Best Carbon Monoxide Alarms
Carbon monoxide is an invisible, odourless gas produced by faulty fuel-burning appliances — gas boilers, hobs, fires and heaters — and it can be dangerous. In a flat you may also be affected by a neighbour’s appliance through a shared flue or wall. A carbon monoxide (CO) alarm is a small, inexpensive safety device that gives you an early warning, and it is one buy every flat with any fuel-burning appliance should have.
This guide covers what to look for — chiefly that the alarm meets the recognised British/European standard — and picks reliable models. It is general information; always follow the manufacturer’s instructions and official safety guidance.
QUICK ANSWER
A carbon monoxide (CO) alarm is a safety essential in any flat with a gas boiler, hob, fire or a shared flue. Choose one that meets the British/European standard (BS EN 50291), ideally with a long-life sealed battery, fit it following the maker’s instructions, and test it regularly.
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Who this guide is for
Anyone in a flat with a gas boiler, gas hob, open fire, heater or a shared flue — which is most flats.
Our picks at a glance
| Pick | Best for |
|---|---|
| FireAngel Carbon Monoxide Alarm (FA6813) | A trusted, standard-approved CO alarm |
| Kidde 5CO Carbon Monoxide Alarm | Reliable protection on a budget |
| X-Sense Carbon Monoxide Detector | Seeing the CO reading at a glance |
Our picks in detail
BEST OVERALL — FireAngel Carbon Monoxide Alarm (FA6813)
Best for: A trusted, standard-approved CO alarm
From a well-known UK fire and CO safety brand, with a sealed long-life battery so there is nothing to replace for years, and it meets the recognised safety standard.
Pros: Trusted brand, sealed long-life battery, standard-approved.
Cons: No digital readout.
BEST VALUE — Kidde 5CO Carbon Monoxide Alarm
Best for: Reliable protection on a budget
A dependable CO alarm from a major safety brand at a low price, using a replaceable battery.
Pros: Trusted brand, very affordable, simple.
Cons: Battery needs replacing over its life.
BEST WITH DISPLAY — X-Sense Carbon Monoxide Detector
Best for: Seeing the CO reading at a glance
A CO alarm with a digital display so you can see current levels, with a replaceable battery.
Pros: Digital display, clear alerts, good value.
Cons: Replaceable battery to maintain.
Prices and availability on Amazon are accurate as of the date of publication and are subject to change.
How to choose
- Look for BS EN 50291: buy an alarm that meets this British/European standard (and ideally carries a kitemark).
- Battery type: a sealed long-life battery needs no replacing; replaceable-battery models cost less upfront.
- Placement: fit it as the manufacturer instructs — usually in rooms with fuel-burning appliances and near sleeping areas.
- One alarm may not be enough: consider one per relevant room.
- Test it regularly and note the replace-by date — CO alarms expire.
- Not a substitute for servicing: have gas appliances serviced by a qualified engineer.
Common questions
Where should I put a carbon monoxide alarm?
Follow the manufacturer’s instructions. As a general guide, alarms are fitted in rooms with fuel-burning appliances and where you sleep. Avoid dead spots and areas of high humidity; the product guide gives exact positioning.
Do I need a CO alarm in a flat?
If your flat has any fuel-burning appliance — a gas boiler, hob, fire or heater — or shares a flue with a neighbour, then yes, a CO alarm is strongly recommended and in many rented properties is a legal requirement.
How long do carbon monoxide alarms last?
Typically five to ten years depending on the model. Every alarm has a replace-by date printed on it — replace it by then even if it still seems to work.
Is a CO alarm the same as a smoke alarm?
No. A smoke alarm detects fire; a CO alarm detects carbon monoxide gas. They are separate devices and you need both for full protection.
Our recommendation
For most flats the FireAngel FA6813 is our top pick — a trusted brand with a fit-and-forget sealed battery. On a budget, the Kidde 5CO is reliable; if you want to see live readings, the X-Sense has a display. Whichever you choose, fit and test it per the instructions.
