7 Best Smoke & Carbon Monoxide Combined Alarm Detectors of 2021

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Investing in a smoke and carbon monoxide alarm detector is both practical and valuable for life and property.

Over the years, domestic fires have been killing householders and destroying properties. In the United States alone, an average of three of five home fire-related deaths from 2012 to 2016 were due to the absence of an early warning system. Installing and maintaining a working smoke alarm at home could have prevented such tragedies.

On the other hand, carbon monoxide poisoning is responsible for the trip to the emergency room for several people due to accidental carbon monoxide poisoning and around 400 people die every year in the United States.

Same with the smoke alarm, carbon monoxide alarm notifies on irregular presence of carbon monoxide in the home or establishment so that the necessary steps can be taken.

So what can you get out of combined smoke and carbon monoxide alarm detectors?

Extra sense of security as a result of convenient monitoring, all in one unit.

So what things should you consider when looking to purchase these alarms?

  1. Check with Your Local Requirements. Before you shop for your combined alarm, you must check with your local authorities regarding specific requirements about the type and quantity of detectors and installation areas that you need for your home or building. Compliance is important because you may be required to produce a Compliance Certificate for your smoke and carbon monoxide alarms when you sell or transfer your home.
  2. Look for the Underwriters Laboratories Rating Stamp. Buy a combined alarm with an Underwriter Laboratories (UL) Stamp to ensure that your device meets the UL standards. The package should also bear the manufacturing date because smoke and carbon monoxide alarms have expiration too, whereby they lose sensitivity, usually after five to ten years.
  3. Choose Your Power Source. You can install smoke and carbon monoxide alarms by hardwiring, plugging-in, or running batteries . Hardwired requires professional assistance because the installation involves your home wirings. For easy installation, you can choose either the battery-operated alarm that requires battery replacement annually or the plug-in one.
  4. Decide between Standalone and Interconnected. A standalone alarm is for alerting you if there is detection within its coverage area only while interconnected alarms provide maximum protection by sounding all the connected alarms in the home even if it is from one area only. Interconnected alarms can be hardwired or wireless, and more expensive too compared with the standalone. Moreover, you may be limited to one brand only for all the alarms to work without a glitch.
  5. Understand the Types of Smoke Detectors. Electrochemical sensor is the most accurate technology available used to detect carbon monoxide, so when buying a carbon monoxide alarm, there is nothing much to assess regarding how it works. However, smoke detection is a different story because of the different types of smoke detectors.

Therefore, before you shop for a combined smoke and carbon monoxide alarm, understand first how would you like the smoke alarm to detect potential fire in your home.

  • Ionization: This detector uses the ionization chamber as well as radiation to detect smoke. Simply put, it identifies the amount of gaseous smoke generated by flaming fire.
  • Photoelectric: Smoke alarm that uses photoelectric is more reliable with reduced false  alarms than ionization because it detects smoke from slow smoldering fire quite quickly. This means that even the smallest particles of fire will trigger the alarm.
  • Dual sensors: This is the powerful combination of ionization, and photoelectric sensors. 

Now on to the best brand names for smoke and carbon monoxide alarms;

Top 4 Smoke and Carbon Monoxide Alarm Brands

1. Kidde.

Walter Kidde, who pioneered the integration of smoke detection and carbon dioxide extinguishing system to detect fires on board ships, founded the Walter Kidde Company in 1917. His dedication to preventing fires and saving lives was continued by his successors until today, making the company a leader in the fire safety industry under the company name, Kidde.

At present, Kidde is a brand and a division of another known brand name, Carrier Global, a group of manufacturers specializing in fire detection and containment equipment.

The company is known for innovative products to protect people, property, and processes from fire hazards. From the first portable carbon dioxide extinguisher to smoke alarm, kitchen suppression systems, and now the combination of smoke and carbon monoxide detectors, you can’t go wrong with Kidde as your go-to for your fire and gas detection and protection.

Although there have been complaints about the quality of customer services, many are still patronizing the company for their reliable products with excellent value for money.

By maintaining a balance between the quality and top-notch performance, Kidde is one of America’s largest manufacturer of fire safety and carbon monoxide warning systems.

