Nest Protect Review: Smoke and Carbon Monoxide Alerts Delivered to Your Smartphone

Nest Protect, one of the few combination CO/smoke detectors on the market, takes the guesswork out of smoke and CO detection in your home. The app and even the devices themselves tell you what’s wrong and where, and the Protect can integrate with other Nest devices, as well as a few other smart home devices. With its second generation, Nest has rectified many of the issues of the first-generation Protect, and we love its many features that give you an insight into what’s happening in your home.

nest protect
  • Pro BulletCO and smoke detector capabilities
  • Pro BulletMonthly automatic tests
  • Pro BulletMobile app alerts and monitoring
  • Pro BulletGentle early warning sounds before an alarm
  • Pro BulletSilencing capabilities from your phone
  • Pro BulletNightly Promise to alert you of any issues before you go to bed
  • Pro BulletBattery-powered and wired versions
  • Con BulletNo ability to connect to non-Nest smoke/CO detectors
  • Con BulletHigher cost than other smoke/CO detectors
  • Con BulletShort 2-year warranty

How Nest Protect compares

If you want a smoke/CO detector that will send alerts to your smartphone, you’ll need to be prepared to pay three or four times as much per device as you would pay for a regular smoke detector. There are only a handful of such detectors on the market, and because of its robust features, quality hardware, and excellent user interface, Nest Protect ranked on our review of combination smoke/CO detectors.

False alarms were a big problem with the first-generation Nest Protect, so in this second generation, Nest has upgraded the Protect from a single photoelectric sensor to a split-spectrum sensor. This improved sensor can better distinguish benign debris such as dust or bugs from smoke particles, leading to fewer false alarms. If you do happen to get a false alarm, the second generation allows you to silence the alarm with your mobile device. Other new features of the second generation are its automatic self-testing, easier installation, and convenient battery access. With all of these improvements, it’s clear that Nest listens to criticism and responds with real changes to its products.

Nest Protect
Nest Protect
Tech Specs
  • Batteries: 6 AA lithium batteries (Energizer Ultimate included)
  • Microphone: Omnidirectional 70dBA SNR
  • Speaker: 2 Watts
  • Alarm: 85dB
  • Power: 1.5 volts
  • Ambient operating temperature: 40°F to 100°F
  • Weight: 1 pound
  • Dimensions: 5.3 H x 5.3 W x 1.5 D inches
  • Warranty: 2-year limited

Nest Protect compatibility

Nest Protect is compatible with all other Nest products, Google Home, and IFTTT. It’s not compatible with Apple HomeKit, and linking it up with your Z-Wave or ZigBee devices takes some extra creative runaround.

The most important compatibility is with the Nest Thermostat because home temperature and fire dangers go hand-in-hand. When Nest Protect detects CO or smoke, your Nest Thermostat will automatically turn off any fossil fuel-powered heating and forced air systems to help prevent the problems from spreading.

Philips Hue Lights

Your Nest Cams will automatically record an emergency clip and start streaming video to your cellphone, and any other Nest devices you have in your home will also begin sounding an alarm to help you find the source of the smoke or CO. You could also set up IFTTT rules to flash your Philips Hue lights if smoke is detected. If you have Google Home, you could set up a rule to automatically order more batteries on Google Express so you don’t have to remember to later.

All that said, Nest is a great option for building a smart home. Check out a list of our favorite smart home devices that work with Nest.

Nest Protect availability

Nest Protect is available either as a wired or battery-operated device, and the price is the same for both. I haven’t found a retailer that offers a discount for buying multiple devices at a time, but the Nest store will give you free shipping if you purchase more than one.

Should I get wired or battery operated?

Be sure to check out your local smoke detector laws to ensure your home is in compliance. California state law, for example, requires hardwired detectors with battery backup in any home built after 1992. If you live in California or you have an existing wired smoke detection system, you might as well go with wired so you don’t ever have to worry about replacing batteries. Battery-powered detectors are good if you have a home without an existing wired system, or if you want to place a detector in an unusual area, such as a garage, workshop, or barn.

Nest Protect’s features

Here’s what you get with Nest Protect:

