The best smoke detectors of 2019

Choosing the best smoke detectors for your home is no easy feat, since there are hundreds of models on the market, from the cheap basic smoke detectors that use one type of sensor to the complex, smart smoke detectors, which, besides being capable of detecting any type of smoke or CO leakage, they can also be connected to a smart home hub, interconnect wirelessly to other devices and notify the user on the mobile phone any time there’s an emergency.

So, in order to make it easier, I compiled a list of some of the most capable and popular smoke and CO alarms, along with some new devices that promise to have a fast ascension towards the top (as always, each smoke detector will be analysed in-depth separately).

UPDATE 01.10.2019: First Alert SCO501CN-3ST Smoke Alarm With Voice Location has been added to the best smoke detectors list.

1. NEST Protect (2nd Gen)2. OneLink Safe and Sound Smoke/CO Alarm3. Leeo Smart Alert
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4. Roost RSA-4005. First Alert 2-in-1 Z-Wave6. First Alert SCO501CN-3ST7. First Alert P1010 Atom
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1. Nest Protect (2nd Gen) Smoke Detector



The second generation of NEST Protect is the most talked about smart smoke detector of the last couple of years, especially since it is an IoT product which can be integrated into a smart-home network and can communicate with other smart devices (those which were compatible with Nest). Of course, the smoke detection feature takes priority over the IoT integration and, thankfully, it does fulfil its role using lots of different technologies (such as CO detection, Split-Spectrum Sensor and steam check).

The first Nest Protect is proof that sometimes, manufacturers test the waters before releasing a proper device and, as expected, it was plagued by numerous issues. Some of the problems of the previous generation (such as the recurring false alarms) seem to have been fixed to a certain degree but this is a very complex device, so a lot of things could go wrong (more often than with the non-smart smoke detectors). Surprisingly, the Nest Protect is stable enough, so it deserves a place in this article, but be aware that it has a high price.


Usually, smoke detectors aren’t known as improving the aesthetic value of your room, but the Nest Protect is the better looking one from the bunch. The detector features a rectangular case, with rounded corners and on the the front, the device is covered by lots of puncture holes, with a solid circular button in the middle which is surrounded by a small canal to make way for the LED light to break through (it looks surprisingly similar to a speaker). Turn the device around and you can see four narrow, but fairly long ventilation holes on the edges, four holes for ceiling mounting, a battery door and a micro-USB connector (in case the smoke detector needs servicing).

This is available for the battery-powered Nest Protect, but, of course, you can also purchase the wired variant, which will have additional AC connector pins on the back side to attach a 230V cable connector. The device itself is not really bigger than the average smoke detector from the market, measuring 1.63 x 5.28 inches and the install process follows the same steps: after choosing the rooms in which you’re going to install the Nest Protect (at least in every room which has a fuel burning appliance), you need to make sure there is a minimum of 10 feet from any cooking appliance and avoid placing it on a corner (you can choose either a wall or the ceiling).


Then, you need to take the provided backplate and fix it to the wall/ceiling using the four screws and afterwards, just connect the smoke detector to the backplate using a circular motion (if you have the wire-powered version, the installing process also includes connecting the device to a power source, but, it’s ideal that this is done by a qualified person, to make sure the installation is made in accordance with the country or state’s regulations). The way to differentiate the first and the second generation of Nest Protect is by verifying if it has a battery door (the Nest Protect 1 does not have one), verify the back plate (the second generation has a round backplate, while the first has a square plate) and the easiest one is to look at the edges of the device (the second generation has rounded corners all around the case, while the first gen has straight edges).

Right now, on the market, there are three types of smoke detectors: those that use ionization sensors, those that use photoelectric sensors and lastly, those that use both type of sensors (also called dual-sensor smoke alarms). The Nest Protect, theoretically, falls into the last category, but things are a bit more complicated because it doesn’t have a ionization sensor, but it does use the Split-Spectrum Sensor which nullifies the need of the radioactive ionization sensor (as you know, it detects smoke produced by flaming fires which burn at a fast rate so, if the ionized air is disrupted by smoke, it triggers the alarm). The photoelectric sensors is used to detect any smouldering fires (that uses a light beam which, normally does not hit the sensor, but when smoke scatters the light particles, it will hit the sensor, therefore triggering the alarms – this method is used to detect a fire in its early stages, therefore reacting a lot faster).


Now, the Split-Spectrum Sensor should detect both the flaming fires and the smouldering ones, by adding a blue LED light (at a wavelength of 450nm) to look for small particles (which are an indicator of a rapid, fast burning fire) and keeping the usual photoelectric sensor to detect smouldering fires. To make sure it doesn’t repeat the mistakes of its predecessor (annoying false alarms), the new sensor is isolated from any outside light and the encasing is designed to only allow smoke in and nothing else (this worked just fine since the second generation of Nest Protect is indeed less prone to false alarms).

Besides the Split-Spectrum sensor, there’s also an Electrochemical carbon monoxide sensor (yes, the Nest Protect is also a Carbon Monoxide Detector) which detects the CO concentration level inside the room and, if it’s beyond safe levels, it triggers the alarm (CO detectors usually last about 6-7 years, but Nest advertises that the sensor on the Protect can last up to 10 years). Furthermore, there’s also a heat sensor (so you’ll get notified when the home gets either too cold or too hot), a humidity sensor (so it makes it unlikely that the alarm will be triggered when there’s lots of steam), an ambient light sensor (so the detector knows when the lights are shut off and it can activate the Pathlight feature or the Nightly Promise – the LED will be green if everything is fine, otherwise, it will become yellow) and an occupancy sensor (it is used with the Pathlight feature, so it will detect movement and will shine a light on your path during the night – so you don’t stumble on the furniture).


