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Best WiFi Smart Alert Smoke and Carbon Monoxide Detectors for 2018

For this review and buying guide, we look at the best devices from Nest, First Alert, Ecobee, Birdi, Halo smart labs, Roost, Netatmo and others. In some cases, you can even use Nest, Amazon Alexa, or Google Home to integrate everything into your smart home. Most are available as either battery powered or hard-wired with battery back-up in case of power outages.

Smart smoke / carbon-monoxide detectors, monitors and alarms work with your homes wireless WiFi network to connect to the outside world via the internet to alert you when they are triggered by an event. Many can send messages to your phones, automatically call a security monitoring service and/or fire department, turn on your house lights, and more.

Here’s the list of detectors we cover in this review:

Nest Protect Smoke Plus Carbon Monoxide Alarm, Battery Powered (Second Generation) ($119.00)
Nest Protect Smoke Plus Carbon Monoxide Alarm, Wired 120V S2001LW ($160.00)
Roost PP3 (9v) Specialty Battery ($38.45)
2nd Generation Roost Smart 9V Battery ($74.99 for 2 pack)
Roost 960-00001 RSA-400 ($79.99)
Onelink Safe & Sound Smart Smoke + Carbon Monoxide Alarm and Speaker with Amazon Alexa ($249.32)
First Alert GLOCO-500 Onelink Wi-Fi Environment Monitor ($75)
First Alert 1036469 Onelink Smoke and Carbon Monoxide Detector ($119.95)
First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide Alarm ($39.43)
Halo Safer & Smarter ($129.00)
Halo+ Smart Smoke & Carbon Monoxide CO Alarm ($149.99)
Birdi’s Smart Detector ($99 est.)
Netatmo Smart Smoke Alarm ($100 est.)
Leeo Smart Alert Smoke and CO Monitor ($99.99)

At first read, these smart alarms are pricier than the traditional non-connected devices. For example, a top pick for a Combination Carbon Monoxide and Photoelectric Smoke Detector is the $35 First Alert PRC710 unit which comes with a sealed, 10-year battery. Compare this with the $100+ price for a smart detector, and multiply by 5 to 8 for full house coverage, and it’s quite a difference.

So when you’re deciding on a smart versus standard detector, think about how much you value functions such as being able to customize the system, getting alerts anywhere in world if your home is in danger and warnings throughout your house in the case of an emergency. And some other little features like path-lighting, talking alarms, app controls to test or temporarily silence a device, and more. Plus, for a smart home, these devices allow you to integrate many features of your home systems and let the work together for better safety and comfort.

Regardless of whether you get a smart detector or a standard one, they all rely on two basic types of sensors to detect a “smoke event”: ionized and photoelectric.

Ionized detectors are cheaper but more prone to false alarms than their photoelectric counterparts. Ionization sensors respond slightly quicker to fast-burning fires, while photoelectric sensors are faster at detecting smoldering fires (the more common type in homes). Ionization sensors are more prone to nuisance / false alarms, making them more likely to be disabled by the home’s residents and leaving that house at greater risk. Ionization alarms are not recommended for use in kitchens or near bathrooms due to a higher likelihood of false alarms in these areas. Conversely, photoelectric sensors help reduce false alarms such as from cooking or shower steam.

All the devices in this review are combination smoke plus carbon monoxide. Our view is that if you are going to the trouble and expense of installing detectors, you should make sure you are covered as best as possible against loss of life for you, your family and pets. The additional cost for the carbon monoxide detection is worth your safety. The only place we don’t recommend the dual detectors is in a garage / parking area, since the automobile exhaust will set off the carbon monoxide alarm.

Nest Protect

Smoke Smart Nest Protect Smoke and Carbon Monoxide AlarmThe Nest Protect is our top pick for smart, connected alarms. These are available in both battery powered, and direct wired (with a battery back-up) to your house electrical. You also have a choice of colors: White or Black.
Nest Protect Smoke Plus Carbon Monoxide Alarm, Battery Powered (Second Generation) ($119.00)
Nest Protect Smoke Plus Carbon Monoxide Alarm, Wired 120V S2001LW ($160.00)

With the Battery Powered device, Nest includes the required six (6) lithium AA batteries, which are designed to last five years. These are replaceable, and you should always use lithium batteries in the Nest.

In addition to detecting smoke, heat and carbon monoxide, the Nest Protect’s sensors can detect humidity, motion / room occupancy, and ambient light. Smoke detection is through their “Split-Spectrum Sensor” technology. The Split-Spectrum Sensor enhances a traditional infrared photoelectric sensor with a second, blue LED, to detect a wider range of particle sizes in the air. While this technology has been used in commercial grade alarms, it wasn’t until now used in residential alarms. Tests at Nest labs suggest these sensors are supposedly better at detecting smoldering fires, which are the leading causes of at home incidents.

