Safety & Outdoors
The 10 Best Carbon Monoxide Alarms UK
· Top 10 comparison · Amazon.co.uk prices checked at publication
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How we choose: Buy Wise Hub hasn't tested these products in person. Our rankings are based on published specifications, Amazon ratings and buyer reviews, and this guide was researched and written with the help of AI tools, then checked by our team. Prices and ratings were correct at the time of writing and may change.
Carbon monoxide (CO) has no colour, smell or taste, and it's produced whenever fuel doesn't burn properly. That includes gas boilers, gas fires, log burners, open fires, oil boilers and blocked flues. October and November are exactly when the risk goes up: the heating goes on after months off, windows stay shut and chimneys get their first use of the season. A CO alarm costs less than a takeaway and is the only reliable way to know there's a problem.
To find the best carbon monoxide alarms in the UK, we started with Amazon.co.uk's Carbon Monoxide Detectors best-seller chart. We shortlisted the best-reviewed models from established brands and a few strong newcomers, then read every product page to check the price, rating, review count and specs. Where a listing doesn't confirm something, we say so.
Prices, ratings and review counts are correct at the time of checking (27 October 2026) and change often. Always check the live price before you buy.
Quick Picks
- Best overall: Kidde 5CO, £13.75, 4.7★ (59,605 reviews)
- Best budget all-rounder: FireAngel FA6813, £13.98, 4.7★
- Best with a digital display: Kidde 5DCO, £17.99, 4.7★
- Best sealed 10-year battery: FireAngel FA3820, £21.07, 4.6★
- Premium pick: FireAngel FA3322, £37.99, 4.6★, with temperature and humidity alerts
Comparison Table
- #1 Kidde 5CO | Rating 4.7 | 59,605 reviews | £13.75 | Best overall | View
- #2 FireAngel FA6813 | Rating 4.7 | 8,699 reviews | £13.98 | Budget all-rounder | View
- #3 Kidde 5DCO Digital | Rating 4.7 | 12,101 reviews | £17.99 | Digital display | View
- #4 X-Sense XC0C-SR | Rating 4.7 | 6,469 reviews | £15.98 | Display + peak memory | View
- #5 FireAngel FA6812 Digital | Rating 4.8 | 2,090 reviews | £18.99 | Highest rated | View
- #6 FireAngel FA3820 | Rating 4.6 | 3,485 reviews | £21.07 | Sealed 10-year battery | View
- #7 Kidde 2030-DCR | Rating 4.7 | 2,885 reviews | £13.99 | Compact | View
- #8 Firehawk CO7B-10Y | Rating 4.4 | 2,035 reviews | £19.42 | Sealed battery, small | View
- #9 XINDUM CO12 | Rating 4.6 | 1,274 reviews | £18.99 | Sealed battery + LCD on a budget | View
- #10 FireAngel FA3322 | Rating 4.6 | 739 reviews | £37.99 | Premium (CO + humidity) | View
The 10 Best Carbon Monoxide Alarms Reviewed
#1 Kidde 5CO: Best Overall
The Kidde 5CO is the #1 best seller in Carbon Monoxide Detectors on Amazon.co.uk, with a 4.7-star average from a huge 59,605 reviews. It keeps things simple. It monitors continuously, has a test/reset button and green and red status LEDs, and gives an end-of-life alarm when the sensor is due for replacement. It runs on AA batteries (included), and the title states a 10-year sensor life. The listing also states a 7-year manufacturer's warranty, which is longer than most rivals offer. It's small (3.9 × 12.7 × 7.3 cm, 0.2 kg), so it sits easily on a shelf or goes on a wall. There's no display, so you won't see CO levels, but for a reliable alarm from a major safety brand at under £14, it's the one we'd buy first. Note that the listing doesn't name EN 50291 (unverified, so check the packaging), and its "Photoelectric" sensor field looks like a listing error. Read our full Kidde 5CO review.