With the new released WiFi systems and home automation hubs, I noticed an increased interest towards simplicity and minimalism in both design and functionality, which meant a simple design and a single LED which showed the status of the system with different colours. Of course, for me it did not make much sense since there is no intuitive way to understand all those flashing or solid colours, so I said that a voice feedback would make much more sense. It seems that Nest Protect actually implemented such a system and, using an omnidirectional microphone, it will speak to you in words (besides also using the appropriate colours): there are two types of alerts, the Heads-up (it’s a calmly spoken warning + yellow LED, when smoke or CO levels are rising but have not yet reached dangerous levels) and the Emergency Alerts (when smoke or CO are at dangerous levels, the Nest Protect notifies you where is the problem, it turns the LED red and triggers the loud sound alarm – 85dB). Head-Up and Emergency alerts can be silenced by pressing the circular button.
Note: This device is not intended for people with hearing problems (it lacks a flashing strobe of light and the 85db alarm may not be enough in such cases).

The Nest Protect runs self tests regularly (every 200 seconds) to see the status of the batteries and sensors and you can also run a full test to check at any time (during this process, you’ll notice a blue light rotating around the button). If you have more than one Nest Protect detectors, you can interconnect them wirelessly (the device supports the 802.11b/g/n standard and Bluetooth Low Energy technology) and, in case of an emergency, all the devices will speak at once telling you the location of the triggered alarm (the devices shouldn’t be more than 50 feet apart from each other). The wired and battery models can be connected wirelessly (up to 18) and you can also connect the Nest Protect with other Nest smart products (such as the Nest Learning thermostat).


All the Nest products also come with a dedicated app (compatible with iOS or Android) which shows the status of all the connected devices (you can easily add devices by scanning the QR code) and it allows you to perform sound checks, configure the Pathlight feature or the Notifications you will receive to your phone (the speed at which the notifications arrive depends a lot on the network latency and cellular connection).

Now, let’s talk about the elephant in the room (or the Nest!): the security and privacy of your data. As you know, Nest is owned by Google, so this already makes people more cautious about their privacy. There has been a reported backdoor more than a couple of years ago on the Nest thermostat, but the Nest Protect was and remains unaffected by the IoT vulnerabilities (and there are many). Now, Nest admits on collecting data from your system to analyse the average battery life, it records data about any adjustments you make to the product and the history of all changes, but it insists that all collected data is not sold to third-party companies and the info may be shared but not before the user gives explicit permission to do so.

Note: Inside the package, there is a Nest protect unit, the backplate, four mounting screws, the User Guide, a Welcome Guide, six batteries (Energizer Ultimate Lithium L91 AA) and a 2-year limited hardware warranty (if installed by a professional, the warranty is 5 years). If you opted for the wired device, you’ll additionally get three wire nuts and a 120V AC connector.

2. OneLink Safe and Sound Smoke/CO Alarm



The First Alert Onelink Safe & Sound is the newest smoke and Carbon Monoxide detector from the US-based manufacturer and it is the second attempt at creating a worthy competitor to the widely popular Nest Protect 2nd Generation.
I purposely skipped the first generation of OneLink because it was a mess software-wise (the app was unstable and the device would constantly trigger false alarms), so the company has worked hard to fix these issues and hoped that this new device would receive more positive feedback from the audience. To further set it apart from its predecessor (and its competitors – which are not that many), the First Alert Onelink Safe & Sound has included a built-in speaker and has embedded Alexa Voice Services, while also keeping the compatibility with Apple’s HomeKit (of course, this has driven the price up significantly).

Since the Halo Smoke Alarm got discontinued (and the Cloud-based support got closed as well), I can understand why people may be reluctant with giving start-ups a chance and instead may prefer to go with a more mature company that’s been in the business for longer and that’s where the likes of Nest and OneLink Safe & Sound come into play and remain overall favourites (in spite of the usually higher price tags).
The First Alert Onelink Safe & Sound detector features a fairly large oval case made of plastic, with the front side divided into multiple inner sections by narrow plastic bands, the device mostly being covered by lots of puncture holes (the middle section is slightly elevated). Surrounding the top area there’s a metallic ring while towards the bottom, the case gets significantly slimmer and it features narrow holes all around to allow the smoke to enter the inner chamber.


It’s hard not to see the striking similarities with the Nest Protect, which is also covered by lots of small holes on the front side, as well as the overall shape of the smoke detector and the LED light which shines from the circular middle section on both smoke detectors (it’s clear that all smart smoke & CO detectors follow the same design pattern, so it’s not surprise that both the First Alert Onelink and Nest Protect look so similar: it seems that developers either think that this is the most ergonomic design or are simply afraid to try something new).
Similarly to the Nest Protect 2nd Generation, the Safe & Sound also has a NightLight which can be adjusted in terms of intensity or colour depending on the time of day, but it cannot be set to turn on only during the night (while Nest does allow it).

The Onelink Safe & Sound alarm is slightly larger than your average non-smart smoke detector (it measures 6.8 x 6.8 x 2.26 inches and weighs 1.5 lbs), but, because of its flush mount aspect it does give some aesthetic value to the room. The main attraction is the speaker, which is located on the small middle section which will work (in most cases) along with the LED ring (for example, when using Alexa, the LED will be solid blue when Alexa is processing your request and will become half red when the microphone is muted). I can’t really say that the speaker is among the best, but the fact that you position the device on the ceiling definitely makes it sound better than the regular Alexa devices.


The Onelink Safe & Sound is a wired smoke and CO detector (a battery-only variant for has not yet been released), so, it is advisable that the installation should be conducted by a professional. If you decide to go at it by yourself, these are the steps you need to take: first, you need to make sure not to mount the device in locations where the temperature is either below 40ºF or above 100ºF and the humidity is within the 20 to 80 % range (non-condensing); secondly, try to avoid spaces where the air is not circulating properly (such as in the corners of the room – you can mount in on the wall or on the ceiling) and also keep at least 20 feet from any cooking appliance (the main source of false alarms).

Now, you will need three wires to comes out of the ceiling (wall), a neutral (white), a hot (black) and an interconnect wire (orange/red/yellow) and you’ll need to connect the First Alert power connector to the wires using wire nuts (of course, you need to match the colours). Next, install the mounting plate using the provided screws, take the OneLink detector and attach the 120V power connector to the back port and simply twist the device into the mounting plate.


