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

It’s not uncommon to confuse smoke detectors with carbon monoxide (CO) detectors. And for good reason: the two devices are essentially small boxes (often battery-powered) that emit an alarm when their sensor detects a certain harmful gas in dangerous quantities in the house. However, these detectors are different devices that have unique functions, as smoke and carbon monoxide are different gases.

Smoke detector, carbon monoxide detector: are they the same thing?

Although you might think they’re the same device, smoke and carbon monoxide detectors serve very different home safety functions. Even their packaging, descriptions and similar location on shop shelves or online can be confusing.

There’s a good chance that your home already has a smoke detector (one or more). Meanwhile, it’s less likely that you have a carbon monoxide detector, as these are less common.

Smoke detectors and carbon monoxide detectors also have different objectives. A smoke detector essentially alerts sleepers when a fire breaks out during the night, while a carbon monoxide detector sounds when levels of this harmful, colourless and odourless gas are too high in your home. Carbon monoxide levels can rise and compromise your safety due to poor combustion processes within your home devices, most often in heaters.

Most of the time, when one of these detectors sounds an alarm, the other one won’t go off as well. That’s because you’ll often have smoke present with no carbon monoxide present, or vice versa.

However, the alarms in both types of detector could sound at the same time for some fires. If there’s smoke in your home, there might also be carbon monoxide emission. But if there’s unsafe levels of carbon monoxide in your home, there won’t often also be smoke. For that reason, it’s useful to equip your home with both detector types, so you’re able to ensure your safety at all times.

Smoke detectors and carbon monoxide detectors are both important devices for home or apartment safety. However, each detector product serves a different purpose.

Are smoke and carbon monoxide detectors mandatory?

In the UK, as of October 2015 private rented sector landlords are required by regulations to install:

  • At least 1 smoke alarm on every storey of a rental property that is used as living accommodation

  • A carbon monoxide alarm in any room that is used as living accommodation where solid fuel is used

Landlords also need to ensure that the detector alarms are fully functional when each new tenant moves into the rental property.

A smoke detector is mandatory on all living area floors

The smoke detector has been a compulsory installation on every floor of a rental property that the tenants use as living space since October 2015.

It’s important to know that there are optimal places to install smoke detectors in a property. Ideally, you’d install these detectors on the ceiling of the landings, or in the hallways leading to the property’s bedrooms.

To make sure that your smoke detector complies with all the applicable regulations, take the time to check the standards and markings on the device. This information will tell you whether the product has gone through all the relevant safety, quality and performance tests.

Landlords are required to check that smoke detectors are in working order when each new tenant moves into a property. If anything needs replacing (either the smoke detector itself, or just a battery or two), then the landlord should fund and carry out the replacement. However, tenants should take responsibility for regularly checking their smoke detectors during their time living in the property.

A carbon monoxide detector is mandatory in any living area with a solid fuel device

As of October 2015, it is compulsory to install a carbon monoxide detector in any room used as living accommodation that contains a solid fuel-burning device. For example, this includes home heating that is powered by wood.

Remember to regularly check the battery level and alarm function in your smoke and carbon monoxide detectors at home. This is the best way to ensure your safety!

How to avoid confusing the different gas detectors: smoke detector and carbon monoxide detector

A smoke detector sounds the alarm in the event of a fire, while a carbon monoxide detector alerts you when a combustion appliance in your home emits dangerous carbon monoxide.

In each case, a sensor detects a specific gas and triggers an alarm sound. As a result, both detectors are highly effective in improving your home safety.

The 2 types of detector have a lot in common

For one thing, they’re both fairly low maintenance. All you have to do is check that they are still charged, or that their batteries aren’t dead.

There are also specific guidance points for both types of detector when it comes to installing them in your home. You should place a smoke detector on the ceiling, but you should install a

CO detector on the wall. This is because smoke rises, but carbon monoxide does not.

Another common point is that these detectors work in the same way. When the target gas (smoke or CO) enters the detection field of the device installed in the appropriate place, it causes a chemical reaction that produces an electric current. This electric current then triggers the audible alarm. As soon as you hear it, you have to act quickly.

For the two detectors (smoke detector and carbon monoxide detector), there are many models available: wired or wireless, battery-operated or no battery, connected or classic, entry-level or high-end, and so on. You’ll find a product for all price ranges.

However, there is one nuance to note: there are also dual-function detectors. These are detectors that play the role of a smoke detector and a carbon monoxide detector. These detectors are the most complete option in terms of home safety, since you run much less risk.

A third detector that improves home safety: the heat detector

Finally, it’s useful to note that there’s also another type of detector that can improve your home safety levels.

This is the heat detector, a device which also alerts you in the event of fire. While it’s less effective than a smoke detector, a heat detector can be used in addition to your smoke and carbon monoxide detectors for wider detection capability in the home.

Whether it's smoke or carbon monoxide we’re dealing with, they’re both poisonous, dangerous and potentially deadly gases. It’s for this simple reason that a detector is not just an accessory or a gadget, but an important ally in improving your home safety. Watch out for the battery, as its lifespan isn’t eternal!