Do I Need a Carbon Monoxide Alarm?

If your home burns gas, oil, coal or wood, you need a carbon monoxide alarm, and you need one in every room where that burning happens. The NHS is direct about it: get one alarm for each room of your home containing appliances that burn gas, oil, coal or wood¹. That covers a gas boiler, a gas fire, a gas hob, an open fire, a wood burner and a paraffin heater. If your home is powered entirely by electricity, you do not need one².

Carbon monoxide is a gas you cannot see, smell or taste, and an alarm is the only thing in the house that will warn you it is there. Its job is narrow and vital: to alert you and give you time to get out of the building safely³. It does not stop the gas being produced, and it does not replace having your appliances serviced and your flues checked⁴.

So the practical answer has two halves. Fit alarms where the fuel is burned, and keep the appliances that burn it in good order. This page sets out who needs an alarm, where it goes, how often to test it, what the law requires of landlords, and what to do about alarms when you go away.

Homes that burn gas, oil, coal or wood need an alarm

The test is simple: does anything in your home burn fuel? If it does, you need an alarm in the room where it burns. Guidance from Warwickshire County Council puts it plainly: if you have a fuel-burning boiler, fire or stove, whether it runs on gas, LPG, oil or wood, you should have an alarm in every room where fuel is burned, and a home powered entirely by electricity does not need one².

Fire and rescue services across the country say the same thing in their own words. Devon and Somerset Fire and Rescue Service says you should have an alarm in every room containing boilers, cookers, ovens, open fires or wood burners⁸. Greater Manchester Fire and Rescue Service recommends placing one in rooms with a fixed combustion appliance, such as a gas fire, gas boiler, log burner or open fireplace⁹. The NHS adds its own list, covering appliances that burn gas, oil, coal or wood¹⁰.

That list matters because people often think only of the boiler. A gas hob in a kitchen, a wood burner in a living room and an open fire in a front room are all sources, and each needs its own alarm in that room. A single alarm in the hallway will not reliably pick up carbon monoxide building in a closed kitchen or a bedroom above a boiler.

All-electric homes do not need one

If nothing in your home burns fuel, there is no carbon monoxide to detect. Warwickshire County Council's guidance is unambiguous: if you live in a house or flat that is entirely powered by electricity, you will not need a carbon monoxide detector². Which? repeats the same point, adding that if you do have a fuel-burning boiler, fire or stove you should have one in every room where fuel is burned¹¹.

The position changes the moment you add a fuel-burning appliance. A new gas hob, a wood-burning stove or a gas fire means you now have a source, and you should fit an alarm in that room. If you are unsure whether an appliance burns fuel, check its manual or ask the installer.

Where to fit a carbon monoxide alarm

Placement is where most people get this wrong, usually by fitting one alarm in a hallway and hoping it covers the house. It will not. Fit one in each room where fuel is burned, and site it so it can be heard.

The general rule is to put the alarm near the appliance, usually 1 to 3 metres away, and to follow the instructions that come with your specific alarm⁵. Guidance for rented homes is more precise: fit it in every room used as living accommodation that contains a fixed combustion appliance, apart from gas cookers, at head height on a wall or shelf, about 1 to 3 metres from the potential source¹². Warwickshire County Council advises mounting it on the wall or ceiling as the manufacturer instructs, at a height of 1 to 3 metres above the ground, away from obstacles or ventilation sources, and making sure it can be heard from all areas of the house².

North Wales Fire and Rescue Service adds the detail that decides many installations: the alarm must be 1 to 3 metres away from the appliance³. In a room with a sloping ceiling, site it at the highest point of the ceiling, and keep it above the line of any doors or windows in the room¹³.

Beyond the room itself, alarms should ideally be near bedrooms and living areas, so that they wake you⁶. Every household should have at least one alarm, with additional units recommended for each floor, near sleeping areas, and close to potential sources such as gas appliances, wood-burning stoves or an attached garage².

Why an alarm does not replace servicing your appliances

An alarm is a warning, not a fix. The Health and Safety Executive for Northern Ireland is firm on this: carbon monoxide alarms can help alert you to the dangers if gas escapes, but they must never be regarded as a substitute for the proper installation, maintenance, servicing and cleaning of appliances that use gas, coal, oil or any other solid fuel⁴. Devon and Somerset Fire and Rescue Service says the same: detectors are not a substitute for proper installation and maintenance of fuel-burning appliances⁸.

The reason is straightforward. An alarm tells you carbon monoxide is present. It does not tell you why, and it does not stop the appliance producing more. A blocked flue, a poorly maintained boiler or a faulty appliance will keep generating carbon monoxide whether or not an alarm is fitted. Servicing catches those faults before they become dangerous.

