Batteries for carbon monoxide alarms: the whole answer.
A CO alarm with a dead battery can't warn anyone. In a Michigan winter, with the furnace running all night and the windows shut, it's the one device in the house that most needs to be awake. Here's when to change the batteries, and the thing the battery aisle won't say: sometimes it isn't the battery.
How often should CO alarm batteries be changed?
Once a year, in the fall, before the furnace starts running every night. Between changes, press and hold the Test button for a few seconds; it should sound a loud siren. A small blinking light on the alarm shows it's getting power.
Why does a CO alarm chirp with a new battery?
Check the date on the back. The sensor wears out, and a CO alarm is done at about seven years. Its end-of-life chirp sounds a lot like a low battery, so count the beeps and check the manual to tell them apart. A single chirp every minute or so is the low-battery signal.
Four beeps over and over: is that the battery?
No. That pattern means the alarm is reading carbon monoxide. Get everyone outside, pets included, and call 911 from outside.
How to change the battery in a CO alarm.
Twist the alarm counterclockwise off its bracket, open the battery door and fit a fresh battery of the type printed inside, 9-volt or AA, with the terminals matched. Remount it and press Test. Smoke alarms follow the same schedule and last about ten years; a combination unit follows the shorter CO span.
Where should CO alarms go?
One on each floor and one outside the sleeping areas. Not inside the furnace room itself, where nuisance readings live.
When to replace the whole alarm.
An alarm past its date, or one that stays silent with a fresh battery in it, gets replaced as a whole unit. So does one that's yellowed or cracked. An alarm on a cathedral ceiling that a step stool can't reach is a job for a taller ladder and a second pair of hands.
Or never think about alarm batteries again. On either plan the fall visit tests the CO alarms and replaces their batteries, and puts fresh batteries in the smoke alarms, as part of the included seasonal list. Plans
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