(2021 Update) 8 Best Carbon Monoxide and Gas Alarms

Carbon monoxide and gas leaks kill many people all over the world every year. According to The Centers for Disease Control and Prevention, over 400 people die from carbon monoxide poisoning in the US every year. Natural gas accidents account for an average of 17 fatalities per year. Although this number may seem small, natural gas accidents result in much property damage and severely impact the environment over a long period.

Carbon monoxide is an invisible, odorless gas that can leak from appliances like heater, gas stove or appliances that use fossil fuels like coal and oil. Many people do not know that they are suffering from CO poisoning until it is too late. Carbon monoxide detectors are powerful SOS alarms that can detect the presence of this gas. It is nearly impossible to detect carbon monoxide without a CO detector. As recommended by The Consumer Product Safety Commission, every home should have at least one CO alarm with an audible warning siren installed near sleeping areas.

The UL 2034 standard will only allow the detector to sound the alarm under the following conditions:

  • 30 ppm for up to 30 days.
  • 70 ppm for up to 4 hours.
  • 150 ppm for up to 50 minutes.
  • 400 ppm for up to 15 minutes.

Gas leak detectors are used by engineers and service personnel to identify and pinpoint the source of combustible gas leaks that occur in commercial and residential areas. These detectors use semiconductor sensors that can detect a variety of combustible and toxic gases like ethylene oxide, benzene, gasoline, jet fuel, industrial solvents, lacquer, alcohol, acetone, hydrogen sulfide, refrigerants, propane, and many others.

Read on to find out the best carbon monoxide and gas alarms that are available on the market today.

Best Carbon Monoxide Alarms

1. First Alert SCO5CN

First Alert SCO5CN

The First Alert SCO5CN is a battery-powered alarm that can continually monitor carbon monoxide levels even in the event of a power failure. It has dual sensors to detect both smoke and carbon monoxide. It has a photoelectric sensor that can detect the larger particles in a smoldering fire as well as an electrochemical Carbon Monoxide sensor that can detect CO leaks from multiple sources like blocked chimneys, generators running inside the house and faulty fuel-burning appliances. The face of the unit has indicator lights that signal the presence of carbon monoxide or smoke. The alarm rings at a volume of 85 dB upon detection. Both the alarm and indicator light signal differently for gas and carbon monoxide.

Running on just two AA batteries, it is possible to set up this alarm without any help from an electrician. The alarm has a low battery warning signal that rings continuously once the battery charge has reached below a certain level. It is possible to mute the low battery signal for up to 8 hours. The alarm is simple to operate with just one test/silence button to test the unit, silence a false alarm or mute a low battery warning. You do not need to remove the alarm from the ceiling to change the battery as the battery compartment can be accessed easily.

The alarm is backed by 7 years limited warranty. The alarm is also equipped to notify you with three chirps when it reaches the end of its lifespan so you can replace it in time for safety. All alarms from First Alert are rigorously tested to meet Underwriters Laboratories (UL) standards.

You can choose if you want to buy a single unit or a pack of 3 or 4 units. Included with the alarm are two AA batteries and a user’s manual.

You can also opt for a more expensive model which has voice and location alert feature. The voice alert notifies you of whether it is a smoke or CO danger and also provides the location of the room where it was detected so that you can plan the best escape route. Free Amazon tech support is included with this product.


  • Loud 85-decibel alarm.
  • Indicator lights.
  • Battery-powered so it can run during power failures too.
  • Low battery warning signal and end of lifespan notification.
  • Dual sensors for smoke and carbon monoxide detection.
  • Seven-year limited warranty.
  • Voice location model tells you of the location so you can plan the best escape route.
  • Easy to install.
  • Easy to operate with just one button to test, silence false alarms or mute low battery. warning signals.


  • Many users have received faulty units. The alarm gets triggered for no reason. You should clean the alarm once a month to avoid this problem. If it persists, you can contact the manufacturer to get it replaced. Customer service is good but can still be frustrating to be woken up in the middle of the night for no reason.