Specs (listing): AA batteries · 10-yr sensor · 7-yr warranty · 200 g
Pros: biggest review base in the category · 7-year warranty · cheap enough to buy several
Cons: no CO level display · replaceable batteries need changing · standard not named on the listing
#2 FireAngel FA6813: Best Budget All-Rounder
FireAngel is one of the UK's best-known alarm brands, and the FA6813 is its best-selling CO alarm here, at #2 in the chart with 4.7 stars from 8,699 reviews. The listing confirms an electrochemical sensor and a 85 dB(A) at 3 metres alarm (four loud chirps plus a flashing red "CO" LED). It's powered by two replaceable AA batteries (included), and the title calls it a 10-year CO alarm. A useful "Sleep Easy" feature lets you mute a low-battery chirp for 8 hours by pressing the test button, so you're not up at 3am hunting for batteries. It comes with a mounting bracket and screws, or it can stand freely, and FireAngel pitches it as travel-friendly. The warranty is 3 years, shorter than Kidde's 7. At £13.98 it's essentially the same price as our top pick, with more detail on the listing.
Specs (listing): Electrochemical · 85 dB(A) @ 3 m · 2 × AA · 3-yr warranty · 141 g
Pros: loudness stated clearly · Sleep Easy chirp mute · portable or wall-mounted
Cons: 3-year warranty · no display
#3 Kidde 5DCO: Best Digital Display
If you want to see what's happening, the Kidde 5DCO adds a digital screen to the 5CO's formula. It has 4.7 stars from 12,101 reviews. The listing is unusually specific. It displays CO levels from 30 ppm and alarms from 50 ppm, and it's Kitemarked to BS EN 50291-1 (domestic use) and CE and UKCA marked. It runs on two replaceable AA batteries (supplied), has a 10-year sensor lifespan, and shows a low-battery warning chirp and on-screen message. It's a slim 127 × 73 × 39 mm and 170 g, and the listing gives a 7-year warranty. Being able to read a ppm figure is genuinely reassuring when an appliance seems off, or after a boiler service. For about £4 more than the 5CO, this is the upgrade most households should consider.
Specs (listing): Display from 30 ppm · alarm from 50 ppm · BS EN 50291-1 Kitemark · 2 × AA · 7-yr warranty · 170 g
Pros: shows CO levels · Kitemark confirmed · 7-year warranty
Cons: batteries need replacing · costs more than the 5CO
#4 X-Sense XC0C-SR: Best Display with Peak Memory
X-Sense has built a strong following, and the XC0C-SR has 4.7 stars from 6,469 reviews. It has a clear display of the current CO level and a peak-level check button, which is handy for spotting brief CO spikes that happened while you were out. A three-colour LED shows the status at a glance: red for alarm, yellow for fault or low battery, green for normal. The listing states a 10-year sensor and replaceable AA batteries rated to last 3 years. It measures 75 × 142 × 32 mm, stands freely or mounts with the screws included, and has buttons of different sizes so you can find the right one in a hurry. The listing we checked doesn't state the EN 50291 standard, the loudness or the warranty term (unverified). Check the box for the EN 50291 marking.
Specs (listing): Display + peak memory · 10-yr sensor · AA (3-yr battery life) · 181 g
Pros: peak CO memory · tri-colour status LED · easy-to-use buttons
Cons: standard, dB rating and warranty not on the listing · slightly larger than others
#5 FireAngel FA6812 Digital: Highest Rated
The FA6812 has the highest rating in our top 10 (4.8 stars from 2,090 reviews). It's essentially the FA6813 with an LCD screen. The screen shows current CO levels in standby, an active alarm, "AL" for an alarm that went off while you were out ("Alarm in Absence"), battery status and an "EOL" end-of-life warning. It uses a 10-year electrochemical sensor, two replaceable AA batteries (included), and four loud chirps with a flashing red light. The listing confirms compliance with BS EN 50291-1:2018 and BS EN 50291-2:2019 and CE marking. The -2 standard covers use in leisure accommodation such as caravans and boats. It measures 120 × 73 × 35.5 mm and comes with a bracket and screws. The warranty is 3 years.
Specs (listing): LCD · electrochemical 10-yr sensor · EN 50291-1 & -2 · 2 × AA · 3-yr warranty · 145 g
Pros: top-rated · Alarm in Absence memory · standards for home and leisure use stated
Cons: 3-year warranty · fewer reviews than the leaders
#6 FireAngel FA3820: Best Sealed Battery
You'll never change a battery on the FA3820. It has a sealed, tamper-proof 10-year battery that lasts the life of the alarm, and it warns you with a flashing amber "!" and a beep when it's time to replace the unit. It has 4.6 stars from 3,485 reviews. The listing confirms an electrochemical sensor and an 85 dB(A) at 3 m alarm. A clever high-sensitivity mode gives an early "pre-alarm" with a "ventilate" instruction if it predicts CO will rise to 180 ppm or above. Alarm memory flags any activation while you were out. It measures 125 × 67 × 33 mm and 95 g, and stands freely. The warranty is 5 years. If you're buying for an elderly relative, a rental or anyone who won't keep on top of batteries, this is the one.
