• Nest Protect

  • How We Tested

  • What You Should Know About Smart Smoke / Carbon Monoxide Detectors and Monitors

  • Other Smoke and Carbon Monoxide Detectors We Tested

  • More Articles You Might Enjoy

Best Overall Smoke Detector
Credit: Reviewed / Betsey Goldwasser

It takes about five minutes to set up the Nest Protect, and the process is impressively thorough, asking you for the detector location, as well as your self-testing and night light preferences.

Best Overall
Nest Protect

The Nest Protect Smoke & Carbon Monoxide Alarm is a reasonably priced smart detector with ample functionality. The 2nd generation Nest Protect comes in both battery and hardwired models, and instead of traditional photoelectric or ionization technology, this alarm uses a split-spectrum sensor to monitor for both smoldering and fast-burning fires. In addition to sending you push notifications when it senses smoke or carbon monoxide, it offers voice alerts, a night light option, low-battery alerts, and a monthly self-test feature.

It takes about five minutes to set up the Nest Protect, and the process is impressively thorough, asking you for the detector location, as well as your self-testing and night light preferences. The Nest app is intuitive and easy to use on both iPhones and Androids—not surprising given that Nest is a leader in the smart home space. In our tests, the smartphone notifications arrived around 30 seconds after the alarm sounded, which wasn’t the fastest, but we liked that the alerts specify whether it’s a just a “Heads Up” (a little bit of smoke) or a genuine “Emergency” (get out of the building).

Overall, we’d feel safe with this smart smoke alarm protecting our homes, and there are thousands of positive reviews that testify to the superior performance of this product. Plus, it’s significantly less expensive than other comparable smart smoke detectors with similar features.


  • Choose from battery or hardwired models

  • Nest App runs on iOS and Android devices

  • Quick setup


  • Nothing we could find

How We Tested

The Tester

I’m Camryn Rabideau, a freelance contributor for Reviewed. From household linens to smart home gadgets, I've been doing product testing for a number of years. And, like most people, I want to keep my humble abode as safe as possible. That's why I dived back into the world of smart home to test the best smart smoke and carbon monoxide detectors available today.

The Tests

To test these smoke detectors, we first installed and synced each device with its app. After the initial setup, we ran a “self-test” on each model and navigated around both the iOS and Android versions of the apps to assess usability.

Finally, we used aerosol-sprayed smoke to set each alarm off. We did this twice for every model—once while the phone was connected to WiFi and once when it was not—to see if there was a difference in how quickly notifications were delivered. During these tests, we also evaluated the quality/volume of the alarm, quality of the smartphone notifications, and ease of silencing the detector. Other factors we took into account were interconnectivity, app connectivity, and perceived reliability.

What You Should Know About Smart Smoke / Carbon Monoxide Detectors and Monitors

What is a Smart Smoke Alarm?

Like most smart home devices, smart smoke and carbon monoxide detectors connect to your home’s Wi-Fi and, subsequently, your smartphone. In other words, they go a step further than your traditional smoke alarm. This is the main appeal of smart smoke detectors, but some high-end models include additional “smart” features like voice controls via Alexa, weather updates, voice alerts, customizable night lights, and more.

What is a Monitor?

Monitors essentially “listen” for your smoke and carbon monoxide alarm, and if they hear it going off, they send a smartphone notification to let you know. They're typically installed in proximity to your existing smoke detectors—some plug into an electrical outlet while others are battery-powered—and they’re connected to your home Wi-Fi network. However, they don’t allow you to silence your smoke alarms and they won’t save you from 2 a.m. low-battery chirps.

Why Does it Make Sense for Smoke Alarms Be "Smart"?

Smoke detectors are a perfect example of a device that benefits from smart functionality. Why? Standard detectors have a few major shortcomings, mainly that they’re not all that useful when you’re not home. If your detectors aren’t connected to the local fire department (which most are not) and a fire starts when no one is home, the alarms simply beep away to no avail. Plus, that’s not to mention the dreaded 3 a.m. low-battery chirps—we could all live without those.

Smart smoke detectors solve both these issues, as they send you smartphone notifications when the alarm goes off and give you a heads up when the battery is low. The "smart" functionality can not only give you peace of mind while you're away from home, but it can also save you time and energy when it comes to replacing those pesky smoke alarm batteries. Plus, if you ever burn popcorn and accidentally set off your smart alarm, you can quickly silence the detector from its app, saving you from having to grab a chair and climb up there to manually silence it.

Photoelectric vs. Ionization Smoke Detectors

There are three types of smoke detectors you can buy: photoelectric, ionization, and dual-sensor. These terms refer to the technology used to sense smoke.

Photoelectric smoke detectors have a light source that’s pointed into a sensing chamber, and when smoke particles enter the chamber, they reflect light onto the sensor, triggering the alarm. This type of smoke detector is more efficient at sensing fires that begin with a long period of smoldering, according to the U.S. Fire Administration.

On the other hand, ionization smoke detectors have a small amount of radioactive material between two electrically charged plates. This ionizes the air (hence their name) and creates a current that flows between the plates. If smoke particles enter the chamber, it will disrupt the current and activate the alarm. This style of smoke detector will typically sense flaming fires more quickly.

