The Best Smart Smoke and Carbon Monoxide Detectors of 2026

Requirements are set by states and local codes, and they often differ for homeowners and landlords, so check what applies to your home; if you rent, ask your landlord who installs and maintains the alarms. Whatever the rules, put a smoke alarm on the ceiling, ideally in the hallway outside the bedrooms. A CO alarm is strongly recommended if you have a furnace, boiler, water heater, fireplace or stove that burns fuel.

Interconnected alarms are better in any home with more than one floor, because they all sound as soon as one detects smoke, so you hear a downstairs alarm from the bedrooms. Wireless interconnected alarms with sealed 10-year batteries avoid rewiring. Smart alarms add phone alerts when you're out. European models are certified to EN 14604 for smoke or EN 50291 for carbon monoxide; in the US, smoke alarms are listed to UL 217 and CO alarms to UL 2034, so check the listing of the version sold in your country.

Follow the instructions that come with the alarm, since manufacturers specify the distance from the appliance and the mounting height. As a rule, it goes in the room with the furnace, boiler, fireplace, stove or other fuel-burning appliance, away from windows, vents and exhaust fans. Adding one near the bedrooms is wise, so it wakes you at night. A CO alarm doesn't replace a yearly inspection of your heating equipment by a qualified technician or regular chimney cleaning.

Replace smoke alarms every 10 years, or by the date printed on them, because the sensor degrades even if the alarm still sounds. CO alarms typically last 5 to 10 years and give an end-of-life warning. Once a month, hold down each alarm's button until it sounds, vacuum dust from the vents and, on hardwired alarms with a backup battery, replace that battery when it chirps. Models with a sealed 10-year battery skip battery changes altogether.

A single chirp every 30 to 60 seconds almost always means a low battery or, on sealed units, that the alarm has reached the end of its life. Replace the battery or the whole alarm. If it goes off while you're cooking or after a shower, move it farther from the kitchen or bathroom, or install a heat alarm in the kitchen instead. Hardwired alarms that chirp after a power outage may just need resetting with the hush button.