Carbon monoxide (CO) is often called the ‘silent killer’ – it’s a colourless, odourless gas that can be deadly.
Because you can’t see or smell CO, a carbon monoxide detector is a vital safety device for any home or workplace that uses fuel-burning appliances.
These detectors continuously monitor the air for CO and sound a loud alarm to warn you if dangerous levels are present.
But where to install a carbon monoxide detector?
In this article, we explain what a carbon monoxide detector is, why you need one, where to install a carbon monoxide detector, and how it works.
We also cover the different types of CO detectors, common sources of carbon monoxide, and what to do if the alarm goes off.
A carbon monoxide detector (or CO alarm) is an electronic safety device designed to detect the presence of carbon monoxide gas in the air and alert you before it becomes harmful.
It works much like a smoke alarm, but instead of sensing smoke, it uses special sensors to detect CO gas.
When the device senses a high level of CO, it triggers a loud alarm to warn everyone nearby.
Most CO detectors are small devices that run on batteries or mains power and can be mounted on a wall or ceiling.
Some models have digital displays that show the CO level, but many simply have an alarm sound and indicator lights.
Since carbon monoxide has no smell, taste, or colour, people cannot detect it on their own.
A CO detector is the only reliable way to get a warning about this invisible hazard and prevent carbon monoxide poisoning.
You should install carbon monoxide detectors in the proper locations throughout your home for maximum protection.
Ideally, have at least one CO alarm on every level of your house (including the basement).
It’s especially important to place a detector near bedrooms or sleeping areas – if you only have one CO alarm, put it in the hallway outside the bedrooms so it will wake you up if it goes off at night.
You may also want an alarm near potential sources of CO, such as a furnace, boiler, or fireplace (keep it a few metres away from the appliance to avoid false alarms).
Follow the manufacturer’s instructions on mounting height, typically CO detectors should be installed high on a wall (around 1.5 metres or 5 feet above the floor) or on the ceiling.
Also avoid putting detectors in very humid spots (like bathrooms) or near vents, windows, or fans, where airflow might disrupt their readings.
A carbon monoxide detector is needed because carbon monoxide gas is extremely dangerous and impossible to detect without an alarm.
CO is produced by burning fuels (like gas, oil, wood, or petrol), and if it builds up indoors it can poison anyone breathing it.
You cannot see it or smell it – so without a detector, you probably wouldn’t realise there’s a problem until you start feeling symptoms of CO poisoning.
Carbon monoxide poisoning can cause headaches, dizziness, nausea, confusion, and weakness.
In severe cases, or if you are asleep, it can make you lose consciousness or even be fatal before you notice any symptoms.
Sadly, hundreds of people die from accidental CO poisoning each year, and thousands more become ill, often because they didn’t have a working CO alarm to warn them.
A detector will sound an alarm while CO levels are still low enough that you can safely get outside or ventilate the area.
This early warning can save lives by giving you time to act before the situation becomes critical.
A carbon monoxide detector works by continuously monitoring the air and sounding an alarm if CO is detected at hazardous levels.
Inside the device is a sensor (typically an electrochemical sensor) that reacts when carbon monoxide gas is present.
If CO in the room rises above a certain threshold, the detector’s circuitry triggers a loud alarm to alert you.
CO detectors are calibrated to go off before carbon monoxide concentrations reach a life-threatening stage.
They generally ignore very low traces of CO (to avoid false alarms from brief, minor exposures) but will definitely alarm if a dangerous concentration builds up.
When activated, the alarm makes a loud beeping pattern that should be audible throughout your home.
Some models also flash a light or show a digital message when alarming.
The key point is that the detector warns you early, giving you time to get to fresh air and deal with the source of the carbon monoxide.
Carbon monoxide detectors come in a few different types, mainly based on their power source:
These units run on batteries.
They are easy to install anywhere and will work during a power cut.
You must replace the batteries periodically.
These plug into a wall outlet for power (usually with a battery backup).
They are convenient but their placement is limited to where outlets are available.
The backup battery keeps them working during a blackout.
These alarms are wired into your home’s electrical system.
They typically have battery backups and can often be interconnected, so that if one alarm sounds, all alarms in the house sound together.
This type of alarm is fire detection and carbon monoxide in one unit.
Combination detectors come in battery-operated or hardwired versions.
They provide both types of protection in a single device, which is convenient and saves space.
Carbon monoxide is produced by the incomplete combustion of fuels.
Common sources of CO in homes and buildings include:
Furnaces, boilers, and water heaters that burn gas, oil, or coal can produce CO if they malfunction or lack proper ventilation.
Burning wood or charcoal in a fireplace or stove generates CO.
If chimneys or flues are blocked or the ventilation is poor, carbon monoxide can build up indoors.
Car exhaust contains CO, so never run a vehicle in a garage (even with the door open) because the CO can accumulate and seep into the house.
Likewise, using a petrol/diesel generator or other fuel-powered engine indoors (or too close to the house) can cause dangerous CO levels.
Barbecue grills that use charcoal give off a lot of CO, so they must never be used indoors or in an enclosed area.
Portable propane or kerosene heaters (and camping stoves) also emit CO, so use them only with plenty of ventilation or outdoors according to their instructions.
If your carbon monoxide alarm goes off, you should take the following steps immediately:
You should have enough carbon monoxide detectors to adequately cover your entire home, rather than relying on just one.
As a general rule, have at least one CO alarm on every floor of your home and at least one near the bedrooms or sleeping areas.
This typically means multiple detectors are needed in a normal house.
For example, a two-storey house with a basement should have three CO alarms – one on each level (including one to cover the bedroom area on the top floor).
The goal is full coverage: no matter where a CO leak might start, there will be an alarm nearby to detect it and alert you.
In larger homes, you may need additional detectors to cover all areas.
It’s also wise to consider using interconnected alarms that all sound together – this way, even if a CO leak begins in a far part of the house, the alarm near your bedrooms will still go off to warn you.
In the United States, many states have laws requiring carbon monoxide detectors in homes.
If your home has any fuel-burning appliance or an attached garage, you are typically required to have CO alarms installed (usually at least one on each floor and near bedrooms).
Landlords must provide CO detectors in rental properties, and most new houses come with them as part of the building code.
Workplace safety regulations also address carbon monoxide.
Workplaces with potential CO sources (for example, garages, factories or kitchens using fuel-burning equipment) are required to monitor CO levels and often must use detectors or alarms to protect workers.
It’s important to check the specific rules in your area, because requirements can vary.
Even if a carbon monoxide detector isn’t explicitly mandated by law in your location, it is strongly recommended for safety.
In practice, virtually all fire safety guidelines and many insurance policies expect homes to have CO detectors because of their life-saving value.
You should now have an understanding of where to install a carbon monoxide detector.
Carbon monoxide detectors are a small investment that can save lives.
By installing them in the right places and keeping them in working order, you create an early-warning system against a deadly threat that you can’t otherwise detect.
Remember to test your CO alarms regularly and replace the batteries (or the unit) as directed by the manufacturer.
Alongside smoke alarms, carbon monoxide detectors form a critical defence in your home’s safety plan.
They provide peace of mind, knowing that if a CO build-up occurs, you will be alerted in time to take action.
Having properly installed and maintained carbon monoxide detectors in your home is not just about obeying regulations – it’s about protecting your family from harm.
Stay safe by being prepared and vigilant, and make sure CO detectors are part of your safety measures at home.
