Nest Protect Smoke and Carbon Monoxide Alarm Review

This do-it-all smart device provides protection and user-friendly features

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Nest Protect Smoke and Carbon Monoxide Alarm

Nest Protect Smoke and Carbon Monoxide Alarm

The Spruce

What We Like

  • Smart device connectivity

  • Early warning system alerts you before alarm sounds

  • Auto-testing and automatic battery monitoring

  • Motion-sensor night light

What We Don't Like

  • Expensive

  • Potential for Google to collect homeowner data

The Nest Protect Smoke and Carbon Monoxide Alarm is intuitive to set up. Plus, the warnings and alarms delivered by audio prompt, pulsing light codes, and smart device app integration make it easy to figure out when there’s an issue to address.


Nest Protect Smoke and Carbon Monoxide Alarm

Nest Protect Smoke and Carbon Monoxide Alarm

The Spruce

Smoke alarms and carbon monoxide detectors are invaluable when it comes to detecting actual fire or gas leaks, but most leave something to be desired when it comes to everyday performance. There’s the periodic high-pitched chirping that tells you the nine-volt battery is about to die, and the blaring alarm that signals not plumes of real smoke, but a bit of steam that’s wafted off your stir-fry. These false alarms are super annoying, and they force you to drop everything you’re doing to wave a hand towel in front of the unit just to silence it. The Nest Protect remedies the problems that plague cheaper detectors—but it also does so, so much more. Simply put, Nest has made one of our most essential home products into a smart, user-friendly, and intuitive device. We tested out two Nest Protects in our home so we could give you the lowdown on setup, performance, and design. Read on to see how they fared.

Nest Protect Smoke and Carbon Monoxide Alarm
The Spruce 

Setup: As easy as it should be

For a web-enabled device, the Nest Protect’s setup is paint by numbers—especially if you go with the battery mode. Wired models are also available, but they require electrical wiring to mount. After unpacking the device, all we had to do was pull out the plastic tab to connect six internal AA batteries to the unit’s receptors, and then download the Nest app. After creating an account (you can also log into an existing one), we used the app to scan the QR code printed on the back of the device, and then the app guided us through syncing the gadget to our Wi-Fi.

To add another Nest Protect, simply set up the other device in the same fashion. In-app prompts make it easy to follow along, and you can assign names to each device like "living room” or “basement.” Once you’re done setting up all the Nest Protects, push the button on the product and voice prompts guide you through the final parts of setup, which includes a full test of the alarm’s horns—preceded by a polite warning that the alarm is very loud (which it is).

For a web-enabled device, the Nest Protect’s setup is paint by numbers—especially if you go with the battery mode.

After the test, you’ll need to mount the devices, positioning them either on the ceiling or high up on a wall. Get rid of your old alarms and mount the Nest Protect backplate—little screw/no-screw icons on the hard plastic make it easy to put the right side facing outward. Simply place the plate in the desired position and mark spots for the four included mounting screws with a pencil. At 1.65 pounds, the device isn’t heavy; we were able to drill narrow holes in the ceiling and then screw the back plate into the drywall without needing anchors. Mounting the device on the plate is also simple—just line up the tabs on the back of the device to the gaps in the plate, push up, and rotate clockwise. Press the button on just one of the Nest Product devices and voice prompts will finalize everything, offering reassuring confirmation that each unit is working properly. The whole setup process for two Nest Protects (on the main and second floors of our home) took about 20 minutes.

If your plan is to convert your whole home to smart devices by adding other Nest products like the smart thermostat or video doorbell, you may consider investing in a Google Home or Google Home Mini as well. Because Nest products can sync to the Google Home app, you can control every device by voice command.

The whole setup process for two Nest Protects (on the main and second floors of our home) took about 20 minutes.

Performance: Simple, intuitive, and LOUD

Nest redesigned the traditional smoke and CO detector with a split-spectrum sensor that detects high and low carbon monoxide levels (for up to ten years) as well as smoke from both smoldering and fast-burning fires. The Nest Protect is also smart enough to distinguish real smoke from shower steam or minor cooking smoke. Two lesser models we kept for comparison testing sounded off in quick succession when a cloud of steam rose from a hot cast-iron pan that was steam-cooking sausage, but the Nest Protect—which was mounted right next to one of the offending alarms—remained silent.

Another plus of the Nest Protect? Even if it were to go off, it would provide a calm audio “heads up”—partnered with a push notification from the app and a pulse of yellow light on the device—before sounding a full-blown alarm. When the alarm does go off, you can also silence it simply by toggling it off in your app.

The Nest Protect is smart enough to distinguish real smoke from shower steam or minor cooking smoke.