Please see our full review on the Nest Protect to get even more details on the sensors, go in-depth on the other features, and find out more on this device. We just don’t have the space here to cover everything, and still have room for all the other devices.

If something does trigger the device, you’ll get a standard high-volume alarm and you’ll also get a talking voice to tell you which room is being affected. The Nest will also tell you what type of alert it is. And, the 6 LED RGB light ring will change color on the Nest so you get a visual identification of the alert type, and which unit is affected.

Bonus technology features include smart lighting in the device to act as a motion triggered night light which comes on when you get within about 20 feet, and stays on for a programmable time duration. You can set the brightness levels and dimming functions, as well as set for an always-on night-light. With the ambient light sensors, it is very good with energy usage, which is especially good if you are using the battery powered unit.

All this by itself is pretty amazing, but only a bit more than you might get on a high-end standard detector. Add in the “smart” part, and that is where the real value of the Nest Protect comes in. The Nest works with Amazon Alexa, Google Home, Philips Hue, Lutron, Wink and “IFTTT”. And, as you would expect, it works with all other Nest products.

There are two levels to the Nest connectivity. The first is through it’s own network to allow all of the Nest devices in your home to talk with one another. So if one device is set off, it will spread the message to all the other connected devices, setting them off as well. This internal network use a proprietary protocol (“Weave“) over a 250 kbit/s IEEE 802.15.4 low-rate wireless personal area network (LR-WPANs) standard. So even if you’re power goes out, or your WiFi network stops working, the Nest devices are still communicating with each other. All your Nest Protects can communicate if they’re within about 50 feet (15m) of each other inside your home. If range is an issue, you’ll need to add more Nest Protects to establish a network.

One thing to keep in mind, the Nest wireless Interconnect will not work with other brands of alarms. This is generally true for all brands of smart alarms – they only work within their family of devices. For your safety and best protection, use the same brand of smoke / carbon monoxide alarm throughout your home.

The second level is connecting your house to all your smart devices, computers, monitoring services and the rest of the outside world. Nest works with your standard home WiFi network using the familiar 2.4 GHz / 5.0 GHz IEEE 802.11 b/g/n. With an app on your iPhone / iPad / Andriod device you can set up how alerts are sent, who gets an alert, and the ability to monitor your home in real time.

With the app, your can also test your Nest devices as well as silence a device.

If you have other Nest products, or compatible devices, you can do even more. For example, coupled with a Nest Thermostat ($235 on Amazon), you can set up the Nest Protect to instruct the Nest Thermostat to shut down your HVAC / ventilation system if smoke or fire is detected. If you have a Nest Security Camera ($185 on Amazon), you can have one, any or all of the cameras start recording when an incident occurs. And have your monitoring service notified.

Other noteworthy benefits:

  • Push alerts to phones, and silencing an alarm from a phone can be done in under 30 seconds. Other smart devices can take up to 2 minutes, a long time when your house is screeching at you from all devices.
  • Customization of each device to have it’s own room / location name. Most other devices only let you choose from a selection menu of about a dozen options.

Issues with Nest Protect:

  • One of the most expensive devices.
  • Only has 2-year limited warranty, compared with 5- and 10-years of other smart alarms.

Final thoughts on Nest Protect – this is the top of the line for smoke, fire and CO monitoring, and worth the cost if you have the budget to outfit your home with these devices. The features and benefits merit the price, and the availability of other devices in the Nest product family to inter-operate with is the largest available from any brand.

Buy now through Amazon, in either the house-powered or battery-powered, in Black or White:

Nest Protect Smoke Plus Carbon Monoxide Alarm, Battery Powered (Second Generation) ($119.00)
Nest Protect Smoke Plus Carbon Monoxide Alarm, Wired 120V S2001LW ($160.00)

Roost PP3 (9v) Specialty Battery

Smoke Smart Roost Wi-Fi battery for smokeOur runner-up for best smart alarm, isn’t an alarm at all. It’s a smart battery which replaces the traditional 9V battery in your existing standard alarm, and will also work as a replacement for the battery back-up in a hard wired unit.

The Smart Battery will soon be updated with a newer release. The original and next generation will work together, so you can get started now Roost PP3 (9v) Specialty Battery ($38.45) and buy more 2nd Generation Roost Smart 9V Battery ($74.99 for 2 pack) as they become available. Keep in mind, this only works to replace a 9V battery, and not AA or AAA.