The most common types of smoke detectors are those that are equipped with either a ionization sensor or with a photoelectric sensor (or, of course, both). The first type of sensor is very sensitive to smaller particles, so, they’re very good at detecting fast burning flames, but, unfortunately, are also prone at giving false positives (for example, while cooking). The second type of sensors relies on detecting larger particles (specific to slow burning, smouldering fires – such as a cigarette left on the sofa) by using a light source inside a chamber which points away from the sensor, but will deviate its course towards it at the moment smoke enters this chamber. The First Alert Onelink Safe & Sound uses a photoelectric sensor for detecting smouldering fires and an electrochemical sensor for detecting CO emissions (so it uses minimal power to accurately detect any change in the concentration of CO from the atmosphere).

In case the sensors detect rising levels of smoke or CO, the LED light will flash a red colour and you’ll hear a voice telling you the location of the detector (in case you have more than one devices inter-connected). The alerts can be silenced by pushing the Test/Silence button for a minimum of 3-5 seconds (or using the app), but be aware that this is only temporary and you will need to identify and fix the problem until the alarm will sound again (you get 15 minutes in case the sensor detects smoke and 4 minutes when the sensor detects high levels of CO).
The Onelink Safe & Sound smoke/CO alarm can interconnect with other Onelink alarms, so, in case there’s a fire in the kitchen, all the devices will sound the alarm and will tell you the room where the emergency originates.


Furthermore, OneLink Safe & Sound works well with the Apple HomeKit home automation hub (compatible with the Apple Home app) and it has embedded Amazon Alexa Voice Services (I’ve got to admit that one of the reasons why this device caught my attention is the integration with Alexa, especially after seeing it working with Linksys Velop and Netgear Orbi). The Onelink Safe & Sound smoke detector also comes with a mobile app which allows you to choose the location of the device, interact with Siri, see the status of the sensors, adjust the NighLight, mute/unmute the microphone, play music and more. Furthermore, you will also receive notifications for any changes which occur in your house even if you’re not at home.
Note: Inside the package, you can find the Onelink Safe & Sound smoke / CO alarm, a mounting bracket and additional hardware, as well as a User Manual and a Quick Start Guide (the product comes with a 3 year limited warranty).

3. Leeo Smart Alert Smoke/CO Remote Alarm Monitor



During the last decade, we’ve witnessed a great advance in technology and nowadays, we use apps and gadgets that improve our lives and well-being. While before we had entertainment devices with lots of interesting features on one side and more practical conservative products devices on the other side, this line is being constantly blurred and the Leeo Smart Alert Smoke/CO Remote Alarm Monitor for iOS and Android proves that we can have a practical device while also providing some interesting features (such as integration with IoT), therefore making it worthy of our attention.

Let’s see how this looks like. The Leeo Smart Alert Smoke is a small (about 3.4 inches or 87.36 mm, in metric system), I would say, like a coaster and light device, about 4.4 ounces or 125 g. Its depth (the plug face) is about 1.2 inches and with the prongs it goes to about 1.9 inches. So it’s a small device, but very pleasing aesthetically speaking. It has a microphone on the front, the shape is round, it’s made of plastic and the only colour you can find on this product is white. You can also use it as a night light and change it to any colour you prefer.


In order to use it properly, you will need a WiFi network, a smartphone or iPhone and the app itself (which is free): from both iOS and the Android Store. The device doesn’t require batteries and it is very easy to install: you basically plug it into an outlet (you will need 100-240V – most houses have this) and install the app on your phone. This works on iPhones 4S or later running iOS 8+ or Android 4.3+ phones with Bluetooth 4.0 (it’s important to have Bluetooth enabled and have a good WiFi connection before you start the configuration). It’s very important to know that the device only recognizes letters and numbers in the WiFi name and will not connect to a WiFi that has symbols(?,!,><,.,;_) in its name.

So the setup will begin and you will have to create an account, with a name and password. Make sure it’s something you will remember and if you’re not sure, just write it down. Then, the app will automatically search for your device (once again, make sure that your Bluetooth is enabled and the phone is in the range of the device). You will notice that the white light on the device will shine, which means that the device and your phone are now connected. On the screen, you’ll see the “Add a new Residence” message, which means that you can give a name for your home, maybe “bedroom”, “hallway”, whatever you like and next, you will have the “WiFi setup”, which will ask you to connect it to your wireless network. Afterwards, click on your wireless name and enter the password (be patient as it will take a few moments to load).


Once this process is over, the app will ask you about your address, email and phone number and then, you get to the terms and condition and the updates. Next, the app will show you the conditions of your home, the temperature and the humidity and will give you a message on the screen about these two parameters. On the bottom of the interface, you will see two buttons, the one on the left is for the Settings of the app and the one on the right for the Settings of the light. You can set the app to give you a notification if the humidity or the temperature are above or below a number set by you.

Now that we’ve set this up, it’s time to put it to work. The Leeo Alert is compatible with smoke alarms, carbon monoxide alarms and with water leak detectors that are already installed in your house. It “hears” the specific noise that these make and lets you know of any potential danger. The standard smoke alarms emit the Temporal-3 signal (T3), which is a sharp noise or long beeps in sequences of 3 separated by a pause, while the carbon monoxide alarms emit a Temporal-4 (T4) signal, which consist of short beeps in sequence of 4 separated by a pause and, lastly, the continuous tone water alarms make a sharp prolonged beep. This means that the alarm won’t start from other noises in the house, like a microwave or from a fridge which has the door open for too long.


Note: Right now, the water alarm feature only works using the iOS app, but the manufacturer promised that the Android version will also have it available soon.
When the device will recognize the specific alarm, it will flash red and you will receive an alert on your phone (it can also call you). You can set the device to play a short recorded message of the sound of the alarm when you are called (some complained about the low volume). Besides your own phone number, you can set other emergency contacts on the app: it will try to contact you first by pushing a notification, then call you and if you don’t answer/acknowledge the notification alarm, it will contact the other numbers you added to the list.