Specs (listing): Sealed 10-yr battery · 85 dB(A) @ 3 m · predictive pre-alarm · 5-yr warranty · 95 g
Pros: no battery changes · early-warning pre-alarm · alarm memory
Cons: no display · the whole unit is replaced at end of life
#7 Kidde 2030-DCR: Best Compact
The Kidde 2030-DCR has 4.7 stars from 2,885 reviews and is the smallest Kidde here, at 61 × 96 × 38 mm. The listing says it alarms from 50 ppm, uses an electrochemical sensor, is TÜV certified to EN 50291-1:2018, and is CE marked and UKCA tested. It runs on AA batteries (included) with a low-battery warning and has a 3-year warranty. One note from the seller: Kidde's listing describes it as suitable for homes in England and Wales but not for homes in Scotland. If that matters to you, the sealed-battery FireAngel FA3820 or Firehawk CO7B-10Y may suit you better.
Specs (listing): 50 ppm alarm · EN 50291-1:2018 (TÜV) · AA batteries · 3-yr warranty · 138 g
Pros: very compact · standard and alarm threshold confirmed · trusted brand
Cons: listing says not suitable for Scottish homes · 3-year warranty · no display
#8 Firehawk CO7B-10Y: Best Small Sealed-Battery Alarm
Firehawk is a long-standing UK alarm brand, and the CO7B-10Y has a sealed 10-year lithium battery, an end-of-life indicator, LED indicators and a versatile mounting system. It has 4.4 stars from 2,035 reviews and costs £19.42. The listing confirms an electrochemical sensor. It's sparse on detail, though. It doesn't state the alarm loudness, the EN 50291 certification or the warranty (all unverified), and its "30 × 30 × 30 mm / 40 g" dimensions look implausible for a CO alarm, so treat them as a listing error. Its rating is also the lowest here. It's still a sensible choice for a fit-and-forget sealed unit from an established name, but the FireAngel FA3820 gives you more confirmed information for a little more money.
Specs (listing): Sealed 10-yr lithium battery · electrochemical · end-of-life indicator
Pros: no battery changes · established UK brand · compact design
Cons: sparse listing · lowest rating in our top 10 · dimensions look wrong
#9 XINDUM CO12: Best Budget Sealed Battery with LCD
The XINDUM CO12 combines a sealed 1600 mAh lithium 10-year battery with a real-time LCD of CO levels. Usually you'd have to pick one or the other. It has 4.6 stars from 1,274 reviews and costs £18.99. The listing claims EN 50291 compliance and CE certification, an electrochemical sensor and an 85 dB alarm. It has a yellow LED and a beep every 60 seconds for a low battery, plus an end-of-life warning. It stands freely, sticks on with double-sided tape, or screws to the wall with its bracket. It's a lesser-known brand, so we'd want to see EN 50291 printed on the unit itself, and the listing doesn't state a warranty (unverified). It weighs 102 g.
Specs (listing): Sealed 10-yr lithium battery · LCD · 85 dB · EN 50291 (claimed) · 102 g
Pros: sealed battery and display together · flexible mounting · good value
Cons: lesser-known brand · warranty not stated
#10 FireAngel FA3322: Best Premium Pick
The FA3322 is the most capable alarm here. As well as CO, it shows temperature and humidity and warns if either hits an extreme, which is handy in bedrooms, nurseries or damp-prone rooms. It has 4.6 stars from 739 reviews and costs £37.99. The listing confirms a digital display, an electrochemical sensor, a sealed 10-year battery and an 85 dB alarm. A low-level CO pre-alarm (a short then long chirp, an amber screen and "WARNING" with the ppm value) alerts you to a sustained low exposure before it reaches full alarm, when the screen turns red and flashes "EVACUATE!". It measures 120 × 76 × 31 mm, comes with a bracket and screws, and has a 5-year warranty. It's expensive for a single alarm, but excellent for one key room.