2. Kidde KN-COPP-3 Nighthawk Carbon Monoxide Alarm

Kidde KN-COPP-3 Nighthawk Carbon Monoxide Alarm

Kidde is globally known for fire detection and suppression equipment and systems starting from portable fire extinguishers to flame detection and explosion suppression systems.

The Kidde KN-COPP-3 Nighthawk has a battery backup and a digital display. It is an Underwriters Laboratories (UL) listed, A/C powered plug-in Carbon Monoxide alarm. It utilizes sophisticated sensor technology and electronic components for CO detection and warning. It can be plugged into a standard A/C outlet. A 9-volt battery provides backup during power outages.

This alarm is unique because of its digital display. The display shows levels of Carbon Monoxide that the sensors have detected from 30 to 999 pm. It updates every 15 seconds to indicate any changes or alarming trends. It also shows the peak CO levels recorded since it was last reset or unplugged. If unhealthy CO levels are reached, the alarm will emit four quick beats every five seconds until the reset button is pressed or the CO levels have come down.

The lower right-hand corner of the display has a blinking dot to denote that it’s functioning normally so you need not worry about whether it is working or not. You can verify if the horn and electric circuitry are working properly by pressing the test/reset button at any time.

The alarm has a low profile design that is suitable for any room in your home. It can be plugged into a standard A/C outlet. Even if the power adapter is plugged in horizontally, the wire that attaches to the back of the unit can be rotated so the unit always remains upright. This allows you to read the display easily. Also included with the alarm is a 6-foot cord extension so you can plug it into a wall outlet and place it on a shelf or table. For maximum protection, it is best to place an alarm on every level of your home. The fact that you can unplug the device and walk around your home to detect any change in readings can come in handy.

The KN-COPP-3 Nighthawk is backed by a five-year limited warranty and has a seven-year lifespan. Included in the box are a Kidde KN-COPP-3 Nighthawk CO Alarm, mounting hardware, 9-volt battery, and an installation guide. When it is time to replace the alarm, it will beep two times every 30 seconds. Free Amazon tech support is included with this product. You can contact Amazon if you are facing difficulty while replacing the battery.

We would caution you to buy from Kidde, the original manufacturer instead of a third party seller as some of them are selling really old units. Be sure to check the manufacturing date on the back of the unit when you get the product delivered.


  • The display shows CO levels, updated every 15 seconds.
  • The test button can be used to verify if the alarm is working properly.
  • Blinking light on the lower right hand of the display shows that the sensors are functioning.
  • 9-volt battery backup.
  • 6-foot cord extension is included so you have more options when installing the alarm.


  • Not a con but many old units are being sold by third parties on Amazon that you should be wary of. The link given here takes you to the original manufacturer’s product.
  • Some faulty units eat up the battery every few days even when it is plugged in. You should check if the AC connection is working properly, If there is no issue with your connection, you can get the unit replaced from Amazon.

3. First Alert SCO501CN-3ST

First Alert SCO501CN-3ST

The First Alert SCO501CN 3ST Combination Smoke and Carbon Monoxide Alarm can detect both carbon monoxide and smoke in a single device. You can connect the alarm with up to 18 other First Alert alarms to create a wireless safety network in your home. When one alarm goes off, it sends out a wireless signal to all the alarms connected to it and each alarm booms out an 85 dB siren. The alarm uses a photoelectric sensor to reduce false alarms from shower steam or cooking smoke but remains sensitive to real danger. Its electrochemical carbon monoxide sensor can detect leaks from multiple sources like generators and faulty fuel-burning appliances.

The SCO501CN 3ST uses a voice alarm with 11 programmable locations to indicate where and what the danger is along with a loud 85-decibel siren. The programmable locations are Living Room, Basement, Family Room, Kitchen, Office, Dining Room, Child’s Bedroom, Hallway, Master Bedroom, Guest Bedroom, and no location.

It is also quite simple to operate. It has a single button that can be used to silence a false alarm or test the unit. The battery can be replaced easily without the need to remove the alarm from the ceiling.