The Smart Battery has the advantage of being a very low cost option to bring all your alarms to the connected world. It’s also the simplest to install, since you are only replacing a battery in an existing, already mounted device.

The downside is that Roost has the least amount of smart features. It’s basic in that you can set up a list of contacts to receive alerts and notifications when an alarm condition is triggered. You can also check individual battery status, and get a history of the alarm activity. Currently, it only works with other Roost products, so it’s limited if you are looking to create an entire smart home system – you’ll need to rely on “IFTTT” functionalities to tie it to other products,

Roost Smart Battery is a lithium battery with module containing a microphone, a WiFi antenna and some computing chips. You connect each Roost to your WiFi, and when the microphone hears the alarm horn sounding, it triggers the messaging through your WiFi to send you alerts.

The battery is anticipated to last about 40,000 hours / 5+ years, and when it runs low you can replace the battery part for about half the price of the entire smart battery. The “smarts” module snaps off the old battery and on to the new one. Since Roost is only about 3 years old as a company, there isn’t any data yet on just how long the battery last in real-world usage.

It comes with a 1 year limited warranty, which is suitable for this type of product to make sure there aren’t any manufacturers defects.

The 2nd gen is supposed to have a longer battery life, with a stronger WiFi signal. These are minor improvements, so feel confident to purchase the Roost PP3 (9v) Specialty Battery ($38.45) to get started and migrate to the 2nd Generation Roost Smart 9V Battery ($74.99 for 2 pack) as you convert all of your detectors.

Roost RSA-400

Smoke Smart Roost Smart Smoke Alarm RSA-400Following on with the success of the smart battery, Roost decided to release their own alarm which detects Smoke, Fire, CO and Natural Gas (i.e.., Methane). The Roost 960-00001 RSA-400 ($79.99) is only available as a hard wired electrical installation, with its Smart Battery as the battery back up.

The internals to the detection unit, and the sensors, originally come from Universal Security Instruments (which makes their own non-smart  4-in-1 Detector for $43) using their “IoPhic” modified ionization sensor. There have been mixed reviews on this sensor, so keep that in mind when evaluating this device. There is a second  photoelectric sensor, and the combination is used for detecting fast flaming fires, slow smoldering fires, carbon monoxide and methane gas.

To indicate the type of trigger event, the horn has a standard alarm for smoke / fire, a second alarm for CO and a third for Natural Gas detection.

Note that this is the only device on our list that has a Natural Gas / Methane detector. If that’s a must-have for your home, then the RSA-400 is the choice for you. Alternatively, if you only want smoke and fire detection, without the Natural Gas and CO detection (useful where cars are parked), check out the $59 RSA-200 .

The Roost RSA-400 by itself is a standard, non-connected device. It’s the Smart Battery described above that gives it the smarts and connectivity. You’ll get the same alerts, notifications and WiFi connectivity; Inter-operability with other connected devices in your smart home will likewise on by through “IFTTT”.

This is another lower cost option to getting your home set up for smart fire, smoke and CO alerts, and especially appealing if you are not planning on installing near term other connected devices. Look for this on Amazon,  Roost 960-00001 RSA-400 .

First Alert OneLink Safe & Sound
Smoke Smart First Alert Onelink Safe & Sound Carbon Monoxide Alarm and Speaker with Amazon AlexaAlso for consideration: The most recent entry by First Alert to compete with Nest Protect is their “Safe & Sound” branded device. Onelink Safe & Sound Smart Smoke + Carbon Monoxide Alarm and Speaker with Amazon Alexa ($249.32). This is a hard-wired only installation, and it has some nice features that need dedicated and continuous power. At $250 per device, it’s the most expensive on our list and about $90 more than the hard-wired Nest.

Similar to the Protect, this is a smoke and carbon monoxide detector, with a sealed battery for back-up power. The battery is rated for10-years, as is the CO detector sensor. As with all CO monitors, the entire unit needs to be replaced when this detector gets to the end of its life.

What sets the Safe & Sound apart from others on the market, and gives it the second half of its name, is the built-in 10-Watt speaker. This unit acts as a wireless speaker for whole-house sound. Using the app you can stream music to any or all of the devices, as well as have it read you audio books or anything else you normally listen to.

With both Alexa and Google Assistant built in, the omni-directional microphone turns this into a hands-free, voice-activated speaker. Everything that you can do on $85 Amazon Echo or $40 Amazon Dot , you can do with the Safe & Sound. It’s this feature that First Alert hopes to justify the $90 price over its Nest competitor. Simply ask Safe & Sound to play music and audio books, read you news, control smart-home devices, and more, just as you would your Amazon Echo or Google Home. (Note that HomeKit support is in the works, so you’ll have even more features to work with).

