The Best Carbon Monoxide Detectors of 2021

Protect your home from this silent danger with a not-so-silent alarm.

BobVila.com and its partners may earn a commission if you purchase a product through one of our links.

Best Carbon Monoxide Detector

Photo: istockphoto.com

A home fire safety plan is incomplete without a set of carbon monoxide detectors, which sense this odorless poisonous gas and alert you to its presence. Without a comprehensive system of carbon monoxide detectors, your family can be at serious risk. This gas can overwhelm your home’s occupants overnight as they sleep and when typical symptoms—dull headache, dizziness, and confusion—may not be noticed.

There are a variety of different types of these crucial devices, so read on to learn how to choose a model and why the units described here are considered among the best carbon monoxide detectors available.

  1. BEST OVERALL: Kidde Nighthawk Carbon Monoxide Detector
  2. BEST BUDGET: Kidde Carbon Monoxide Detector
  3. BEST COMBINATION: First Alert SCO5CN Smoke/Carbon Monoxide Detector
  4. BEST DIGITAL DISPLAY: X-Sense Carbon Monoxide Alarm Detector
  5. BEST MULTIPACK: X-Sense Combination Smoke & Carbon Monoxide Detector
The Best Carbon Monoxide Detector Options

Photo: istockphoto.com

Carbon Monoxide and How It’s Detected

Carbon monoxide (CO) is generally a byproduct of combustion: Any appliance that uses a fuel source (a water heater, furnace, or boiler, for example) produces carbon monoxide when it’s running. That excess carbon monoxide is meant to be released outside through chimneys and vents. These appliances are extremely safe when working properly, but when something goes wrong, the carbon monoxide can build up to dangerous levels.

Carbon monoxide is measured in parts-per-million (PPM). Exposure of 50 PPM is safe for up to 8 hours, 150 PPM is dangerous after 50 minutes, and 1,600 PPM can kill a healthy adult in less than an hour.

Carbon monoxide detectors are so important because the gas is colorless and odorless, so it’s impossible for people to sense its presence until it’s too late. Carbon monoxide detectors track levels of the gas over time and sound a loud alarm when those levels exceed certain parameters. For instance, a 50 PPM measurement will activate most alarms after 8 hours, 150 PPM within 50 minutes, and 400 PPM within 15 minutes.

Detector Locations

The general consensus is that a carbon monoxide detector should be installed on every floor of a house and either inside (or just outside) of every bedroom. A unit should be placed in the basement and the garage as well.

Testing Intervals

To ensure proper operation, follow the same guidelines used for smoke detectors. Carbon monoxide detectors should be tested monthly, and batteries should be replaced at least once a year, regardless of whether the low-battery alarm sounds.

Device Lifespan

Even if the batteries in a carbon monoxide detector are changed regularly, the detectors themselves don’t last forever. Check the back of your devices to find out what their expected lifespan is, which is usually between 5 and 7 years. If you can’t remember when you purchased the device, consider replacing it now.

Types of Carbon Monoxide Detectors

There are two types of carbon monoxide detectors on the market: stand-alone and combination models. Choosing the correct type for your home depends on several factors.

Stand-Alone

A stand-alone carbon monoxide detector’s only job is to detect and measure the levels of this gas in the home. Battery-operated models can be placed nearly anywhere and are the more popular choice. For a more stationary placement, choose a plug-in detector. These models often have digital readouts that display the current level of carbon monoxide being detected.

Combination

Combination units are multipurpose, monitoring carbon monoxide levels while also detecting smoke or explosive gases. The benefit of combination units is that they take a lot of the planning and guesswork out of building a fire safety system. The downfall is that for optimal use, combination carbon monoxide detectors shouldn’t be placed close to gas or oil-fired appliances. In that situation, a stand-alone smoke detector is best with a separate stand-alone carbon monoxide detector installed farther away.

Contrary to popular belief, a standard carbon monoxide detector alone will not detect the presence of explosive gases. Explosive gases don’t contain carbon monoxide unless they’re accompanied by burnt fuel. However, carbon monoxide detectors equipped with explosive gas detection capabilities will pick up on these gases and alert you to their presence.

What to Consider When Choosing the Best Carbon Monoxide Detector

Battery-Powered, Plug-In, or Hardwired?

