Nullius in verba

[Houdi]

I had a question banned from the 'How it Works' section. I'm pretty certain there's no reasonable explaination for this, only an unreasonable one. Also, I've just received an email which defines 'science' as: (knowledge obtained from) the systematic study of the structure and behaviour of the physical world, especially by observing, measuring and experimenting, and the development of theories to describe the results of these activities.

With all this in mind I'm going to chance my arm and post it under the 'science' section instead. I do hope you find it a reasonable question and I apologise in advance for any unintentional offence I might cause. I'm really curious to read any theories that you might have.

Why do we worry about carbon monoxide poisoning from gas fires and gas boilers but not from gas hobs?

I do realise I should probably know the answer (as should my tutors) so I'd be grateful if you could save me from the purgatory of everlasting ignorance.

[Tom Braider]

USA figures for 2002 show that only 2% of CO deaths were associated with gas hobs. I guess that it's just a matter of ventilation. A gas fire or boiler will burn a lot more gas than a hob and will depend on a flue to vent the waste gases out of the room. A hob burns openly and the waste gases are just dispersed within the room. If you were to do this in a small kitchen with no ventilation then I guess therer would be a genuine risk. But practically speaking it isn't a problem. Having said that, I do have a detector in my kitchen...

[gregwithnail]

It can't be just about ventilation. Boilers and hobs are often in the same room. And to point ouit the boiler is in a cupboard os not helpful... Nobody sleeps with their head in the kitchen cupboard - the fumes come to find you.

Many years ago (long before carbon monoxide alarms and general public awareness) I was camping by myself in a very small (one man) tent. I got very cold during the night and lit a gas stove and went back to sleep. The tent was an old fashioned design with no gauze ventilation strips etc. By conventional layman's wisdom I should have never woken up. So what is the key thing we're missing here? Anyone?

[boogieboogie]

I suppose gas hobs are not on for many hours per day like fires/heating. It's about space and balance. A fire on for 14hrs per day will have more time to burn up all the oxygen in the room. Same with the boiler. Must be well ventilated. A hob is not on for lengthy periods so is not likely to use up all the oxygen unless as stated above the room is tiny tiny with no ventilation. Maybe you are presuming carbon monoxide is produced from the gas itself.. It's produced when the fuel cann't burn as intended.
Found this now:
Carbon monoxide is produced when fuels such as gas, oil, coal and wood do not burn fully. When a fire burns in an enclosed room, the oxygen in the room is gradually used up and replaced with carbon dioxide. Following a build up of carbon dioxide in the air, the fuel is prevented from burning fully, and starts releasing carbon monoxide instead.

[gregwithnail]

Thanks for including the bit about fuel not completely burned boogieboogie. I had forgotten to mention it.

Still doesn't explain why I'm alive though.

[chakka35]

In a boiler or a heater, which doesn't have access to the open air as a hob does, the partial burning of the gas into carbon monoxide instead of carbon dioxide is usually due to an inadequate air supply caused by a blockage or restriction in the air inlet to the device.

[Houdi]

Why are boilers designed in such a way that the air supply can be restricted?