2. Google Nest.

Even before the acquisition by Google, Nest Labs was a well-known home automation provider specializing in programmable WIFI-enabled products that let you control home electronics through a web service.

The company was founded in 2010 and was acquired by Google in 2015.

Years later, Google merged all its home electronic products with Nest and marketed them under the brand name Google Nest.

These include the Nest Learning Thermostat (the first thermostat to earn Energy Star certification, the Nest Protect (smoke and carbon monoxide detector), Nest Cam (home monitoring webcam), Nest Hello (video doorbell), Nest Secure (home alarm system), Nest x Yale Lock (Nest-app based key-free deadbolt lock) and Nest Aware (subscription-based 24/7 video recording for 30 days).

Generally, many of Google Nest products are well embraced and loved.

3. First Alert.

Founded in 1958, the company created its first commercial smoke alarm. The innovation then started and paved the way for more fire safety products such as the first residential smoke alarm, first battery-operated carbon monoxide alarm and fire extinguishers.

The company now also offers WIFI-enabled alarms, including combination alarms, to further promote smart home protection.

The company sees to it that it continues to implement the latest technology to give customers the kind of home safety devices they deserve, and they are no doubt doing a great job because they have some of the best product lines of smoke and gas alarms both individually and combined.

These devices come with wired and wireless options, so customers can choose whatever is the best for their household.

Fire Alert offer their customers not only the prevention (alarms) but also the solution in the form of fire extinguishers with varying features and compatibility range depending on the use.

It is unavoidable that there will be complaints about some products, but First Alert always thrives on giving its customers the best customer service, from warranty filing to granting.

4. X-Sense.

It was only in 2014 that X-Sense established itself as a home safety brand. It may be one of the youngest brands in the field, but it is already playing side-by-side with big players in the industry and is even considered one of the most innovative brands.

Within six years, they are now offering advanced home safety solutions from smoke alarms to carbon monoxide alarms and currently the combination of both in one device.

Because of their continuous effort to innovate their products to incorporate more features, X-Sense has already gained clientele in more than 48 countries and has established a global presence in most parts of the United States, South America, Europe, Southeast Asia, Middle East, and Africa.

These brands have a wide array of home safety products in their respective portfolios, but to narrow down your search for a combined smoke and carbon monoxide alarm, we have reviewed some of their top-selling units below.

Review of the Best Smoke and Carbon Monoxide Alarms

1. Best Value for Money: Google Nest Protect Smoke + Carbon Monoxide Combined Alarm Detector

This 2nd generation battery-operated smoke and carbon monoxide alarm by Google Nest takes home safety to the next level by enabling you to access notification and warning history of the alarm system through your mobile phone via an application.Google Nest Protect Smoke + Carbon Monoxide Combined Alarm

You can also consider this as one of the calmest alarms in the market because not only will it warn you in a composed human voice, but it will also give an initial warning if triggered by a small amount of smoke without turning into full emergency alarm.

Further, it is equipped with a path light that slightly illuminates your way when you walk within its sensor coverage as well as a relaxing green glow when everything is great.

The unit has a photoelectric sensor that can detect smoldering fire or embers. Therefore, it acts faster than an ionization-based alarm.

Similar to most smoke and carbon monoxide alarms, Nest Protect has a lifespan of ten years.

Fortunately, you don’t have to guess when you should replace the batteries because the device will flash a yellow light to remind or notify you that you have to replace your battery already.


  • Battery-operated using 6 AA lithium batteries.
  • UL and California Fire Marshal certified unit.
  • It requires a Wi-Fi, iOS, or Android gadget and free account registration at Nest for wireless interconnects and mobile notifications.
  • It has the following sensors: Photoelectric for smoke, Carbon monoxide
  •  It will give an early warning for a low-risk fire so you can immediately act without the emergency sound.
  • It enables you to receive immediate alerts on your mobile phone.
  • It emits a green glow, indicating that everything is safe.
  •  It has a specific carbon monoxide notification that tells you how much of it and how long it was in the air before the alarm. 
  • A red glow on the unit will appear when smoke or CO levels in the room have reached dangerous levels.
  • The alarm can be interconnected, particularly with Nest Learning Thermostat that can work asynchronously.
  • It is compatible with Google Assistant and Alexa.
  •  It has a voice alarm that calmly notifies you of the danger.