Carbon monoxide detectors can be purchased with a few different power supply options:

  • Battery-powered options don’t require outlets or preexisting wiring and can be placed virtually anywhere in the home. This convenience makes it a smart idea to put an easy-to-install, battery-powered unit in a garage workshop that uses propane heat.
  • Plug-in models require an outlet. This drastically reduces the flexibility of installation but, should the power go out, these units do have battery backups. Plug-in models are useful for extra protection in areas that already include smoke detectors.
  • Hardwired models use preexisting fire-alarm wiring and battery backups for their power source. Hardwired units are the most desirable and should be used wherever possible, but not every home has specific wiring for fire alarms to run to every room.

Depending on the situation, a comprehensive system could include units from all three categories.

UL Listing

Just like smoke detectors, carbon monoxide detectors must be listed by Underwriters Laboratories (UL). The UL listing on the back of the unit indicates the design was tested and passed UL’s stringent requirements. Considering how important carbon monoxide detection is, purchase only UL-listed models.

Digital Displays

Digital displays may seem like a gimmick, but they actually serve a fairly important purpose. These units will display the PPM of any amount of carbon monoxide they detect, even if the alarm mode needn’t be activated. This can help a resident determine if there is more baseline carbon monoxide in their home than they thought; a standard carbon monoxide detector won’t offer this feature.

Interconnectivity

Carbon monoxide detectors that can be programmed or wired with other alarm devices in the home through radio-frequency, Wi-Fi, or direct wiring are considered interconnect-capable units.

With homes rapidly becoming more connected and smart, interconnect-capable units can be an added benefit for those comfortable with linking household systems together. For example, an interconnected carbon monoxide activation in the garage will trigger other alarm devices in the home, which will alert the occupants no matter where they are in the house. If the device reports back to a central monitoring station, an alarm company will notify first responders and send help without you even picking up the phone. This can be an especially huge benefit at night, when sleepers might not hear the garage alarm sound and when symptoms of carbon monoxide poisoning are less likely to be noticed.

Smart Features

In a world where appliances, like faucets and refrigerators, are smart, why shouldn’t there be smart detection devices? These models are often combination smoke and carbon monoxide detection units. They can communicate to a smartphone app, base station, or smart-home system. They can be programmed to describe the area and type of device that’s been activated as well as provide real-time condition updates, such as room temperature, to an app.

Our Top Picks

Carbon monoxide detectors are a crucial aspect to home safety. Now that you understand what features to look for and how to choose the best model for your needs, consider the following models suited to a variety of situations.

Best Overall

The Best Carbon Monoxide Detector Option: Kidde Plug-In CO and Explosive Gas Detector
Photo: amazon.com

The Kidde Nighthawk carbon monoxide detector can sense the presence of carbon monoxide, providing continuous protection even during a power outage. Its digital display alerts to real-time carbon monoxide levels in the home and updates every 15 seconds to indicate any sudden changes. The peak level function shows the highest CO level recorded since the unit was last reset.

This unit can be plugged directly into an outlet or used with the included corded adapter, and it has battery backup. When CO levels reach an unhealthy level, the Nighthawk emits four quick audible beats every 5 seconds until the levels decrease or the reset button is pushed.

Pros

  • Built-in digital display
  • Comes with battery backup
  • Multiple power sources
  • Updates every 15 seconds to indicate sudden changes

Cons

  • Not smart-home compatible


Best Budget

The Best Carbon Monoxide Detector Option: Kidde KN-COB-LP2 9CO5-LP2 21025778 Carbon Monoxide
Photo: amazon.com

Reliable protection against poisonous levels of carbon monoxide needn’t be expensive, so those on a budget may wish to look into Kidde’s KN-COB-LP2. This detector, which uses three AAA batteries, has a handy lockout feature on the battery door to prevent it from shutting without batteries in place, ensuring the home is always protected.

This model has a loud 85-decibel alarm to alert residents if it detects carbon monoxide. It also has a low-battery signal, a built-in test button, and two LEDs: a green LED indicates proper operation and a red LED indicates dangerous levels of carbon monoxide.

Pros

  • 85-decibel alarm
  • Built-in LED lights; 2 settings
  • Low battery signal and test button
  • Batteries included

Cons

  • Mounting hardware not included


Best Combination

The Best Carbon Monoxide Detector Option: First Alert SCO5CN Smoke Carbon Monoxide Detector
Photo: amazon.com

Rather than the latest smart technology, some folks just want a dependable, easy-to-use detector they can install and check several times a year. This First Alert combination model is exactly that. It features a photoelectric sensor for smoke detection and an electrochemical sensor for carbon monoxide detection—both tried-and-true, reliable sensors. And it’s battery-powered, allowing it to be easily installed anywhere.