Public Health Wales makes the point in its winter guidance: know the symptoms of carbon monoxide poisoning and have a working alarm, but fitting an alarm should not be used instead of regular checks of appliances¹⁴. Staffordshire County Council advises anyone using gas, wood or coal appliances to ensure they are serviced and to consider a carbon monoxide alarm¹⁵. The NHS advises getting appliances serviced regularly and fitting an alarm wherever there are flame-burning appliances or open fires¹⁶.

Suffolk Fire and Rescue Service sums up the limitation: these alarms may warn you of the presence of carbon monoxide, but they are not a replacement for regularly servicing household appliances¹⁷.

Testing your alarm every month

A carbon monoxide alarm that is not working is worse than none, because it gives false reassurance. Test it once a month. Warwickshire County Council advises testing alarms at least once per month², and Devon and Somerset Fire and Rescue Service says to test your smoke alarms and carbon monoxide alarms once a month⁷. Surrey County Council goes further, advising that carbon monoxide detectors should be installed in every room with a gas or solid fuel burning appliance, and that alarms should be tested weekly alongside your smoke alarms¹⁸.

Whichever routine you adopt, the point is regularity. Pick a fixed day, test every alarm in the house, and replace batteries or the whole unit as the manufacturer instructs. If an alarm starts beeping for no obvious reason, do not assume it is a fault: check the manufacturer's guidance and treat any alarm activation as a possible real event until you know otherwise.

What the law requires of landlords

If you rent, your landlord has legal duties. In England, landlords must ensure a carbon monoxide alarm is fitted in any room used as living accommodation that contains a fixed combustion appliance, excluding gas cookers, and must check it is working at the start of the tenancy¹⁹. Cornwall Council's fire and rescue service explains that landlords must supply a carbon monoxide detector and alarm in any room used wholly or partly as living accommodation that contains a solid fuel burning combustion appliance²⁰.

The legal basis is the Smoke and Carbon Monoxide Alarm Regulations, amended in 2022. North Yorkshire Fire and Rescue Service explains that under the amendment all relevant landlords must ensure a carbon monoxide alarm is fitted in any room used as living accommodation containing a fixed combustion appliance, excluding gas cookers²¹. Wiltshire and Swindon Prepared notes that landlords of private residential rental properties in England are required by law to install a carbon monoxide alarm in any room containing a solid fuel burning appliance, such as coal or wood burning fires and stoves²².

Landlords must also have smoke detectors on each floor²⁰. Cherwell District Council advises that alarms in rented homes should comply with British Standards BS 50291¹².

If your landlord has not provided an alarm where one is required, ask in writing and keep a copy. If you are a landlord yourself, fit the alarm, check it at the start of each tenancy, and keep a record.

Do alarms need to be linked to each other?

No. A carbon monoxide alarm does not need to be linked to your smoke alarms. The Scottish Government's guidance on what each home needs says a carbon monoxide detector does not need to be linked to the smoke alarms²⁴, and the Scottish Fire and Rescue Service says the same²⁵. The Scottish fire alarm standard also confirms that where there is a carbon-fuelled appliance or a flue, a carbon monoxide detector is required and does not need to be linked to the fire alarms²³.

That said, linking has practical value. If your CO alarm is in a boiler room at the back of the house and your bedroom is at the front, an unlinked alarm may not wake you. The priority is that the alarm can be heard from bedrooms and living areas⁶. If it cannot, either move it or choose a linked system. For more on how linking works, see Interlinked Alarms: How Linking Works.

Taking an alarm on holiday

Carbon monoxide does not stay at home, and neither should your protection. Which? advises that if you go to a holiday cottage in the UK or a hotel, it should be fitted with carbon monoxide detectors, and notes that alarms are small, light and easy to pack if you are travelling abroad¹¹.

A travel alarm gives you the same early warning in unfamiliar accommodation that you have at home, where you know the appliances and their history. If you are staying somewhere with a gas boiler, a gas fire or a wood burner, and you cannot see a carbon monoxide alarm, ask the owner or the hotel. For more on choosing an alarm to take with you, see Carbon Monoxide Alarms: What They Do and How to Choose.

What to do if your alarm sounds

An alarm's purpose is to alert you to carbon monoxide and give you time to exit the building safely¹³. If it sounds, act on that. Get everyone out into fresh air, including pets, and do not go back in until you have been told it is safe. Call the gas emergency number for your area if you have a gas supply.

Do not assume it is a false alarm. Carbon monoxide poisoning can develop gradually, and the symptoms are easy to mistake for other illnesses. For the signs to look for, see Carbon Monoxide Poisoning Symptoms, and for step-by-step instructions, see What to Do If Your CO Alarm Sounds or You Suspect Carbon Monoxide.

Some households have extra protection. Anglesey Council's Telecare service offers a carbon monoxide detector that raises an audible alarm within the home and also sends an instant alarm call to a monitoring centre when carbon monoxide levels rise, for example from a blocked flue or a faulty appliance²⁶. That is worth knowing about if you or someone you care for would not hear or act on an alarm alone.