Where should you install a CO detector? Anne Marie Helmenstine, Ph.D., ThoughtCo.com's chemistry expert, notes that carbon monoxide is lighter than air, so the best place to install a CO detector is high on a wall (at least five feet above the floor) or on the ceiling. The National Fire Protection Association (NFPA) recommends placing CO detectors in a central location outside of sleeping areas, as well as on every level of your home. Dr. Helmenstine notes that if you are only purchasing one CO detector, put it in your bedroom and "make certain the alarm is loud enough to wake you up." On the other side of the coin, you shouldn't place CO detectors near appliances that produce open flames, such as a kitchen stove, or next to a fireplace.
Battery-powered or hardwired? Detectors may be hardwired, plugged into an outlet, or battery operated, depending on the model. Most plug-in and hardwired units use batteries as a backup during a power failure and will not operate if they are not installed. An interconnected system provides the best protection for a typical home. Most interconnected alarms are hardwired, but battery-powered interconnected systems that communicate over a radio network are also available, and are easier for homeowners to install. That said, if your current carbon monoxide detectors are hardwired, you will most likely want to keep that system.
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 -- and having a battery back-up is a good idea in all cases. The National Conference of State Legislatures is a good resource for determining what regulations apply to you.
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. Details on Underwriters Laboratory standard UL2034, which covers sensitivity and alarm thresholds for residential use, can be found in the introduction of this report. All of the CO alarms in this report meet that standard.
Do you need a smoke alarm, too? If you also need a smoke alarm, opting for a combination smoke and carbon monoxide alarm can save money and clutter. Be aware, however, that some installation locations are more suitable for one type of alarm but not for another. Smoke alarms also use different technologies to detect different types of fires -- ionization, photoelectric, or both. We discuss different types of smoke detectors, including combination smoke and CO detectors -- and which ones are best for certain situations -- in our smoke detectors report.