Pros

  • Detects smoke and carbon monoxide
  • 85-decibel alarm
  • Batteries included
  • Easy installation

Cons

  • No voice feature included
  • Expensive


Best Digital Display

The Best Carbon Monoxide Detector Option: X-Sense Carbon Monoxide Alarm Detector
Photo: amazon.com

Those who want to easily see carbon monoxide levels at all times should check out the X-Sense Carbon Monoxide Alarm Detector. This battery-operated carbon monoxide detector features an LCD display on the face that indicates the battery life and carbon monoxide PPM with a reading every 10 seconds; this allows users to monitor the PPM in their homes even before they reach dangerous levels.

This model has a sensor with a 10-year lifespan and an 85-decibel alarm to notify residents when carbon monoxide reaches over 30 PPM. This carbon monoxide detector also has three LEDs to indicate alarm, fault, and normal operation.

Pros

  • LCD display
  • Readings every 10 seconds
  • Long-lasting lifespan
  • 85-decibel alarm

Cons

  • Not smart-home compatible
  • Moderate difficulty when installing


Best Multipack

The Best Carbon Monoxide Detector Option: X-Sense 10-Year Battery (Not Hardwired) Combination
Photo: amazon.com

When it comes to having enough coverage for an entire home, purchasing a set of detectors may make the most sense. With this three-pack of combination smoke and carbon monoxide detectors, users can cover most of their fire safety needs. Each unit has a built-in battery with a 10-year lifespan.

Each detector in this set senses both smoke and carbon monoxide. The carbon monoxide sensor takes a reading once every 10 seconds and displays the PPM on the easy-to-read LCD display. These units each have an LED light that indicates green for proper function, yellow for a fault, and red for an alarm condition.

Pros

  • Comes with three units
  • Built-in battery
  • Long-lasting lifespan
  • Smoke and carbon monoxide sensitive

Cons

  • Not smart-home compatible
  • Expensive


Our Verdict

Selected for its two-in-one functionality, digital display of real-time carbon monoxide levels, and the versatility of multiple power sources, the Kidde Nighthawk option is our top choice for the best carbon monoxide detector. With the ability to sense carbon monoxide and smoke, this detector comes with a battery backup and is easy to set up by simply plugging it in.

Alternatively, the First Alert option on this list requires almost no maintenance. Made with the same two-in-one smoke and carbon monoxide detection, this model comes with an 85-decibel alarm, easy installation, and all batteries included for reliability and low maintenance.

How We Chose the Best Carbon Monoxide Detectors

The right carbon monoxide detector can ensure that your family is safe from possible hazardous gases. Selections for the best carbon monoxide models depended upon effectiveness, level of maintenance required, ease of installation, and lifespan.

Each of the above picks comes with effective carbon monoxide detection, plus select options have dual functionality by also sensing smoke. Built-in LCD or LED displays also show current carbon monoxide levels for constant peace of mind. These options also come with battery operation or can plug in for easy, one-time installation and limited maintenance required.

Select options also come with loud 85-decibel alarms for notification even when your household is asleep. Finally, many of the above picks come with a long lifespan so you don’t have to worry about replacing them frequently.

FAQs

Although you’ve read up on carbon monoxide detectors and how to choose one, you may still want more information on purchasing and using these essential devices. Check out the answers to the most frequently asked questions about the best carbon monoxide detectors to be more fully informed.

Q. Where is it best to place a carbon monoxide detector?

Carbon monoxide is slightly lighter than air and will travel with warm rising air, so the best height is about 5 feet above the floor. Also place the detector in a common hallway outside of sleeping areas, if not in the bedrooms themselves. Make sure there is at least one carbon monoxide detector on each floor and inside a garage. Be sure to follow placement and use instructions provided by the manufacturer of your unit.

Q. How many carbon monoxide detectors do I need for my home?

The Centers for Disease Control and Prevention (CDC) recommends installing at least one carbon monoxide detector per floor. With that said, the more the better.

Q. Is it better to have a battery or plug-in carbon monoxide detector?

They each have their benefits, and one is not more effective than the other. In fact, for the best coverage, you might find a combination of battery, plug-in, and hardwired detectors could be the best move.