Smoke and Carbon Monoxide Alarms Buying Guide

Smoke and Carbon Monoxide Alarms Buying Guide
Nearly two-thirds of the deaths suffered in home fires happened in homes without working smoke alarms, according to the National Fire Protection Association (NFPA). In addition, carbon monoxide (CO) is an invisible, odorless gas that affects between 20,000 to 30,000 people each year and kills at least 500, according to This makes it important to install smoke and CO detectors throughout your house to warn you of the presence of these deadly gases and keep you and your family safe.
In the article below, Part 1 discusses the difference between battery-operated and hardwired smoke alarms and CO detectors, Part 2 covers the different types of smoke and CO detectors, and Part 3 talks about some of the common features you can find with both types of detectors.

Part 1 of 3: Battery-operated vs. hardwired detectors

When choosing a smoke or CO detector, you need to determine what kind of power source you want to use. The section below details the different versions of detectors you can buy.
  • Battery-operated detectors: Battery-operated detectors operate via a battery. Smoke and CO detectors that use batteries sound a tone, usually a chirping, to let you know when the battery life is low. Regardless, you should test a detector at least once a month and replace the batteries if necessary.
  • Hardwired detectors: Hardwired detectors tie directly into the power supply of your home. In case the power goes out, a hardwired detector uses a battery backup. Just like with a battery-operated detector, you need to test a hardwired version at least once a month to make sure the battery still works.
  • Plug-in CO detectors: In addition, some CO detectors come in models that plug into an electrical outlet. Just like hardwired models, plug-in detectors also have a battery to act as a backup in case of a power outage. You should test the device to make sure the battery is still good at least once a month.

Part 2 of 3: Types of fire detectors and carbon monoxide alarms

Smoke and CO detectors use various ways to detect the toxic gases in the air. The following section reveals the different types of detection methods used by these detectors.
Smoke Detectors
  • Photoelectric smoke detector: A photoelectric detector uses light reflecting off smoke particles to trigger the alarm. This happens when the light produced by the bulb of the detector reflects back into the photocell.
  • Ionization smoke detector: An ionization detector detects the presence of smoke by ionizing air particles in the vicinity of the detector. When attaching to smoke particles, the electric flow through the ionized particles is changed, setting off the alarm.
CO detectors
  • Biomimetic detector: Biomimetic detectors use a synthetic hemoglobin that darkens in the presence of CO. You can find two types of biomimetic detectors, those you have to look at to determine if CO is present and detectors that connect to a light sensor and sound an alarm if CO is present in the air.
  • Electrochemical detector: An electrochemical CO detector uses an electric current to determine the amount of CO in the air. When CO levels reach a high level, this highly accurate detector lets you know by sounding an alarm.
  • Semiconductor detector: In a semiconductor detector, the presence of elevated levels of CO in the air allows a higher current to trigger an alarm by reducing resistance at a semiconductor sensor.

Part 3 of 3: Common smoke and carbon monoxide detector features

Once you decide on the type of detector you want to install in your home, you need to determine what other features you want, if any. The following section goes into more detail on some of the more common features found in smoke and CO detectors.
Smoke detector features
When buying a smoke alarm, you should look for certain features to allow you to better protect your home. And while all smoke detectors sound an alarm when smoke is present, some offer additional functions, as detailed below:
  • Interconnectivity between detectors
  • Display screen
  • Low-profile or micro-design models
CO detector features
CO detectors come with a variety of useful features. You can find some of the more common features in the section below:
  • Interconnectivity between detectors
  • Voice alert
  • Digital display
  • Five-year lifespan (or longer)
As you can see, you have a lot of choices when picking the right smoke or carbon monoxide detector for your home. The most important thing to remember when maintaining detectors in your home is to check them regularly to make sure they are working properly and to change them out when they malfunction. This can help protect you and your family from a fire, harmful carbon monoxide, or other hazard in your home.