Specs (listing): Display · CO + temp + humidity · sealed 10-yr battery · 85 dB · 5-yr warranty · 121 g
Pros: low-level CO warning · humidity and temperature alerts · sealed battery
Cons: costs nearly three times our top pick · smaller review base
Buying Guide: How to Choose a Carbon Monoxide Alarm
1. Look for EN 50291
The European and British standard for domestic CO alarms is EN 50291-1. EN 50291-2 also covers leisure accommodation such as caravans and boats. A Kitemark (as on the Kidde 5DCO) or third-party certification (TÜV on the Kidde 2030-DCR) is a stronger signal than the seller's own claim. Some best sellers, including our #1, don't name the standard on the Amazon page, so check the packaging when your alarm arrives.
2. Sealed battery or replaceable AA?
- Sealed 10-year battery (FA3820, Firehawk CO7B-10Y, XINDUM, FA3322): you never change a battery, and you replace the whole unit at the end. It's ideal for rentals, older relatives and anywhere hard to reach.
- Replaceable AA (Kidde 5CO/5DCO/2030-DCR, FireAngel FA6813/FA6812, X-Sense): cheaper to buy, but you must replace the batteries when the alarm warns you.
3. Display or no display?
A basic alarm just sounds. A digital display shows CO in ppm, and often a peak level (X-Sense) or an "alarm in absence" memory (FireAngel FA6812), so you can spot low-level or intermittent problems. If someone in your home is vulnerable, a display or a low-level pre-alarm (FA3820, FA3322) is worth the extra few pounds.
4. Sensor and loudness
All the alarms whose sensors are listed here use electrochemical sensing, the standard technology for CO. The FireAngel models and the XINDUM state 85 dB alarms. The Kidde 5CO, X-Sense and Firehawk listings don't state the volume (unverified).
5. Placement
Fit an alarm in every room with a fuel-burning appliance: boiler, gas fire, log burner, open fire. Consider one in bedrooms too, because CO is most dangerous while you're asleep. Follow the manufacturer's height and distance guidance, and avoid bathrooms, spots directly above cookers and places with no air flow.
CO alarms are required in some homes, so check what applies to yours.
6. A CO alarm isn't a smoke alarm
Every product here detects carbon monoxide only. Kidde's listing says so directly. You still need working smoke alarms, ideally on every floor.
How we chose
We started from the Amazon.co.uk Carbon Monoxide Detectors best-seller chart on 27 October 2026. We prioritised established brands (Kidde, FireAngel, X-Sense, Firehawk) and strong review bases, then read each live product page for price, rating, review count and specs. We haven't lab-tested these alarms. Our rankings reflect the confirmed specs, buyer ratings, value and warranty.
FAQ
What is the best carbon monoxide alarm in the UK?
For most homes, the Kidde 5CO is the best all-round choice. It's the #1 best seller on Amazon.co.uk, with 4.7 stars from more than 59,000 reviews, a 10-year sensor and a 7-year warranty for £13.75. If you want to see CO levels, the Kidde 5DCO adds a Kitemarked digital display for £17.99.
Where should I put a carbon monoxide alarm?
Put one in every room with a fuel-burning appliance, such as a boiler, gas fire, log burner or open fire, and ideally in bedrooms. Follow the manufacturer's guidance on height and distance from the appliance. Avoid bathrooms, spots directly next to the appliance and enclosed areas with no air flow.
How long do CO alarms last?
Most modern alarms have a 10-year sensor life and give an end-of-life warning when they need replacing. Sealed-battery models (such as the FireAngel FA3820) never need a battery change. AA-powered models need new batteries when they warn you. Write the installation date on the alarm.
Are cheap CO alarms on Amazon safe?
Price alone isn't the issue. Certification is. Look for EN 50291-1, ideally with a Kitemark or third-party certification, and buy from a known brand or a seller with a strong review history. Check the markings on the unit when it arrives.
Should I get a CO alarm with a display?
A display isn't essential, because every alarm here sounds when CO reaches a dangerous level. A screen lets you see the CO level in ppm, and some models also keep a peak-level reading or an alarm-in-absence memory (X-Sense XC0C-SR, FireAngel FA6812). That makes it easier to spot low-level or intermittent problems. The Kidde 5DCO is our pick if you want a display.
Sealed battery or AA: which CO alarm is better?
A sealed 10-year battery (FireAngel FA3820, Firehawk CO7B-10Y, XINDUM CO12) means you never change a battery, but you replace the whole unit at end of life. AA models (Kidde 5CO, FireAngel FA6813) cost less to buy, but you need to replace the batteries when the alarm warns you.
Getting ready for winter? See our upcoming guides to the best head torches, best rechargeable torches and best wind-up radios for a complete power-cut kit.
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