Given that our new house is three stories, we opted to create a network of Nest Protects, with one on the ground level and another on the second floor. The volume of the voice messages is clear without being too loud, and communication is broadcast from both devices as well as through the app. As for the smoke and carbon monoxide alarms themselves, they are LOUD and audible from anywhere in the house—even in the basement laundry room while the dryer is running. During the setup and testing of the device, both alarms sound and even though the polite voice reminds you that they’re loud, we still jumped.

When it comes to updates, you really don’t have to do anything other than sit back and let the Nest do its thing. The device uses a constantly-updating carbon monoxide detection algorithm, checks its own battery level 400 times a day, and quietly tests its speaker and horn once a month via Sound Check. It’ll also alert you when the battery levels are low, when the sensors have failed, when the Wi-Fi connection has dropped, or when the device has expired so you don’t have to worry about checking it manually.

Nest Protect Smoke and Carbon Monoxide Alarm
 The Spruce

Design: Sleek, smart, and very 21st century

Nest was founded by Tony Fadell, a one-time Apple employee and one of the fathers of the iPod, so you can bet his design-forward pedigree was applied to the Nest Protect. The square-shaped unit has soft, curved edges that blend seamlessly with most decor, and it has just one button in the center. Press it once and it’ll quiet the alarm if it sounds; press it twice and the device will wake up for testing.

The smoke and carbon monoxide alarms...are LOUD and audible from anywhere in the house—even in the basement laundry room while the dryer is running.

Encircling the center button is a thin ring of light that displays various colors to communicate what the device is detecting. A red pulse indicates a smoke or carbon monoxide emergency; a yellow pulse gives you a “heads up” that smoke or CO has been detected but hasn’t reached a critical phase; a quick flash of green notes everything is performing as desired when you flick the lights off; a pulse of blue light evidences setup or testing. The Nest Protect also casts a mellow white light—triggered by internal motion sensors—when it’s dark. The sophisticated glow triggers silently and helped our first house guest navigate around a maze of yet-to-be-unpacked cardboard boxes on the second floor.

That may sound like a lot of color prompts to remember, but you don’t have to commit anything to memory. The Nest Protect also employs a speaker that announces the issue(s) it detects in a tone reminiscent of Google Voice (which isn’t surprising given Google now owns Nest). The same voice also guides you through the setup process and offers helpful prompts like “Heads up—there’s smoke downstairs” before triggering a full alarm.

Price: Steep but warranted

Make no mistake, at $119 MSRP, the Nest Protect is one of the priciest smoke and carbon monoxide detectors on the market. But, if you value an intuitive, Wi-Fi-enabled system that’s faulty alarm-free, it may be worth the investment. Surprisingly, for us, the subtle night light feature also turned out to be one of the device’s most appreciated components.

Competition: Few are as sophisticated

First Alert Onelink Smoke Detector and Carbon Monoxide Detector: This $120 First Alert unit comes the closest to Nest Protect in terms of smart performance. With Amazon Alexa integration, the alarm offers voice alerts and can easily connect to other Onelink devices to form a network of smart devices. If Amazon is your go-to smart system, it’s a good option. If Google is your preferred smart product manufacturer, however, Nest Protect is superior.

Elvicto Smoke Combination Photoelectric Smoke & Carbon Monoxide Detector: This simple combination smoke and carbon monoxide detector follows the traditional model (and thus has its pitfalls). While it doesn’t have Wi-Fi connectivity, it can reliably alert you to gas leaks or potential fires with simple indicator lights on the face of the unit and a loud, 85-decibel siren. Plus, it retails for $69.99 (but can often be found for $30 or less)—a fraction of the cost of Nest Protect.

Final Verdict

An absolute hit for smart home junkies.

The Nest Protect won over this skeptic thanks to its ease of set-up, legion of backup systems, and simple integration via the Nest app. The night light offered a quiet victory we didn’t know our house needed, and the ability to get “polite” warnings before the system sounds or the batteries run out make it just as unobtrusive as this type of product should be.


  • Product Name Protect Smoke and Carbon Monoxide Alarm
  • Product Brand Nest
  • MPN S3000BWES
  • Price $119.00
  • Weight 1 lbs.
  • Product Dimensions 5.3 x 1.5 x 53 in.
  • Color White
  • Batteries 6 AA batteries
  • Duration of Carbon Monoxide Sensor 10 years
  • Heat Sensor -/+ 1.8º F
  • Humidity Sensor -/+ 3 percent RH
  • Occupancy Sensor 120º field of view up to 20 ft
  • Horn Volume 85 dB at 10 ft
  • Warranty 2-year limited