Best Carbon Monoxide Alarms UK (2026): Top 5 We'd Buy
Kitemarked CO alarms for rooms with a boiler, fire or stove, plus the UK rules and where to put one
Quick answer
- Best overallFireAngel FA3820 – sealed 10-year battery, Kitemarked
- Best 10-year warrantyKidde K10LLCO – sealed battery, sold for Scottish rules
- Best value for two roomsKidde 5CO Twin Pack – two Kitemarked alarms in one pack
- Best with a displayKidde 5DCO – shows CO levels from 30ppm
- Best budget and travelFireAngel FA6813 – cheap and portable for caravans and trips
The best carbon monoxide alarm UK homes can buy, for most people, is the FireAngel FA3820. It has a sealed battery that lasts its 10-year life, and its listing says it is Kitemarked to BS EN 50291-1:2018, the current British Standard for home CO alarms. If you need two alarms, the Kidde 5CO twin pack is the best value.
Carbon monoxide has no colour or smell, so an alarm is the only way to know it is there. The NHS advises a loud CO alarm in each room with an appliance that burns gas, oil, coal or wood, such as a boiler, gas fire, wood burner or open fire. An alarm is a backup, not a fix: appliances still need proper installing and regular servicing. Electric heaters do not burn fuel, so they do not make carbon monoxide. Compare them in our best fan heater UK and best oil-filled radiators UK guides. If you are sealing draughts in a room with a fire or boiler, keep its vents clear, as our best draught excluders UK guide explains. We have not tested these ourselves.
1 to 3m
Rough distance from the fuel-burning appliance that GOV.UK guidance suggests for a CO alarm, generally at head height
Source: GOV.UK
Editor's Choice
FireAngel FA3820 Carbon Monoxide Alarm, 10-Year Sealed Battery
Our top pick. No batteries to change for 10 years, current-edition Kitemark certification, and useful extras, for under £20.
Diagnose your problem
How to Choose a Carbon Monoxide Alarm
Four quick questions to find the right one.
Problem
Do you live in Scotland, or are you a landlord?
Some rules say what kind of battery a CO alarm must have.
Recommendation
In Scotland, the Scottish Government says a battery CO alarm must have a sealed battery that lasts its whole life. Choose the FireAngel FA3820 or Kidde K10LLCO. GOV.UK guidance for landlords in England also says that where battery alarms are chosen, sealed-for-life batteries are the better option.
Products
Problem
How many rooms have a fuel-burning appliance?
Count rooms with a gas or oil boiler, gas fire, wood burner, open fire or other appliance that burns fuel.
Recommendation
The NHS advises one alarm for each of those rooms. For two rooms in England or Wales, the Kidde 5CO twin pack is the best value. For more rooms, buy more than one pack or several single alarms.
Products
Problem
Do you want to see the CO level on a screen?
Most alarms just beep. Some show a reading.
Recommendation
The Kidde 5DCO shows CO levels from 30ppm and alarms from 50ppm. BSI says alarms to this standard are designed to warn of dangerous CO, not to track low levels for health reasons.
Products
Problem
Do you need one for a caravan, motorhome or boat?
BS EN 50291-2 covers CO alarms for leisure vehicles and boats.
Recommendation
The FireAngel FA3820 lists BSI approval to both parts of the standard. The FireAngel FA6813 is a cheaper portable choice that FireAngel says is designed to conform to both parts.
Products
Quick Picks
The right carbon monoxide alarm for each kind of home
Our Top 5 Picks
Compare all
FireAngel
FireAngel FA3820 Carbon Monoxide Alarm, 10-Year Sealed Battery
“Our top pick. No batteries to change for 10 years, current-edition Kitemark certification, and useful extras, for under £20.”
Best for
Most homes, renters, landlords and Scottish homes
Skip it if
You need two or more alarms on a tight budget, where the Kidde 5CO twin pack is cheaper per alarm (but not for Scotland).
