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Home Safety: Smoke and Carbon Monoxide Detectors

Oct 29, 2021 | Blog Post

Get your family ready for a safe and cozy winter

The month of October is when we start to hunker down and prepare for the next Minnesota Winter. It is also fire safety month, because winter is when we see most home fires in Minnesota. As a part of fire safety, it’s important to make sure both your smoke and carbon monoxide (CO) detectors are current, have fresh batteries, and are placed correctly throughout your home. These topics aren’t exactly something that comes up often in casual conversation, so don’t fret if you’re feeling a bit lost – that’s we’ve got it covered! 


Smoke Detectors

Most folks are passing familiar with smoke detectors. In fact, it’s safe to assume most people have tripped them with some well-done toast or a molten wad of pizza cheese lodged at the back of the oven.

But did you know that there are two different technologies available for smoke detectors? 

The first technology is the ionization-type alarm, which is far more responsive to flaming fires. According to the National Fire Safety Association (NFSA), this type of alarm has “a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm.”

The second technology is the photoelectric-type. These are better at detecting the slow smoulder fires. The NFSA explains: “Photoelectric-type alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm.”

Which kind of smoke detector should you have in your home? The answer is: both, since some fires start with a flash and keep going, and others build from a slow smoulder. The good news is there are smoke detectors out there that have combination ionization and photoelectric technology! 

Carbon Monoxide Detectors

Carbon Monoxide is an invisible killer. It’s an odorless gas that displaces oxygen in the air as well as in the bloodstream.  Symptoms of Carbon Monoxide poisoning can include headaches, dizziness, fatigue, mental confusion, vomiting, loss of consciousness. Ultimately, too much exposure will lead to death.

Since carbon monoxide is a by-product of combustion, gas powered furnaces are the primary culprit for carbon monoxide exposure in the home. CO detectors work by utilizing an electrochemical sensor. Electrodes in a chemical solution sense changes in electrical currents when they come into contact with carbon monoxide. This change triggers the alarm.

Combination Detectors

There are now a great many combination CO and Smoke Detectors on the market, so if you  have spaces where both are needed – such as the  hallway of a sleeping area – you can take care of both needs in one unit. 

Combination Smoke and Carbon Monoxide Detector
Combination Smoke and Carbon Monoxide Detector


Smoke Detectors

Smoke detectors should be placed on every level of the home, including the basement. Working from bottom to top and in-between, smoke detectors should be placed:

  • In the basement on the ceiling at the bottom of the stairs leading to the next level.
  • In the living room (or den or family room) or near the stairway to the upper level, or in both locations.
  • Inside each bedroom
  • Outside each sleeping area 
  • At least 10 feet (3 meters) from a cooking appliance to minimize false alarms when cooking.


Smoke alarms should be mounted high on walls or on ceilings, since smoke rises. Wall-mounted alarms should be installed not more than 12 inches away from the ceiling (to the top of the alarm).

On pitched ceilings, install the alarm within 3 feet of the peak, but at least four inches down from the peak.

Carbon Monoxide Detectors

Since Carbon Monoxide is slightly lighter than air, and often found with warm, rising air, CO detectors should be mounted on the wall about five feet above the ground. It is also acceptable to ceiling-mount CO detectors. Detectors should be placed:

  • On each floor
  • Within 10 feet of sleeping areas
  • Away from appliances and fireplaces with open flames.

Checking your detectors

Expired Detector Joke


Changing out batteries in smoke and CO detectors is a lot like flossing – we all know we should do it regularly, but… do we, really? It should be done at least once a  year and immediately when the low battery warning sounds.

The worst-case scenario was almost realized when a family woke to their CO detector sounding the low battery alarm. The exhausted parents removed the battery and went back to sleep. Days later, one-by-one members of the family started to feel dizzy and experience headaches. The call to emergency services went out just in the nick of time.

It can be hard to remember to do something that you don’t think about for months at a time, so here are some helpful tips to keep on top of this chore:

  • Put it on your calendar. Digital, print, whatever works for you.
  • There are a variety of secular and sacred holidays in the autumn – pick a holiday that is always the day you swap out batteries.
  • Place a note on top of the winter jackets when you put them away in the  spring reminding you to change your detector batteries when you pull the jackets back out in the fall.

Expiration Date

Did you know that smoke and carbon monoxide detectors can expire? They do! Every detector comes with a date of manufacture stamped on the back. Yes, I’m sorry – there’s math involved. Just subtract ten years from the date you check the detector, and if the date of manufacture is older than that, it’s time to replace. Make checking this date part of your yearly routine.

Check out the video below for creative uses for expired detectors!

Expiration Date on a Smoke Detector
Check the date of manufacture!