FA3820-EUX10 Carbon Monoxide Alarm – 10-Year Sealed Battery

Press the test/hush button on the FA3820-EUX10. You will hear two loud sequences of four beeps and the LED will flash, confirming the alarm is working. Test at least once a month and vacuum around the unit every six months to remove dust. See our full guide to testing your CO alarm for more detail.

If the alarm sounds, open all windows and doors immediately to ventilate the room. Turn off any fuel-burning appliances if it is safe to do so. Move everyone, including pets, outside into fresh air and call the Gas Emergency Service on 0800 111 999. Do not re-enter the property until a qualified engineer has confirmed it is safe. See our step-by-step guide to what to do if your CO alarm goes off.

Install a CO alarm in every room with a fuel-burning appliance such as a boiler, gas fire, or wood-burning stove. Position it on the ceiling or high on a wall, between 1m and 3m from the CO source. For full coverage, fit one in every bedroom and living area too. See our guide on how many carbon monoxide alarms you need for room-by-room advice.

Early symptoms include headaches, dizziness, nausea, breathlessness, and tiredness. These are often mistaken for flu because carbon monoxide is colourless and odourless. Prolonged exposure can lead to confusion, loss of consciousness, and can be fatal. If several people in the same building feel unwell at the same time, suspect carbon monoxide and evacuate immediately. Visit our carbon monoxide safety page for more information.

A continuous loud alarm with four beeps means carbon monoxide has been detected – evacuate immediately and call 0800 111 999. A single chirp at regular intervals usually means the battery or sensor is reaching end of life and the unit needs replacing. The 30-day memory function on the FA3820-EUX10 lets you check whether CO was detected while you were away. See our guide to CO alarm beeping for a full explanation of each sound pattern.

If your home has any fuel-burning appliance – including a gas boiler, gas cooker, gas fire, oil burner, or wood-burning stove – you should have a carbon monoxide alarm. In England, a CO alarm is legally required in any room with a fixed combustion appliance (excluding gas cookers) under the Smoke and Carbon Monoxide Alarm (England) Regulations 2015 (amended 2022). Scotland and Wales have similar requirements.

Replace your end-of-life CO-9X with the FA3820-EUX10. It offers an advanced electrochemical sensor, a 10-year sealed battery, a ventilate pre-alarm warning, and BSI Kitemark certification. The FA3820-EUX10 fits in the same location as your old alarm. For a model with a digital display showing the CO reading in parts per million, consider the FireAngel FA3322. See our complete installation guide for step-by-step instructions.

No – a carbon monoxide alarm detects CO only, not natural gas (methane) or LPG. If you smell gas, turn off the supply at the meter, open windows, leave the property, and call the Gas Emergency Service on 0800 111 999. For smoke and CO protection in a single unit, consider the FireAngel SCB10-R combination smoke and CO alarm.