Smoke Alarms and Carbon Monoxide Monitors - How They Work and Why They Matter

7/1/2021

Smoke alarms and carbon monoxide detectors are essential for the early detection and mitigation of common home hazards. Inexpensive and easy to maintain, these alarm systems should be a part of every home.

There’s a lot of questions about how these systems work, where they should be and how to maintain them. This post will walk you through both of these alarm systems to ensure your home is safe. We recommend creating a home escape plan with your family to ensure members know what to do in case of hazards.

Smoke Alarms

More than half of home fire related deaths occur when occupants are asleep and are unaware of the fire. Smoke alarms give families the precious time needed to exit the home, saving many lives every year.

Two types of smoke alarms are present in most homes: 

  • Photoelectric detectors work by shooting a laser beam at a sensor, and go off when smoke particles disrupt this beam from hitting the sensor. 
  • Ionization detectors, more common in US households, react to the change in electrical current from smoke particles neutralizing ions in a radioactive chamber. 


Regardless of detector type, these should be placed on every level of your home, outside sleeping areas and inside bedrooms. Photoelectric detectors may be better in your kitchen due to their tendency to produce less nuisance alarms in reaction to cooking. Alarms should be placed on your ceiling, or near the ceiling if placed on a wall. Avoid locating alarms near windows, bathrooms and heating appliances.

Despite being connected to your home’s power mains, smoke alarms often depend on a battery backup in case power is lost during a fire. Batteries should ideally be changed twice a year- many people use daylight savings as a reminder to change the batteries in their smoke alarms. All smoke alarms should be tested once a month, and be replaced when they are more than 10 years old. 

Carbon Monoxide Monitors

Carbon monoxide is an odorless and colorless gas that is poisonous to humans. Known as the “silent killer”, this common hazard makes alarms a necessity in all homes. Carbon monoxide detectors are essential for keeping your home safe and detecting hazardous levels of this gas.

There are three common types of carbon monoxide monitors:

  • Electrochemical sensors sense changes in electrical current when it comes into contact with carbon monoxide.
  • Biomimetic sensors have a gel that changes color after absorbing carbon monoxide, triggering the alarm. 
  • Metal oxide conductors use a silica chip to detect and trigger the alarm. 


Carbon monoxide detectors should be placed near each bedroom or sleeping space and by doors leading to attached garages. There should be at least one detector on every level of your home.

These alarms take time to go off as monoxide levels build to detectable levels. It’s important to act quickly and get outside when an alarm sounds as low concentrations are still dangerous.

These alarms should be tested monthly to ensure working operation. Alarm batteries should be changed bi-annually like smoke detectors, and alarms should be replaced every 5 to 7 years.

Both alarm systems should be present in every home and tested on a schedule. Bundl Home includes alarm testing and battery replacement as a part of our seasonal handyperson maintenance checklist. Learn more about Bundl Home’s subscription packages here.