There is a latching mode feature for this alarm. If you have created a wireless network of alarms, exposure to smoke for an alarm in the network will activate the Alarm Latch mode for that particular alarm. After the smoke has dropped below danger levels, the red LED light for smoke will begin flashing on for 2 seconds and off for 2 seconds. This will continue for 15 minutes so that you have enough time to determine which unit initiated the alarm.

Two AA batteries and a user manual are included in the box. You should note that multiple units don’t need to be the same model to get hooked up to a wireless network. Other alarms from First Alert can be connected too. Also, First Alert advertises that they provide 7 years warranty but in practice, they are not providing a warranty beyond 5 years.


  • It can link up to 11 other alarms to create a wireless network.
  • 85 dB Siren.
  • Voice alarm with 11 programmable locations.
  • Easy to operate with a single test/silence button.
  • Dual sensors for smoke and carbon monoxide detection.


  • The manufacturer should be more upfront about the level of maintenance required. Many users are not aware that the front vent needs to be vacuumed for 15 seconds every month. This lack of information leads to too many false alarms creating a very disturbing experience, especially if there are old people or small children at home.
  • The silence button may not work at times after the alarm is triggered.

4. Kidde KN-COPP-B-LPM


The Kidde KN-COPP-B-LPM Carbon Monoxide Alarm has been carefully designed and tested to detect carbon monoxide concentration in a residential environment. It uses an electrochemical sensor and is battery-powered.

Like the KN-COPP-3, this model also has a digital display that updates its CO reading in PPM (parts per million) every 15 seconds. This is very helpful in catching alarming trends, providing an advanced level of protection. It is a key feature that we have come to expect in a Kidde product. You can either attach it to a wall or place it on a counter or nightstand because of its free-standing design.

The device works by measuring the exposure to Carbon monoxide over some time. The 85 dB alarm will get triggered at 10 feet in the following circumstances:

  • When it detects 70 ppm of CO for 60 to 240 minutes consistently.
  • When it detects 150 ppm of CO for 10 to 50 minutes consistently.
  • When it detects 400 ppm of CO for 4 to 15 minutes consistently.

The front of the alarm has a Test/Reset button that can be used to test the unit’s horn and electronic circuitry and also resets the alarm when it gets triggered. There are two LED lights- the green LED flashes once every 30 seconds to indicate normal operation while the red LED flashes when the alarm gets triggered until the CO threat is eliminated or the device is reset. It also shows the peak CO levels recorded since it was last reset or unplugged.

The KN-COPP-B-LPM runs on battery so you are protected even during power outages. The letter “B” in its name means it is battery-powered. Kidde has another model KN-COPP-LPM which is AC powered. This model requires three AA batteries. When the charge in the battery reaches below a certain point, the unit will alert you to replace the battery. It also has a Battery Safeguard feature which makes it difficult to close the cover without installing batteries first. It is very easy to replace the batteries because of the slide-out battery door that gives easy access to the batteries. Another benefit of having a battery-powered CO detector is that you need not worry about having to place it near a power outlet.

You can purchase this product as a single unit or in a pack of 4. It has an expected seven-year lifespan and is backed by a five-year limited warranty.


  • The large digital display constantly updates its reading every 15 seconds.
  • Battery backup with the Battery Safeguard feature.
  • The simple test/reset button makes it easy to operate.
  • Peak level memory displays the highest Carbon Monoxide concentration recorded by the device since the last reset.
  • The free-standing design gives flexibility for placement.
  • Five-year limited warranty from the manufacturer.
  • 85 dB siren.
  • UL2034 compliant.
  • Low battery warning feature.


  • The yellow/off white color makes the model look 10 years old which can be off-putting for some people with aesthetic sensibilities.
  • The included batteries are of low quality.
  • The display has no backlight.

5. First Alert CO605

First Alert CO605

The First Alert CO605 Plug-In CO Alarm with Battery Backup works with any standard A/C outlet. It also has a battery backup so carbon monoxide levels will be monitored even in the event of a power failure. This can bring peace of mind during storms when there is no power and you are more likely to use generators that could emit dangerous levels of carbon monoxide. Battery backup is provided by two AA batteries.

