What the best carbon monoxide detector has

  • Audio alarm. Devices certified by Underwriters Laboratories (UL) have a minimum 85-decibel horn that can be heard within 10 feet.
  • Interconnectivity. Interconnecting units are helpful in large homes because they communicate with one another; when one alarm detects a hazard, it triggers them all to sound an alarm. To work properly, all units must be made by the same manufacturer. While traditionally hardwired, battery-operated wireless interconnecting units are now available.
  • Five-year sensor lifespan. The sensors on carbon monoxide detectors do wear away over time. Expect your unit to last at least five years. The better models have an end-of-life timer to alert you when the unit needs to be replaced. Kidde's newest CO detectors, released in March, last for 10 years.
  • Long warranty. Carbon monoxide detectors can malfunction, and the best units come with a warranty of at least five to seven years.
  • Digital display. UL-certified carbon monoxide detectors are designed to sound an alarm if they sense CO levels of 70 parts per million (ppm) or higher. Exposure of 100 ppm for 20 minutes may not affect healthy adults. However, people with cardiac or respiratory problems, infants, pregnant women and the elderly may be harmed by lower concentrations. A device with a digital display can show these concentrations and give you the peace of mind.
  • Testing functionality. CO detectors should be tested once a month. The best detectors have a test/silence button to test the device and also silence the alarm in the event of a false alarm.

Know before you go

What are the regulations in your state or municipality? Most states require a carbon monoxide detector to be installed in new homes or before the sale of a home. Some require hardwired or plug-in units to have battery backup in the case of a power outage. The National Conference of State Legislatures is a good resource for determining what regulations apply to you.

How are your current carbon monoxide detectors installed? Detectors may be hardwired, plugged into an outlet or battery operated, depending on the model. Some plug-in and hardwired units use batteries as a backup during a power failure and will not operate if they are not installed. If your current carbon monoxide detectors are hardwired, you will most likely want to keep that system. Otherwise, battery-operated and plug-in models are the easiest to install.

Do you need a smoke alarm, too? If you also need a smoke alarm, a combination smoke and carbon monoxide alarm might be best. Decide whether you need the smoke alarm to use ionization or photoelectric technology. The U.S. Fire Administration provides background on the different technologies.

How many alarms do you need? CO alarms should be installed in a central location outside each sleeping area and on every level of the home, according to the National Fire Protection Association, which also recommends interconnecting all alarms.

Does your unit meet safety standards? Check to see that the detector is certified by an independent testing agency such as Underwriters Laboratories or Canadian Standards Association.

What's to come

Kidde released two new carbon monoxide detectors in March under its Worry-Free product line that last a decade and do not require battery changes. These UL-certified units have a sealed-in lithium battery, which is designed to last the life of the alarm. All of the detectors include a 10-year limited warranty and will sound an end-of-life warning after 10 years. But unlike other detectors, it also comes with an end-of-life Hush button that will temporarily silence the warning for three days. These detectors are only sold at Home Depot and, because of their recent release date, only have a handful of reviews at HomeDepot.com and could not be considered for ConsumerSearch's Best Reviewed designation.

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