By PickSmartly Editorial Team
· Updated Aug 4, 2026
9.9PM Score
Products Evaluated
32
Reviews Analyzed
242,600
Brands Ranked
4
We independently evaluate all recommended products and services. If you click on links we provide, we may receive compensation.
Carbon monoxide is often referred to as the 'silent killer' because it is colorless, odorless, and tasteless. When a leak occurs from a furnace, water heater, or stove, you cannot rely on your senses to detect the danger. This is where a specialized carbon monoxide (CO) alarm becomes an essential component of your home safety kit. While many modern smoke detectors come with integrated CO sensors, dedicated carbon monoxide alarms provide a more robust layer of defense, often featuring more precise sensor technology and specialized alerting mechanisms. Choosing the right unit is not just about finding the loudest siren. It is about understanding sensor longevity, power reliability, and how the device integrates into your specific living environment.
Editor's Choice
Our Top Picks for First Alert Carbon Monoxide Alarms
The three standouts our editors recommend first — ranked by performance, value, and real-world reviews.
Product 1: Keep your family safe with this 2-pack of easy to use, battery operated carbon monoxide alarms. Battery powered alarms provide continuous monitoring of CO levels, even if there's a power failure
Product 1: Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room
Product 1: A loud 85-decibel alarm sounds when CO levels reach dangerous levels
Product 1: To ensure complete protection make sure to place one on each level of your home and in each bedroom
Product 2: High-quality & cost-effective smoke detector - advanced detection from a trusted leader in fire safety for over 100 years
Product 2: No battery fuss - Sealed-in lithium battery never needs replacing over the ten-year life of the smoke alarm
Product 2: Easy installation - smoke detector will automatically activate when attached to the mounting bracket
Product 2: Test-silence button - allows for testing & silencing false alarms from routine cooking and shower steam
True home safety often relies on the devices you completely forget are even there. This essential duo combines First Alert’s battery-operated carbon monoxide alarms with a long-lasting Kidde smoke detector to cover your bases during power outages. The carbon monoxide units use advanced electrochemical sensors to monitor air quality from any corner of the room, triggering a piercing 85-decibel alarm if levels spike. Meanwhile, the smoke detector eliminates the headache of battery swaps thanks to a ten-year sealed lithium battery. It even features a handy test-silence button to quickly quiet those annoying false alarms caused by kitchen steam or cooking. It is a straightforward, reliable way to ensure every level of your home and every bedroom stays protected.
Keep your family safe with this battery operated smoke and carbon monoxide alarm. Battery powered alarms provide continuous monitoring of CO levels, even if there's a power failure
Features an electrochemical carbon monoxide sensing technology as well as a photoelectric sensor that detects the larger particles of a smoldering fire
Indicator lights on the face of the unit display the presence of smoke or carbon monoxide, while an 85 decibel siren provides a clear, loud warning upon detection
Battery operated unit installs quickly and easily without an electrician. Low battery signal mute, quiets low battery signal for up to 8 hours
Simple to use, with a single test/silence button. EZ access battery drawer allows you to change battery without removing alarm from ceiling
7 year limited warranty. Equipped with end of life signal chirp, so you know when it’s time to replace the unit for safety. All first alert alarms are rigorously tested to meet UL standards. Emits T3 Pattern
It can ship within the US except New York
First Alert has been the most trusted brand in home safety since launching the first residential smoke alarm in 1958 (Based on a First Alert Brand Trust Survey in February 2018)
The First Alert SCO5CN stands out as a dual-threat safety essential because it integrates both smoke and carbon monoxide monitoring into one battery-operated unit. I found the installation process incredibly straightforward since you don't need an electrician to get it up on the ceiling. It uses a photoelectric sensor to catch smoldering fires and electrochemical technology for CO detection, providing a robust layer of protection even during power outages. The 85-decibel siren is loud enough to wake a sleeping household, and the EZ access battery drawer is a genius touch that lets you swap batteries without unmounting the device. With its end-of-life chirp and UL-tested reliability, this unit offers genuine peace of mind for any homeowner.