So, in case of smoke, you will get a notification: Smoke alert, Emergency, which will prompt you can take action, by listening to the 5 second recording of the beeping, calling 911 or clicking on the “false alarm” button. The app gives you the numbers of the local authorities to contact in case of an emergency (what’s great about this, is the fact that it will direct you to the authorities close to the location of the device, not close to your current location, which I think it’s smart). The app won’t alert the authorities on its own, but it makes the reaction more quickly for you, by giving the necessary options.


app, you can touch any colour (as it has a wide range of colors – about 15000 tones to choose from) and be aware that the LED light is a bit brighter for the eye during the night, so if you sleep facing the device, it might bother you (you can adjust the brightness). It’s useful when you want to go to the bathroom or if you want to grab a snack during the night (I don’t judge) and it helps you see, so you won’t bump into something in the house. The light will turn on automatically when it’s dark, but it’s not as sensitive as I would like it to be, because, if you put it in the hallway, in a darker corner, the light will stay on all the time (even during the day).

You only need one if you live in a small home, but you may want a larger amount of Leeo units if you live in a larger house (although one detector per floor should be enough). The device must stay in the range of the alarms, no further than 75 feet and not behind a shut door.
If the power goes out, the device doesn’t have a battery inside to back it up and if the WiFi turns off, it will disconnect from the devices. But, if this happens, you will receive a notification letting you know that Leeo it has been disconnected. If this happens regularly, you can use an UPS to make sure that the power supply is constant.


But what about privacy? The fact that the device records sounds from your alarms must raise some concerns. Well, the creators say that Leeo is designed to listen only to sounds from the alarms and nothing else, protecting your privacy. A closer look at their privacy policy reveals that the Leeo Smart Alert Nightlight gathers info about the surrounding area (temperature, humidity and ambient light), but it also detects noise frequency and specific sounds (makes short recordings of any detected alarm). The Leeo team uses the collected data to make predictions and suggestions, but also to alert the assigned contacts in case of an emergency.
Overall, it’s an interesting product which can integrate a generic, non-smart alarm system into an IoT environment, therefore, it’s a promising, future-proof device.

4. Roost RSA-400 Smoke/Fire/CO/Natural Gas Alarm



Roost RSA-400 Smoke/Fire/CO/Natural Gas Alarm was created to make the best use of the Roost Smart Battery, a device born from a crowd funded project (similarly to Halo, but, this time, using Kickstarter) and because of its unique abilities, it quickly became a very popular product. The Roost Smart Battery is equipped with a WiFi adapter, a microphone and, if used with an already existing smoke alarm, it can bring a new array of functions for an increased level of convenience and to make your home a lot safer (after it gets connected to your home WiFi network, you get notifications in case of emergencies, when the battery is running low, allows snoozing in case of false alarms (this feature did not work with hard-wired alarms) and an easy-to-use app to monitor your device).


The Roost RSA-400 takes things further and, besides delivering every function of the Roost Smart Battery, it detects the usual trio: smoke, CO and fire and, additionally, it can also sense the presence of natural gas (a unique addition for this type of detector).
Even if the Roost RSA-400 could fit among the smart detectors, when compared with Halo Smoke Alarm, Onelink or Nest Protect, its design is pretty unremarkable. So, similarly to the traditional smoke detectors, the case of the Roost RSA 400 is circular, while towards the bottom, the body gets narrower and finishes into a larger, thin plate where the device gets in contact with the ceiling (or wall).

Since the plastic case is covered by a white matte finish, it will easily blend in on a ceiling (it actually looks like a flush mount lighting) and, since it is a relatively small device (it measures 5.63 x 5.63 x 1.75 inches), it won’t attract too much attention. On the top of the detector, there is a recessed zone on which resides an elevated button (press to silence the CO/smoke alarm and hold it to test weekly), a CO/GAS indicator, a Power/Smoke indicator and four circular cut-outs for the speaker. There are no other flashy design elements, such as a large LED light, so compared with other ‘smarter’ detectors, it may look a bit plain, but it does have everything one would expect from a smoke/CO/gas/fire alarm.


In order to ensure that the four types of sensor will work properly, Roost claims that it had to make the RSA-400 a hard-wired only device and this is a shame since it takes away from the convenience of placing it anywhere on the ceiling (or wall). Furthermore, if previously you didn’t have a wired alarm, you may need to install the necessary wires, which implies additional costs (of course, as with any other hard-wired alarms, it is advisable that it is installed by a professional).

If you decide to do it yourself, the installation process is not really that difficult: first, you need to remove the mounting bracket by twisting the main body of the alarm, attach it to the wall and you will now connect the three wires from the wall to the Quick Connector as following: black to the hot side of the AC wire, white to neutral and yellow, if you need to interconnect with other existing alarms (the Power has to be turned off prior to this operation). Afterwards, insert the Roost battery, plug the Quick Connector into the Roost RSA-400’s base, reattach the body of the alarm to the bracket and turn on the AC power. The green LED will indicate that the device is powered on and the red LED will blink once every 40 seconds to indicate a proper operation.


Note: Roost RSA-400 can be interconnected with a maximum of 24 devices (for a complete list of the compatible alarms, check the user manual) and, be aware that the detector has two tamper resistant locking features, one for keeping people from removing the detector from its bracket and the other, for preventing the removal of the battery (to unlock them, you need to use the provided locking pins).

The RSA-400 has implemented what it calls the Universal Smoke Sensing Technology™ (USST), which is an equivalent to the existing dual-sensor, ionization or photoelectric technologies and it uses one ion sensor and a microprocessor to detect smouldering and fast flaming fires. The USST allows for an early smoke detection during stratification for both fast and smouldering fires using the same sensor for both and, in order to avoid false alarms, the device will operate at a low sensitive level and, in case smoke is detected, it will signal the alarm; it also adjusts and maintains a constant alarm threshold, therefore minimizing the effect of ambient conditions and it features a regulated 5V power supply for the ion chamber.


