Installing a Carbon Monoxide Detector

Carbon monoxide is a silent killer. It's odorless, colorless, and produced by any fuel-burning appliance in your home — furnaces, water heaters, dryers, fireplaces, even cars running in attached garages. A functional detector catches dangerous levels before they harm your family. Unlike smoke detectors, CO detectors need deliberate placement near the appliances that generate the gas, and they require active maintenance. Installing one takes fifteen minutes but protects everyone in your house every single day.

1. Pick Your Detector Type. Decide between plug-in models, battery-powered units, or hardwired detectors with battery backup. Plug-in units work well in basements and main living areas near outlets. Battery-powered detectors offer flexibility for bedrooms and hallways. Hardwired models with backup batteries are the gold standard for primary coverage. Plan to install at least one detector on every level of your home, plus one in the basement near fuel-burning appliances.
2. Mount on Interior Wall. Choose a wall 4 to 6 feet above the floor, away from windows, doors, and exterior walls where drafts interfere with sensor accuracy. If mounting on a basement wall near a furnace or water heater, place it on the wall where exhaust vents are located. Avoid corners, peaks of cathedral ceilings, and areas blocked by furniture or curtains. If using a plug-in model, simply insert it into an outlet on that wall.
3. Secure Battery-Powered Units. For bedrooms and upper floors, use battery-powered CO detectors. Mount them using the adhesive backing provided or drill two small pilot holes and use the included screws and anchors. Position them on an interior wall, away from vents and heating ducts. Install at least one per bedroom level so occupants hear the alarm while sleeping.
4. Go Hardwired for Reliability. If running electrical work in your basement, hardwired CO detectors with battery backup offer continuous monitoring without battery replacement. Turn off power at the breaker, run 14-2 NM cable to a switched circuit (the detector should turn on when power is available), and have a licensed electrician make final connections. Hardwired units are optional but recommended for primary protection in finished basements.
5. Sound the Alarm Quarterly. Press and hold the test button for 3 to 5 seconds until the alarm sounds. If it doesn't, check that batteries are installed correctly or the unit is plugged in. Write the installation date on a piece of tape and stick it to the detector's base. Set a phone reminder for one month and one year to test and replace batteries respectively.
6. Refresh Batteries Yearly. Change batteries in battery-powered units every October (or the same month you change your clocks). Check the manufacturer's website annually for recalls — CO detector technology improves, and older units may have defects. Most battery-powered detectors last 5 to 7 years before the sensor degrades; hardwired models last longer. Mark the expiration date on the back of the unit with a permanent marker.
7. Evacuate and Call 911. If the alarm sounds continuously or in short bursts, evacuate everyone to fresh air immediately — get outside or into a room with open windows. Call 911 from outside and report suspected carbon monoxide. Do not re-enter the home. If the alarm chirps once every 30 seconds, the battery is low; replace it immediately. If the alarm chirps briefly during cooking or showering, it's likely a false alarm, but investigate for gas appliance issues anyway.