gas flue/chimney etc

[TOPTON]

We are in the process of getting a new gas fire and I have been reading up on the efficiency and different type of flues available.

Anyway, why does a gas fire need a flue/chimney? obviously to take away fumes of the poisonous type.
But in my kitchen I have a gas cooker, although I do have an extractor hood, this is mainly for taking away the cooking smells and steam, certainly not a legal safety requirement. I could leave the cooker on all day, slowly cooking,simmering pans away and not die because of it.

So back to the question---why does a gas fire need a flue but a gas cooker not

[dirkgently]

Cookers are used for a relatively short period of time and there are ventilation requirements to be taken into consideration when installing.People have died through using cookers as a heating appliance when their boiler had broken down.

[King Herald]

TOPTON said:

So back to the question---why does a gas fire need a flue but a gas cooker not

I asked this recently, in connection with 'flue-less gas fires'. It was explained that the gas fire has to be specially tuned to not give off any poisons, has to be accurately regulated and have an auto-switch-off if it goes outside of parameters.

http://www.pistonheads.co.uk/gassing/topic.asp?h=0...

Edited by King Herald on Saturday 5th December 16:31

[Ferg]

Cookers can only be fitted in a room with an openable window.

Edited to add.
Current regs dictate that Commercial Kitchens (imagine the ammount of gas being burnt!!) must have an extractor hood interlocked to the gas supply.

Edited by Ferg on Saturday 5th December 17:25

[Simpo Two]

I would imagine there's also the fact that a gas flame uses oxygen. Regardless of what the ocmbustion products are, if there's no fresh air getting in, you will die of asphyxiation if nothing else

[TOPTON]

so in effect they do require an extractor of some sort, be that an opening window or extraction fan.

Slightly off topic, but seeing as its my op

Especially for King H, well we have read every brochure in the world and looked at every web site (50 times at least).
Three types of gas fire:

Flue less---up to 100% efficient but not usually putting out much heat 2-3 kw ( catalytic converter, my guess is the cat soaks up a lot of the heat as well as naughty fumes)

Flue or chimney---up to 80% ish efficient, especially if it is glass fronted fire. 3-4 kw (some even higher, lookalike multi fuel stoves, up to 9 kw

Balanced flue (like a C/H boiler for those that don't know) up to 87% efficient, but also put out more heat 3-5.5 kw.

We (read she) have decided on a hole in the wall balanced flue, glass fronted fire. Manufactures web site says 84% efficient.

I think they all look like a wall mounted TV, but probably with a better quality of programme

[Simpo Two]

TOPTON said:

I think they all look like a wall mounted TV, but probably with a better quality of programme

Something like a documentary on the bombing of Dresden

[King Herald]

Simpo Two said:

I would imagine there's also the fact that a gas flame uses oxygen. Regardless of what the ocmbustion products are, if there's no fresh air getting in, you will die of asphyxiation if nothing else

Well, I beleive they've changed/scrubbed the law requiring you to fit air vents in any room you have a fire in, as they have obviously realised that more than enough air gets into the average house.

Strange they would do that now, now that most houses are absolutely air tight with UPVC double glazing fitted on every orifice.

[davidspooner]

Simpo Two said:

TOPTON said:

I think they all look like a wall mounted TV, but probably with a better quality of programme

Something like a documentary on the bombing of Dresden

Lol - sorry germans!

[Ferg]

King Herald said:

Well, I beleive they've changed/scrubbed the law requiring you to fit air vents in any room you have a fire in, as they have obviously realised that more than enough air gets into the average house.

Strange they would do that now, now that most houses are absolutely air tight with UPVC double glazing fitted on every orifice.

No. Fires over 7kW still require ventilation.

On a slightly connected issue, where we used to put gas pipes in floor/ceiling voids without venting, we aren't allowed to do this now due to the air-tightness of chipboard floors over old T&G floors.

I'm not sure if the 'non-construction industry' PHers are aware that new builds are tested for air-tightness these days?

[Simpo Two]

Ferg said:

I'm not sure if the 'non-construction industry' PHers are aware that new builds are tested for air-tightness these days?

I'm not sure now if air-tightness is good for reasons of insulation or bad for reasons of safety!

Ferg, how much time does someone in your position have to spend going on courses/keeping up to date to stay on top of all the ever-changing legislation?

[Ferg]

The only ones that are of interest to me really, John, are the Gas Regulations.
All my Certificates run for 5 years and I'm reassessed then.
My Core Safety plus Boilers, Pipework, Cookers, Gas fires (the bread-and-butter stuff) take about 4 days of training and written & practical assessment.
Then there's Commercial Gas, Commercial Catering, LPG etc

Then...
Unvented Hot Water
Water Regulations

All necessary, though. I'm acutely aware of the potential there to kill.

[King Herald]

Ferg said:

I'm not sure if the 'non-construction industry' PHers are aware that new builds are tested for air-tightness these days?

Wasn't it Tommy Walsh, the builder guy, who reckoned half the 'dumbing down' of the population is caused by oxygen starvation from people living in air tight UPVC-sealed houses?

I'm not positive he was joking either.

[Simpo Two]

Ferg said:

All necessary, though. I'm acutely aware of the potential there to kill.

Most definitely (and your liability therein). I think a major secret to successful DIY is knowing when to stop DIYing and get in professional help.

My 21-year-old boiler can't last for ever and when it does go pop you'll be my first call