How many carbon monoxide alarms do I need?

Carbon monoxide (CO) is a silent danger – it’s colourless, odourless, and tasteless. The only way to protect your home is with a carbon monoxide alarm. But how many CO alarms do you actually need, and where should you place them? Here’s a clear guide for UK households, with tips on products and placement to keep your home safe.

Legal Requirements in the UK

In England, private landlords must install a carbon monoxide (CO) alarm in any room used as living accommodation that contains a fixed combustion appliance (excluding gas cookers).

However, this is the minimum requirement. For full protection, it’s best to install CO alarms in every room containing a gas, oil, or solid fuel appliance. Organisations like Gas Safe Register recommend alarms near all fuel-burning appliances, including boilers, fireplaces, and stoves.

How many CO alarms should I install?

The number of alarms depends on the size of your home and the number of appliances:

• Rooms with fuel-burning appliances: Install one alarm in every room containing a gas boiler, fire, or stove. For example, the compact FireAngel FA6812-EUX10 Carbon Monoxide Alarm is ideal for kitchens and living rooms, featuring a digital display and a 10-year sensor.
• Sleeping areas: Place an alarm in or near bedrooms. Even if no appliance is present, CO can travel through walls, so having coverage near where you sleep is crucial.
• Large or multi-storey homes: Consider interlinked alarms, like the FireAngel Pro Connected Smart CO Alarm, which ensures that when one alarm sounds, all alarms in the house alert you.
• Portable alarms: Useful for holiday homes, boats, or temporary accommodation. The FireAngel FA3322 Digital Display Carbon Monoxide Alarm is compact and portable, ideal for travel.

A typical three-bedroom house with a gas boiler, a wood-burning fireplace, and an attached garage with a car stored inside, may need three to five alarms to provide comprehensive coverage.

Where to place CO alarms

Placement is crucial. Most governing bodies suggest following manufacturer instructions, but general guidance includes:

• Mount alarms at head height, on a wall or shelf.
• Keep them 1-3 metres away from appliances. Do not place directly above or beside the source.
• Avoid dead air zones like corners or behind curtains.
• Cover all levels in multi-storey homes, ideally in circulation areas and near bedrooms.

For bedrooms and sleeping areas, the FireAngel FA3313-T2 Carbon Monoxide Alarm is perfect – reliable, battery-powered, and designed for bedrooms or living rooms.

Why is my CO alarm beeping?

If a CO alarm starts beeping or flashing, it could indicate:

• Low battery: A regular chirp every 30-60 seconds means it’s time to replace the battery.
• CO detected: Four loud beeps with a pause indicate CO presence. Evacuate immediately, ventilate the room, switch off appliances if safe, and call 999 or your gas supplier.
• End-of-life: All alarms have a limited lifespan (typically 5-10 years). FireAngel alarms will alert you when they need replacing.

Take a look at our troubleshooting guide here for more information.

How CO Alarms Work

CO alarms are designed to measure the concentration of carbon monoxide in the air (in parts per million, or ppm) and sound an alarm if enough of the chemical is around long enough to become a problem. Some advanced models, like the FireAngel Pro Connected series, can even notify your smartphone, providing peace of mind when you’re away from home.

Explore FireAngel’s range of carbon monoxide alarms and get in touch with our Customer Service Team who can provide advice on installation, product selection, and technical support.