Similar to all the detectors, you’ll get a (very) audile an 85-decibel alarm.

A 10-watt speaker will also let you play tunes through the hardwired smoke detector, and, when an alarm sounds, the Safe & Sound will send an alert to your smartphone.

Similar to Nest Protect, the Onelink creates its own dedicated network for the devices to communicate with each other. In this case, it’s a standard Bluetooth mesh network. If your power or WiFi stop working, these alarms can stilltalk to each other, so you can get an alert throughout your entire house. Like the Nest Protect, Onelink’s alarms will tell you in which room it has detected smoke or carbon monoxide.

Like the Nest “Pathlight”, Onelink has a dimmable nightlight, so you can see your way in the dark.

In addition to Alexa, the Onelink alarm also works with Apple HomeKit, which means you can have it turn on HomeKit-compatible lights when the alarm sounds. However, the Onelink is compatible only with iOS devices. it doesn’t perform self-tests or give you a heads-up before sounding the siren, and it’s compatible with only iOS phones and tablets. Android is not yet supported, but in the works for future app release.

When activated and sounding the horn, the Onelink will voice announce which device is triggered and the type of event (smoke, fire, CO),  You can’t set a custom name for a room, as you can with the Protect, but the options available from the selection menu should be more than enough to cover all your rooms.

One bonus feature the Onelink offers is an add-on First Alert GLOCO-500 Onelink Wi-Fi Environment Monitor ($75), a separate device that monitors room temperature, humidity, and can detect carbon monoxide. Designed primarily for use in sensitive areas like a nursery, the device plugs into the Onelink app, giving you a single point of entry for both it and your smoke / CO detectors. You can also use the Environment Monitor independent of the detector.

Buy from Amazon: Onelink Safe & Sound Smart Smoke + Carbon Monoxide Alarm and Speaker with Amazon Alexa ($249.32)

First Alert OneLink Wi-Fi Smoke and CO Alarm
Smoke Smart First Alert 1036469 Onelink Smoke and Carbon Monoxide DetectorThe OneLink is First Alert’s original alternative to the Nest Protect, with similar design, and features.  First Alert 1036469 Onelink Smoke and Carbon Monoxide Detector ($119.95). This installation is hard-wired with sealed battery back-up, at about $40 less than the Nest electrical wired device. As a review, it’s best to do this as a comparison to our top pick.

Similar to Nest, the OneLink has a ring of LED lights to alert you to danger (red) or malfunctions (yellow), but no monthly automated self-test feature. The unit does give voice alerts in addition to the horn / siren, so you will know exactly which room has the incident, and the type of triggering event (e.g., smoke, heat, CO).

Detection is with a standard photoelectric smoke sensor, compared with the sensor plus LED technology found in Nest. Reported response times to both smoke and CO events are some of the fastest of residential detectors, and are slightly faster than the Nest Protect.

The OneLink also comes with an adjustable night-light feature, and since this is a hard-wired unit you’ll never need to worry about running down the batteries.

Unlike Nest, and many other smart detectors,  OneLink can communicate to your existing non-First Alert hardwired detectors.This can be a significant cost savings, allowing you smarten up your whole house one unit at a time. Not having to replace all your devices at one time lowers the barrier to entry for whole-home smart smoke detection. However, and not unexpected, the Nest brand of products do not currently communicate with First Alert, so you don’t have the option of using both in your some network. Check with First Alert website for up-to-date list of compatible brands and devices.

The OneLink alarms interconnect with each other, and other smart devices in your home using a 915 MHz Industrial, Scientific, and Medical (ISM) Radio Frequency (RF) signal, with  3-channel frequency hopping to mitigate any interference from other devices (see ISM Band Coexistence And Compliance For Wireless Applications for more details). Devices can be within 50 feet (15 m) to establish a reliable network.

To communicate  with the outside world, First Alert devices connect to your 2.4 GHz home WiFi network using standard IEEE 802.11 b/g/n. The app allows you to set up alerts, notifications, test the system and silence any false alarms.


  • Works with Siri and Apple HomeKit, as well as Amazon Alexa
  • Good price for hard-wired smart alarm


  • Push alerts and silencing false alarms are slow and can take up to 2 minutes
  • ISM 915 MHz communications band can have interference from other electronics

For a lower-priced, hard-wired device this is a good entry into setting up your smart home. If you are looking to make your home centered around Apple products, and use Siri, this would be a preferred option. You can order from Amazon at: First Alert 1036469 Onelink Smoke and Carbon Monoxide Detector ($119.95)

The First Alert 2-in-1 Z-Wave
Smoke Smart First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide AlarmWorth mentioning is the First Alert 2-in-1 Z-Wave Smoke Detector & Carbon Monoxide Alarm ($39.43). If your home is already set-up with Z-Wave, and you have a hub to connect to your WiFi, this is a basic detector at a low price.