  • It uses a photoelectric sensor that can quickly detect fire danger.
  • Alerts and notifications are accessible with a mobile phone.
  • Human speaking voice tells you what’s wrong
  • Green glow gives you the assurance that everything is ok and the batteries are working.
  • You get early warnings even when there is very little smoke
  • You can hush the alarm conveniently on your phone with App Silence.
  • Alarms from different areas or floors of the house can be interconnected, therefore providing a convenient, higher safety level.

Customer Feedback

Many customers bought this item because of the wireless capabilities were able to monitor their houses even when away. It is easy to install too, and as a battery-operated unit, it gives them peace of mind that the function will not be interrupted as long as the the batteries were working. Generally, customers love the nightly green glow that gives the assurance of safety and the fact that one can conveniently get notifications on their phones on looming dangers even while you’re away from home is a plus that users appreciate. What’s more, its compatibility to smart assistants like Alexa is a welcomed bonus that makes control and operation so much easier.

2. Kidde KN-COSM-BA Battery-Operated Combination Carbon Monoxide and Smoke Talking Alarm

Whether buying a combined smoke and carbon monoxide alarm for the first time or replacing your old one, this talking combined alarm by Kidde can be your new home’s safety buddy.Kidde KN-COSM-BA Battery-Operated Combination Carbon Monoxide and Smoke Talking Alarm

It boasts of two fundamental safety devices in one unit and has a voice warning system that will alert you if the battery needs replacement or if you and your family are at risk of fire or carbon monoxide.

The battery-operated feature is ideal because it eliminates the risk of interrupted protection during a power outage.

It uses ionization sensing technology that is more responsive to flaming fires that release ionized gaseous components.

With a life expectancy of  ten years under a 7-year limited warranty, smoke and carbon monoxide are not the only concern that Kidde wants to resolve with this product, but also the risk of tampering with the device, most notably by children ready to climb heights to feed their curiosity.

The KN-COSM-BA alarm has a tamper-resistant feature, which you can activate by breaking off the posts in the trim ring’s square holes. Doing this will enable the tamper resist tab to connect to the mounting bracket, and you will hear a snap after rotating the bracket, which means it is locked already. This safety feature will ensure that children cannot detach the alarm from the mount.


  • It is battery-operated and will not be affected by a power outage. Requires 2 pieces of AA batteries.
  • Ionization from smoke, and electrochemical from carbon monoxide triggers the alarm sensor.
  • Its audio alarm measures 85 decibels at 10 feet.
  • It can detect a temperature of 4.4°C to 37.8°C.
  •  UL approved.
  • It is not interconnection-ready.


  • It has a voice warning as loud as a power lawnmower.
  • It uses a common type of battery.
  • It has a battery safeguard feature.


  • Ionization triggers the smoke sensor, which means there is an actual flame already before detection.
  • You can’t connect each alarm. Therefore, if there is a trigger on the 2nd floor, the alarm downstairs won’t alarm unless triggered.
  • Not a smart detector

Customer Feedback

Customers embraced this unit well because of its easy-to-install and battery-operated features. Many of them were also delighted about the “Hush” button that they can use to pause a loud beeping triggered by smoke coming from cooking.

3. First Alert SC05CN Smoke Detector and Carbon Monoxide Detector Alarm

The SC05CN alarm boasts a powerful performance with the combination of photoelectric smoke sensor and electrochemical sensor.First Alert SC05CN Smoke Detector and Carbon Monoxide Detector Alarm

The photoelectric smoke sensor provides optimum safety from smoldering fires while isolating cooking fires and shower steam to reduce false alarms.

On the other hand, the electrochemical sensor accurately detects carbon monoxide even from the smallest gas leak from faulty appliances, generators, and other gas-based occurrences.

It has a mute button for silencing the device in case of a rare false alarm, low battery notification, an 85dB sound level, and a so-called “End-of-life” timer and alarm chips to remind you that it’s time to replace the device.