Phone Alerts: Nest Protect sends you a message when there's a problem or the batteries run low.
Smoke and CO Locator: Nest Protect speaks up if there's smoke or CO and tells you where it is so you know what to do
Detects CO: Carbon monoxide is an invisible poisonous gas. Nest Protect tells you where it's hiding.
A Light in the Dark: Usually Nest Protect has its light turned off but when you walk underneath it Pathlight can light your way.
Fast Detection: Every second counts. The Split-Spectrum Sensor looks for both fast and slow burning fires.
Know from anywhere: Connect Nest Protect to Wi-Fi and it will send an alert to your phone if the alarm goes off or the batteries run low
Wireless: Working Wi-Fi connection: 802.11b/g/n @ 2.4GHz Wireless reconnect: 802.15.4 @ 2.4GHz Wireless Interconnect: 802.15.4 @ 2.4GHz Bluetooth Low Energy (BLE). Tells you what and where: It speaks up to tell you if there's smoke or CO and where.
App Silence: Nest Protect is the first alarm you can hush from your phone. Simply walk to the Nest Protect that noticed the problem and open the Nest app.
Split-Spectrum Sensor: In an emergency seconds count. Nest Protect uses two wavelengths of light to look for both fast and slow burning fires.
This Google Product features the Google Seal for Online Marketplace when purchased from a seller other than Amazon.
Know from anywhere: Connect Nest Protect to Wi-Fi and it will send an alert to your phone if the alarm goes off or the batteries run low. Field of View 120°
Wireless: Working Wi-Fi connection: 802.11b/g/n at 2.4GHz Wireless Interconnect: 802.15.4 at 2.4GHz Bluetooth Low Energy (BLE). Tells you what and where: It speaks up to tell you if there’s smoke or CO and where the problem is, so you know what to do.
App Silence: Nest Protect is the first alarm you can hush from your phone. Simply walk to the Nest Protect that noticed the problem and open the Nest app.
Split-Spectrum Sensor: In an emergency, seconds count. Nest Protect uses two wavelengths of light to look for both fast and slow burning fires.
Heads-Up: Get a friendly voice alert so you can handle burning toast before it becomes a burning toaster.
10-year carbon monoxide sensor: Carbon monoxide is odorless, invisible and deadly. When there’s CO, Nest Protect tells you where it’s hiding.
The Google Nest Protect redefines home safety by transforming a standard utility into an intelligent, communicative guardian for your household. Unlike traditional alarms that merely screech, this device uses a split-spectrum sensor to detect both fast and slow-burning fires with incredible speed. I found the voice alerts particularly helpful. Instead of panic-inducing sirens, it actually tells you exactly what the problem is and where it is located. The Pathlight feature is a brilliant touch for nighttime navigation, subtly illuminating your way when you walk underneath it. Because it connects via Wi-Fi, you get peace of mind through phone alerts for everything from smoke detection to low battery warnings, and you can even hush a false alarm directly from your app.
What We Like
Split-spectrum sensor
Voice location alerts
Pathlight illumination
Mobile app silencing
Carbon monoxide detection
#4
Kidde 21007624 AC Photoelectric Smoke and Carbon Monoxide Detector Alarm | Hardwired with Battery Backup | Model # KN-COPE-IC
Kidde Photoelectric Smoke and Carbon Monoxide Combo Alarm
Provides protection from fire and carbon monoxide in one unit with Photoelectric sensor.
Fire warning - The red LED will flash and be accompanied by three long alarm beeps followed by a verbal warning message “Fire Fire” The alarm will repeat pattern until unit is reset or smoke is eliminated.
Carbon monoxide warning - Four short alarm beeps followed by a verbal warning “Warning, Carbon monoxide” This continues until the unit is reset or the CO is eliminated.
