Home › Carbon monoxide alarms
Carbon monoxide alarms: 4 models compared on power, life and standards
The government's Fire Kills campaign puts it plainly: you can't see, taste or smell carbon monoxide, so an alarm is the only way to detect it (Fire Kills). Every alarm below states the same European standard for domestic CO alarms. The differences are how it's powered, whether it has a display, how long it lasts and whether it can link to other alarms.
What to look for
- Check whether batteries are replaceable or sealed, and what the low-battery warning requires you to replace. [fireangel.co.uk]
- Check the alarm replacement date separately from battery replacement. Follow the date marked on the device. [fireangel.co.uk]
- If you want a numerical CO reading, check that the model has an LCD showing ppm. [fireangel.co.uk]
- For interconnection, check compatible alarms and whether a separate radio module is required. [aico.co.uk]
- Check the exact model's stated standard, including its part number and year. [aicodatasheets.epim.online]
- Follow the model's siting instructions, including distance from fuel-burning appliances and locations to avoid. [fireangel.co.uk]
Sealed battery, replaceable battery or mains
A sealed battery lasts the life of the alarm and you replace the whole unit at its replace-by date. A replaceable-battery alarm needs new batteries along the way but still has a fixed working life. A mains alarm is wired into the house supply and keeps a backup battery. Whatever you choose, the replace-by date on the label is the one that counts.
A CO alarm is not a smoke alarm
FireAngel says a CO alarm does not replace a smoke alarm, and Aico says its CO alarms do not detect natural gas or bottled gas. You need smoke alarms as well: see our smoke alarm guide.
4 carbon monoxide alarms compared
Listed in no particular order. Facts link to the maker's own page or document they came from; prices change, so check before you buy.
FireAngel FA3313 Carbon Monoxide Alarm (replaceable batteries)
- Power
- Two replaceable AA batteries supplied; maker describes one-year battery life. [fireangel.co.uk]
- Sensor life
- 10 years. [fireangel.co.uk]
- Replacement guidance
- Replace after 10 years of operation; follow the REPLACE BY marking. [fireangel.co.uk]
- Display
- LED status indicators for power, fault and CO warning. [fireangel.co.uk]
Standards stated by the maker: "BS EN 50291-1: 2018 & BS EN 50291-2: 2019" [fireangel.co.uk]
The maker says it does not: A CO alarm does not replace a smoke alarm or combustible gas detector. [fireangel.co.uk]; The alarm cannot be silenced when CO exceeds 150ppm. [fireangel.co.uk]
FireAngel FA3322 Digital Display Carbon Monoxide Alarm
- Power
- Sealed lithium battery designed for 10 years; battery is not replaceable. [fireangel.co.uk]
- Sensor life
- 10 years. [fireangel.co.uk]
- Replacement guidance
- Replace after 10 years of operation; follow the REPLACE BY marking. [fireangel.co.uk]
- Display
- Colour LCD displays CO in ppm, room temperature and humidity. [fireangel.co.uk]
Standards stated by the maker: "BS EN 50291-1:2018 and BS EN 50291-2:2019" [fireangel.co.uk]; "BSI Kitemark approval" [fireangel.co.uk]
The maker says it does not: A CO alarm does not replace a smoke alarm or combustible gas detector. [fireangel.co.uk]; LCD performance can be affected below 0°C. [fireangel.co.uk]; The alarm cannot be silenced when CO exceeds 150ppm. [fireangel.co.uk]
FireAngel's UK product page · a UK retailer listing (£43.00 when checked on 7 November)
Aico Ei208WRF RadioLINK+ Battery Carbon Monoxide Alarm
- Power
- Sealed lithium battery for the alarm's 10-year life; battery cannot be removed. [aico.co.uk]
- Sensor life
- Electrochemical sensor with a 10-year life. [aico.co.uk]
- Replacement guidance
- Replace at the REPLACE UNIT BY date on the side label, or when end-of-life or low-battery indication requires replacement. [aico.co.uk]
- Display
- The model chart states no LCD for Ei208WRF. CO level is indicated by red LED flashes. [aico.co.uk]
- Interconnection
- Built-in RadioLINK+ radio interconnection; House Code the alarms together during installation. [aico.co.uk]
Standards stated by the maker: "Kitemarked to BS EN 50291-1:2018 & BS EN 50291-2:2019" [aicodatasheets.epim.online]
The maker says it does not: Does not detect natural gas, bottled gas or other combustible gases; does not provide suitable early smoke warning. [aico.co.uk]; Is not designed for people with impaired hearing. [aico.co.uk]
Aico's UK product page · a UK retailer listing (£85.00 when checked on 7 November)
Aico Ei3018 Carbon Monoxide Alarm
- Power
- 230V AC mains with 10-year rechargeable lithium backup. [aico.co.uk]
- Sensor life
- Electrochemical CO sensor with a 10-year life. [aico.co.uk]
- Replacement guidance
- Replace after at most 10 years and check the replace-by date on the side label. Disconnect mains before removal. [aico.co.uk]
- Display
- Green power, red alarm and yellow fault indicators; red flash rate indicates the CO level detected. [aico.co.uk]
- Interconnection
- Hardwired interconnection, or wireless interconnection with a separately purchased Ei3000MRF module in each alarm; up to 12 devices. [aico.co.uk]
Standards stated by the maker: "Kitemarked to BS EN 50291-1:2018" [aicodatasheets.epim.online]
The maker says it does not: Does not detect natural gas, bottled gas or other combustible gases. [aico.co.uk]; Do not hardwire it to battery-powered or low-voltage Aico devices, or alarms from another manufacturer. [aico.co.uk]
Aico's UK product page · a UK retailer listing (£71.58 when checked on 7 November)
How we put this guide together
- Products were chosen to cover the main choices a UK buyer faces, from models listed on the makers' UK sites or major UK retailers on 7 November 2026.
- Every fact comes from the source linked beside it. Where a maker doesn't publish something, we leave it out rather than guess.
- See how we research and our advertising disclosure.