Pros
- +Sealed 10-year battery, as Scottish rules ask for battery CO alarms
- +Kitemarked to BS EN 50291-1:2018 (listing says)
- +Also approved to EN 50291-2 for caravans and boats (listing says)
- +Early warning and alarm memory
Cons
- −You replace the whole alarm after 10 years
- −Costs more than AA battery alarms
- −No digital display of CO levels
All specifications
| Battery | Sealed 10-year |
| Standard (listing) | BS EN 50291-1:2018 and EN 50291-2:2019, Kitemarked |
| Display | Lights, early warning |
| Scottish Homes | Yes, sealed battery |
Kidde
Kidde K10LLCO 10-Year Longlife Carbon Monoxide Alarm
“A strong sealed-battery alternative from a big alarm brand, with the longest warranty here. It has far fewer Amazon reviews than our top pick.”
Best for
Scottish homes and landlords who want a long warranty
Skip it if
You want the alarm with the most UK buyer reviews, as our top pick has far more.
Pros
- +Sealed lithium batteries for 10 years
- +10-year manufacturer’s warranty (listing says)
- +Sold as suitable for the 2022 Scottish rules
- +Shows if CO was detected while you were out
Cons
- −Only around a hundred Amazon UK ratings
- −Listing does not mention a Kitemark
- −Slightly dearer than the FireAngel
All specifications
| Battery | Sealed lithium, 10-year |
| Standard (listing) | EN 50291-1:2018 |
| Display | Status lights |
| Scottish Homes | Yes, sold as suitable |
Kidde
Kidde 5CO Carbon Monoxide Alarm, Twin Pack
“The best value if you have two rooms with fuel-burning appliances, say a boiler in the kitchen and a wood burner in the lounge. It was the best selling CO alarm on Amazon UK when we checked.”
Best for
Homes in England or Wales with two rooms that need an alarm
Skip it if
You live in Scotland, or you do not want to change batteries.
Pros
- +Two alarms for not much more than one sealed alarm
- +Kitemarked to BS EN 50291-1:2018 (listing says)
- +Number one in CO detectors on Amazon UK when we checked
- +7-year warranty (listing says)
Cons
- −AA batteries need changing
- −Not suitable for Scottish homes, which need sealed batteries
- −No display
All specifications
| Battery | AA, replaceable |
| Standard (listing) | BS EN 50291-1:2018, Kitemarked |
| Display | None |
| Scottish Homes | No, replaceable batteries |
Kidde
Kidde 5DCO Digital Carbon Monoxide Alarm
“The pick if you want to see a reading, not just hear a beep. Remember it is still an alarm for dangerous CO, not a health monitor.”
Best for
People who like to see a CO reading in England or Wales
Skip it if
You live in Scotland, or you are a landlord who wants a sealed battery.
Pros
- +Digital display of CO levels from 30ppm
- +Kitemarked to BS EN 50291-1 (listing says)
- +Low battery warning on screen
- +Over 12,000 UK ratings
Cons
- −AA batteries need changing
- −Not permitted in Scottish homes (listing says)
- −Readings below 30ppm are not shown
All specifications
| Battery | AA, replaceable |
| Standard (listing) | BS EN 50291-1, Kitemarked |
| Display | Digital, from 30ppm |
| Scottish Homes | No (listing says) |
FireAngel
FireAngel FA6813 Portable Carbon Monoxide Alarm
“The cheapest pick and handy for caravans and holidays. For a fixed home alarm, we prefer models certified to the newer 2018 edition.”
Best for
A cheap travel alarm for caravans, holiday lets and trips
Skip it if
You live in Scotland, or you want a Kitemarked alarm for your home.