CO levels are detected by an advanced electrochemical sensor. the most accurate technology available today. It can be easily plugged into a standard outlet and no additional mounting is needed.

There is a single test/silence button on the front, similar to other First Alert models that can be used to silence false alarms or test if the siren is working properly. The alarm has been rigorously tested to meet Underwriters Laboratories (UL) standards.

An “Alarm Action” chart is included with the unit that gives you instructions on what to do when the alarm sounds. If the CO605 sensor detects alarming levels of CO, the siren will ring at 85 dB, giving you a chance to safely evacuate or ventilate the area. The Consumer Product Safety Commission recommends that every home have at least one CO alarm with an audible warning signal in their bedroom like the CO605.

The alarm will warn you when it is time to replace the batteries. The mute button will quite the low battery signal for up to 8 hours. It is easy to replace the batteries without dismounting the alarm. An end-of-life chirp will notify you when it is time to replace the alarm. The model is backed by a five-year limited warranty.

There are three different types of warning sounds. One chirp per minute indicates a low battery. Three chirps per minute indicate a defective unit and you should get a replacement. Five chirps per minute mean it is at the end of its expected lifespan. It is advised to always use alkaline batteries and not regular, rechargeable or heavy-duty batteries.


  • Easy to operate with a single test/silence button.
  • 5-year manufacturer’s warranty.
  • Battery backup.
  • Easy to set up.
  • End of unit life and low battery warning system.
  • UL2034 compliant.


  • Included batteries are of low quality.
  • It does not have a digital display.

Best Gas Leak Alarms

1. Kidde Nighthawk KN-COEG-3

Kidde Nighthawk KN-COEG-3

The Kidde KN-COEG-3 Nighthawk is an AC powered explosive gas and CO combination alarm protects you from two deadly threats. It can be directly plugged into a standard A/C outlet and also includes a 9V battery backup that provides protection during a power failure.

The gas sensor is a metal oxide sensor that can detect propane or natural gas (methane). The alarm works in temperatures ranging from 40 to 100-degree Fahrenheit.

When placed on every level of your home, the KN-COEG-3 Nighthawk can help protect you and your family by giving out an unmistakable signal when gas levels have reached a critical point. The alarm will beep every other second with “GAS” shown in the display when this happens. The alarm will emit four quick loud beeps every five seconds if unhealthy carbon monoxide levels are detected. This will continue till the levels have decreased or the reset button is pressed.

As with all Kidde alarms, the KN-COEG-3 comes with an easy to read digital display. This is why it is preferred by most people over traditional CO and explosive gas alarms. The display clearly shows how much CO levels the sensors have detected from 30 ppm to 999 ppm. The display updates every fifteen seconds to indicate alarming trends or abrupt changes. The peak CO level since it was last reset is also stored by the alarm. The display also indicates if gas is present.

The display has a blinking dot on the lower right-hand corner that indicates that the alarm is functioning normally. You can test if the horn and electric circuits are functioning properly by pressing the test/reset button.

Like the KN-COPP-3 Carbon Monoxide Alarm, the KN-COEG-3 can be rotated to remain upright regardless of whether the electrical socket is mounted horizontally or vertically. The low profile design makes it blend in with any room in your home. This alarm is UL-listed, has a seven-year lifespan and a five-year limited warranty.


  • Dual sensors for explosive gas and carbon monoxide leaks.
  • Tested to meet UL standards.
  • A unique alarm pattern helps you recognize whether it’s a gas or CO leak.
  • Easy to read display shows if gas is present and updates the CO levels every 15 seconds.
  • Easy to use test/rest button can be used to silence false alarms and test if the horn and electric circuits are functioning properly.
  • 9V battery backup.
  • Reputed brand.
  • Loud 85 dB siren.


  • The backup battery life is short.
  • Prone to false alarms if installed incorrectly.

