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November 30, 2022

What and How Do Carbon Monoxide Detectors Work? A Homeowner’s Guide

Carbon Monoxide Detectors - LG Home Comfort

Carbon monoxide (CO) detectors are vital to any home safety plan, but many people should know how they work. What’s worst is they are not aware of its potential dangers. According to records, there are more than 300 deaths and 200 hospitalizations per year in Canada due to carbon monoxide poisoning. In the US, CDC says that around 50,000 people go to the emergency for accidental CO poisoning.

What Is Carbon Monoxide?

Carbon monoxide (CO) is an odorless, tasteless, colorless, and poisonous gas that’s produced whenever any fuel is burned. CO forms when there is incomplete combustion of fossil fuels, like natural gas, propane, fuel oil, wood, or coal.

Any appliance that uses these types of fuel can produce carbon monoxide. When inhaled and entered the bloodstream, it can prevent oxygen from being carried to the brain, heart, and other vital organs. This can lead to tissue damage and, eventually, death. It only takes a small amount of CO to poison someone.

In most cases, people poisoned by carbon monoxide (CO) didn’t even know the problem until it was too late. That’s because this gas is odorless and invisible. That’s why working CO detectors in your home is crucial, especially if you use any fuel-burning appliance.

If you have the following appliance in your home, you are most likely to experience CO-related issues:

  • Dryers

  • Furnaces or boilers

  • Motor vehicles

  • Fireplaces (gas and wood burning)

  • Grills

  • Wood stoves

  • Water heaters

  • Generators

  • Power tools and lawn equipment

What Are Carbon Monoxide Detectors?

Carbon monoxide detectors are devices that sound an alarm when this dangerous gas is present in the air. These are similar to smoke detectors but designed to sense invisible gases like carbon monoxide. Not that CO detectors are not meant to be used as smoke alarms and vice versa.

There are types of carbon monoxide detectors, such as:

  • Plug-in detectors with battery backup. These are the most common type of detectors. You can plug them into any standard electrical outlet. Some models have a digital display showing the CO level in your indoor air.

  • Battery-operated detectors. These are ideal for homes that don’t have many outlets or for those who frequently experience power outages. Most brands come with LED displays that show the temperature and CO levels when detected. They don’t require installation, so you can place them on tabletops, coffee tables, or even your bookshelf.

  • Hardwired. The biggest advantage of these detector types is that they can be linked to each other. However, if the power goes off, they will not work.

How Do Carbon Monoxide Detectors Work?

When CO enters carbon monoxide alarms, it reacts with a chemical that produces an electric current. This current is then processed by the microprocessor, activating the alarm when it reaches a certain level. Some models have a LED display that will show the level of CO in your indoor air. The detector can only be silenced once the source of CO is removed.

CO alarms have a few key components that work together to detect the presence of carbon monoxide and to sound the alarm when needed. These are:

  • Sensor. It can detect carbon monoxide concentrations and signal when the gas reaches predetermined levels.

  • Microprocessor. It receives electrical signals from the sensor and sends signals to the alarm horn and the control panel.

  • A visual display (LCD panel). It communicates CO level and other related information.

  • Alarm circuit. It generates a loud sound to wake or warn people near the detector.

  • Power connection. This can be AC plus, battery, connection, or both.

  • Circuit board. It serves as a base for electronic components.

  • Plastic housing. It holds the components together.

Where to Install Carbon Monoxide Detectors?

The International Association of Fire Chiefs (IAFC) suggests placing carbon monoxide detectors on every floor in your home, including the basement. 

Place them on a wall around 5 feet from the floor. This way, it can measure the air at a height that you and your family are breathing. You may also place them on the ceiling, six inches from the wall. They should be located within 10 feet of each bedroom door, and you must not put a CO alarm near or over any attached garages. The best rooms to place them in are the kitchen, outside bedrooms, and basements.

How Long Does a Carbon Monoxide Detector Last?

Although most manufacturers claim that their products can last up to 5 to 6 years, replacing your detectors every four years is a good idea. Note that the lifespan of your detector will also depend on how often you use it and the environment where it is placed. To know when it’s time to replace your carbon monoxide detector, check your device’s user manual. Most manufacturers have a replacement schedule that you can follow.

What Is the Ideal Level of Carbon Monoxide in Your Home?

Ideally, the carbon monoxide concentration in your indoor air should be the same as outdoors. But since homeowners use fuel-burning appliances daily, there’s always a chance for carbon monoxide to seep into the home.

There are no standard guidelines on the safe level of this dangerous gas indoors. But the Environmental Protection Agency (EPA) considers anything below nine parts per million (ppm) or 40,000 micrograms per meter cubed to be safe outdoors for 8 hours. On the other hand, 35 ppm for 1 hour is considered safe for short-term exposure indoors.

In Canada, the Canadian Environmental Act of 1999 says that 25ppm for 1 hour is the maximum permissible level of this odorless gas in any indoor environment. On the other hand, ten ppm is the maximum permitted level in 24 hours.

Signs and Symptoms of CO Poisoning

The EPA listed down the most common symptoms of CO poisoning that homeowners should be aware of, as follows:

  • Nausea

  • Fatigue in healthy people

  • Angina

  • Chest pain in individuals with heart conditions

  • Impaired vision and coordination

  • Headaches

  • Dizziness and confusion

  • Other flu-like symptoms

Note that in severe carbon monoxide exposure, fainting and death may occur. When these symptoms are present, and you suspect CO poisoning, visit your doctor immediately.

Final Words

Carbon monoxide detectors are important devices in every household. They can help you and your family avoid the dangers of carbon monoxide poisoning. Also, having more than one carbon monoxide alarm in your home is good, especially if you have fuel-burning appliances. Place them in strategic locations, such as near the bedrooms and in the basement. Test them regularly to make sure they are working properly. Lastly, remember to replace the batteries every year.


How many carbon monoxide detectors do I need?

Your home should have at least one CO detector on every floor, including the basement. So, if you have a two-story house, you should have three detectors. You may also want an extra one in the kitchen because this is where most fuel-burning appliances are located.

Do carbon monoxide detectors detect natural gas?

Carbon monoxide detectors cannot detect natural gas. They are only designed to sense invisible gases like carbon monoxide. You need to buy a natural gas detector if you want to detect natural gas.

Do smoke detectors detect carbon monoxide?

Some detectors are designed to sense both smoke and carbon monoxide. However, it’s hard to tell if a smoke alarm can detect CO. You may check your device’s instructions, website, or user manual to see if it can detect both gases. To be sure, buy a combo detector if you want a detector that can sense smoke and carbon monoxide.

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