First Alert Carbon Monoxide Alarms & Detectors

The CO710 is the best overall choice for most households. Its sealed 10-year lithium battery eliminates annual replacements; the digital display shows real-time CO PPM and room temperature; and the 10-year warranty matches the alarm's full service life. It's freestanding — no mounting needed, renter-friendly. If zero battery maintenance and a display aren't priorities, the CO606 (plug-in + 9V backup) delivers code-compliant protection at the lowest plug-in cost.

NFPA 720 requires a CO alarm on each level of the home (including basements) and within 10 feet of each sleeping area. A two-story, three-bedroom home typically needs a minimum of four alarms: one per bedroom and one per additional floor. Many states have adopted NFPA 720 or similar requirements into residential code; check your local building or fire code for the specific requirement in your jurisdiction. If you have an attached garage, a CO alarm near the interior garage door is advisable even if not code-required — CO from an idling vehicle can migrate into living spaces within minutes.

UL 2034 is the residential CO alarm standard published by Underwriters Laboratories. It defines the CO concentration levels and time durations at which an alarm must sound — for example, the alarm must activate at 70 PPM after 60–240 minutes, at 150 PPM after 10–50 minutes, and at 400 PPM within 4–15 minutes. Every model in this collection is UL 2034 listed. Most state residential CO alarm codes require UL 2034 listing; non-listed alarms do not meet code regardless of stated function. All nine First Alert models in this collection satisfy this requirement.

In residential use, the terms are used interchangeably. All nine models in this collection are alarms — they detect CO and respond with an 85 dB audible signal when threshold levels are reached. In professional settings, "CO detector" sometimes refers to a monitoring device used for continuous measurement and data logging without a built-in audible alarm. For homes, any UL 2034 listed unit with an audible alarm meets the definition of a CO alarm under residential codes.

Unlike smoke, CO is slightly lighter than air but distributes nearly evenly throughout a room — high-wall or ceiling mounting is not required. First Alert recommends placing CO alarms at least 5 feet from the floor to avoid interference from ground-level drafts. NFPA 720 permits placement at any height in a room. The most important placement rule is distance from sleeping areas: within 10 feet of each bedroom door. CO alarms should never be placed directly adjacent to fuel-burning appliances, inside bathrooms, or in areas of high humidity or extreme temperature.

The electrochemical CO sensor in most First Alert residential alarms has a rated service life of 5–7 years. Warranty terms reflect this: the CO400 and GCO1 carry 5-year warranties; most other models in this collection carry 7-year warranties; the CO710 has a 10-year warranty matching its sealed battery life. When the end-of-life alarm activates, replace the unit — do not silence and continue using it. An aging electrochemical sensor may fail to detect CO reliably even though the audible circuitry continues to function.

If your CO alarm activates: (1) Do not ignore it or assume it is a false alarm. (2) Immediately move all occupants and pets outside to fresh air. (3) Call 911 or your local emergency number from outside. (4) Do not re-enter the building until emergency responders have investigated and cleared it. (5) If a CO source is identified (a running generator indoors, a malfunctioning furnace), do not operate it again until it has been inspected and repaired by a licensed professional. CO is colorless and odorless — there is no safe way to verify an alarm is false without proper equipment.

Battery-powered First Alert CO alarms (CO710, CO410, CO400) can be used in RVs where they are placed in stable locations away from heat sources, cooking appliances, and high-vibration areas. They are not specifically certified for marine use. For boats and marine applications, look for CO alarms carrying UL 2034 plus UL 1524 marine listing. For RVs, some states and RV manufacturers specify alarm requirements — check applicable codes before installation.

Yes — they are different sensors detecting different hazards. CO alarms detect colorless, odorless carbon monoxide gas from combustion sources. Smoke alarms detect particles from burning. A CO alarm will not detect smoke, and a smoke alarm will not detect CO. Both are required by residential codes in most states. Combination smoke/CO alarms exist, but the nine models in this First Alert CO-only collection are dedicated CO alarms optimized for CO detection — if you want combination units, see the combination alarm category.

A single chirp every 30–60 seconds is almost always a low-battery signal, not a CO alert. Replace the battery and the chirping should stop. A series of 4 chirps in a pattern (distinct from the continuous alarm tone) is the CO alarm — take this seriously and evacuate. A chirp pattern of 5 beeps every minute indicates the end-of-life signal — replace the entire unit. Never remove the battery to stop chirping without first identifying the chirp pattern: a low-battery chirp is a maintenance reminder, but the CO alarm and end-of-life chirp both require immediate action.