If smoke has been detected, the alarm will beep three times, pause for two seconds and then repeat, the green power LED will turn off and the red smoke LED will start blinking once every second (if smoke is detected by another interconnected alarm, the red LED will not turn on).
Furthermore, if rising CO levels have been detected, the alarm will beep four times, pause for 5 seconds and repeat, while the power LED will turn off and the red CO LED will blink in sync with the 4 beeps (the CO LED will stay off if the source of the emergency is in another room detected by another interconnected alarm). Lastly, if there are any gas leaks detected, the alarm will beep once, pause for two seconds and repeat, while the Power Led will turn off and the blue GAS LED will blink in sync with the once-every–two-seconds beep (if the gas leaks are detected by another interconnected alarm, the GAS LED will not turn on). As a side note, the alarm should be tested weekly to ensure that it is working properly.

The main selling point of the Roost Smart Battery was its ability to connect to a home network and allow its users to access a proprietary interface to configure the notifications system. Since the Roost RSA-400 uses this battery, users gain access to this features become available, as well. While before, the battery had a limited functionality since it could not connect to a smart home environment, it has last year gained this ability thanks to IFTTT (if this then that) and this way, you’ll be able to use Roost to interact with other compatible devices.


The app user interface allows you to can add the Roost battery (which is the smart part of the alarm) to the app by tapping Add new and selecting Smart battery, choosing the location of the device, connecting to the local WiFi network and starting the setup process (which will guide you through preparing the battery by pulling the tab, locating the speaker on your phone, turning up the volume and let the phone and the battery ‘speak’ to each other to establish the connection). Next, the app will let you know if everything is fine with your device and, by selecting the menu, you can configure the Profile, Change the Password, set up Invitations (add other people, so they also receive notifications when the alarm gets triggered), read info About the device, Logout or Delete the Account. Also, by tapping on one of the installed alarms, you can check the Activity, view the Alarm Information, Change Location and Name, read Technical Information or Delete.
Note: Inside the package, you can find the Roost RSA-400 Smoke/Fire/CO/Natural Gas Alarm, the Roost Smart Battery, the Quick Connector and the User Manual.

5. First Alert 2-in-1 Z-Wave Smoke Detector & CO Alarm



First Alert is definitely one of the most experienced American company when it comes with developing safety products (has gathered more than 50 years of experience), but, with the rapid development of the IoT products and the emergence of full-fledged smart-homes (which get more and more complex over the years), First Alert had to adapt to the new market and create its own line of smart smoke and CO detectors to rival the popular Nest Protect. This way, it came into existence the First Alert 2-in-1 Smoke Detector & CO Alarm which has some new technologies implemented (such as compatibility with Z-Wave products).

The First Alert 2-in-1 is not necessarily the most complex from the American manufacturer, but it does have enough built-in features and an acceptable price, therefore, making it a proper smoke detector. Off course, it’s fine as long as it’s not trying to imitate the Nest Protect and yes, I’m fully aware of the existence of the Onelink Wi-Fi Smoke + Carbon Monoxide Alarm, but I purposely left it out of this article since I am waiting for the next generation to sort things out (it’s quite a mess right now).


I wouldn’t really call the Nest Protect an elegant device (since for me, it looked more like a wireless speaker), but there is no doubt that it did take a step into the right direction when it came to the aesthetic value of smoke detectors. The Onelink took inspiration and adopted a similar design, but the cheaper First Alert 2-in-1 Z-Wave remained humble, featuring an octagonal rugged plastic case, lacking the flashy circular LED light, but still being equipped with everything one would expect from a smoke and CO alarm. So, on the front of the device, there is a fairly large Test/Silence Weekly button, a Power/Smoke Alarm LED and a CO Alarm LED light. On the lateral side, towards the front, there is a sliding compartment where you can enter or replace the batteries (simple AA).

All around the case (and on the front), there are lots of cut-out areas to allow a proper air ventilation and for the smoke to enter the device and trigger the alarms. If we take into account the backplate, the First Alert 2-in-1 Z-Wave is thicker than your average smoke detectors, measuring 5.0 x 2.0 x 5.0 inches (but it’s fairly lightweight, weighing only 1.0lb). This particular model does not come as a hard wired detector, (the only way to power it remains through the use of batteries) and the only smoke/CO detectors from First Alert that can be connected to the home’s power source are the 120V AC Smoke & Carbon Monoxide alarm and the already mentioned OneLink detector.


In order to install the First Alert 2-in-1 Z-Wave detector, you need to take the mounting bracket and fix it to either the ceiling or the wall using the provided screws (don’t mount it in the corners of the room and keep a minimum of 5 feet from any cooking appliances, since the air currents carrying the cooking smoke could get to the smoke sensor, thus triggering unwanted alarms). Afterwards, attach the smoke & CO detector to the mounting bracket by twisting the device into place (depending on the spot where you want to install it, you may need to take additional steps to prevent any unauthorized removable – you can lock the battery compartment and/or the detector using the locking pins).

As you know, the smoke alarms use two types of sensors to detect any life-threatening emergencies: the ionization sensors to detect fast burning fires and the photoelectric sensors to detect fires in their early stages (smouldering fires). The ionization sensor uses a chamber filled with ionized air and, when smoke enters it, the sensor triggers the alarm. Because of its nature, the ionization sensor tends to be more sensitive at detecting small particles, therefore more often triggering false alarms. The First Alert 2-in-1 steered clear of the ionization sensor and only went for the photoelectric type. The photoelectric sensor is better suited at detecting larger particles (usually from smouldering fires, that don’t erupt immediately into flames) by using a light beam inside the detector which doesn’t directly hit the sensor, but will do so in case smoke enters the device and forces the light towards the sensor.


Besides the smoke detecting sensor, the First Alert 2-in-1 also has a Carbon Monoxide Electrochemical sensor which has the role of detecting any rising levels of CO inside the room and triggering the alarm when the concentration crosses the safety levels (there will be both visual and audible signals – up to 85dB at around 10 feet). If the sensor detects increasing levels of Carbon Monoxide, the CO LED will flash a red colour and the audible alarms will have the following pattern: four beeps, then pause, four beeps and then pause. Otherwise, if the sensor detects smoke in the room, the Power/Smoke LED will flash a red colour, while the audible alarm will beep three times, pause and again three beeps and pause. You can silence any of the alarms by pressing the Test/Silence button: if the smoke alarm has been silenced, then it will remain silent for about 15 minutes before reactivating if the smoke has not been cleared; if the CO alarm has been silenced, it will remain silent for up to 4 minutes before reactivating again if the CO levels haven’t decreased.