2. Techamor Y201

Techamor Y201

The Techamor Y201 is a portable, handheld gas leak detector. It is armed with a 12-inch long probe that is flexible so it can be used to access hard-to-reach areas. It can detect almost all common gases like propane, methane, gasoline, ethanol, etc.

The Techamor Y201 offers great value for money because of its high-sensitivity sensor (50 ppm), 2-second response time, six-red LEDs (visual) and 85 dB audible alerts that increase with gas concentration. It packs many of the features that are available in more expensive models.

Because of its lightweight, slim and ergonomic design, you can use it in your home as well as job sites. It is powered by three AAA 1.5-volt batteries that can give 8 hours of continuous use. You will need to purchase the batteries separately though.

There is not much we have to complain about the Techamor Y201. It works great, has a simple design and $30 is a small price to pay for such an accurate and sensitive alarm.


  • 50 ppm sensitivity.
  • Detects several common gases.
  • 85 dB alarm.
  • Runs on three AAA batteries that give 8 hours of continuous use.
  • 12-inch flexible probe.
  • Ergonomic and lightweight design.
  • Affordable price.


  • Batteries are not included.

3. Amprobe GSD600

Amprobe GSD600

With the Amprobe GSD600 Gas Leak Detector, you are keeping safety as your top priority. This device uses a semiconductor sensor to detect methane and propane gas leaks from closed piping systems quickly and reliably. It can be used at home and in HVAC maintenance applications. The concentration level of the combustible gas is indicated in PPM (parts per million).

Attached to the device is a 17.6 inches long stainless steel probe that is flexible enough to provide access to hard-to-reach areas. It also is equipped with both a visual and audio warning system. A buzzer is set off when the sensor detects the presence of gas and the beeps get more frequent as the concentration of gas increases. This helps to pinpoint the source of leaks. The front of the device has an LED display panel that shows the concentration level of the gas detected in PPM.

Calibration is done automatically as soon as you switch on the detector, which helps you get more accurate measurements. If you are using the device at a quiet workplace, you can press the mute button to silence the buzzer. You can also connect a headset through a headphone jack on the side of the detector. After ten minutes of staying idle, the device will automatically turn off to save battery. A low battery signal will notify you when the batteries need to be replaced. The sensor can remain well protected during storage and transportation if you use the included sensor cap and carrying case. The device runs on four 1.5 V AA alkaline batteries that are included in the box.


  • Quickly identifies and pinpoints leaks.
  • Automatic calibration feature.
  • Auto power off.
  • Built-in earphone jack with mute function.
  • Flexible probe to access hard-to-reach areas.
  • 5 level LED alarm.


  • There is no way to turn off the auto power-off feature. This can be annoying if you want to use the device for more than 10 minutes, especially since it takes a full minute to calibrate itself every time you turn it on.
  • The device is useful for pinpointing where the leak is but its not good for detecting if there is a leak in the first place.

Why do I need Carbon Monoxide Detectors?

Since carbon monoxide cannot be identified by any sound, odor or taste, it is nearly impossible to detect without a CO detector.

Depending on age, carbon monoxide poisoning symptoms will vary but there are a few common symptoms. If the gas enters the bloodstream, it may cause nausea, vomiting, loss of alertness, confusion, weakness, dizziness and chest pain.

Picking the right CO detector can save your life. These are some of the different carbon monoxide detectors that you can consider installing in your home.

  • Alarm clock CO detectors: These detectors accurately detect the CO levels in PPM and trigger different alarm sounds based on the CO level and the estimated amount of time left to safely evacuate. For example, if the alarm for 50 PPM rings, it means you have sixty to ninety minutes to evacuate safely. But you should still leave immediately when you hear the alarm because CO levels can rise quickly.
  • Temperature adjusting CO detectors: In the case of humidity or fluctuating temperatures, these temperature-sensitive detectors accurately measure CO levels to limit false alarms.
  • Smoke and CO combination detectors: They are space-saving and cost-effective since you do not have to maintain different alarms. Both smoke sensors and CO sensors are present in the alarm, using the same power source and audio and visual signals.
  • Smart CO detectors: These detectors use high-tech features like smartphone access through a mobile app so that you remain notified when you are away from home. With some CO detectors, it is possible to program voice locations through a control panel or a mobile app. The alarm’s voice tells you where carbon monoxide is detected.

