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Don't Buy carbon monoxide detectors

by Matt Stevens

We reveal the dangerous Don't Buy carbon monoxide detectors that failed our tests. 

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Our tough independent lab tests help us find the best carbon monoxide detectors on the market – the ones you can rely on to sound the alarm when there’s a build-up of carbon monoxide.

But the same tests also uncover the carbon monoxide detectors that do a pitiful job and could even endanger your life.

Three of the 16 alarms we've tested failed to go off in at least one of our carbon monoxide detection tests. If you have one in your home, the stark reality is that there’s more than a one-in-three chance it will let you down when you need it most.

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Unsafe carbon monoxide detectors

If a fifth of crash helmets, seatbelts or anything else solely designed to save your life failed to work, it would be front-page news. But that’s exactly what we found when we tested carbon monoxide alarms.

Compared with Best Buy carbon monoxide detectors, the Don't Buy alarms that we've named and shamed on this page just can’t be relied upon to detect the gas and sound the alarm. In our tests, the Don’t Buys failed to detect carbon monoxide in more than one-in-three of our tests. This adds up to 26 failures out of 72 tests. By contrast, the Best Buys passed all 312 of our carbon monoxide gas tests.

The potentially deadly CO alarms all claim to have passed the relevant EU safety standard, EN 50291. But repeated failures in our lab tests – which mirror those of the safety standard – lead us to doubt that they actually did. And we’re as concerned about several lookalike models as we are about the three models that failed our tests. 

Join Which? to find out which models are Don't Buys, as well as our Best Buy carbon monoxide detectors.

We carry out numerous carbon monoxide tests on each alarm we test from a huge range of brands, including Dicon, Ei Electronics, First Alert, FireAngel, Kidde, Lifesaver and Nest, as well as from some smaller names. 

The results of our rigorous lab tests – which mirror sections of the EU safety standard for carbon monoxide detectors – mean we can recommend alarms that detect carbon monoxide and go off when they should every time.

The models we name and shame as Don't Buys are proven in test-lab conditions to not be sensitive enough to detect when carbon monoxide is in the atmosphere.

  • We test each brand of carbon monoxide detector 24 times in the presence of carbon monoxide. We record how quickly they detect the killer gas, how loud they are when they do sound and whether they continue to work after initially being installed.
  • We also expose the carbon monoxide detectors to a cabinet filled with carbon monoxide to replicate a catastrophic leak. We then check that they continue to work at lower levels of the gas afterwards. A good carbon monoxide detector should still be reliable after such an event; a bad one might not be able to recover.
  • Inspection of the installation instructions is also important. Instructions for the best carbon monoxide detectors are very clear about installing them in the correct place and certainly in the same room as an appliance that could produce carbon monoxide. Don’t Buys have potentially unsafe instructions that advise to not install the detector in the kitchen, which could have potentially deadly consequences if that’s where your gas boiler is, for example.

Safety alert carbon monoxide alarms

All of the carbon monoxide (CO) alarms that we've made a Don't Buy and that we've published with a safety alert, are listed below. Click on the link to be taken through to the review, then click on the yellow full safety alert banner to read more information on why each of these alarms have scores low enough to make them Don’t Buy carbon monoxide alarms and detectors.

1. Unbranded Carbon monoxide alarm
2. Aico Ei208 Carbon monoxide alarm
3. X-Sense CO03D Carbon monoxide alarm

Which? is independent – we work for you, the consumer, so you can be sure that our product recommendations are influenced only by our test results. We're not influenced by third parties and we don't accept freebies from product manufacturers or retailers. We buy all the products that we test ourselves, so our advice helps you to make the right choice first time and avoid costly mistakes.

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