For conscientious homeowners planning to replace their smoke detector batteries when the clocks fall back on Nov. 5, here's a "Who knew?" Most smoke detectors are good for only about 10 years. After that they begin to lose sensitivity, according to the U.S. Fire Administration, and should be thrown away and replaced.
In other words: Those fresh batteries won't do much good if they're going into a dying smoke detector.
Smoke alarm makers now include expiration or manufacture dates so you can check the age of your detectors. Older models without dates are already likely expired. And if you've recently moved into a home or apartment built before 2007, just assume it's time to replace.
When you do, make sure your new detector uses both ionization and photoelectric sensors. (If you can't find one with both technologies in the same unit, you'll want to buy one of each). That's because ionization alarms sound more quickly in a flaming, fast-moving fire, while photoelectric alarms are better at detecting smoky, smoldering fires.
You'll also want to follow newly revised guidelines for where to locate them. Today's standards call for a detector in every bedroom in addition to what most of us grew up with – one on every level and one in the hallway leading to bedrooms. The best spot is on the ceiling or high on the wall, since smoke rises. For pitched ceilings, mount detectors no lower than three feet from the peak, but not higher than the top four inches.
And chances are, if it's time to replace your smoke detectors, your carbon monoxide detectors are ready to retire, too. Their warranties typically end after five to seven years, according to Consumer Reports. To receive the Underwriter Laboratories (UL) seal, alarms made after 2009 are required to emit an "end of life" signal. However, safety experts urge consumers just to replace them after five years, rather than relying on alerts from a faltering device.