Your guide to smoke and carbon monoxide alarms

The difference between a smoke alarm and a carbon monoxide detector can seem a mystery. But both play an important part in keeping you safe. In this article we look at how they differ, what insurers need to know – and the best place to mount them in your home.

Summary

• Carbon Monoxide and Smoke Alarms detect different things. It is recommended that you have both
• You should regularly check your alarms to make sure they are working and replace them if they’re not performing as expected
• You can contact your local fire & rescue service or your local Age UK to help with testing and fitting. You may even qualify for a free alarm

What's the difference between a smoke alarm and a carbon monoxide detector?

Smoke alarms and carbon monoxide detectors do very different jobs. A smoke alarm is designed to detect particles from a fire – either smoke or sometimes tiny particles invisible to the naked eye. “That's one reason people are more aware of fires earlier these days,” says West Yorkshire Fire and Rescue Service firefighter Paul Ashfield. “Getting alerted sooner means fires can be less developed when we arrive, which means less damage to the house and a better chance of everyone getting out.”

A carbon monoxide alarm, on the other hand, detects the gas – which you can’t see, taste or smell. Carbon monoxide can come from fuel‑burning appliances such as boilers, gas fires, wood‑burning stoves and cookers if they are not working properly or if flues and chimneys are blocked. “Carbon monoxide is a silent killer, so we always recommend having coal, oil and natural gas appliances serviced annually,” Ashfield explains.

Can smoke alarms detect carbon monoxide?

Standard smoke alarms cannot detect the gas, so they will not warn you about a carbon monoxide leak. If you have gas appliances or a solid‑fuel fire, you will need a separate carbon monoxide alarm for full protection.

Similarly, a carbon monoxide detector will not react to smoke from a fire. This is why having both types – or a combined smoke and carbon monoxide alarm – is so important.

In most homes, what people might call a fire alarm is usually a set of battery- or mains‑powered smoke detectors rather than a full system. Larger or shared buildings are more likely to have a wired or monitored set-up that can alert everyone in the building at once.

Many areas offer systems that link detectors to careline services. “These can pick up something like burning from cooking and can send help automatically,” says Ashfield. “They’re an invaluable safety net for people living on their own.”

Fire alarm vs smoke detector – can they impact your home insurance?

When you arrange home insurance, you may be asked whether you have working, reliable, regularly tested smoke and carbon monoxide detectors fitted. In some cases alarms are a condition of cover and could reduce your premium.

Who is eligible for free smoke alarms in the UK?

Many fire and rescue services offer free home fire safety checks, sometimes called Safe and Well visits, which can include fitting free smoke alarms for those most at risk. You can usually find details on your local fire and rescue service website. Some charities, such as your local Age UK, offer assistance with contacting your local service and can even help with fitting smoke alarms and carbon monoxide detectors for you.

Where do you mount your detector?

A carbon monoxide detector works best when it’s placed at about head height, either on a wall or a shelf, between one and three metres from the appliance it’s monitoring. If you have a gas boiler in the kitchen or a wood‑burning stove in the living room, your detector should be close enough to sense any build‑up of gas but not right next to the appliance.

Avoid placing the carbon monoxide detector directly above a cooker, by a window or next to an extractor fan, as draughts and steam can affect how it works. If you have several fuel‑burning appliances or sleep on an upper floor, you should install more than one detector so any alert can be heard, wherever you are in the home.

“Smoke alarms should be on every level of your home and in all regularly used rooms. The more smoke detectors you have, the better protected your home is. Place detectors where they can be heard throughout your home, especially while sleeping.”

How long do carbon monoxide detectors and smoke alarms last?

This depends on the model but many have a lifespan of around 10 years. When it reaches the end of its life, it will normally give a warning chirp or show a light on the front to tell you it needs replacing.

Ashfield says: “It's worth checking or speaking to a qualified electrician if you're not sure. Many modern alarms have sealed batteries that cannot be removed. It means the whole unit will need replacing once it reaches the end of its life.”

How do I test a carbon monoxide detector – and what if it goes off?

Most alarms can be tested by pressing and holding the test button until the alarm sounds, then releasing it. This checks the sounder and the battery.

If a carbon monoxide detector goes off continuously and you are not pressing the test button, treat it seriously. Open doors and windows, switch off fuel‑burning appliances if it’s safe to do so, leave the property and get fresh air. If you smell gas, call the emergency gas number on 0800 111 999 even if your alarm is quiet.

How do you turn off a smoke detector?

The safest way to turn the alarm off on a smoke detector is to open a window or door and waft the air away from the alarm rather than taking the battery out. Some alarms have a hush or silence button that turns the sound off for a short time while the air clears.

Do vapes set off smoke alarms?

Vaping does not produce smoke in the same way cigarettes do, but the vapour can still be dense enough to trigger some types of smoke alarm or carbon monoxide detector – particularly optical alarms that react to particles in the air. If you have a combined smoke and carbon monoxide alarm, heavy vapour might still trigger the smoke sensor in the device.

Here are the key things you need to know about smoke and carbon monoxide alarms:

• The two types of alarm are very different. You will need both – or an alarm that detects both smoke and carbon monoxide.
• Make sure you have one smoke alarm installed per floor in your home.
• If you require assistance in installing alarms, contact your local fire service.
• Alarms have a lifespan and will eventually expire. Pay attention to warning chirps or changes to the lights.