Carbon monoxide detector buying guide
Updated: 20 October 2026
You have a boiler, a stove or an open fire, and amazon.co.uk is showing a white disc, a star rating, and a title that might mean carbon monoxide, carbon dioxide or smoke. This carbon monoxide detector buying guide puts the checks in order before those stars count: name the gas, find a dated BS EN 50291 claim, then match the battery to the nation. The Products Compared editorial team read twelve amazon.co.uk listings on 19 October 2026, from about £3.42 to about £25.98, with no lab test of our own. A qualifying purchase can earn us a commission at no extra cost to you. The cards stay on the [carbon monoxide detector comparison](/hub/fire-protection/co-detector).
You have a boiler, a stove or an open fire, and amazon.co.uk is showing a white disc, a star rating, and a title that might mean carbon monoxide, carbon dioxide or smoke.
You have a boiler, a stove or an open fire, and amazon.co.uk is showing a white disc, a star rating, and a title that might mean carbon monoxide, carbon dioxide or smoke. This carbon monoxide detector buying guide puts the checks in order before those stars count: name the gas, find a dated BS EN 50291 claim, then match the battery to the nation. The Products Compared editorial team read twelve amazon.co.uk listings on 19 October 2026, from about £3.42 to about £25.98, with no lab test of our own. A qualifying purchase can earn us a commission at no extra cost to you. The cards stay on the carbon monoxide detector comparison.
Our top picks
| Badge | Product | Sensor line | Standard on the listing | Battery | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Kidde Kidde 5CO | Photoelectric on the spec line | Not printed | AA, not called sealed | 6.3 | about £13.75 | View offer |
| Best value |  FireAngel FireAngel FA6813 | Electrochemical | EN 50291-1:2008 and 2:2019 | 2 × AA, replaceable | 8.7 | about £13.98 | View offer |
 FireAngel FireAngel FA3820 | Electrochemical | Kitemark, 2018 and 2019 | Sealed 10 years | 9.4 | about £22 | View offer |
On this page
Carbon monoxide, not carbon dioxide and not smoke
Carbon monoxide is the gas a faulty boiler, fire or stove can send into a room. The NHS describes it as odourless, with headache, dizziness, nausea and confusion that can ease once you are outdoors. A carbon dioxide monitor tracks stuffy air, and a smoke alarm listens for fire particles.
Electrochemical wording matches a carbon monoxide alarm. On the Kidde 5CO, about £13.75 on that capture with 4.7 from 59,540 reviews, the specification says photoelectric and the standard field is n/a. Both FUMIXTEX packs use the same photoelectric line, which is smoke-alarm language, and we are leaving that conflict unresolved. The title's 10-year sensor is sensing life, and the listing does not call the AA cells sealed.
A BS EN 50291 claim with a year
BS EN 50291-1 is the British standard for a domestic carbon monoxide alarm. BSI's scope for the 2018 edition is an acute warning from a faulty appliance, which is a different job from a health monitor for months of low-level exposure. FireAngel publishes the windows behind it: about 50 ppm within 60 to 90 minutes, 100 ppm within 10 to 40 minutes, and 300 ppm or more within 3 minutes. We have not repeated those tests.
In this set only the FireAngel FA3820 prints a BSI Kitemark. At about £22, with 4.6 from 3,466 reviews, it cites BS EN 50291-1:2018 and EN 50291-2:2019, and it has a sealed 10-year battery. The XINDUM CO12 is sealed, at about £14.43, and it does not print a Kitemark.
Battery versus the nation
In this set the sealed models are the FireAngel FA3820 and the XINDUM CO12. The FA6813, the EiBEST listings and the Fenary s07 use replaceable cells, and none of the twelve is a mains alarm.
Scotland expects a life-of-detector battery, or hard-wired mains with a sensor-failure warning, in a room with a fixed combustion appliance or a flue. The CO12 is sealed and still lacks the Kitemark mygov.scot points towards. The FA6813, at about £13.98, uses replaceable AA cells, cites BS EN 50291-1:2008, and the maker says it is not for Scottish homes. Wales, the English battery wording, and the silence on Northern Ireland are on the carbon monoxide alarm landlord rules page.
