First Alert CO615
First Alert CO615

Best plug-in carbon monoxide detector

The First Alert CO615 is an effective and easy-to-use plug-in carbon monoxide detector that can run on its battery backup during power outages. It is recommended by one professional testing organization and generally receives positive reviews from individual users. However, its poorly constructed battery cover frustrates many owners.
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First Alert CO-400
First Alert CO-400

Battery-operated carbon monoxide detector

The First Alert CO-400 is a basic carbon monoxide detector that runs on two AA batteries, giving users more placement options than plug-in models. This is a good model for people who simply want to be alerted when carbon monoxide is detected. But owners who want more data from their units, such as current CO levels, should look elsewhere.
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Combination carbon monoxide smoke detector

The Kidde KN-COSM-B is a dual alarm, sensing for both smoke and carbon monoxide. Verbal warnings and a loud horn alert owners about the nature of the emergency. The unit runs on three AA batteries and is easy to install. It also fits on the older model's mounting plate.
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See a side-by-side comparison of key features, product specs, and prices.

Carbon Monoxide Detectors Runners Up:

First Alert Onelink SCO501CN Est. $60

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Kidde KN-COPP-B-LP Est. $30

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Kidde KN-COPP-3 *Est. $45

1 pick including:,…

Carbon monoxide detectors save lives

Carbon monoxide (CO) is an odorless and colorless gas that can kill people before they realize it's in their homes. CO is a by-product of incomplete combustion and comes from malfunctioning appliances, such as gas or oil furnaces, wood burning stoves and gas clothes dryers. When these appliances are not adequately ventilated, carbon monoxide can build up in the home to lethal levels.

A carbon monoxide detector is designed to sound an alarm if it senses dangerously high CO levels in a short time. There are three different types of detectors on the market: plug-in, battery-operated and hardwired (connected to the home's wiring system). A basic unit will cost less than $20. However, some detectors have features such as current CO-level displays or peak-CO memory buttons; others sound an 85-decibel horn in addition to emitting verbal warnings. Depending on the features, shoppers should expect to pay as much as $60 for these higher-end models.

To the surprise of many consumers, CO detectors have a finite lifespan. The sensors wear out within five to seven years, and the newest detectors come equipped with an end-of-life timer. At that point, the devices essentially self-destruct -- beeping constantly until replaced.

The Consumer Product Safety Commission (CPSC) has recalled some CO detectors in the last couple of years, all hardwired units that must be professionally installed. In August 2012, the CPSC published a revised recall for ESL SafeAir 240-COE carbon monoxide hardwired alarms, updating model numbers involved in the recall. They were sold nationwide from November 2000 through October 2003. In 2011, the CPSC recalled ADT's CO 1224T carbon monoxide detector, which was sold between October 2008 and December 2010, and certain GE Telaire Airestat CO2 and temperature sensors. Check the CPSC website for the most current recall info.

The best CO detectors are reliable, easy to install and test. We identified the best units by consulting professional testers and experts such as and as well as individual owner reviews on sites such as,,, and

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