Kidde 7COC Carbon Monoxide Alarm £10.95  (+£4.49 Non Prime) @ Amazon UK
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Kidde 7COC Carbon Monoxide Alarm £10.95 (+£4.49 Non Prime) @ Amazon UK

£10.95£12.9916%Amazon Deals
11
Found 16th MayEdited by:"Brutes"
  • Power supply of 3 x AA batteries; Continual monitoring
  • Multi-feature green and red LEDs
  • 10 year sensor life and warrenty
  • End-of-life warning
  • Test/Reset button
  • It has replaceable batteries
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11 Comments
Great price! I need one of these so thanks very much for sharing.
Thanks, OP! Great price, and essential product!! I have two, one by Boiler, and one by fireplace.
My chimney sweep urged me to install at least one. He also told me that it should not be on the ceiling, as carbon monoxide is heavier than air?! Anyone able to confirm that?
Price of the digital alarm (7DCOC) has dropped to £11.
Bestbitter16/05/2019 08:31

Thanks, OP! Great price, and essential product!! I have two, one by …Thanks, OP! Great price, and essential product!! I have two, one by Boiler, and one by fireplace. My chimney sweep urged me to install at least one. He also told me that it should not be on the ceiling, as carbon monoxide is heavier than air?! Anyone able to confirm that?


Yup, carbon monoxide is CO whereas air is mostly made of nitrogen, N. The atomic weight of CO is 28 and nitrogen is 14 so roughly twice as heavy as air.
Perfect... just on the lookout for this
Edited by: "icklechief" 7 h, 27 m ago
ctw9916/05/2019 16:24

Yup, carbon monoxide is CO whereas air is mostly made of nitrogen, N. The …Yup, carbon monoxide is CO whereas air is mostly made of nitrogen, N. The atomic weight of CO is 28 and nitrogen is 14 so roughly twice as heavy as air.


The statement about the weight of Carbon Monoxide being heavier than Nitrogen and therefore heavier than air is misleading. It is an urban myth. It is actually slightly lighter than air.

See what the professionals at 'Nest' say about the correct positioning of a CO detector etc:

nest.com/uk/…oor
kporourke16/05/2019 20:45

The statement about the weight of Carbon Monoxide being heavier than …The statement about the weight of Carbon Monoxide being heavier than Nitrogen and therefore heavier than air is misleading. It is an urban myth. It is actually slightly lighter than air. See what the professionals at 'Nest' say about the correct positioning of a CO detector etc:https://nest.com/uk/support/article/Shouldn-t-a-carbon-monoxide-CO-alarm-be-installed-near-the-floor


I think you'll find that atomically CO is definitely heavier than air. In the real world where we have convection and air currents, it really doesn't make any difference, especially since most CO emitter appliances (gas hobs and boilers) will be hot anyway so the CO will rise.
ctw9916/05/2019 16:24

Yup, carbon monoxide is CO whereas air is mostly made of nitrogen, N. The …Yup, carbon monoxide is CO whereas air is mostly made of nitrogen, N. The atomic weight of CO is 28 and nitrogen is 14 so roughly twice as heavy as air.


I'm afraid that argument is incorrect. Nitrogen gas as is found in air is a diatomic molecule, N2, hence the molecular weight is 28. The three covalent bonds between the two nitrogen atoms is what makes nitrogen gas so incredibly inert.

Elemental nitrogen of course has a Mw of 14.
hcc2716/05/2019 21:42

I'm afraid that argument is incorrect. Nitrogen gas as is found in air is …I'm afraid that argument is incorrect. Nitrogen gas as is found in air is a diatomic molecule, N2, hence the molecular weight is 28. The three covalent bonds between the two nitrogen atoms is what makes nitrogen gas so incredibly inert. Elemental nitrogen of course has a Mw of 14.


Of course, what a stupid oversight on my part - my apologies for any confusion!
ctw9916/05/2019 20:55

I think you'll find that atomically CO is definitely heavier than air. In …I think you'll find that atomically CO is definitely heavier than air. In the real world where we have convection and air currents, it really doesn't make any difference, especially since most CO emitter appliances (gas hobs and boilers) will be hot anyway so the CO will rise.


I agree with you about convection currents and heat moving the air, but you are wrong about the atomic weight (mass) of air versus carbon monoxide (remember that air contains more than just Nitrogen, for example oxygen is a heavier element).

The molar mass of dry air is 28.9647 g/mol. (source: engineeringtoolbox.com/mol…tml).

The molar mass of carbon monoxide is slightly less at: 28.0101 g/mol (source: convertunits.com/mol…ide).

That's the real science and not the urban myth about "heavier than air" carbon monoxide!
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