  • It works with 2 AA batteries.
  • It is compliant with UL217 and UL2034 standards.
  • It has an 85-decibel siren that provides loud warning upon detection.
  • It has 3 alarms: Carbon Monoxide, Smoke Detected and Low battery warning,  End of Life alarm.
  • Equipped with a low battery signal that alerts when it’s time to replace the battery as well as a end-of-life alarm consisting of three chirps notifies you it’s time to replace the unit.
  • It has a mute button to silence nuisance alarms, and also used for test alarms.
  • The battery compartment is easily accessible .
  • It emits a T3 pattern or three intermittent beeps followed by a pause.


  •  Single button for silencing a false alarm
  • Indicator lights on its LCD display for smoke and  carbon monoxide warning 
  • It is easy to install and easy to replace batteries.
  • Notifications on battery and unit replacement


  • Not a smart alarm. It cannot connect to the Internet and mobile phones for convenient notification.

Customer Feedback

This alarm has many positive customer reviews for its proven performance in alerting the households, whether it is a fire or carbon monoxide risk. For a majority, this scores highly when it comes to overall value for money.

4. X-Sense Smoke and Carbon Monoxide Combination Detector Alarm with Display

This X-Sense’s combined alarm in a single device uses photoelectric and electrochemical for smoke and carbon monoxide, respectively, but work independently of each other.X-Sense Smoke and Carbon Monoxide Detector with Display

What is great about this device is that you can monitor the carbon monoxide concentration in the air through its large LCD.

If the alarm detects carbon monoxide between 30 to 999 parts per million (ppm), the screen light will turn blue while the LED indicator will flash red 4 times every 5.8 seconds.

On the other hand, the smoke alarm keeps false triggers at a minimum like a cigarette smoke and cooking particles. unless directly blown into the alarm.

When silenced, it stays quiet for less than 9 minutes for smoke and less than 6 minutes for carbon monoxide. If you don’t act on it, the alarm will resume.


  • It uses a 10-year sealed lithium battery
  • The alarm loudness is 85 decibels.
  • It conforms to the UL 217 and UL 2034 regulatory requirements.
  • It has a LED indicator light that flashes red, yellow, or green.
  • The sensor types are photoelectric and electrochemical.
  • It has a test/silence button for test alarms and silencing of nuisance alarms.
  • It has an LCD display for carbon monoxide concentration, battery life and the status of the alarm.


  • LCD Display with indicator lights
  • Equipped with a mute button for easy silencing in case of false alarms
  • No guessing, you’ll get malfunction and low battery warnings if and when it happens.


  • It cannot interconnect.
  • Battery is not removable or replaceable
  • Not smart operating

Customer Feedback

Most customers are generally happy with this buy. The LCD allows them to see the level of carbon monoxide levels inside their home at any given time for peace of mind. Users also loved how easy it was to install with the provided mounting kit.

5. Smoke and Carbon Monoxide Detector Combo with Sound Warning by Arikon

If you are not keen on in-depth do-it-yourself work, you will prefer this Arikon battery-operated dual-sensor alarm that doesn’t require any wiring installation. It will help you keep your home and family safe from both  fire or carbon monoxide.Smoke and Carbon Monoxide Detector Combo with Sound Warning by Arikon

The device has a voice announcement that will alert you if triggered with a loudness of 85 decibels, comparable to the sound of window-type air conditioner at work.

With this alarm, there is no need to worry that you might overlook battery replacement because it will remind you by giving off a low power alarm.


  •  It uses a 3V battery.
  • It has an alarming level of 85 decibels.
  • It detects smoke with its infrared photoelectric sensor while it detects carbon monoxide with its highly accurate electrochemical sensor.
  •  The light indicator for smoke is a blue light flash and a buzzer. The light indicator for carbon monoxide is red light flash and a buzzer.
  • It is compliant with NFPA 72 standards/UL standards.
  • It has a voice warning, announcing fire carbon monoxide and low battery
  • It has a test and reset button.


  • Attractive design
  • It is easy to install.
  • LCD display with warning lights
  • Human voice that announces the dangers
  • Interconnection Capability of up to up to 24 Units
  • It has a hush button for a false alarms.


