Learning CenterHow to Choose the Best Smoke Detector

How to Choose the Best Smoke Detector

Keep your family safer with the right smoke and carbon monoxide detectors for your household.

Kid's bedroom with Nest smoke detector on the wall next to the bed.

According to the National Fire Protection Association (NFPA), three out of five home fire deaths happen in homes without working smoke alarms. When it comes to keeping your home or business safe, technology is ready to help you avoid disaster. Fire alarms aren’t a new invention, but year after year, safety alarms get more accurate and faster to respond, with a variety of features that provide a comprehensive alarm system to save lives and protect your property. Make sure you have the best home fire safety plan in place by ensuring you have the best smoke and carbon monoxide detector installed.

The Different Types of Safety Alarms 

Of the home hazards, smoke, fire, and gas are among the deadliest. Thankfully there are multiple ways to safeguard against them with smoke alarms and carbon monoxide or CO detectors.  

 Your home-defense system can be built from any combination of these types of safety alarms: 

  • Carbon monoxide alarm 
  • Fire alarm 
  • Smoke alarm 
  • Combination alarm

It’s important to know what it means when you hear a carbon monoxide or smoke alarm beeping. Let’s take a quick look at the differences between the different alarms.

What Is A Carbon Monoxide Detector?

Illustration of carbon monoxide formula and CO sensor.

Carbon monoxide is a byproduct of burning carbon-containing material, which can include common household sources such as those that use natural gas, propane, or even wood. It is tasteless, odorless, and colorless, and even smaller concentrations can be very dangerous if undetected in a home or business over time. Every year, the CDC reports hundreds of deaths due to carbon monoxide poisoning, as the heavier gas interferes with the human body’s ability to use oxygen, and many states have mandated the installation of CO detectors in new construction and rental homes as a preventative measure. 

 A carbon monoxide alarm reduces the risk of carbon monoxide poisoning by monitoring the air and alerting when CO readings rise suddenly or to harmful levels. They are designed to monitor the CO levels in an area over time, measuring fluctuations that allow an area to be aired out for low levels of accumulation or evacuated for more dangerous levels. Many states have specific statutes regarding the type and placement of carbon monoxide detectors, with a CO detector required to be installed and kept in regular working order. 

 A CO detector takes readings of only carbon monoxide and does not warn against other gases such as natural gas, propane, or methane. There are multiple ways the carbon monoxide detector measures the CO levels, with the most common types being either a biomimetic sensor or an electrochemical detector. They can last from five to ten years, depending on the type of detector you choose and the battery type.

What Is A Smoke Detector?

Smoke detector, yellow waves indicating alarm, smoke rising.

A smoke detector recognizes the presence of smoke in the air and triggers an alarm to warn the surrounding area, sometimes most of the home depending on the size of the home. There are two types of smoke detectors with specific recommendations for the number of fire alarms and their locations within the home. They can be battery operated or hardwired to an alarm system.  

 The detector alert may be too quiet to be heard throughout the home, so for safety’s sake, plan for a smoke detector in every room except the bathrooms. Steam and moisture can interfere with the reliable operation of the sensors. Keep in mind that smoke detectors become less accurate over time and should be replaced every ten years. If in doubt, it’s better to replace it.

What Is A Fire Alarm? 

Shield icon with orange flame.

A fire alarm is not the same as a smoke detector, though the two alarm types work together. A traditional fire alarm system in a commercial building can be an interconnected, manual alarm system, with multiple alarms connected throughout the building so that when an alarm is triggered in one area, the warning is instantly heard in every room and hallway via the other alarms in the building.  

The fire alarm system requires someone (or something) to trigger it. That’s why modern fire alarms are paired with a sensor-triggered device, from a security network to smoke and carbon monoxide detectors. The fire alarm is hooked into the other device to make the warning heard across the building, but it doesn’t do the work of detecting the trouble itself. 

How Do They Work 

To choose the best safety alarm for your home, it’s a good idea to know a little about how they work and what it means when the smoke detector beeping wakes the household up at night. 

There are two different types of smoke detectors, which monitor different types of hazards. 