It functions similar to the other smart devices: when it detects smoke or CO, it sounds the horn and simultaneously sends an alert to your smartphone letting you know there’s a problem.

This comes as a battery only, with a 7 year limited warranty. It has a photoelectric smoke sensor and electro-chemical  CO detector.


Halo+ Safer & Smarter

Smoke Smart Halo+ Smart Smoke & Carbon Monoxide CO Alarm with Battery Backup, HardwiredAnother new entry into the smart home with a combination smoke and CO detector, Halo has the Halo Safer & Smarter ($129.00) and Halo+ Smart Smoke & Carbon Monoxide CO Alarm ($149.99).

The former is a battery only unit, with a sealed 10 year lithium battery included.  The latter is a hard wired only, with battery back-up. It also gives you integrated weather monitoring. Unique to this device is a Barometric Pressure Sensor and built-in weather-band radio that can be set to alert you to emergency-level weather conditions. If you live in areas that may be prone to hurricanes, tornadoes, wildfires and floods then this may be just the added feature you are looking for. Both devices have a 3 year limited warranty.

These Halo devices have features you would expect in a smoke / CO detector – Photoelectric Sensor, Ionization Sensor, Carbon Monoxide Sensor, Temperature Sensor and Humidity Sensor. You’ll also get color-coded visual indicators of trigger types, which device was triggered and low-battery warnings.

Halo devices create their own network using 2.4 GHz IEEE 802.15.4 (ZigBee), and these are compatible with the Lowe’s Iris smart home system. There is also support for Amazon Alexa, Samsung SmartThings and some other third party hubs.

They connect to your WiFi network with standard 2.4 GHz IEEE  802.11 a/b/g/n. You can use the app to set up notifications, check the status of each device, get battery levels and silence false alarms.

You can buy these now from Amazon: Halo Safer & Smarter ($129.00) and Halo+ Smart Smoke & Carbon Monoxide CO Alarm ($149.99)

Birdi Smart Detector

Smoke Smart Birdi I DesignSuccessfully Indigogo crowd funded over a year ago (but looks like still not shipping) Birdi’s Smart Detector upcoming devices will monitor air quality as well as smoke and carbon monoxide. It has a $99 price estimate, and comes ready for either hardwired or battery-operated.

For hard wired installation, there is a custom Birdi USB Electrical Adapter/Power Converter, to connect to any 230V or 120V home electrical system. As with other hard wired devices, it has a 10-year battery-backup. It can also be battery-operated, powered by 3 Energizer Ultimate Lithium AA batteries.

Birdi distinguishes itself by offering air-quality and weather monitoring in addition to providing dual smoke sensing and CO detection.  The Smart Detector will track dust, VOC’s (Volatile Organic Compounds) temperature, and humidity, as well as how stale the air is inside your home. It is also supposed to be mountable outside to tracks pollution, pollen, and particulates, and provide weather updates.

This will work with your WiFi network, and provide the expected updates, alerts and controls.

Netatmo Smart Smoke Alarm

Another brand new entrant, and still showing as “Coming Soon”, the Netatmo Smart Smoke Alarm is worth looking into when it releases. Expected price is under $100 for the battery powered unit.

Leeo Smart Alert

Smart Alert Smoke and CO Monitor
The Leeo Smart Alert Smoke and CO Monitor ($99.99) is similar to the Roost Battery in that it monitors your already installed detectors for an audible alert, and when it hears the horn it communicates with your WiFi network to send out alerts. You simply plug it into any standard wall socket, and configure it though the app.

It also works as a night-light.

That’s it for our round-up. There are many other similar devices on the market, and more coming each year. We think these are the best from both the major established brands with a long record of quality and reliability, as well as some of the newer entrants to the market.

A final note – If you’re upgrading to smart detectors, and especially hard wired models, it’s important that you replace all the detectors in the chain with the same make and model. One of the reasons for hard wiring a smoke detector is that if one detects a dangerous condition, it can trigger all the others to go off. But there’s no guarantee that feature will work if you have a mix of devices from different manufacturers wired together.
Smoke alarms are either battery-powered or hardwired (meaning you can install that kind only where the house has wiring to support it), but even hardwired alarms have batteries in them in case the power goes out.

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