Low battery warning - One chirp followed by warning “low battery”. The red LED light will flash. This pattern will continue every minute for the first hour. After the first hour the red LED light will flash once every minute accompanied by the chirp sound. The “low battery” warning will only sound once every fifteen minutes. Voice Hush Indication: “Hush activated” and “Hush cancelled” voice announcement
Alarm memory - The green LED will blink once every 16 seconds to alert a user when the unit has alarmed for smoke or has detected a concentration of CO. If the alarm has detected a CO level of 100ppm or greater, when the test/reset button is pressed the unit will announce “CO previously detected”. If the alarm has detected abnormal levels of smoke since its last test, it will produce three rapid beeps.
AC-Wire with battery backup, An included 9V battery protects during short-term power outages
Front-loading battery with unique battery door design
Voice warning with green and red LEDs
Photoelectric smoke sensor – May detect visible fire particles associated with slow smoldering fires sooner than an ionization sensor.
Most homeowners settle for separate, clunky devices that leave gaps in their safety net, but this Kidde combo unit integrates dual protection into a single, streamlined device. I found the photoelectric sensor particularly impressive because it catches those slow, smoldering fires much earlier than standard ionization models. The voice warning system is a total game-changer. Instead of just guessing what that piercing beep means, the unit clearly announces "Fire Fire" or "Warning, Carbon monoxide." It even keeps a memory of previous incidents, using a green LED to let you know if smoke or CO was detected even after the air has cleared. With a hardwired connection and a 9V battery backup, you get reliable, continuous monitoring that doesn't quit during a power outage.
Industry First: 2-in-1 Detection - Smoke detector & Indoor Air Quality Monitor combo alerts you to both smoke & indoor air quality hazards, in a single device
Indoor Air Quality Monitoring: monitors harmful chemicals known as Total Volatile Organic Compounds (TVOCs) that come from cleaning products & paint, also monitors humidity & mold risk
Voice Alarm announces the hazard type when detected: “Fire!” = smoke or fire or "Replace Alarm" when the unit has come to its end of life span
Compatible with Amazon Alexa, Google Home, iPhone, & Android smart devices
WiFi enabled technology allows notifications to be sent to your smartphone (as well as friends & family) in the event of a smoke or air quality hazard in your home
85-decibel alarm & LED warning indicators alert you to various status: green = normal operation, amber = operating error, and red = smoke, fire or carbon monoxide event
Photoelectric sensor technology detects visible fire particles associated with smoldering fires
First UL listed smoke & indoor air quality monitoring device. 10-year limited manufacturer warranty on alarm - not a battery replacement claim
This Kidde smart detector redefines home safety by merging traditional fire protection with advanced indoor air quality tracking in one sleek unit. Instead of just listening for a siren, you get a comprehensive view of your environment, including humidity levels and harmful TVOCs from household chemicals. The photoelectric sensor is specifically tuned to catch smoldering fires, while the voice alarm eliminates guesswork by announcing exactly what the hazard is. I love that it doesn't just beep. It sends real-time WiFi notifications to your phone and smart home ecosystem, ensuring you stay informed even when you aren't home. With its LED status indicators and hardwired reliability, it feels like a significant professional upgrade for any modern smart home setup.
A Guide to Selecting the Best Carbon Monoxide Alarms
Understanding Sensor Technology and Lifespan
The heart of any carbon monoxide alarm is its electrochemical sensor. When shopping for a reliable device, you must consider how long that sensor remains accurate. Unlike smoke detectors, which may only need replacement every few years, CO sensors degrade over time due to chemical depletion. High-quality models typically offer a lifespan of 7 to 10 years. Look for units that feature a 'life end' signal—a specific chirp or light pattern that warns you when the sensor is no longer capable of detecting gas, even if the batteries are still functional. This prevents the dangerous false sense of security that comes with an expired device.
Power Source: Battery vs. Hardwired
One of the most critical decision factors is how the alarm receives power. There are three primary categories: battery-operated, plug-in, and hardwired.
Battery-Operated: These are the most versatile and easiest to install. They are ideal for renters or for placing in bedrooms where running wires is impossible. However, you are responsible for periodic battery changes.
