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Can anyone give me some advice on purchasing a carbon monoxide detector? What are the important features, safety standards etc. to look out for? Which makes/models are particularly recommendable?
TIA.
There are on-a-card based versions & electronic versions.
Electronic versions fall into 2 categories - wall-mount & plug-in. o I have a plug-in one, but would have preferred wall-mount o However, plug-in units can be moved from room-to-room
If your sockets are on the skirting board the plug-in ones need air to flow from bottom-to-top which can be blocked by carpet.
Recent electronic models have gone beyond "ok / you're-dying" qualitative silent/alarm and provided quantitative CO countage. Thus they can indicate marginal situations, which can be more useful where CO levels are sufficient to cause drowsiness etc.
Some would say a good Corgi inspection of the appliance may be money better spent - eg, chimney clean, new backplate tape, jets cleaned, gas tap re-greased, wallet greased is less beneficial.
The cardboard items do not cost much, electronic ones £25-40. Cardboard ones can monitor several rooms (gas fires), especially a room with gas fire rarely used and often "service neglected". It isn't uncommon to find soot right up to the fire's exhaust outlet.
B&Q to
What do you believe to be your potential sources of carbon monoxide?
I don't believe it's possible to make a carbon monoxide detector which doesn't eventually get contaminated such that it's readings become unreliable after around a year. So I wouldn't spend a lot of money on something which lasts a long time unless it has replacable detector elements.
I believe that it's possible to do accurate measurement, even over time, with IR spectroscopy.
Then again, I've not looked into it closely enough to see if this is how the electronic versions do it.
I may be out of date -- it was around 4-5 years ago when I looked, and I don't think any of them used IR spectroscopy at that time. IIRC, they used a chemical cell which changed conductivity, but some other chemical (ozone, solvents, can't remember) steadily degrades them.
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SNIP
I have gas central heating, with the boiler behind a gas fire in the living room - no other gas appliances. It is serviced annually.
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SNIP
Thanks for all the replies so far.
I had a quick look in B&Q, and the detectors they stock were 'Kidde' - are they good products/a reputable brand?
Kidde are well known. CO detectors though are of very dubious worth. There are two common types of sensor. The electrochemical type, which require the detector to be renewed every few years and the more common metal oxide semiconductor (MOS) type which has the advantage of less maintenance but is quite unreliable. MOS sensor sensitivity varies considerably with humidity and the sensor is poisoned by a number of household items such as silicone based furniture polishes. This can lead to a false sense of security.
MOS sensors also react to gasses other than carbon monoxide and their non-linearity means the display readings are often very inaccurate leading to false concerns. Life of MOS sensors is supposed to be 5 years but from what I have seen of them they degrade after 1 year.
The Kidde Nighthawk uses a proprietary electrochemical cell which has the potential to fail unsafe (and a previous model was withdrawn because of sensor problems). The Health and Safety Executive has an ongoing review of CO sensor at
I would not trust an electrochemical sensor after 2 years at the most and all in all, I'm not at all convinced CO detectors are worth having or contribute much to safety.
While you can certainly do very accurate CO monitoring with IR spectroscopy, the price of a basic broad band device would be a couple of grand, which is probably outwith the average domestic budget for this type of kit.
cheers
David
Agreed. The worst of it is that the 'alarm' might inhibit practices which do lead to better safety such as:
1) Installing equipment which is inherently safer. 2) Correctly inspecting an maintaining potentially less safe equipment. 3) Ignoring other real signs of danger because the alarm say 'OK'.
As a point arising, I've got a CO meter for car use. Does it suffer from the same problems?
Yes - the sensor may be electrochemical or MOS. If MOS I would have thought the problem of poisoning of the sensor by contaminants would be more likely than in a house. If electrochemical you should also be aware that they take about 30 minutes to start working after power on. Not an issue in a house but may be if its powered from the car battery and off when ignition out.
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