that water is toxic because you can drown in it.

Shorely shome mishtake here. If there's no oxygen in the room, the fire will go out. CO2 doesn't burn.
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Chris Bacon wrote:

Correct, carbon dioxide is in our lungs nearly all the time, given that we inhale oxygen and exhale carbon dioxide.

There's always /some/ oxygen in the room, it's just that high concentrations of CO2 cause the hydrocarbons in the gas to not burn properly, when this occurs the gas produces CO instead of CO2....it doesn't actually *turn* CO2 into CO, but CO2 does cause the production of CO, given that it's presence is in place of oxygen.
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wrote:
|Dave Fawthrop wrote: |> "Phil L" wrote: |> |andyv wrote: |> |> OK I just found a government report on this at |> |> http://www.hse.gov.uk/research/rrpdf/rr023.pdf |> |> |> |> Basically what it says is that when they had several of these fires |> |> tested, they ended up with CO2 in excess of permitted occupational |> |> exposure levels. These were admittedly tested at extreme conditions |> |> but it doesn't fill me with much confidence.. |> | |> |CO2 isn't toxic. |> |> Not strictly true. |> http://en.wikipedia.org/wiki/Carbon_dioxide | |It is true, CO2 is non-toxic. To say it is toxic is like saying |that water is toxic because you can drown in it.
If you read what you snipped 5% CO2 is lethal which leaves about 15% oxygen http://en.wikipedia.org/wiki/Air
If you took the trouble to read the rest of http://en.wikipedia.org/wiki/Carbon_dioxide and followed the internal links, you would find the reason in great detail. .
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Dave Fawthrop wrote:

So water is toxic, too. Whatever you want.
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wrote:
|Dave Fawthrop wrote: |> Chris Bacon wrote: |> |> |Dave Fawthrop wrote: |> |> "Phil L" wrote: |> |> |andyv wrote: |> |> |> OK I just found a government report on this at |> |> |> http://www.hse.gov.uk/research/rrpdf/rr023.pdf |> |> |> |> |> |> Basically what it says is that when they had several of these fires |> |> |> tested, they ended up with CO2 in excess of permitted occupational |> |> |> exposure levels. These were admittedly tested at extreme conditions |> |> |> but it doesn't fill me with much confidence.. |> |> | |> |> |CO2 isn't toxic. |> |> |> |> Not strictly true. |> |> http://en.wikipedia.org/wiki/Carbon_dioxide |> | |> |It is true, CO2 is non-toxic. To say it is toxic is like saying |> |that water is toxic because you can drown in it. |> |> If you read what you snipped 5% CO2 is lethal which leaves about 15% |> oxygen http://en.wikipedia.org/wiki/Air |> |> If you took the trouble to read the rest of |> http://en.wikipedia.org/wiki/Carbon_dioxide and followed the internal |> links, you would find the reason in great detail. |> . | |So water is toxic, too.
In huge quantities taken by mouth, Yes.
|Whatever you want.
Not me Wikipedia, or Google will get you lots of other URLs saying the same things.
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Dave Fawthrop wrote:

CO2 isn't toxic inthat it will kill you by poisoning, it may kill you via the non-presence of oxygen but it's not toxic like carbon monoxide, I think this is all getting pedantic now anyway, we breath carbon dioxide every day from our birth to our deaths, if it was poisonous we wouldn't live very long. Carbon monoxide is poisonous and worse still it has cumulative effects, meaning that levels of it can build up in the bloodstream for weeks, months or even years unnoticed until one day it reaches the point where it causes death.
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wrote:
|Dave Fawthrop wrote: |> |> Not me Wikipedia, or Google will get you lots of other URLs saying |> the same things. | |CO2 isn't toxic inthat it will kill you by poisoning, it may kill you via |the non-presence of oxygen but it's not toxic like carbon monoxide, I think |this is all getting pedantic now anyway, we breath carbon dioxide every day |from our birth to our deaths, if it was poisonous we wouldn't live very |long.
Some people should learn to use Google, and read what they find
http://en.wikipedia.org/wiki/Carbon_dioxide

Carbon dioxide content in fresh air is approximately 0.04%, and in exhaled air approximately 4.5%. When inhaled in high concentrations (about 5% by volume), ***it is toxic to humans and other animals.***
This is sometimes known as choke damp, an old mining industry term, and was the cause of death at Lake Nyos in Cameroon, where an upwelling of CO2-laden lake water in 1986 covered a wide area in a blanket of the gas, killing nearly 2000.
Hemoglobin, the main oxygen-carrying molecule in red blood cells, can carry both oxygen and carbon dioxide, although in quite different ways. The decreased binding to oxygen in the blood due to increased carbon dioxide levels is known as the Haldane Effect, and is important in the transport of carbon dioxide from the tissues to the lungs. Conversely, a rise in the partial pressure of CO2 or a lower pH will cause offloading of oxygen from hemoglobin. This is known as the Bohr Effect. <<<
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