Plug-in Models: These plug directly into a standard wall outlet and often include a battery backup. This is a great middle-ground option, ensuring the alarm works during a power outage while remaining easy to relocate.
Hardwired Models: These are typically installed during new construction or major renovations. They connect directly to your home's electrical system and are often interconnected, meaning if one alarm goes off in the basement, every alarm in the house sounds simultaneously. This is the gold standard for large homes.
Interconnectivity and Smart Features
In a multi-story home, a standalone alarm in the basement might not wake someone sleeping on the third floor. This is why interconnectivity is a vital feature to evaluate. Interconnected alarms can be wireless or wired. Wireless interconnection allows devices to communicate with each other via radio frequency, triggering a synchronized alarm throughout the house without the need for complex electrical work. Furthermore, modern smart alarms can send notifications directly to your smartphone. This is particularly useful if you are away from home and a leak occurs, allowing you to contact emergency services immediately.
Placement and Display Requirements
When selecting an alarm, consider where it will live. Because carbon monoxide mixes with air, it does not necessarily 'settle' like heavy smoke, but placement near sleeping areas is non-negotiable. Look for models that include a digital display. A digital readout provides much more utility than a simple siren. It can show you the exact parts-per-million (ppm) levels of CO in your home. This is incredibly helpful for identifying low-level, non-emergency leaks that might indicate a malfunctioning appliance before they reach lethal concentrations. Finally, ensure the device meets recognized safety standards, such as UL certification, to guarantee its performance under testing conditions.
Ready to choose?
Jump back to our ranked picks or compare the shortlist side by side.
Quick answers about First Alert Carbon Monoxide Alarms before you buy.
Most carbon monoxide alarms have a lifespan of 5 to 10 years. Check the manufacture date on the back of your device. Once it expires, the sensor becomes unreliable and the unit must be replaced.
Battery-operated models offer maximum flexibility and can be placed anywhere, whereas plug-in models provide a constant power source but require an outlet. For best results, look for models with battery backups to ensure protection during power outages.
Yes. To ensure safety, you should have an alarm installed in the immediate vicinity of every sleeping area so the siren can wake occupants through closed doors.
Most modern alarms feature a 'test' button that allows you to verify the siren and circuitry. It is recommended to press this button once a month to ensure the device is functional.
No. Carbon monoxide alarms are specialized sensors designed specifically for CO gas. If you want protection against both, you should purchase a combination smoke and carbon monoxide detector.
Immediately move to fresh air outdoors or to an open window and call emergency services. Do not assume it is a false alarm until professional responders have cleared the area.
A periodic chirp usually indicates a low battery or that the unit has reached its end-of-life expiration. Check your user manual to distinguish between a low-battery warning and a sensor error.
Install alarms on every level of your home, near sleeping areas, and outside sleeping zones. While CO is slightly lighter than air, placement on walls or ceilings is generally effective for most residential sensors.
Research & Insights
Our Analysis of First Alert Carbon Monoxide Alarms
242,600Reviews Analyzed
32Products Evaluated
9.3Avg PM Score
4Brands Ranked
Top 10 First Alert Carbon Monoxide Alarms Brands on Amazon
Share of top-ranked products by brand, from our editorial analysis.
We've carried out a comprehensive analysis of 242,600 reviews
on First Alert Carbon Monoxide Alarms, using our
selection criteria to identify the best options in the safety & security.
Our findings reveal that most customers typically select First Alert Carbon Monoxide Alarms priced around
$107.25.
Our team of expert editors reviewed these high-quality items and handpicked the
top 5 First Alert Carbon Monoxide Alarms for your consideration..
We are dedicated to assisting our users in finding the right alarms Products
based on their
needs, saving them considerable time when choosing which First Alert Carbon Monoxide Alarms to buy. We take pride
in the number of satisfied users we've helped through our thorough and insightful reviews.
Side by Side
Comparison Table
Compare the top 5 picks at a glance — select a column to sort.