Now, let’s get to the smart part of this smoke/CO detector. There isn’t really a dedicated app for the First Alert Z-Wave, but it can be integrated into a smart home environment by using the Samsung SmartThings hub. The whole process is incredibly simple and it requires using the SmartThings app on either your mobile phone or on a tablet and having the First Alert device ready: start the app and afterwards, in My Home, tap Add a Thing and Connect Now; the app will now look for ‘Things’ and as it does so, slide the batteries into the device while holding the Test button (wait for the detector to beep and release the button). After it is powered on, the SmartThings app will detect the device (it will be called Z-Wave Smoke Alarm) and you can tap to configure it (give the detector a name and select the room where it will be mounted).

Note: The First Alert 2-in-1 works with most other smart home hubs from the market, but it is not compatible with WINK.
After finishing the process, you can access the device from the app (where you can see the percent of battery left, silence the alarm or checking the notifications) and you can pair the First Alert 2-in-1 with other smart devices from your network (for example, when the alarm gets triggered, you can configure the lights to turn on or activate any available fans).
Note: Inside the package, there is the First Alert 2-in-one Z-Wave smoke & CO detector, two AA batteries, two screws, two nuts and some documents, including a User Guide (the device gets a 7-year limited warranty).

6. First Alert SCO501CN-3ST Smoke Alarm Smoke Detector



The advent of the IoT (Internet of Things) has shown that there’s great potential for connecting all your home devices and creating a single large network to maintain and configure everything using a single hub (which is the heart of every smart home). But, while there are some futuristic advantages (your whole house can be controlled by a single phone app from anywhere in the world), there are also some disadvantages: while easier to configure, the smart devices tend to rely on more complex functions to properly operate, so they’re more prone to bugs and failures and, because of that, the warranty usually comes with fewer years than on the devices which lack any smart capabilities (these devices are also in continuous draft state since the technology still evolves at an unprecedented pace).

That’s why some people may feel more comfortable with the traditional smoke detector which has proven its value over the years, instead of going with the more expensive smart smoke alarms (such as Nest Protect, OneLink safe and Sound or Halo). One such product is the First Alert SCO501CN-3ST, a device which can detect both smoke and Carbon Monoxide, while also offering a 7-year limited warranty.


Even though this isn’t a smart (IoT) smoke detector, you still can inter-connect up to 16 First Alert alarms wirelessly and, since the SCO501CN-3ST also comes with a programmable talking alarm, it deserves a place in this article.
Some may argue that smoke detectors shouldn’t necessarily have an elegant exterior and that functionality is more important than the design. While it is true that a smoke detector should have its main focus on the reliability factor, it is also a device that will undoubtedly attract some attention since it will be either mounted on the wall or ceiling. So, aesthetics are important and it is nice to see that the newer smart detectors are better looking with each iteration and have taken advantage of different types of LEDs.

But, sometimes, a flashy design is overkill and a simple, non-intrusive case is the better choice (some don’t like a multitude of LEDs to shine from their ceiling). As you may have guessed, the First Alert SCO501CN-3ST indeed features a relatively simple white round case, on the front with a large Test/Silence Weekly button, as well as two LED indicators (CO and Smoke) and several cut-out areas in form of a leaf and underneath it, there’s the speaker. On the lateral side, you’ll be able to identify a small cover which, when removed, will reveal a dedicated space for inserting the two batteries.


The device is available as a battery-only model and, unlike the PRC710 which has a sealed battery, the First Alert SCO501CN-3ST allows you to change the batteries as soon as necessary (it requires 2 AA batteries – the negative aspect is that unlike the sealed batteries which can go up to 10 years which is usually the life expectancy of the smoke alarm, the removable type of batteries will last a lot less). The case of the SCO501CN-3ST is a bit more slimmer than the usual bulky smoke detectors, while maintaining an average diameter (it measures 5.0 x 5.0 x 2.0 inches), so, it may fit nicely even in the living room (although some may not appreciate the slight industrial look of the device).

The installation process of the SCO501CN-3ST involves choosing the right place in the room (keep at least 15 feet from any furnace or fuel burning heat sources, otherwise, it may trigger false alarms and also, it is advisable not to install the smoke detector near the corners of the room), attach the mounting plate to the ceiling or wall using the plastic screw anchors + screws (provided into the package) and later, simply rotate the device into place (lastly, you can test the SCO501CN-3ST by pressing the Weekly Testing button from the front side and this way, you’ll also be able to set the location – press and hold the button until you hear the suitable location and then release it and press and hold it again until you hear that the location has been saved).


The back panel has lots of info printed, partially covered by the removable base (an outer plastic shell) which allows the attachment with the bracket. In case the smoke & CO detector is located in a public place and you don’t want it to be removed by unauthorized personnel, the SCO501CN-3ST provides an optional locking feature (consists of a locking pin moulded in the mounting bracket).

Multiple SCO501CN-3ST can also be inter-connected wirelessly and to do so, take the second unit, insert the batteries and press the Test button (release it as you hear the device chirp); the power button will start flashing green for about 2 minutes and this is the sign that it is ready to be paired: now, press and hold the Test button on the first unit until the LED stops blinking on the second alarm – and, you’re done, you’ve successfully paired two First Alert smoke alarms.


Smoke detectors usually feature two types of sensors, an ionization-type sensor and a photoelectric one. The ionization sensor detects small particles which are usually caused by fast flaming fires (the device uses a small amount of radioactive material – Americium 241), while the photoelectric sensor detects larger particles which are generated from slow burning, smouldering fires (using a light beam which, by default, points away from the sensor, but will deviate its course towards it in event the smoke enters the device).

