The alarms in a home you just bought were installed by someone else, on a date you do not know, and may already be past the age at which they should have been replaced. Establishing their condition is one of the few first-week tasks that is genuinely urgent.

If a carbon monoxide alarm sounds

Treat it as an emergency, not a fault. Get everyone outside to fresh air first, and call 9-1-1 or your fire department from outside rather than from indoors. Do not stay inside to hunt for the source.

Follow the instructions printed on your alarm and any direction your fire department gives you. Because you cannot see or smell carbon monoxide, the alarm is the only warning you will get.

Test every alarm on a schedule

Every smoke and carbon monoxide alarm has a test button, and pressing it confirms that the alarm's own electronics and sounder are working. The U.S. Fire Administration recommends testing alarms monthly.

Alarm maintenance

Monthly

  • Press the test button on every smoke and carbon monoxide alarm in the home
  • Replace the batteries in 9-volt smoke alarms at least once a year, and the backup batteries in hardwired alarms on the same yearly schedule
  • Replace the entire smoke alarm 10 years from its manufacture date, which is printed on the alarm body

The ten-year figure is a replacement age. An alarm that passes its test button today can still be past the date at which the U.S. Fire Administration says it should be replaced, so check the manufacture date on every alarm in the house early on. Record each alarm's location, type, manufacture date, and replacement date in your home record.

Carbon monoxide needs its own alarm

The U.S. Fire Administration calls carbon monoxide the "invisible killer" because it is a colorless, odorless, poisonous gas that is undetectable to the human senses. Smoke alarms do not detect it, so a home needs alarms built specifically for carbon monoxide.

The USFA's placement guidance is to install carbon monoxide alarms in a central location outside each separate sleeping area and on every level of the home. It also advises testing carbon monoxide alarms at least once a month, on the same rhythm as your smoke alarms.

Important

Smoke alarms and carbon monoxide alarms are different devices detecting different things. Combination units exist, but do not assume a given alarm covers both. Check the label on each one you already have before deciding what is missing.

Keep fuel-burning appliances in the routine

Alarms are the last line of defense. The U.S. Fire Administration explains that carbon monoxide poisoning can occur when a fuel-burning appliance or machine, such as a furnace, heater, or generator, is not working or is not vented properly. Keeping that equipment serviced by a qualified professional, on the schedule its manufacturer states, is what prevents the situation the alarm exists to warn you about.

The USFA also advises keeping vents for your furnace, stove, fireplace, and dryer clear of snow and debris, and running portable generators outdoors only, well away from doors, windows, and vents.

This work belongs to a professional

Servicing furnaces, boilers, water heaters, fireplaces, and other fuel-burning appliances should be handled by a qualified professional, and licensing requirements differ from state to state. Testing your alarms and booking the service visit are homeowner tasks. Opening, adjusting, or repairing the appliance itself is not.

Requirements depend on where you live

The number of alarms a home must have, where they must be placed, and whether they must be interconnected are set by state and local building and fire codes, and those requirements differ considerably from one jurisdiction to the next. Treat the federal guidance above as the baseline and confirm the specific requirement with your local fire department or building department.