  • Photoelectric smoke detectors are triggered by smoldering fires, which burn low for a long period and produce a lot of smoke and flames. They operate by monitoring an internal light source within a sensing chamber inside the detector. When smoke enters the sensing chamber, it reflects light onto the sensor and sets off the alarm.  
  • Ionization smoke detectors are better with smaller particles, such as with quick-flaming fires. The unit has an internal chamber that ionizes the air to create an electric current that is interrupted by the presence of smoke, setting off the alarm. Ionization smoke detectors also react to steam and are very reactive to kitchen fires.

A combination alarm uses a dual-sensor system to utilize both ionization and photoelectric sensors in one unit in order to better warn against the different occurrences of smoke in the air. These dual-sensor smoke alarm types are effective and recommended. 

 Like a smoke detector, there are a few different types of carbon monoxide detectors, which break down into either a biotechnology-based sensor system, or an electrochemical type that relies on an electrical current. Electromechanical detectors are the more popular type of residential CO detector due to their accessibility and reliability, while biotechnology-based biomimetic sensors are preferred for the demands of larger, industrial environments.  

 The test buttons on the smoke alarms and carbon monoxide detectors are only capable of testing whether the alarm works, as the only way to test their detection capabilities is to release a test gas around the detector. Because of the different response types of sensors contained in the different detectors, the ideal locations for the CO vs smoke detectors may be different. As a result, a CO detector in the same unit as a smoke detector can compromise their accuracy, so it’s a good idea to buy carbon monoxide detectors and smoke detectors as separate units.

Smoke Detector Maintenance Requirements

Wrench and screw driver icon.

Part of your household’s home fire safety checklist should be to test that smoke and CO detectors are in working order if, and when, they’re ever needed in case of an emergency. Plan to replace the entire detector unit every ten years, so keep track of when it was installed. If you don’t know how old the smoke detector is, it’s a good idea to replace it.  

Test the alarms regularly and replace the batteries according to the manufacturer’s instructions. Most units are a simple push-button test and it takes very little time. It is recommended to test smoke and carbon monoxide detectors on a monthly basis, but some models may suggest a different time frame, so check the instructions. 

 Always follow the individual product manufacturers’ recommendations for how to change the smoke alarm battery as some models may have specific battery, installation, or testing requirements. Some battery-operated units will need the batteries changed once a year, while others may be reliable for anywhere from 5 to 10 years of battery life with the right type of battery.  

 Another advantage to regular testing is that it provides an opportunity for everyone in the household to learn the sound of the alarm, how to change the smoke detector or CO detector battery, and how to turn off fire alarms that are responding to a false trigger, such as steam or dust particles. It’s an ideal time to plan and practice for evacuations. These are all an important part of home fire safety and it’s a good idea to make sure everyone knows what to do in case of an emergency. 

 It’s also important to keep the alarm unit clean, free of excess dust or spider webs. They can be dusted with rags or technology wipes as needed or use a vacuum wand to carefully remove dirt and dust. Never paint or apply stickers to a smoke detector or carbon monoxide alarm to ensure the sensors aren’t interfered with.  

 If a smoke alarm chirps unprompted, it means that the battery is low and should be changed right away. Check that the battery is not loose and that the connections are clean. Also pay attention to the use-by date on the battery before installing a new one. With most models, plan to change the CO and smoke detectors batteries every year around the same time, such as Daylight savings time, so that the easy maintenance task is easier to remember and can be done consistently.  

Where to Install Smoke and CO Detectors

Little girl sitting on staircase, Nest smoke detector beneath stairwell.

Different states and regional areas may have specific code requirements for the placement of smoke and carbon monoxide detectors, so it’s a good idea to always check your local regulations. The National Fire Protection Agency recommends multiple detectors throughout the house, and when possible to use interconnected detectors. Networked safety alarms communicate between different parts of the house, including different floors, and alert all occupants of the potential danger at once, either via hardwire connections between alarms or via wireless technology. 

Keep in mind that the detectors can be battery operated or hardwired, which influences where a detector can be installed. They should be somewhere accessible for testing or to turn off the smoke detector beeping from a false alarm, but also where they will provide accurate readings and that their alarms can be heard.