Some detectors use one type of sensors, while other use both, but the First Alert SCO501CN-3ST only uses the photoelectric sensor, so it is ideal for detecting smouldering fires (depending on the room, you may also need an ionization type of detector, but be aware that it is more prone to producing false alarms than the photoelectric type of sensor). Furthermore, the SCO501CN-3ST is also a Carbon Monoxide detector, so, by using an electrochemical sensor, it detects any increase in the CO levels and trigger the alarm in case the CO level rises towards dangerous levels.


In case the First Alert SCO501CN-3ST detects smoke in the room, the LED will flash a red colour in sync with the horn alarm (85dB) which will follow this pattern: three beeps, pause, three beeps and voice (Warning, evacuate smoke in *location*) and, in case the sensor detects high levels of CO, the LED will flash a red colour, while the horn will follow the four beeps, pause, four beeps, voice (Warning, evacuate carbon monoxide in *location*) pattern.

When either sensors trigger the alarm, you get the option of silencing it (by pressing the Test/Silence button for about 3 to 5 seconds) which will make the smoke alarm turn silent for about 15 minutes (it will activate again if the smoke levels are still higher than normal) and will make the CO alarm silent for 4 minutes (but the alarm will get triggered once again if the CO levels are still elevated).

7. First Alert P1010 Atom Micro Smoke Alarm



The new trend this year is to either ‘smarten up’ our regular ‘non-smart’ devices or to get rid of them entirely in favour of the new, improved IoT devices in order to interconnect everything in a smart home environment. The smart devices do offer a high degree of convenience and a lot more features that the regular devices, but there is a price to pay: you often trade simplicity for a more complex system.

In the case of the smoke detectors, many people have favourably exchanged their traditional smoke alarm systems for either the Nest Protect or other smart device from the competition, but a large percent of the population would still prefer not to deal with an app or any other unneeded configurations and thankfully, there are lots of regular smoke detectors on the market to choose from.
One of them is the First Alert P1010 Micro Smoke Alarm, which, while it has all the expected elements of the traditional smoke detector, it is rather unique from the design point of view (yes, I know, First Alert again, but, in truth, there are not that many reliable options on the market right now).


So, while the large majority of smoke alarms feature a flat round shape (that resembles a flush mount lighting), First Alert decided to go on a different route and it has managed to cram the sensors and other pieces of hardware inside a very small case. It is easy to see that the size is the main selling point of this device, which measures 1.8 inches in diameter and 1.8 inches in height (and it weighs 2.0 oz), so you could easily fit three of them in the palm of your hand.

The device itself resembles a salt or pepper dispenser, featuring a cylindrical case, with a soft round cap on the top (with a small hole in the middle) and a slightly larger base, the whole body being almost entirely covered by a white matte finish (does not retain fingerprints and the texture is similar to that of the ceiling), the only exception being in the middle of the smoke detector, where there’s a metallic part with lots of small holes (where the smoke enters to the sensing chamber).


Furthermore, besides the transparent Silence / Test button positioned ion the side, there aren’t any other elements to break the minimalist design continuity. At first glance, you’d be tempted to simply position the smoke detector on a shelf and not bothering installing it on the wall or ceiling, but since you want it to detect the smoke as fast as possible, you should mount it on the ceiling and a bit further from the corners of the room (it’s also ideal to keep it at least 15-feet away from a fuel burning heat source, so it won’t trigger those annoying false alarms). That being said, the installation process is simple and intuitive: all you have to do is remove the card from the bottom of the mounting bracket, attach the ring to the ceiling (or wall) using the fixing anchors (they’re provided inside the package, fortunately) and afterwards, simply rotate the alarm into place.

After the installation is done, make sure to test the alarm weekly to make sure it functions properly – the 3-Volt sealed lithium battery is advertised to offer up to 10 years of continuous protection for your home (you don’t need to change the battery during this time and, when it reaches its end of life, the alarm will provide an audible notice).
Note: Inside the package, you can find one First Alert P1010 unit, a mounting bracket and a User Manual.


The most popular types of sensors that are used to detect the smoke particles are the ionization sensors and the photoelectric sensors (some manufacturers have developed their own proprietary sensors to detect more than one type of fires, such as the case of the Nest Protect with its Split-Spectrum sensor). The ionization sensors are used to detect the small particles from fast burning fires, but because of their nature, they’re more prone to false alarms (these type of sensors are usually found built into older smoke detectors). The photoelectric sensors can detect larger particles, so it is a lot more useful for smouldering fires (those which have not yet erupted into flames), so they’re better for an early detection and are less likely to trigger false alarms.

The First Alert P1010 uses the aforementioned technology, so it has a beam of light inside a small chamber which does not directly hit the photoelectric sensor, but, the moment smoke particles enter the device (through the holes in the metallic section), the light gets diverted and it will immediately hit the sensor, thus sounding the alarm.
In case a fire is detected, you will be able to hear three beeps, pause, three beeps, pause and repeat, while the LED light will flash rapidly – the LED is located inside the Silence / Test button (the horn is loud, reaching up to 85 db, 10 feet away from the device – if you have a hearing impairment, it is advisable to have a look at smoke alarms with built-in strobes).


In order to silence it, simply press the Silence button but not until you are completely sure that there is either a false alarm or that there is no longer any danger inside the house.
Note: Unfortunately, the First Alert P1010 only comes as a single-station unit, so you won’t be able to interconnect it with other smoke alarms and it also lacks any type of WiFi or Bluetooth adapter in order to pair it with an app (if this is what you need there are some more expensive options, such as Nest Protect or more budget-friendly options, such as the First Alert 2-in-1 Z-Wave).


1. Which type of sensors are equipped on the smoke detectors?
Smoke detectors can have two types of sensors: ionization sensors, photoelectric sensors or both (usually called dual-sensors). The ionization sensor is used to sense flashing fires by detecting the small particles generated by these fast burning fires and triggering the alarm. The technology behind it involves using a radioactive isotope of americium (usually, it’s Americium 241) to ionize the air inside a chamber and, if the sensor detects any changes in the air, it triggers the alarm. The disadvantage of using such type of detectors is that they are more prone to false alarms (such as when you’re cooking or when there’s a large amount of steam).

