How do you maintain smoke and CO detectors?
Updated August 2026
The routine is a one-minute test of every alarm each month, fresh batteries once a year, and a hard replacement deadline: smoke alarms at 10 years, CO alarms at 5 to 7. Coverage matters as much as testing, so put an alarm inside each bedroom, one outside every sleeping area, and at least one on every level including the basement. Sealed 10-year lithium units skip the yearly battery swap, and a combined smoke plus CO alarm covers both threats from one spot. See how often to test them and when to replace them.
| Task | Interval | Effort |
|---|---|---|
| Press and hold the test button until it sounds | Monthly | 1 min · DIY |
| Note any chirping (low battery or end of life) | Monthly | 1 min · DIY |
| Vacuum dust off the vents and grille | Monthly | 2 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Replace 9V or AA batteries in non-sealed units | Yearly | $5–15 · DIY |
| Read the manufacture date printed on the back | Yearly | 2 min · DIY |
| Confirm coverage: every bedroom, hall, and level | Yearly | 10 min · DIY |
| Task | Interval | Effort |
|---|---|---|
| Replace CO alarms | 5–7 years | $25–50 · DIY |
| Replace smoke alarms | 10 years | $20–40 · DIY |
| Upgrade to interconnected or sealed 10-year units | As they age out | $150–400 pro |
What neglect costs
A dead or missing alarm is the cheapest failure in the house to prevent and the most expensive to ignore. Most smoke alarms that stay silent in a fire fail for the dumbest reason, a removed or dead battery, which is why the yearly swap and the chirp check earn their place. Carbon monoxide is the quieter threat: it is colorless and odorless, and a stalled CO alarm gives no second warning when a furnace backdrafts or a flue clogs. Re-equipping a whole house with fresh alarms costs about $60 to $200; the downside of skipping it does not carry a dollar figure.
Leave these to a pro
Two jobs justify a pro. Hardwired, interconnected alarms, the kind where one tripping sounds them all, tie into your wiring, so a full replacement set runs $150 to $400 installed by an electrician versus $20 to $40 for a battery unit you clip up yourself. And if you suspect a live CO source, a chirping alarm plus a headache or nausea, do not troubleshoot it: leave, then have an HVAC tech test the furnace and flue ($100 to $200). Everything else, testing, battery swaps, vacuuming, and clipping in a new sealed unit, is a stepladder and five minutes.
This whole checklist ships as reminders in OnOtto: every task above, on the right schedule for your home, snooze-proof.
Load this checklist as remindersFrequently asked questions
Where exactly should smoke and CO alarms go?
Smoke alarms belong inside every bedroom, in the hallway outside each sleeping area, and on every level of the home, including a finished basement, mounted on the ceiling or high on the wall. Carbon monoxide alarms go outside each sleeping area and on every level, especially near attached garages and fuel-burning appliances; keep them at least 15 feet from the stove and furnace to avoid nuisance trips. Combination smoke-and-CO units satisfy both requirements from one spot.
Why does my smoke alarm chirp when the battery is new?
A single chirp every 30 to 60 seconds usually means low battery, but if a fresh battery does not stop it, the alarm has likely reached end of life. The sensor degrades after about 10 years and starts false-chirping. Check the manufacture date printed on the back; if it is 10 or more years old, replace the whole unit rather than the battery. Other chirp causes are dust in the chamber, a loose battery drawer, or two interconnected alarms fighting.
Do hardwired alarms still need batteries?
Yes. Hardwired alarms carry a backup battery so they keep working during a power outage, exactly when generator and candle fires spike. On older units, replace that backup every year; newer hardwired alarms ship with a sealed 10-year lithium backup you never open. Either way they still hit the 10-year replacement wall, because the sensor, not the battery, is what ages out. Test them monthly like any other alarm.
Are 10-year sealed alarms worth it?
For most homes, yes. A sealed lithium unit costs $20 to $40 up front versus $10 to $15 for a basic alarm plus a decade of $5 battery swaps, so the lifetime cost is close, and you lose the 2 a.m. chirp and the temptation to pull a battery while cooking. The catch is that you cannot swap a dead cell; at 10 years the whole unit goes in the trash and a new one goes up. Write the install date on it in marker.