  • The Split-Spectrum Sensor adds a blue LED to the standard infrared LED in order to detect different-sized particles produced by different types of fires. It uses the information gathered by these LEDs to “make more informed decisions” about the nature of the particles and how and when to sound an alarm, leading to fewer false alarms.
  • The Steam Check uses algorithms and a humidity sensor to distinguish smoke from steam so your hot bath won’t be interrupted.
  • The device offers early warnings before sounding the alarm. When you’re cooking bacon, a gentle voice will tell you “there’s smoke in the kitchen,” rather than a full-volume assult to your eardrums.
  • The heat sensor detects sudden rises in temperature so the device can investigate.
  • It talks to your Nest Thermostat to turn off the heat if there’s a carbon monoxide leak or smoke in the house.
  • A self-test called Sound Check automatically runs once a month so you don’t have to remember to do it (who does, anyway?). You can also run a manual safety checkup if you need extra assurance.
  • If enabled on your Nest App, Home/Away Assist will wait until you’re out of the house until it runs the sound check so you never have to hear those horrid chirps.
  • Nightly Promise reassures you that your batteries, sensors, and Wi-Fi are all working before you go to bed. A quick green glow when you turn off the lights means everything’s working, and yellow means there’s a problem. If you push the center button on the Protect, it’ll tell you what the issue is and with which device.
  • Pathlight turns on a low light when you walk under the device in the dark (can be disabled).
  • The Nest app controls Nest Protect, so if you already have other Nest products, like the thermostat or cameras, you can monitor everything from a single highly rated app (four stars in both the iOS and Android stores).

Nest’s no-pressure customer support

Nest provides robust online support for the Nest Protect, with installation videos, startup guides, troubleshooting, and FAQs. If these resources can’t solve your issue, Nest is also available on chat, Twitter, or by phone (855-469-6378). I’ve used Nest’s chat feature a handful of times and their representatives are always courteous, helpful, and honest about the product’s limitations, and they never try to spin my inquiries into a sale, which is truly refreshing.

What customers say about Nest Protect

Positive reviews

"New generation is easy to set up vs first generation. I now have 6. I am replacing all my old wired/connected devices. Just having a device tell you, and clearly which one, it's back up battery is low is worth the cost. The old days of standing in one spot trying to figure out [where] the low battery chirp came from is gone!"

-KiethS, Home Depot customer 12/27/16

"This is my 5th Nest Protect (located in my home office) and it saved my house from a potential catastrophe. I left the gas burner on while sterilizing baby bottles and went to work. The water boiled out and the alarm activated saying there was smoke in the hallway. Since no one was home, I was receiving alerts on my phone initially from the detector in the hallway; that is until all smoke detectors ultimately started alerting me. I immediately sent a relative to the home to find the gas burner on with all bottles melted. The situation could have become worse if I wasn't notified via alerts on my phone. Since I setup the alarm to notify other relatives, they were calling me as well to see if I was ok. Thank you Nest Protect!"

-psychostud, Best Buy customer 7/9/16

Critical reviews

"The only reason for the four instead of five stars is because installation was complex. After changing my router and setting it up with a new password my Nest Protects were disconnected from from the internet. It turned out that it has been very difficult reconnecting them to the internet. You cannot just connect using bluetooth like initially because you have to have the QR code. Unfortunately this code is only located on the back of the Protect. Some of the Protects I installed are a 16 foot ladder climb to access. I have four Protects installed, two of which require a ladder to access. You would think a product this expensive would be able to deal with a router change in a better way. The big takeaway here is write the QR code for all Nest products down somewhere before installing them."

-GreatDane, Amazon customer 1/21/17

"This is a great product if it wouldn't be so expensive to feed it batteries. [...] The first set of batteries failed within a week or so. Nest customer support was great and promptly sent me new batteries - this was November. Just 5 ½ months later the replacement lithium batteries are failing again, and the Nest detector is beeping [constantly] until I replace the batteries. Nest recommends Energizer Ultimate Lithium batteries, which run approximately $26 for the 6 the unit needs. At this rate, it's just not worth the [convenience] of this technology. I'm glad I didn't buy two more Nest detectors at $100 each, and $26 every five months for batteries."

-StlFan5, Best Buy customer 4/26/16

Why get a combination smoke/CO detector?

Combination smoke/CO detectors reduce the number of separate devices you have to install, plus you can monitor two major environmental threats from one app, meaning you’ll have fewer devices to monitor and find places for in your home.

I don’t think I need to throw out a bunch of statistics to convince you that you need working smoke detectors in your home (but in case you were wondering, three out of every five home fire deaths occur in homes without functional smoke alarms). But what about CO detectors? What do they do? Carbon monoxide is a gas already present in the air we breathe, but too much of it can be deadly. Most homes have some sort of fuel-burning appliance (space heater, furnace, hot water heater, fireplace, gas range, etc.). These are designed not to emit unsafe CO levels, but valves get blocked and things break down, so it’s a good idea to have at least one CO detector on every level of your home.

Do I recommend Nest Protect?

Yes—enthusiastically so. Because I’m already on it all the time anyway, controlling my system from my smartphone also makes a ton of sense. While there are a few products out there with similar features, this device outperforms them all in its hardware, user interface, and customer service. Nest Protect eliminates the worst things about smoke/CO detectors and enhances the best things.

Do you have Nest Protect in your home? What do you think of it? What are your favorite features?