Updated July 2026. Carbon monoxide is odourless, colourless and can kill before anyone notices — and since 1 October 2022 fitting alarms is a legal duty for landlords, not just good practice. This guide covers the law, what to look for, and three solid carbon monoxide alarms you can buy today.
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The law: where landlords must fit CO alarms
Under the Smoke and Carbon Monoxide Alarm (England) Regulations, since 1 October 2022 you must fit a carbon monoxide alarm in any room used as living accommodation that contains a fixed combustion appliance — a gas boiler, gas fire, wood burner or oil heater. Gas cookers are the one exception. You must also repair or replace an alarm once a tenant tells you it is faulty. For the wider duty, see our smoke and CO alarm requirements guide, and make sure your gas safety certificate is current.
What to look for in a carbon monoxide alarm
- BS EN 50291 with a Kitemark or equivalent. This is the standard CO alarms must meet — check it is marked on the unit.
- Sensor life. Most alarms last 7–10 years; a sealed 10-year unit is ideal for rentals as there is nothing for a tenant to tamper with.
- Battery type. Sealed lithium (fit-and-forget) vs replaceable AA (cheaper up front).
- A loud alarm (around 85 dB) and, ideally, a digital display and end-of-life warning.
For a whole portfolio, browse sealed 10-year CO alarms on Amazon.
Our top three carbon monoxide alarms
| Alarm | Best for | Power | Sensor life |
|---|---|---|---|
| Kidde K5CO | Budget pick | Replaceable AA | 10 years |
| FireAngel FA6813 | Battery-powered all-rounder | Replaceable AA | Up to 7 years |
| EITO CO alarm (LED display) | Cheapest with a display | Replaceable AAA | Check on listing |
1. Kidde K5CO — best budget CO alarm
A no-frills, reliable alarm with a 10-year sensor life, powered by replaceable AA batteries and a loud, clear sound. If you just need a compliant, dependable alarm at the lowest sensible price, this is the one. Check price on Amazon.
2. FireAngel FA6813 — best battery-powered all-rounder
FireAngel is one of the most trusted UK fire-safety brands. This CO alarm meets EN 50291 with a Kitemark, has a loud alarm and LED indicators, and installs in minutes on a shelf or wall. A dependable choice for most rooms. Check price on Amazon.
3. EITO CO alarm — cheapest with a digital display
An affordable alarm with an LED display showing real-time CO readings, a loud siren and simple battery installation (batteries usually sold separately). Good value if you want a live readout. Check price on Amazon.
Where to install a carbon monoxide alarm
Fit one in each room with a fixed combustion appliance. Position it roughly 1–3 metres horizontally from the appliance, at head height or on the ceiling per the manufacturer’s instructions. Keep alarms away from windows, doors, extractor fans, and the immediate steam/heat of bathrooms and cookers, which can cause false readings or shorten sensor life.
Testing and maintenance
Test alarms monthly using the test button, replace batteries in non-sealed units as needed, and replace the whole alarm at the end of its stated sensor life (typically 7–10 years). Note the install and replace-by dates in your compliance records. It is good practice to test all alarms at the start of each new tenancy and log it.
Frequently asked questions
Are carbon monoxide alarms a legal requirement for landlords?
Yes. Since 1 October 2022 you must fit a CO alarm in any room used as living accommodation with a fixed combustion appliance (gas cookers excepted), and repair or replace faulty alarms once notified.
Can a smoke alarm detect carbon monoxide?
No — a standard smoke alarm cannot detect CO. You need a dedicated carbon monoxide alarm (or a combined smoke/CO unit that explicitly detects both).
How long do CO alarms last?
Typically 7–10 years. Sealed 10-year alarms are convenient for rentals; replace any alarm at the end of its stated sensor life.
What should tenants do if the alarm sounds?
Get everyone out into fresh air, call the National Gas Emergency Service on 0800 111 999, and don’t re-enter until it’s declared safe.
Written by the Landlords Portal team — experienced UK landlords covering the private rented sector. As an Amazon Associate we earn from qualifying purchases. This article is general information, not legal advice; always follow the manufacturer’s instructions and current GOV.UK guidance.
