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How often to replace smoke detectors and carbon monoxide alarms
Smoke alarms are replaced every 10 years, whether they chirp or not. Carbon monoxide alarms wear out sooner, and the date is printed on the back. Here is how to find the dates, test them, and where each alarm belongs.
The dates
| Alarm | Replace | Batteries | Test |
|---|---|---|---|
| Smoke alarm | Every 10 years from the date of manufacture | Yearly; sealed 10 year units have none to change | Monthly, with the test button |
| Carbon monoxide alarm | At the end of life date on the back, usually 5 to 10 years | Yearly, unless sealed | Monthly |
| Combination smoke and CO | Every 10 years, or sooner if the CO sensor end of life is earlier | Yearly, unless sealed | Monthly |
Smoke alarm guidance from the NFPA. Carbon monoxide sensors have a chemical cell that wears out; the alarm chirps a different pattern or shows END when it is done.
How to find the date
Twist the alarm off its base and look at the back. Every smoke alarm sold in the United States carries a date of manufacture; 10 years from that date is the replacement date. If there is no date, the alarm is old enough to replace. Many carbon monoxide alarms print a replace by date instead.
Where alarms go
- Smoke alarms: in every bedroom, outside each sleeping area, and on every level including the basement. On the ceiling or high on a wall, away from the kitchen and bathroom to avoid nuisance alarms.
- Carbon monoxide alarms: on every level and outside each sleeping area. A house with any fuel burning appliance, a fireplace or an attached garage needs them.
- Interconnected alarms, wired or wireless, so one going off sounds them all.
Batteries and chirps
- A single chirp about once a minute is a low battery. Change it the same day.
- Change batteries once a year, in the fall; it is on the fall home maintenance checklist.
- Sealed 10 year alarms have a battery that lasts the life of the unit; replace the whole alarm at 10 years.
- Vacuum the alarm when you change the battery; dust causes false alarms and missed ones.
Keep the dates
Write the install year on the side of each alarm with a marker, and in your house file. Housemap keeps safety dates for the house: the year the smoke and carbon monoxide alarms went in, the fire extinguisher date, the dryer vent cleaning, the sump pump and GFCI tests. It tells you when each is due and emails you before it is.
Questions
How often should smoke detectors be replaced?
Every 10 years from the manufacture date printed on the back of the alarm, according to the NFPA, even if the alarm still tests fine.
How often should carbon monoxide detectors be replaced?
At the end of life date on the back of the alarm, usually 5 to 10 years depending on the model. The sensor is a chemical cell that wears out.
Why is my smoke alarm chirping?
A chirp every minute or so means a low battery. A different pattern, or a chirp that continues after a new battery, usually means the alarm has reached end of life and needs replacing.
How many smoke alarms does a house need?
One in every bedroom, one outside each sleeping area and at least one on every level including the basement, all interconnected if possible.
Sources
Related guides
Keep the safety dates.
Alarms, extinguisher, dryer vent, sump pump, GFCI: Housemap keeps each date for your house and tells you when it is due. Free.