Carbon Monoxide Alarms: The 2022 Rules, Where They Go, and What the Beeps Mean
By the DC Fire & Security engineering team — installing and maintaining fire and security systems since 2010. Updated July 2026.
Quick answer
Since 1 October 2022, rented homes in England must have a carbon monoxide alarm in every room used as living accommodation that contains a fixed combustion appliance — boilers, gas fires, log burners, solid-fuel stoves — with gas cookers the notable exclusion. Landlords must fix or replace an alarm as soon as they're told it's faulty. Placement: at head height (wall or shelf — not the ceiling like smoke alarms), between 1 and 3 metres horizontally from the appliance. Buy alarms certified to BS EN 50291 with a sealed long-life battery, and know the signals: four fast beeps = CO detected, get out and ring 0800 111 999; a single chirp = battery or end of life.
Who must fit CO alarms, and where
| Situation | Requirement |
|---|---|
| Private rentals & social housing (England, since Oct 2022) | CO alarm in every room used as living accommodation with a fixed combustion appliance (excluding gas cookers). Smoke alarm on every storey remains required. Landlord must repair/replace promptly once notified |
| HMOs | Same CO duty, plus HMO licensing conditions commonly add interlinked smoke/heat detection — the landlord fire alarm guide covers the full detection stack |
| New or replacement solid-fuel appliances (any home) | Building Regulations require a CO alarm in the same room when a stove or solid-fuel appliance is installed |
| New boilers and gas appliances | CO alarm in the room is required alongside installation of new fixed combustion appliances (again excluding cookers) — installers should fit or insist on one |
| Owner-occupiers generally | No blanket legal duty for existing appliances — but the same alarms cost £15–£30 and the same gas kills roughly wherever it's ignored. Fit them as if the law applied |
| Scotland, Wales, NI | Scotland requires CO alarms wherever there's a carbon-fuelled appliance or flue (all homes); Wales mirrors the rental duty under its housing standards. Check the nation's rules if you hold stock across borders |
Placement: the metre-by-metre version
Carbon monoxide mixes with room air rather than rising like smoke, so CO alarms don't follow smoke-alarm logic. In a room with an appliance: mount at head height — a wall bracket or a high shelf — between 1m and 3m horizontally from the appliance. Not directly above heat or steam sources, not next to windows, extractor fans or vents (fresh air dilutes the sample), not in dead-air corners, and not behind the curtains.
In bedrooms or rooms where people sleep near an appliance or flue run, mount at breathing height relative to the bed. If the alarm is the combined smoke/CO type, ceiling mounting follows the smoke rules and the unit must be rated for it — read the model's instructions over any general rule, including this one.
- Rooms that need one in a typical rental: the room with the boiler, the lounge with the gas fire or log burner, any bedroom with a combustion appliance or a flue passing through
- Gas cookers are excluded from the legal duty — but a kitchen CO alarm remains a sensible fit where any doubt exists about ventilation
- Buy BS EN 50291-certified (the box will say), sealed 7–10 year lithium battery models — the replaceable-AA versions become non-compliant the day a tenant borrows the batteries
What the beeps mean (the 3am question)
The dangerous mistake is treating four-beep alarms as a battery problem because carbon monoxide is invisible and odourless and everyone feels fine. Headache, nausea and drowsiness — the early symptoms — arrive after exposure, and the alarm exists precisely because your senses get no vote. Out first, investigate second.
If it's your smoke alarm chirping rather than the CO unit, that guide is here.
| Sound | Meaning | What to do |
|---|---|---|
| Four fast beeps, repeating | CO detected — this is the alarm | Get everyone out to fresh air, leave doors open on the way, ring the Gas Emergency line 0800 111 999, don't re-enter or switch appliances back on until checked |
| Single chirp every 30–60 seconds | Low battery or fault | Sealed-battery models: the unit is telling you it's done — replace it. Replaceable-battery models: new battery today, not at the weekend |
| Chirp with an 'END' or red pattern per the label | End of sensor life (7–10 years) | Replace the unit — CO sensors expire even when the battery hasn't |
| Intermittent beeping that stops when you ventilate | Possible low-level CO events | Treat seriously: have appliances and flues checked — low-level exposure is the one that gets missed |
For landlords: the compliance loop that actually holds up
The regulation's quiet second half is the maintenance duty: alarms must be shown working at the start of each tenancy, and repaired or replaced 'as soon as reasonably practicable' once a tenant reports a fault. The practical loop: record alarm positions and test results in the check-in inventory, put a test line in periodic inspections, keep dated photos, and standardise on sealed-battery units so the failure mode is 'replace unit' rather than arguing about AA batteries. Councils can fine up to £5,000 per breach of the smoke/CO regulations — cheaper than one alarm round across a portfolio.
We fold CO alarms into the same visit as smoke and heat detection work for rental stock — one engineer, every room right, one certificate per property. The landlord fire alarm requirements guide and printable checklist cover the full detection stack.
Frequently Asked Questions
Are carbon monoxide alarms a legal requirement in the UK?
Where should a carbon monoxide alarm be placed?
Do I need a carbon monoxide alarm if I have a gas cooker?
Why is my carbon monoxide alarm beeping every 30 seconds?
How long do carbon monoxide alarms last?
Can carbon monoxide alarms be interlinked with smoke alarms?
Landlord or agent? Make the whole detection side compliant in one visit
We install and certificate smoke, heat and carbon monoxide detection for landlords, HMOs and blocks across Luton, Bedfordshire, Hertfordshire and North London — alarms in the right rooms, the paperwork that proves it, and servicing schedules that keep it that way. Send the property list; we'll handle the rest.
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