Factors to Consider when looking for Carbon Monoxide Alarms

There are different types of CO alarms in terms of sensors, power source, and display. Depending on your needs, some carbon monoxide alarms will be more suitable for you.


There are four different types of sensors that are commonly used in CO detectors.

  • Optochemical Sensor: This is the most affordable CO sensor out of all the four. It can only detect whether carbon monoxide is present or not. The presence of CO is indicated by a change in the color of a pad. This sensor may be affordable but the protection that it offers is limited. Without knowing how much CO content is present, the situation could be more dangerous than expected.
  • Biomimetic sensor: This sensor uses a combination of color-changing gel-like elements to detect the presence of CO. They can last up to 3 years.
  • Metal oxide semiconductor: Wired circuits are used in this sensor to monitor CO. These detectors usually last up to 10 years.
  • Electrochemical sensor: This is the best sensor offering maximum home protection from carbon monoxide. It generates currents to show the amount of CO detected. Most longer life span detectors use this sensor. All the detectors we have discussed above use electrochemical sensors.

Power source

Detectors can be plug-in, hard-wired or battery operated. Plug-in detectors can be powered by most standard sockets. They have a battery backup in case of power failures. The hard-wired versions are integrated into the house and electricity system. These will not work when there is a power failure. However, the hard-wired models have battery backup too.

The battery-powered versions either use built-in lithium battery or replaceable AAA batteries. Lithium battery has a long lifespan and it does not need to be replaced until the end of its lifespan. All battery-operated CO detectors will notify you when the batteries are running low. Some CO detectors will not allow you to close the battery compartment unless you have correctly installed the batteries. These are ideal for portability.


Some CO detectors have digital displays that tell you how much CO is present in the air. Reading is usually displayed in PPM (Parts Per Million). Detectors from Kidde update their readings every 15 seconds.

Why do I need Gas Leak Alarms?

Some of the reasons you should install gas leak alarms at your property are as follows:

  • A gas leak alarm will be able to detect toxic and flammable gases in your home environment.
  • The security of your house is enhanced by the gas leak detection system.
  • Real-time results are visible in the event of a leakage.
  • The inspection makes it easy to decide the further steps that are needed to be taken.
  • The process is affordable and time-
  • Disturbing symptoms like vomiting, headache, chest pain, blurry vision, shortness of breath and nausea can be prevented.
  • You will be able to constantly monitor the gas levels in your property.

Factors to Consider when looking for Gas Leak Alarms

There are different gas leak alarms with different features in the market. You should look at the factors discussed so that you can decide which alarm will best fit your needs.

  • Some gas leak detectors come with an integrated red or white light and you can choose either according to your preference.
  • The probe length is usually standard. As a rule of thumb, you should go for a longer and more flexible probe since they can give you easier access to hard-to-reach areas.
  • The type of sensor at the tip of the probe determines the level of sensitivity of the detector. You should find out the specifications of the detector regarding sensitivity levels before purchasing to ensure that it has the necessary sensitivity for your particular needs.
  • Some detectors automatically calibrate themselves as soon as they are powered on to provide an accurate reading.
  • Most detectors come with visual displays and mutable buzzers to pinpoint the exact source of the leakage. Some models have a headphone jack so you can be silent as may be necessary for working areas.
  • The auto-power off feature on some detectors turns the device off after around 10 minutes to save battery.
  • You should find out about the manufacturer’s warranty policy. If you are not happy with your purchase, it is always best to have a warranty to help you get a replacement or a refund.


We have written this comprehensive guide for carbon monoxide and gas alarms with the hope that you will be able to make an informed choice when installing safety and security systems for your home. The products reviewed here have been selected after carefully considering various factors like features, brand, quality, price and user reviews.