It always seems to happen at 3 a.m. One short chirp, then silence, then another chirp a minute later. Here is what that sound means and how to fix it for good.
1. The battery is low
This is the cause most of the time. A single chirp every 30 to 60 seconds is the classic low-battery warning. Replace the battery with the exact type listed on the alarm, close the battery door all the way and press the test button.
Why at night? Many batteries lose a little voltage when the house cools down overnight, which can push a weak battery below the warning level.
2. The alarm has reached the end of its life
Smoke alarms are built to last about 10 years. Many newer models, especially ones with sealed 10-year batteries, chirp to tell you they are done. A new battery will not fix this. Check the manufacture date on the back. If it is 10 years old or more, replace the whole alarm.
3. The battery door or pull tab
A battery drawer that is not fully shut, or a plastic pull tab still in place on a new alarm, can keep it chirping. Open it, reseat everything and close it until it clicks.
4. Leftover warning in memory
Some alarms keep chirping for a short time after you swap the battery because the warning is still stored. Many manuals say to press and hold the test button for 15 to 20 seconds to reset it. Check yours first.
5. Dust, bugs or the environment
Dust and small insects inside the sensor chamber can cause chirps or false alarms. So can humidity and big temperature swings, like an alarm near a bathroom or a drafty door. Gently vacuum the vents and think about whether the alarm is in the right spot.
Hardwired alarms chirp too. Most have a backup battery that wears out on the same schedule. If one hardwired alarm chirps, check its backup battery first.
Which alarm is it?
A chirp bounces around a room and can be hard to pin down. Stand under each alarm and wait for the next chirp. Some models flash a light at the same time, which helps.
Whatever you do, do not leave the battery out to get some sleep. Fix it, then test every alarm in the house while you are at it.
Filed under Smoke Alarms
Two minutes, right now: press the test button on every smoke alarm in your home. Here is how to do it right.