Carbon Monoxide Alarms (aka Detectors) (new rules 2026)
Thoughts and Recommendations

Last updated 2026.01.01

What is Carbon Monoxide (CO)?

Carbon monoxide is a chemical, where a molecule is made up of one carbon atom and one oxygen atom. At temperatures and pressures where humans can survive, it is a gas which is colourless and odourless. It is toxic to humans in even small proportions in the air we breathe, which is called carbon monoxide poisoning. It is a common byproduct of combustion (burning stuff). It is slightly lighter than air, which is 80% nitrogen. It mixes easily in air to be fairly evenly dispersed.

What's a Carbon Monoxide Alarm / Detector?

While the terms are often used interchangeably, a CO detector is usually a handheld device used by a technician for inspecting combustion equipment to look for CO leaks, while a CO alarm is usually installed in place and monitors the air continuously for the presence of CO in dangerous concentrations. Retail packaging may use either term or both.

Are there different kinds of CO Alarms?

Yes. Most perform detection the same way using sensors that react to the chemical properties of carbon monoxide. NIST provides a more detailed accounting of the types and differences, but the key takeaway from that is that the sensors will eventually age out, and the units need to be replaced. Read the instructions with the unit you acquire for the exact replacement schedule. 10 years is typical.

Do Carbon Monoxide Alarms ever need to be replaced?

Yes. See the directions that come with the specific model you are installing. If you have lost them, look for the directions on the Internet. Most major manufacturers have websites (Kidde, First Alert (BRK), Honeywell, and check the packaging for the right one for your unit.
N.B. Carbon Monoxide Alarms made for the U.S. market are not legal for use in Canada (including Ontario). Look for the CSA or ULC logo for acceptable models for use in Canada.

How are Carbon Monoxide Alarms powered?

In general, consumer grade Carbon Monoxide Alarms require an electrical supply to power the sensors, the alarm, and in some cases, a light. Depending on the model, the power may come from a hard-wired household circuit, a plug for a typical wall outlet, a battery or a combination of these.

Can I install a Carbon Monoxide Alarm myself?

Unless your building requires use of only hard-wired Carbon Monoxide Alarms, absolutely you can - and in my opinion, should - install carbon monoxide alarms yourself (after reading the manufacturer's instructions and looking at My Recommendations below). The consumer models are designed to be installed by people with basic reading skills, basic mechanical skills and common tools (typically a screwdriver and something to make small pilot holes in walls, e.g. drywall, and maybe a small level). If you are not comfortable with simple mechanical work, perhaps you have a family member, friend or neighbour who could do this for you. If you cannot do it yourself or find a volunteer, you can hire someone to do the work for you.

(If you really can't do it yourself, or find a family member, friend, or neighbour to do it, you can hire a handy-person service, electrical contractor or general contractor to do it for you. Only if none of those options are open to you, and the alarms are to be installed in western Ottawa, get in touch with me.

Do Carbon Monoxide Alarms require maintenance?

Yes. A Carbon Monoxide Alarm should be tested monthly to ensure it is working and has a functioning power supply.
For this reason, we recommend that the alarm devices should be installed in a location that is easily accessed so the testing will actually get done, and so that replacement of batteries is actually feasible when required.

My Recommendations

Get a unit which is powered by a battery only. While CO poisoning events are rare, one cause is a household power failure which leads people to running generators indoors or beside the building where exhaust can enter the building to provide electricity during the outage. If space heating is affected (e.g. a gas or oil furnace that needs electrically-powered controls to operate, or electric heating), people may use small barbecues indoors or at a doorway to provide heat and cook food. These produce carbon monoxide. The key is that a CO alarm that runs only on household electricity won't work if the electricity is off. At a minimum, make sure your unit has a battery backup.

Many houses just don't have enough outlets to provide a wall outlet for every device we now have in our houses that wants a 120-volt supply, and the locations of outlets may not correspond to where you want to put the CO alarm for best protection. An alarm unit that is not dependent on household electricity provides that freedom in determining location.

Pretty much all smoke and CO alarms today have a low battery alarm, so you will be signaled to replace the battery when it is near end-of-life. (Check packaging before purchase to ensure it has this feature.) If you don't want to pay for disposable batteries, rechargeable batteries for common alarm battery sizes (AA or 9-volt) are available from retailers online and in physical stores.

If you are profoundly deaf, ensure the Carbon Monoxide Alarm you acquire has a visible and very noticeable alarm feature - even when you are sleeping.

A CO alarm does not need to be put near the floor. This misconception may be the result of CO alarms powered by household electricity only, and outlets were typically fairly close to the floor.

Put the CO alarm where it is easily accessible (e.g. not behind a heavy piece of furniture), so you can access it for monthly testing and occasional battery replacement.

Place the alarms where they will actually help, where people spend time in your home. Near sleeping areas, and likely near the main TV or entertainment centre, home office ... The Regulations require at least one alarm per storey, but they don't prevent you from installing more. (Disclosure: I don't sell CO alarms or have an investment in companies that do.)

Pick a specific day of the month for your testing routine, as you do for smoke alarms, e.g. the day of your birthday in the month. Think birthday, think birthday candles, think smoke - test your smoke and CO alarms. (If your birthday is the 29th, 30th, or 31st, just pick the first or last of the month, or some other day you will remember easily.) Put a repeating, monthly reminder in your digital calendar.

Write on the detector body - where it is visible - in permanent marker, the EXPIRY date for the unit per the installation instructions. That way you'll be able to remember when it needs to be replaced, as you'll be looking at it monthly, right?

Store the installation and maintenance instructions for the units with your other device warranty and user manuals.

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Carbon Monoxide Alarms (aka Detectors) (new rules 2026) Thoughts and Recommendations