A screen is optional
BS EN 50291 does not ask for a live ppm readout. Reviews of the Fenary s07, about £9.99 and sold without batteries, say the screen stays blank until you press a button. On that pattern a dark display is standby, and a zero is not a service visit. If you want a figure before the siren, choose a display model and still put the dated standard first. A low price on its own does not replace a year beside BS EN 50291.
Checklist before you open a listing
If an alarm has already sounded, or anyone has headache, dizziness, nausea or confusion, get everyone out and get medical help before you shop. For a gas appliance, a Gas Safe engineer has to make it safe. Otherwise stop at the first line that fails. Compare price and stars last. On 19 October 2026 the set ran from about £3.42 to about £25.98.
A touring caravan or motorhome also needs EN 50291-2, which a home alarm does not cover on its own. The carbon monoxide alarm for caravans page separates a tourer from a static holiday home.
Common questions
What does BS EN 50291 on the listing actually promise?
BS EN 50291-1 is the domestic standard for an acute alarm from a faulty appliance, not a long-term health monitor. FireAngel's published windows are about 50 ppm in 60 to 90 minutes, 100 ppm in 10 to 40 minutes, and 300 ppm or more within 3 minutes. A year on the claim, such as 2018 on the FireAngel FA3820, shows which edition the seller cites. We have not laboratory-tested these listings.
Do I need a Kitemark, or is a sentence that says EN 50291 enough?
A dated EN 50291 sentence is the minimum you can check on the listing. A BSI Kitemark is a separate mark, and Energy UK also mentions an LPCB mark. mygov.scot points Scottish homes towards a Kitemark EN 50291-1 alarm. In this 19 October 2026 set, only the FireAngel FA3820 prints that Kitemark. A bare EN 50291 with no year is a weaker line.
Should the battery be sealed?
Scotland expects a life-of-detector battery, or hard-wired mains with a sensor-failure warning. English landlord rules do not fix the type, though GOV.UK recommends a sealed cell, and Approved Document J expects a life battery or fixed mains for a new qualifying appliance. The FireAngel FA6813 uses replaceable AA cells and the maker says it is not for Scottish homes.
Is an alarm at 100 ppm immediately what the standard describes?
The window FireAngel and Which? describe at 100 ppm is 10 to 40 minutes, which is a wait. Both EiBEST listings claim an immediate alarm at that level, and that sentence is tighter than the published window. We have not tested which behaviour those units follow. Keep the dated BS EN 50291 line as the check, and treat immediate as the seller's wording.
Will a home alarm also do for a caravan?
A domestic BS EN 50291-1 alarm is for a home. A touring caravan or motorhome also needs EN 50291-2. The FireAngel FA3820 cites both 50291-1:2018 and 50291-2:2019, and it is the only Kitemark in this set. A static holiday home is a different case from a tourer, which the caravan page sets out, including when you still need a separate home alarm.
Related pages
Sources
Public UK sources and the FireAngel FAQ, last checked on 19 October 2026.
- The Smoke and Carbon Monoxide Alarm (England) Regulations 2015, regulation 4 (retrieved 19 October 2026)
- GOV.UK smoke and carbon monoxide alarm Q&A for landlords (retrieved 19 October 2026)
- Approved Document J divisional circular on alarm amendments (retrieved 19 October 2026)
- Scottish Government tolerable standard, fire and carbon monoxide detection (retrieved 19 October 2026)
- mygov.scot home fire safety (retrieved 19 October 2026)
- Renting Homes (Fitness for Human Habitation) (Wales) Regulations 2022, regulation 5 (retrieved 19 October 2026)
- NHS carbon monoxide poisoning (retrieved 19 October 2026)
- FireAngel homeowner FAQs (retrieved 19 October 2026)