The photoelectric sensor is more sensitive to larger particles which are specific to slow burning, smouldering fires (which could originate from a forgotten cigarette on the couch), but the sensor is not as sensitive to flaming fires. The way this type of detector works is that it uses a light source (can be infrared, ultraviolet or visible) which points away from the sensor, but, in the event of smoke entering the small chamber, the light particles will be scattered, therefore, some will hit the sensor and trigger the alarm. This type of technology is used a bit different in larger spaces, where the light beam is directed towards the sensor, but if the intensity of the light drops under a certain level due to smoke, the alarm will be triggered.

Ideally, a smoke detector will use both type of sensors to detect each type of fires, but, there are some development being made in the photoelectric field to also detect smaller particles from fast burning fires. This type of technology can be seen working on the Nest Protect second generation in the form of the Split-Spectrum Sensor, which has an additional 450nm wavelength of light to detect the smaller combustion particles generated by fast fires.

2. Does it also have a Carbon Monoxide Electrochemical sensor?
Of course, the more sensors, the better, but is it a good idea to have one detector for smoke and Carbon Monoxide or separate units? It depends on the brand trust and the cost. A single unit which has both type of smoke detecting sensors along with an electrochemical sensor is going to be cheaper, it’s going to be easier to install a single unit than multiple ones and maintenance is way easier. But, as they say, it may be a bad idea to put all the eggs in one basket, so, if you go the multiple units route, even if it’s a more costly solution, in case the smoke detector fails, you’ll still have a CO alarm (and vice-versa). If the 3-in-one detector fails, usually, all sensor will stop functioning.

3. Battery or Hard wired?
Here, the opinions are mixed. On one hand, the battery powered smoke detectors can be easily mounted pretty much everywhere in the room and are not affected in case of a power outage. But, on the other hand, the wired-only smoke detector gives you a sense of peace that you never have to replace the batteries and don’t have to worry that your device will fail to announce you when the batteries are depleted (you’d be surprised by the large number of people that have non-functioning battery-only smoke detectors).

Of course there’s a third variant which involves having a smoke detector hard wired to a 120V power source and also have a battery back-up in case of any power outage.

4. Does it have a Silence button?
This feature is a must-have on any type of smoke detectors since there are times when the alarm gets triggered by mistake and it’s always a pain to have to disconnect the device from its power source (a Silence button implemented on the device and/or on an app could save you a lot of headaches).

5. Can it interconnect with other smoke detectors?
If you have a larger home where you need more than one smoke detector, it is a good thing to be able to interconnect them into a single system, so when one alarm goes off, the other announce you as well, where is the emergency (some alarms allow you to interconnect them wirelessly, other through wires).

6. Can it be integrated into a smart home environment?
If you already have a smart home hub with lots of other devices that connect to each other to form a single network, wouldn’t it be a shame not to be able to control the smoke detectors through voice, app and create IFTTT rules for device interoperability? (Such as when the smoke alarm gets triggered, the thermostat and the stove are turned off, the doors will unlock and the emergency number is dialled, all automatically as part of the same system).

7. Is it suitable for people with special needs?
The usual smoke alarm has an audible alarm of up to 85dB in its vicinity, but, for some people that are either deaf or have any hearing impairment, this may not be enough. Therefore, some smoke alarm, besides having the usual set of sensors and features, can also come equipped with special strobe lights, bed shaker attachments and the audible alarm will use a lower frequency in order to alert the people from the household.


Now that we clarified what are the most important aspects of a smoke & CO detector and saw a small number of the most popular devices on the market, some people may still wonder if a smart smoke detector is better than a traditional one. As expected each has its advantages and its disadvantages. The main appeal of a traditional smoke detector is its simplicity and the low cost. You mount the device on the wall and go on with your life forgetting about its existence until it gets triggered by smoke or CO or if the battery needs replacing. That’s it.

A smart smoke & CO detector brings a lot more to the table, but the price is higher (more often double than that of a traditional device) and there is a lot more complexity, therefore more things that could go wrong. But, the advantages are many: you get to view the status of the battery through an app, silence the alarm remotely, get notified in case of an emergency, automatically call 911, interconnect with other smart devices through a smart home hub, use IFTTT rules and so on.

5 thoughts on “The best smoke detectors of 2019”

  1. You should revise the title of the article to something like the best smoke detectors based on someone opinion gained from reading marketing pieces. The vast majority of the devices your “recommending’ don’t even carry UL listings and your bias towards wireless shows that your focus is on cool technology rather than detection capabilities. All of that rolled up by a recommendation of the Atom. Clearly the writer has never tested or employed these devices in the real world. Article is junk.

    • Hi! Sorry that the article didn’t meet your expectations. It’s true, not all smoke detectors are UL listed, some are ETL listed and of course there’s a bias towards the wireless connection … we’re in 2019. If you have a better list or think I should focus towards a specific product, I am open to any suggestions.

      • I am not sure if being in 2019 has any connection to the effectiveness of a device in an emergency situation. The point is you’re focused on cool tech with an apparent lack of testing focused on response time which I would assume is a critical factor when determining if a device is best. Especially a life safety device. But if I have to escape a fire I will keep in mind that it is 2019 and happy that I choose a device that is really cool tech not knowing how it performs when needed. As to the question “do I have a better list” I would simply state if I was going to post a best of 2019 article I would invest the minimum effort (lacking here) to develop one that focused on functionality over cool 2019 tech…

        • I didn’t know that people were so much against the smart features added to the smoke detectors, but I get that a no frills device would probably feel safer. I usually update my articles, so I will update this one as well as soon as possible to add the response time for each smoke detector.

  2. When selecting the best smoke detector you just need to depend on the popular brands, but during installation, you need to take help from professional Electricians Chester Springs PA ( because they will test large alarm systems and this is the best way to ensure that your smoke detector will sound during a fire.

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