Where to Install Smoke Detectors 

To ensure accuracy and effectiveness, there are certain areas of the house that are vital to keep monitored when installing a smoke detector. We’ve collected a few tips to help plan the number of smoke detectors you’ll need and the best layout for installing them. 

Install a smoke alarm:  

  • Inside of every bedroom 
  • Outside of every sleeping area, such as in a hallway 
  • In the living room or den 
  • On the stairwell ceilings 
  • In the basement 
  • On every floor of the home 

Smoke detectors should be installed on the ceilings, however when working with pitched or sloped ceilings, or stairwells, the smoke detector can be mounted to the wall instead. For wall-mounted installations, make sure to keep the detector as high on the wall as possible, within 12” of the ceiling for best results. Keep in mind that you will still have to know how to turn off the smoke alarm as well as be able to reach it to do so, which may mean installing the alarm on the wall in hard to reach places such as stairs if the ceiling is too difficult to safely access with a ladder on a regular basis. 

Don’t install a smoke alarm near ventilation systems, windows, or doorways, as they will disperse the airflow around the sensor and prevent it from picking up on smoke and debris in the air. Installing too close to an exterior air supply can also result in false alarms from poor outdoor air quality, with some sensors picking up everything from particles caused by humidity, dust and other allergens, or a neighbor’s outdoor BBQ. 

Tiled shower and tub with exhaust fan above it. Exhaust fan above toilet.

Some alarm types will register steam as well as smoke, so it’s best not to install a smoke detector in a bathroom or other high-humidity room. Even with a bathroom exhaust fan to help circulate the air, the reflective particles of the moisture in the air could trigger the sensors in most alarms. Place smoke alarms in the hall outside the bathroom door instead.

Food being made on cooktop, stainless steel range hood.

There should be a smoke detector in or near the kitchen but be sure to install the detector at least 10 feet away from the cooking area to avoid false alarms from normal steam and cooking vapors. You can also help minimize false alarms by using the range hood when preparing meals.

Where to Install Carbon Monoxide Detectors 

Because of the different types of sensors, standards for installing a carbon monoxide detector may vary depending on the unit. There are, however, some recommendations for how many CO detectors are needed in a home.  

Make sure your home has a carbon monoxide detector installed: 

  • Outside of every sleeping area and bedroom 
  • Near any appliance that may create carbon monoxide, such as a gas furnace, water heater, stove, or generator 
  • On every level of the home 
  • The garage or workshop 

Remember that carbon monoxide is a gas, with a similar density as the air you breathe, so it accumulates and builds up everywhere. The best location of the CO detector then will depend on the type and sensitivity of the sensors in the unit, so always consult the manufacturer’s instructions to verify where a CO detector should be placed in the home.

What to Look for In A Safety Alarm System 

Looking glass icon.

Finding the best smoke and carbon monoxide detectors for your home means knowing what to look for before you buy. The first alert from the fire alarm must be effective and timely in order to keep your household safe, so look for the features that will guarantee it is noticed when it needs to be.

Single Detectors vs Dual-sensor Smoke Alarms 

With two different types of smoke detector sensors, it’s important to pay attention to which one you choose. The NFPA recommends dual-sensor smoke alarms that include both photoelectric smoke sensors and ionization sensors because they pick up warnings for both smoldering and flaming fires.  

However, keep in mind that the most effective place to install a smoke detector may be at odds with the most effective place to install a carbon monoxide detector, as they are sensitive to different problems. A combination smoke and CO alarm placed too close to gas furnace may be subject to more false alarms, for instance. To ensure long-term effectiveness, it’s a good idea to purchase separate smoke alarms and CO detectors in many cases. Always check the device’s instructions for guidance on where to install and how far the detectors should be from appliances and other conditions that might interfere with reliable sensor readings. 

Choose UL Rated Products

Because of the scientific nature of safety detectors, it is important to choose products that offer public smoke and carbon monoxide reviews and are certified as effective by a recognized testing laboratory or standards organization, such as Underwriters Laboratories (UL). These alarms are clearly marked on the product labeling. Smoke alarms and CO detectors with the UL label have met the recognized standards for home fire safety and efficient operation, which can help reduce false alarms and ensure speed and accuracy in the product’s emergency response time. 

