What to know
- Smoke detectors expire at roughly 10 years; CO detectors at 5–7 years — the sensors degrade even if the unit still chirps on test.
- Detectors need monthly test-button checks and battery changes on a regular schedule (or 10-year sealed batteries).
- Every bedroom, hallway outside sleeping areas, and every level of the home needs coverage; CO detectors belong near sleeping areas and fuel-burning appliances.
- Hardwired, interconnected alarms — when one sounds, they all sound — are the gold standard and required in new construction.
Why detectors expire
The sensing elements inside smoke and CO alarms degrade with age, dust, and humidity. An expired detector can still beep when you press the test button — the button tests the horn and battery, not the sensor. Check the manufacture date printed on the back: past 10 years for smoke (5–7 for CO), replace the unit, not just the battery.
The service schedule that keeps them working
Detectors are only reliable when they're maintained like the safety equipment they are.
- Monthly: press the test button on every unit.
- Twice a year: replace batteries (a good habit: when clocks change) unless the unit has a sealed 10-year battery.
- Yearly: vacuum dust from vents and verify every sleeping area and level is covered.
- At expiration: replace the whole unit — smoke at ~10 years, CO at 5–7 years.
CO risk is real in fuel-burning Puget Sound homes
Any home with a gas furnace, gas water heater, gas range, fireplace, or attached garage can produce carbon monoxide. CO is colorless and odorless; a detector is the only warning you get. Eco technicians check combustion safety during furnace and water-heater service, and our electricians install hardwired CO/smoke combination alarms where they protect best.
Upgrade to hardwired and interconnected
Battery-only alarms fail silently when batteries die. Hardwired detectors with battery backup, interconnected so every alarm in the house sounds together, give your family the earliest possible warning — especially important in multi-level homes where a basement alarm may not be heard in an upstairs bedroom.
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Common questions
How do I know if my detector is expired?
Look at the manufacture date printed on the back or side of the unit. Smoke alarms should be replaced about 10 years after that date, CO alarms after 5–7 years depending on the model — even if the test button still works.
Where should CO detectors go?
Outside every sleeping area, on every level of the home, and near (but not directly beside) fuel-burning appliances and attached garages. Follow the manufacturer's placement guidance — CO mixes with air, so wall or ceiling placement both work for most models.
Can Eco install hardwired interconnected alarms in an older home?
Yes. Our licensed electricians retrofit hardwired, interconnected smoke and CO alarms in existing homes, and wireless-interconnect models let us link alarms without opening every wall.