10 Best Carbon Monoxide Detectors 2026 in the United States

The First Alert BRK SC9120B-3 is a reliable choice for anyone looking to protect their home from both smoke and carbon monoxide hazards. It uses two types of sensors: an electrochemical sensor for detecting carbon monoxide, and an ionization sensor that reacts quickly to fast-burning fires. This dual-sensor approach enhances safety by covering different types of fire and gas risks.

One of the standout features is its hardwired design combined with a battery backup. This means the alarms will keep working even during a power outage, giving you peace of mind around the clock. The unit’s alert system includes an 85-decibel siren—loud enough to wake most people—and indicator lights that clearly show what kind of danger is detected.

Installation is straightforward thanks to universal mounting brackets and a tamper-resistant design, making it suitable for use in various locations around the home. The detector can also be interconnected with other compatible First Alert alarms, so if one unit senses danger, all alarms will sound, improving safety. The display is simple, with indicator lights and a single test/silence button that makes it easy to check the system or temporarily quiet a false alarm. It also comes with a dust cover to help keep the sensor clean. This 3-pack is ideal for homeowners who want dependable, long-term monitoring of both smoke and carbon monoxide with backup power, especially in larger homes or multiple rooms. Note that installation requires wiring, which might need professional help if you’re not comfortable with electrical work.

The First Alert SMCO210 is a combination smoke and carbon monoxide alarm designed to provide reliable protection for your home. It uses a photoelectric sensor, which is generally good at detecting smoldering fires and helps reduce false alarms from cooking fumes. The unit is battery powered with a sealed 10-year battery, meaning you won't have to worry about changing batteries or dealing with annoying low-battery chirps during its lifetime. This is a big convenience for busy households.

The slim profile design is sleek and less bulky compared to standard alarms, making it less noticeable on your ceiling or wall. Installation is straightforward, suitable for various indoor locations like bedrooms, hallways, or living areas. It also features an end-of-life warning alert, so you know when it’s time to replace the entire unit after 10 years.

This model doesn’t have a digital display that shows carbon monoxide levels, which some users might find helpful for peace of mind. Being battery powered means you will need to eventually replace the whole alarm after the battery life ends. Although it lacks advanced features like Wi-Fi connectivity or app alerts, its focus on precision detection and long-lasting battery makes it a solid choice for anyone looking for dependable 2-in-1 protection without extra complexity.

The First Alert Combination Smoke & Carbon Monoxide Alarm (SMICO100-AC) is a solid choice for home safety, combining smoke and CO detection in one device. It uses an ionization sensor, which is good at detecting fast-flaming fires but may be less sensitive to slow, smoldering fires compared to other sensor types. This alarm is powered by a corded electric source with a battery backup, meaning it stays active even during power outages, which adds an important layer of reliability.

Installation is made easier with a Quick Connect Plug, allowing for straightforward setup without rewiring, and it supports early warning interconnect, so if one alarm goes off, all linked alarms sound as well—great for larger homes. The unit includes a test/silence button for easy maintenance and nuisance alarm reduction, especially around cooking areas. Its compact size and white color help it blend into most home environments.

This alarm requires a 9V battery, which is included but will need replacing over time. The ionization sensor, while effective, might not be the best option if you want the most sensitive detection of all types of fires. For someone seeking dependable dual-function protection with easy installation and clear alerts, this First Alert model is a very practical and well-regarded choice.