Power Sources for Home Safety Alarms

Electricity icon.

The power source for your carbon monoxide detector or fire alarm can be either a battery-operated system or it can be hardwired into the home’s electric grid. There are advantages to both types of power source, and properly maintained, both are reliable.  

Hardwired alarm systems should be professionally installed to connect to the electrical system. They will usually include a backup battery source that should still be checked regularly. With an alarm system wired into the home’s power supply, the alarms are interconnected so that all alarms in the home will sound when any one of them detects danger. This interconnectivity is recommended by most home safety experts. It also allows the system to connect to other features like a sprinkler system or monitored security system directly to help take preventative action quickly. 

Battery powered detectors are easier to install. The batteries should be changed out every year with new, long-lasting batteries as the unit sensors are constantly working even when the alarms are not going off. It’s important to note that as the battery power drains, the smoke or carbon monoxide detector can become slower and less effective. In an emergency, a battery powered alarm will sound as long as there is battery life, while a hardwired system will sound until the power is cut or the alarm is reset.  

The same networking between alarms can be achieved with battery-powered alarms, provided they are all from the same manufacturer and are equipped with a feature like Wi-Fi or Bluetooth connectivity. Unlike a hardwired system, however, a battery-operated interconnected alarm system would have to be planned around the limitations of the signal type, such as distance between the alarms and whether or not any obstacles block the signal.

Must-Have Features on Smoke Detectors

Test button being pushed on smoke detector.

There are many options when it comes to finding the right carbon monoxide detector or fire alarm, but the manual alarms still do the job quite well. The more conventional designs include helpful features like the alarm test button, and the expected low-battery alerts.  

There should be individual alerts for different issues with the device. The alarm for smoke or carbon monoxide in the air should be noticeably different than the alert for a low battery. Some units will alert you when the device itself needs to be replaced. For households with people who have trouble hearing, look for an alarm setup that sets off warning lights when there’s trouble instead of only the audio alarms. 

Newer carbon monoxide detectors will include digital displays that show the status of the air quality, with the CO levels reported in parts-per-million. Some offer audio read-outs, which announce the levels when they become dangerous, rather than only sounding the alarm. These are all built onto the body of the detector, so it can be seen on the device itself rather than wait for a report from an app.

Security System Connections

Alarm icon.

Home fire safety alarms are often included in home security systems. Whether business or residential, a professionally monitored security system has the added feature of an automatic connection to public safety services, such as the fire department.  

When an alarm goes off, the monitored system at your home immediately notifies the security provider, which then notifies the necessary emergency responders, whether it be the fire department or the police. These comprehensive monitoring programs are a formal service often well worth their monthly fees. These systems can be entirely customized and cover much more than smoke or gas threats, but a fire alarm and CO detector can be part of the protection offered.

High Tech options for Smoke and CO detectors

Phone app showing camera view of backyard of home. Smart home control.

Other high-tech options for smoke and carbon monoxide detectors include the do-it-yourself home security systems, with technology notifying the owner of the system when there’s trouble via message alerts, emails, and video feeds. The systems network between appliances and devices using Wi-fi and Bluetooth to allow instant connectivity and communication between the different services.  

These DIY security systems are built using home automation technology that creates custom security, safety, and environmental controls connecting Smart Hubs and a variety of sensors and accessories. These include products compatible with Amazon Alexa and Google Nest, for smart thermostat controls, interior and exterior lighting controls, security cameras and doorbells, and safety alarms like CO detectors or fire alarms. All of these devices can be controlled via apps on cellphones, tablets, or computers. 

That central hub then allows you to monitor the security cameras and safety alarms from anywhere, so even if no one is home to hear the fire alarm, you’ll be notified promptly on your cell phone. No more wondering how to turn off the fire alarm after a close call when the fire alarm is synced up to and controlled by an app on your phone or tablet. These smart security systems allow you to test and silence alarms with the touch of a button. They provide a high-tech and complete home safety solution while offering the basics of smoke and carbon monoxide alert systems in a whole new, high-quality package.