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Best Carbon Monoxide (CO) Detectors 2021


Nest Protect offers safety features, including fire, smoke, and detection of carbon monoxide. In addition, it has intuitive and smart features. This device also acts as your nightlight and a home companion. You also get an option to reduce panic through voice alerts.

Also, Nest Protect gets connected to the Nest app for users to receive alerts everywhere. To know more, read our full Nest Protect review or compare this CO detector to others.

Top 5 Carbon monoxide (CO) Detectors

★ Top Pick
Best Carbon monoxide detector: Google Nest Protect

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Best voice control: First Alert Onelink

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Budget pick: Alert Plus Carbon Monoxide detector

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Kidde Nighthawk Plug-in

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Kiddie Battery Operated

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Best Carbon monoxide detector: Google Nest Protect

This product combines carbon monoxide and smoke detection. It works with the assistance of an app. It sends alerts and alarms to your smartphone straight. Nest Protect is great for renters and homeowners, thanks to its sensors detecting CO and fire.

nest smoke detector 3rd generation

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  • Double function
  • Works with many smart devices
  • Voice notifications
  • Comes with hardware capabilities and a battery

  • Another alarm is required when the battery dies.

Since batteries in a CO detector cannot be changed, you need to purchase another device altogether. Nest Protect is available at just 120 dollars. It is a good deal if the alarm lasts for ten years.

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The carbon monoxide and smart smoke detector, ‘Onelink,’ is super beneficial. These alarms can communicate with each other through your home’s WiFi.

So if there’s a fire or gas leak, they synchronize and alert you. Users who have an Apple device can control the First Alert Onelink using an app. Get notifications or make the alarm silent as you want.

one link smoke alarm

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  • Mobile app
  • Ten-year battery
  • Syncing system
  • Voice alarm
  • In-built alarm (smoke)

  • Quite Expensive
  • You need another alarm once the battery dies

There is no battery compartment in Onelink to access. So, if the battery goes off, you are required to buy a new device. The price tag is high, around more than 200 dollars. Perhaps the replacement cost is higher than you’d wish to pay. Nevertheless, its voice control is amazing.

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Budget pick: Alert Plus Carbon Monoxide detector

This detector ensures your family stays safe by detecting carbon monoxide and smoke. Of course, there are no such smart features, but the Alert Plus CO detector has a powerful siren of 85 dB. So, everyone at home gets warned.

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  • Batteries included
  • Affordable

  • There aren’t any smart features

Also, the installation of this carbon monoxide detector is easy. First of all, backplate mounting on the wall. Next, add the unit batteries. Finally, set the monitor.

Twenty dollars is a good deal. So, you can easily afford many to set up in your garage, kitchen, and basement. The reviews from those using Alert Plus in their vehicles are also good.

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Easy installation: Kidde Nighthawk Plug-in

It is super easy to install the Kidde Nighthawk CO detector. You do not require screws, drills, batteries. Simply plugin, and it’s done! The device also comes with a nine-volt battery backup just if the power goes off.

kidde carbon monoxide detector

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  • Digital display
  • Affordable price
  • Backup battery
  • Great customer reviews

  • Handwired only
  • Home automation incompatible

Its plugin options are user-friendly. You practically need not drill holes in your walls and ruin them. Or at least, no fuss. There is an LED screen and a test button like other gas detectors.

The levels of CO in your home are visible. If the Kidde Nighthawk detects danger, it emits a beeping. Again, it’s to not create confusion with other alarms at your place.

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Best value: Kiddie Battery Operated

Kidde battery detector is an amazing device as it keeps checking the air for carbon monoxide every fifteen seconds. You can continuously monitor through the electrochemical sensor.

This CO detector will work even when the power goes off, thanks to no reliance on hardwiring. In addition, the eighty-five dB siren signals poisonous gases around.

best carbon monoxide monitor

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  • Test button
  • No drilling needed
  • Beep

  • No battery backup
  • No home automation
  • Cannot detect smoke

Kidde Battery Operated does not possess the smart features of OneLink and Nest CO detectors. But, it is a very reliable device. There’s consistent monitoring and loud siren, red and green light for visual safety.

So, those with hearing impairments can easily get assistance. Since it’s dependable, affordable, you can even get multiple detectors.

Carbon monoxide detectors: Types

You can pick any carbon monoxide detector out of those available. Here are some of the functions they include.