Pros
- +Low price
- +Portable, with a wall bracket too
- +Designed for EN 50291-2 leisure use as well as homes (listing says)
- +Over 8,000 UK ratings
Cons
- −Listing cites the older 2008 edition of BS EN 50291-1
- −Says "designed to conform", not Kitemarked
- −Not for Scottish homes (listing says)
All specifications
| Battery | AA, replaceable |
| Standard (listing) | Designed to BS EN 50291-1:2008 and EN 50291-2:2019 |
| Display | Lights |
| Scottish Homes | No (listing says) |
Compare All Products
Side-by-side specs for quick decision-making
Swipe to compare →
| Product | Battery | Standard (listing) | Display | Scottish Homes | Price | Best For | Action |
|---|---|---|---|---|---|---|---|
| Sealed 10-year | BS EN 50291-1:2018 and EN 50291-2:2019, Kitemarked | Lights, early warning | Yes, sealed battery | £18–£20 | Most homes, renters, landlords and Scottish homes | View | |
 Kidde K10LLCO 10-Year Longlife Carbon Monoxide AlarmBest 10-Year Warranty | Sealed lithium, 10-year | EN 50291-1:2018 | Status lights | Yes, sold as suitable | £19–£21 | Scottish homes and landlords who want a long warranty | View |
 Kidde 5CO Carbon Monoxide Alarm, Twin PackBest Value for Two Rooms | AA, replaceable | BS EN 50291-1:2018, Kitemarked | None | No, replaceable batteries | £22–£25 | Homes in England or Wales with two rooms that need an alarm | View |
 Kidde 5DCO Digital Carbon Monoxide AlarmBest with a Display | AA, replaceable | BS EN 50291-1, Kitemarked | Digital, from 30ppm | No (listing says) | £15–£17 | People who like to see a CO reading in England or Wales | View |
 FireAngel FA6813 Portable Carbon Monoxide AlarmBest Budget and Travel | AA, replaceable | Designed to BS EN 50291-1:2008 and EN 50291-2:2019 | Lights | No (listing says) | £12–£14 | A cheap travel alarm for caravans, holiday lets and trips | View |
If Your CO Alarm Goes Off
Never ignore it. The NHS says to stop using any appliance you think may be making carbon monoxide, go outside, and get medical advice as soon as possible. Do not go back in until you have had advice. Call 999 if anyone finds it hard to breathe, has suddenly become confused, has lost consciousness, or feels weak or has chest or muscle pain. If you think a gas appliance is leaking carbon monoxide, the NHS says to call the free National Gas Helpline on 0800 111 999. An alarm is a backup: HSE says alarms are not a replacement for regular maintenance and safety checks by a Gas Safe registered engineer.
Research Methodology
How We Chose These Products
We have not tested these ourselves. This is desk research, so we have not exposed these alarms to carbon monoxide.
We read GOV.UK guidance on the Smoke and Carbon Monoxide Alarm (England) Regulations, Scottish and Welsh government guidance, NHS and HSE advice and BSI information on BS EN 50291. We then read Amazon UK listings, maker specs and verified UK buyer reviews. We only picked alarms whose listings state the BS EN 50291 standard, and we prefer those that state Kitemark or BSI certification. Prices and ratings are from Amazon UK on the day we checked. We never make up prices or test results.
Selection Criteria
Stated Standard
35% weightListing states BS EN 50291, ideally with Kitemark or BSI certification to the current edition
Battery Type
20% weightSealed 10-year batteries score higher, as Scottish rules require them for battery CO alarms and GOV.UK guidance calls them the better option
Buyer Reviews
20% weightStar rating, number of reviews and complaints such as false alarms or early failure
Value for Money
15% weightPrice per alarm, including twin packs
Alarm and Warnings
10% weightLoud alarm, end-of-life warning, test button and extras like alarm memory
Important Limitations
- •We have not tested these ourselves
- •Standards and certification are as stated on the listings, so check the box and manual when it arrives
- •Rules differ across England, Scotland, Wales and Northern Ireland, so check the rules where you live
- •This guide is not legal advice for landlords
- •Price bands are rough, so always check the current Amazon UK price
Research last conducted: · Price bands checked:
Frequently Asked Questions
Common questions about carbon monoxide alarms in the UK
For most homes, we pick the FireAngel FA3820. It has a sealed 10-year battery and its listing says it is Kitemarked to BS EN 50291-1:2018. The Kidde K10LLCO is a sealed-battery alternative with a 10-year warranty. For two rooms, the Kidde 5CO twin pack is the best value, the Kidde 5DCO has a display, and the FireAngel FA6813 is a cheap travel alarm.
