How Often Should You Test Smoke & CO Detectors?

You may not think about them often, but your smoke and carbon monoxide (CO) detectors are some of the most important safety devices in your home. But like anything else, they only work if they’re tested and maintained regularly.

If you can’t remember the last time you tested your alarms, here’s what homeowners need to know to stay safe, stay legal, and stay protected.

Why Regular Testing Matters

Smoke and CO detectors are your first line of defense in an emergency, alerting you to danger before you can see or smell it. But batteries die, wiring can fail, and internal sensors weaken over time.

This is why testing your alarms is essential. A detector that looks fine but doesn’t actually work could cost you everything. And in many cases, furnace malfunctions or poorly vented HVAC equipment are the root cause of CO buildup, making it even more important to keep these systems – and your detectors – in check.

How Often Should You Test Them?

The National Fire Protection Association (NFPA) recommends testing smoke alarms and CO detectors once a month. This involves pressing the “test” button and making sure the alarm sounds. If it doesn’t, it’s time to replace the battery or the unit itself.

Here’s a breakdown to help you stay on track:

• Test smoke & CO alarms: Monthly

• Replace batteries: Every 6 months (or sooner if the unit chirps)

• Replace smoke detectors: Every 10 years

• Replace CO detectors: Every 5–7 years (check the label)

If your alarms are hardwired with a battery backup, test them monthly too. Just because they’re connected to power doesn’t mean the sensors are functioning properly.

Where Should Alarms Be Installed?

Even if you test your alarms consistently, they won’t help if they’re not in the right spots. Even if you test your alarms consistently, they won’t help if they’re not in the right spots. 

According to Massachusetts regulations and NFPA guidelines, smoke and CO detectors should be installed:

• In every bedroom

• Outside each sleeping area (hallways)

• On every level of your home (including basements)

• Near gas-powered HVAC appliances or attached garages for CO alarms

Avoid placing detectors too close to vents, windows, or fans, which can interfere with their sensors. And if your furnace or water heater is located in a utility room, make sure there’s a CO detector close by, as these are high-risk areas that often go overlooked.

Common Issues That Mean It’s Time to Replace

If your detector:

• Chirps constantly, even after a battery change

• Fails to sound during a test

• Is discolored or yellowed (a sign of age)

• Is older than 10 years

…it’s time for a replacement. Many newer alarms include a built-in end-of-life alert, so you’ll know when it’s no longer reliable.

Bonus Tip: Combine Testing With Routine Tasks

It’s easy to forget monthly testing, so try tying it to something else you do regularly – like paying the mortgage, cleaning the house, or checking your calendar on the first of the month. You can even set a recurring phone reminder.

Many homeowners also test their alarms when daylight saving time changes (spring and fall). It’s a great time to swap batteries, too, and consider scheduling a heating system checkup simultaneously to stay ahead of potential CO risks.

What About Smart Detectors?

Smart smoke and CO detectors (like Nest Protect) often run self-diagnostics and send alerts to your phone. But even smart models should be tested monthly, as batteries can still fail and sensors can still degrade over time.

Protect What Matters Most

It only takes 30 seconds to test your smoke and CO alarms – a small habit that protects your home in a big way.At Super Service Today, we help Wilmington homeowners breathe easier with HVAC maintenance that supports cleaner air and safer systems. If it’s time for a seasonal tune-up or you’re thinking more about your home’s air quality, we’re here to help.