  • Not a smart unit

Customer Feedback

For a majority of users, this is a fantastic alarm that ensures peace of mind with its LCD display for CO levels and protection from these dangers. It works effectively as advertised and the  device’s installation is said to be easy, making it a convenient alarm of choice for customers who don’t know how to hardwire or just want to install an added safety alarm in some areas of the house.

6. Vitowell Combination Smoke and Carbon Monoxide Detector Alarm

This Vitowell alarm detector is sleek with a low-profile design, and like all other alarms on this list, it also promises you protection from two dangerous threats: fire and gas.Vitowell Combination Smoke and Carbon Monoxide Detector Alarm

This device is battery-operated for convenience and assurance that even with power outage, the alarms will still work. Nevertheless, you will need to conduct maintenance checks such as weekly test functions to ensure that it is working with no risk of interruption.

It uses photoelectric sensor for smoke detection, which is much better than the ionization detector since there doesn’t have to be a blazing fire before the smoke alarm detects it. On the other hand, the electrochemical sensor detects carbon monoxide concentration.

It has an LCD where you can see all the notifications of the alarm with or without a trigger.


  • It requires 2 1.5V AA batteries.
  • Its alarm level is 85 decibels.
  • It emits a low alarm when its batteries are running low.
  • It has a sleek and minimalistic design.
  • It has an LCD that indicates a real-time amount of carbon monoxide within the coverage area.
  • Photoelectric sensor for smoke and electrochemical for carbon monoxide
  • It has a silence button to stop the false alarms.


  •  Easy to install with provided mounting bracket.
  • Silence button fitted
  • LCD Display for(CO) concentration, remaining battery life and alarm’s working status
  • Prepare you when batteries are close to running out


  • No voice announcement.
  • Not interconnection-ready.
  • Not a smart detector

Customer Feedback

Customers expressed satisfaction with this  alarm as it provided the desired levels off safety and peace of mind after installing it in their houses. It is easy to install and maintain and works just as advertised.

7. First Alert BRK SC7010BV Smoke and Carbon Monoxide (CO) Combo Detector with Talking Photoelectric Sensor

The BRK SC7010BV detector is another innovative alarm by First Alert, and this time, it is not only battery-operated, but a hardwired talking photoelectric smoke and carbon monoxide alarm.First Alert BRK SC7010BV Smoke and Carbon Monoxide (CO) Combo Detector with Talking Photoelectric Sensor

In case of a power outage, it has a backup battery that will take over so the alarm function won’t be interrupted regardless.

Another exciting feature of this detector is that the voice warnings will not only alert you on smoke or carbon monoxide threats, but it will also inform you of the location of the danger.

It is already interconnection-capable, so you can always connect the device to other compatible detectors.

This device also has a variable horn frequency that makes it applicable to those with hearing loss conditions because they will hear the sound.


  • It requires 2 AA batteries as backup.
  • Its power source is AC hardwired.
  • It has a voice alert and hush feature.
  • It is  UL listed.
  • It has a voice alert that will tell you the location of the danger.
  • It is interconnection-capable.
  • You can pre-program up to 11 areas in your home.
  • It has a variable horn, so people with a hearing problem can hear it.
  • It has a powerful combination of the photoelectric and electrochemical sensors to detect smoke and carbon monoxide faster.


  • It is ready for interconnection.
  • Human voice alarm
  • Tells you the exact  part of the home is that is in danger and from what.
  • Mute button silences any false alarms


  • It is not accessible from a mobile phone.
  • Installation is not a fast as aforementioned models, does need to be hardwired.

Customers Feedback

The majority of customers who reviewed this device commended this is an all-around smoke and carbon monoxide alarm with location-warning feature and overall performance. First Alert is always known for quality and durability, and once again, the company proved itself through this model.


A combined alarm is a cost effective, practical and important piece of precautionary device that most households and establishments could benefit from.

The reviewed brands are just some of the more popular alarms dominating the home safety alarm industry. These are the products that are performing well in the market and recognized by a lot of customers as effectively delivering on what they promise.

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