May 21, 2024

Review: First Alert’s Onelink Smoke + Carbon Monoxide Alarm, the HomeKit smoke detector


If you’re assembling a HomeKit home, First Alert’s Onelink Smoke + Carbon Monoxide Alarm is currently the best smoke detector to purchase. As a smart smoke and carbon monoxide alarm, Onelink sends you alerts when triggered while you’re away and HomeKit support turns Onelink into a trigger for automation. Check out our hands-on review below:

Replacing an old smoke detector with Onelink only takes a few steps. Flip the breaker to the power, twist off and unplug the old alarm, unscrew the old alarm’s bracket, screw on the new bracket, choose from one of three Onelink cable adapters, twist the new alarm in place, and switch the breaker back on.

Setup in First Alert’s iPhone or iPad app is simple too. Onelink connects to your Wi-Fi network and the app lets you assign each alarm a location in your house. Onelink later uses this room location to send an audio warning from the alert that smoke or carbon monoxide has been detected in a specific room.

HomeKit aside, Onelink is smarter than traditional smoke alarms because it can be silenced from your iPhone or iPad after smoke is removed. Onelink can also send you alerts to your iPhone when you’re not home and smoke or carbon monoxide has been detected.

With HomeKit support, Onelink becomes even more useful. Onelink appears in Apple’s Home app on iOS 10 which can also send alerts when the alarm has been triggered. HomeKit support is most useful when using Onelink as a trigger for a scene or automation in Apple’s Home app.


The companion app for Onelink makes it easy to regularly test power, sensors, speakers, and general functionality with the press of a button. You can even see when the last test occurred as well as when the alarm was triggered.

Testing smoke alarms every month — not just when there’s actually a fire — is a good idea. Onelink makes it easy to remember and test. In my testing, the wired version of Onelink even communicated to the traditional smoke detectors in other rooms of my house both when triggered and when tested from the companion app.


HomeKit support means you can ask Siri if smoke is detected at home, although the alarm should alert you first so I don’t think anyone will ever benefit from this specifically. You’re also supposed to be able to control Onelink’s night light with Siri, but it doesn’t appear as a light in Apple’s Home app and Siri can’t find it in my testing.

Onelink is actually useful as a HomeKit sensor, however, especially if you have HomeKit-compatible lights. You can use Onelink as a HomeKit trigger in Apple’s Home app if you have a fourth-gen Apple TV or always-on iPad with iOS 10 on the same network.

For example, I created an automation using Onelink that automatically turns on every ceiling light if smoke is detected, but only after sunset. A separate automation does the same thing with ceiling lights when carbon monoxide is detected.

The idea is that if there’s a fire in the home, you’ll want to be fully able to collect everyone and evacuate if needed without looking for a light switch in the dark. (I actually got to this test automation out on Sunday night when cooking dinner…)

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Design-wise, Onelink is generally neutral as it doesn’t look too gadgety, but still looks modern. It features a big button that you can press to dismiss alarms (although the iPhone app is probably more accessible), a loud speaker that tells you where smoke has been detected, and an adjustable LED status indicator that also acts as a night light.


You can adjust the night light brightness for each unit in the companion app. A slider lets you pick between near 0% to 100% brightness. My unit is visible from my bedroom and I prefer to sleep in total darkness, but this feature could be used to help light a dark area at night or be used in a child’s room as a night light. In my testing, Onelink’s night light does not appear separately in the Home app, although other HomeKit accessories like plugs can pull it off.


Overall, Onelink isn’t the most exciting way to demonstrate what HomeKit can do, but it’s a smarter smoke alarm than most and its ability to be a HomeKit trigger can have real world benefits. Even without HomeKit support, Onelink is useful thanks to remote alerts, easy monthly testing, and dismissing alarms from the mobile app. I’ve seen a few reports of false alarms and alerts that can’t be dismissed online, but in testing I have not experienced these issues.

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