There are also dual-sensor smoke detectors, which use both photoelectric and ionization technology. For comprehensive protection in your home, the U.S. Fire Administration actually recommends dual-sensor detectors, which efficiently sense both types of fires.

Other Smoke and Carbon Monoxide Detectors We Tested

Abode Smoke Alarm Monitor

The Abode Smoke Alarm Monitor gets top marks in terms of performance—it sends push notifications to your phone within seconds of hearing a smoke alarm go off and, unlike other monitors we tested, it also gives off a high-pitched siren of its own.

This battery-powered smoke alarm monitor is easy to install—you can either use screws or double-sided tape to mount the small unit on the ceiling near your existing smoke detectors. It’s also straightforward to pair with the associated app, which is intuitive and easy to use. You can quickly silence the monitor from the app, and we liked that this system sends out push notifications if it ever loses a Wi-Fi connection.

The major downside of this particular monitor is that it must be paired with the Abode Gateway, and the brand’s basic “Starter Kit” costs $199. However, if you already have the gateway or are interested in a DIY security system, this monitor would be a great choice.


  • Sends alerts to your mobile device within seconds

  • Battery-powered

  • Easy installation


  • Requires additional devices in order to use

Leeo Smart Alert Smoke/CO Remote Alarm Monitor

The Leeo Smart Alert Smoke/CO Remote Alarm Monitor is a sleek, easy-to-use device that “listens” for your existing smoke and carbon monoxide alarms and sends notifications to your phone.

During setup, you have to test both your smoke and carbon monoxide alerts for Leeo to “learn” their alarms, so the process takes a few minutes. Once installed, Leeo will send you notifications within a minute or so of hearing an alarm, and one of the monitor’s best features is that the company will call your phone if you don’t dismiss a notification within a few minutes.

Leeo has a few extra features, too. You can adjust its built-in nightlight to display a wide range of colors, and the device will also monitor temperature and humidity in the room. If you’re looking strictly for a plug-in monitor, Leeo is your best option.


  • Easy to use

  • Company calls users who don't dismiss an alert

  • Monitors temperature and humidity


  • Nothing we could find

First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide Alarm

The First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide Alarm is a good, no-frills option if you already have a Z-wave-compatible smart home hub, such as the SmartThings Hub. The setup for this battery-only smoke detector is straightforward—just mount it and put the batteries in—and once we synced it with a SmartThings Hub and set up a SmartApp for it, we received notifications within a few seconds of the detector going off. This is really the detector’s only feature, though, as there’s no in-app testing or alarm silencing.

The First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide Alarm performed well, making it a solid, decently priced option if you already have a Z-wave hub. However, there are better options available if you don’t feel the need to connect it to a smart home hub.


  • Nothing we could find


  • Connectivity issues

  • App crashes

  • Hard to pair

Roost Smart 9V Battery

If you’re happy with your existing smoke detectors but wish they had smart features, you can purchase the Roost Smart 9V Battery and install it into your alarms. The Roost Smart Battery, which is the same smart monitor used in the Roost RSA-400, is actually easier to set up when purchased on its own, and it delivers the same fast, high-quality notifications.

The Roost Smart 9V Battery comes in a specially-designed foam package that makes syncing more straightforward. Once you’ve synced with the app, simply install the battery into your existing smoke detector, and you’re good to go. The battery will push your smartphone notifications within around 30 seconds of the detector going off—although we did observe that the notifications arrived a little quicker when the phone was connected to the same WiFi network as the battery. Further, these notifications make a loud, attention-grabbing sound similar to a smoke detector, which is a feature unique to this brand.

If you’re in the proximity of the detector, you can silence an alarm through the Roost app, but only if the detector is not connected to AC power. The battery’s other shortcoming is that there’s no in-app testing option. However, you can test the detector normally and you’ll receive a test notification from Roost, as well.

Finally, the Roost Battery, which lasts up to 5 years in smoke-only detectors and 2 to 3 years in smoke and CO detectors, will send you notifications when it’s on its last leg, letting you buy a replacement before those annoying low-battery beeps start. With all these features, the Roost 9V Smart Battery is an affordable way to get the perks of a smart smoke detector without having to replace your existing alarms.


  • Works with existing smoke detector

  • Attention-grabbing smart phone alerts


  • Delay between detector alert and smart phone alert

  • No option to test from the app

Kidde RemoteLync Monitor

The other plug-in, smart monitor available is the Kidde RemoteLync Monitor, which is frankly a bit glitchy and unreliable. The RemoteLync app for Android crashed several times during testing, and more importantly, the app’s notifications were inconsistent at best.

When notifications did come, they were simply app badges that appeared after more than a minute. However, during a few tests, the monitor did not send notifications or register that an alarm was sounding at all. Overall, this device didn’t inspire confidence that it would alert us of a fire, and there are definitely more affordable, reliable choices available.


  • Nothing we could find


  • Unreliable alerts

  • App crashes

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Meet the testers

Camryn Rabideau

Camryn Rabideau



Camryn Rabideau is a valued contributor to the Reviewed.com family of sites.

See all of Camryn Rabideau's reviews

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