  • Digital: Levels of CO visible on a screen.
  • Dual-function: Senses threats like smoke, CO, fire.
  • Smart: Sync with the apps of home automation and run diagnostics.
  • Hardwired: Can be wired in the electric grid of your home.
  • Battery-operated: Batteries are required to work and has a basic display and sensing in-built.

Our approach

We have compared detection accuracy, smart features, and installation ease of carbon monoxide detectors. Moreover, we skimmed through customer reviews to know how these detectors actually are. You can check out the methodology section to find more about reviewing products.


Are there any symptoms of CO poisoning?

Yes, there are. Poisoning through carbon monoxide can cause headaches, dizziness, vomiting, nausea, fainting, and confusion.

What to do in case of carbon monoxide poisoning?

Don’t stay inside that place. Just walk out and dial 911. Carbon monoxide poisoning won’t always suddenly hit you. Neither does it leave your place soon. So, seeking medical advice is the right way.

How common is the poisoning through CO?

Nearly 400 citizens of the US die every year due to CO poisoning. Twenty-thousand get admitted to hospitals’ emergency wards.

Are children more susceptible to (CO) carbon monoxide poisoning?

Yes, children, pets, ill people, and older adults are more susceptible to CO. But, anyone can get affected by this gas.

How do these detectors work?

CO detectors are similar to smoke detectors, only that the former detects carbon monoxide levels. Here are the sensors found in CO detectors.

  • Biomimetic detectors: These use gels that change colors as they absorb CO and trigger an alarm.
  • Metal oxide semiconductors: These have chips of silica to detect carbon monoxide. It sends electric signals to trigger the alarm.
  • Electrochemical sensors: These sense electric current changes when CO is present around. Electrodes dipped in chemical solutions sound an alarm.

Many security systems (monitored, professional ones) have an in-built CO detector. In addition, you may take a look at our best security providers. Find out which security system for the home comes with CO monitoring plans and detectors.

Where to install CO detectors?

You can place a CO detector outside all the sleeping spots of your home. Also, fix it outside your kitchen, garage, and basement. You may look for a place far from the source of CO. But, the device should be close to your occupied area. Take a look at the complete installation guide of carbon monoxide (CO) detectors.

How do carbon monoxide detectors work for people with hearing loss?

Almost all carbon monoxide detectors have loud sirens. But what if someone has hearing loss? The good part is there are wire-in-units. These connect to the CO and smoke detectors and trigger a light in case of emergency.

CO detector maintenance

Many CO detectors last for around five years. Generally, the lifetime of a product varies and depends on its model and make. Yet, cleaning the detector regularly to remove dust or debris surely enhances its functioning.

Just as you get the smoke detectors checked monthly, carbon monoxide detectors require it. You can press the TEST button and confirm the siren actually works.

In another case where the detector isn’t new, you can attach a CO meter to monitor the functioning of your product. If the device isn’t working at the testing time, it’s time to purchase a new alarm.

Sources of (CO) carbon monoxide gas

Carbon monoxide does not release any smell, taste, or color. So, it has been known as an invisible and silent killer. In the United States, this gas is among the prevalent death causes. Carbon monoxide is released when you burn natural gas, gasoline, wood, propane, oil, or charcoal.

It isn’t usually a hazard in outdoor spaces because CO gets enough dissipation area. Hence, the particles never conglomerate to create toxicity around. However, carbon monoxide release can be dangerous if it’s your garage, RV, or home.

Any burning substance, including your grill, fireplace, stove, will expel this gas. So here are your regular homely devices that create CO or carbon monoxide.

  • Gas grills
  • Appliances
  • Oil burning or Gas furnaces
  • Gas stoves
  • Water heaters that burn fuel

Detectors Do’s and Don’ts

Lighting up the fireplace is fine as long as the area is well ventilated. However, here’s how you should and shouldn’t handle a place with CO detectors. Also, take a look at the dangers below.


  • Gas appliances should be able to vent appropriately.
  • Ensure to correct the chimney annually, so fumes do not block in.


  • Burning gas grills in the home.
  • Using over or gas stove for heating.
  • Leaving the vehicle running with a closed garage door.
  • Seal or patch vent pipes using unapproved materials or tape.
  • Running a generator inside your home, even at a distance of 20 ft from your place.
  • Turning on the car with a tailpipe blocked due to snow.
  • Burning charcoal inside.