How often should you test your smoke and CO detectors?
Grumpty's answer
Every 6 months
Why bother
The alarm that has to work when it counts. This is an essentials-tier job. Skip it and you're inviting the expensive kind of problem, or the dangerous kind.
What the job involves
- Press and hold the test button on each alarm until it sounds. A loud, clear chirp means it's working. A weak chirp or silence means it isn't, and a silent alarm is just a plastic disc on the ceiling.
- If it sounded weak, chirped on its own, or it's been over a year, swap the battery. Even a hardwired unit has a backup battery that dies, so it gets one too.
- Check the manufacture date printed on the back. Replace smoke alarms at 10 years and CO or combo units at about 7, even if they still beep. The sensor wears out long before the casing does.
- Vacuum the dust off the vents while you're up there, and count heads: one on every level, inside each bedroom, and outside the sleeping areas. Keep CO alarms near the fuel-burning gear, not stuffed right on top of it.
Do it yourself, or pay someone?
Yourself, in a few minutes with a step stool. Pressing a button, swapping a battery, and screwing in a battery-operated unit are not skilled work. The only thing worth hiring out is a hardwired 120V interconnected install: an electrician runs $50-100 an hour, and Angi puts fitted smoke detectors around $110-400 a unit and CO around $120-360, mostly labor.
What skipping it costs
$0-50, and mostly it's the zero. The test costs nothing; the only spend is when it fails, about $5 for a 9V battery or $15-50 for a new combo alarm off the shelf. The reason this one matters isn't the repair quote, it's the thing the dead alarm sleeps through. The NFPA found almost 3 in 5 home fire deaths happen where there's no working smoke alarm. Carbon monoxide is the quiet half, an odorless gas the smoke alarm can't smell, tied to more than 400 accidental deaths a year. A house fire is a near-total loss and a CO leak can kill you in your sleep. A battery is five dollars.
Signs it's overdue
- A single chirp every 30 to 60 seconds, all on its own. That's the alarm telling you the battery's flat or the unit's reached end of life, not a glitch to tune out.
- You press the test button and get a weak sound or nothing. The battery's dead or the unit's failed, and either way it won't be there when it counts.
- The manufacture date on the back is more than 10 years ago for a smoke alarm, or about 7 for a CO or combo unit. The sensor's past its reliable life even if it still chirps when prodded.
When to start thinking about it
A few days' warning does it. Grumpty grumbles 2 days out, then leaves you alone. Mark it done and Grumpty sets the next one, every 6 months, so you can go back to forgetting it exists.
Questions people ask
How often should I actually test them, versus replace the battery?
Test every alarm monthly, button held down, says the NFPA. Replace standard batteries at least once a year; a lot of people peg it to the clock change so they don't forget. Replace the whole smoke alarm at 10 years and CO or combo units at about 7, even if they still answer, because the sensor quietly degrades. Some newer units have a sealed 10-year battery you never change. You still test those monthly, you just bin the whole thing at the end instead of the battery.
Do I really need carbon monoxide detectors if I have smoke alarms?
Yes, they watch for different things. A smoke alarm senses fire. A CO alarm senses carbon monoxide, an odorless gas off furnaces, water heaters, gas ranges, fireplaces, and generators, which a smoke alarm cannot detect at all. The CPSC and CDC put it at more than 400 accidental non-fire deaths a year. Fit CO alarms on every level and outside the bedrooms. A combination smoke and CO unit covers both in one disc if you'd rather not double up.
My hardwired alarm keeps chirping even though it's plugged in. Why?
It still has a backup battery for power cuts, and that battery dies and chirps like any other, so change it first. If a fresh one doesn't shut it up, the chirp is likely the end-of-life signal: check the manufacture date and replace the unit if it's past 10 years for smoke, about 7 for CO or combo. Failing that, dust in the sensor sets off nuisance chirps, so vacuum the vents before you give up on it.
Related jobs
Stop keeping this one in your head
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