It depends where you live. In England, since 1 October 2022, landlords must fit a CO alarm in any room used as living accommodation that has a fixed fuel-burning appliance, apart from gas cookers. In Scotland, every home must have a CO detector in any room with a carbon-fuelled appliance such as a boiler, open fire or wood burner. In Wales, landlords must fit one in each room with a gas, oil or solid fuel appliance. Northern Ireland has its own rules, so check nidirect.
In the same room as the fuel-burning appliance. GOV.UK guidance for landlords says an alarm should generally go at head height, on a wall or shelf, about 1 to 3 metres from the appliance. Always follow the maker’s instructions in the box, as they say where that model works best and where to avoid.
The rules for landlords in England leave out gas cookers, and the Scottish Government says gas cookers and hobs do not need a CO detector. But the NHS lists gas cookers among appliances that can make carbon monoxide, and advises an alarm in each room with an appliance that burns gas, so many people fit one in the kitchen anyway.
It is the standard for carbon monoxide alarms. Part 1 covers alarms for homes, and Part 2 covers caravans, motorhomes and boats. HSE says to make sure an alarm complies with BS EN 50291 and carries a British or European approval mark, such as a Kitemark. The Scottish Government asks for a Kitemarked EN 50291-1 alarm.
A sealed battery lasts the life of the alarm, usually 10 years, so it cannot run flat or be taken out. In Scotland, a battery CO alarm must have one. GOV.UK guidance for landlords in England says that where battery alarms are chosen, sealed-for-life batteries are the better option. AA alarms cost less to buy but you must remember to change the batteries.
All five picks here have a 10-year sensor, according to their listings. When the sensor reaches the end of its life, the alarm warns you and you replace the whole alarm. Check the date on the alarm when you fit it, and press the test button regularly as the manual says.
The NHS says stop using any appliance you think may be making carbon monoxide, go outside, and get medical advice as soon as possible. Do not go back in until you have had advice. Call 999 if anyone has severe symptoms. For a gas appliance, call the free National Gas Helpline on 0800 111 999.
No. Electric heaters such as fan heaters and oil-filled radiators do not burn fuel, so they do not make carbon monoxide. Portable gas and paraffin heaters do burn fuel, and the NHS lists them among appliances that can make carbon monoxide.
No. A smoke alarm detects smoke from a fire, not carbon monoxide. You need a CO alarm as well in rooms with fuel-burning appliances. The rules for landlords in England, for example, require a smoke alarm on every storey and a CO alarm in rooms with a fixed fuel-burning appliance.
Got a boiler, fire or stove?
Our top pick, the FireAngel FA3820, has a sealed 10-year battery and is Kitemarked to BS EN 50291-1, the listing says.
View Our Top Pick on Amazon UKDisclosure & Editorial Policy
Amazon Affiliate: TopMagpie is a participant in the Amazon Services LLC Associates Programme. We earn from qualifying purchases. This doesn't affect our editorial choices or the prices you pay.
No Lab Testing: We have not laboratory-tested these products. Recommendations are based on spec analysis, reviews, and editorial judgement.
Prices: Approximate bands, checked . Amazon prices change frequently – always verify the current price before purchasing. We do not invent live prices.
Data Source: The 1 to 3m figure is from the GOV.UK. Actual results vary based on your specific situation.
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