CARBON MONOXIDE (CO) ALARMS
Table of Contents
CARBON MONOXIDE (CO) ALARMS
CO Alarm Safety
Why it matters
Carbon monoxide (CO) is a poisonous gas that you cannot see, taste, or smell. Because it is completely invisible, exposure can seriously injure or kill you before you even realize what is happening.
What to know
Often called the “invisible killer,” carbon monoxide can build up in homes with fuel-burning equipment or attached garages. CO alarms and smoke alarms do different jobs; you must have both to stay completely protected. Your CO alarms are your only early warning system so you can get to fresh air and call for help before symptoms become severe.
Do this now
- Check your alarms
Walk your home to ensure you have a dedicated CO alarm (or a combination smoke/CO alarm) installed within 15 feet of every bedroom and on every level of your home (including the basement). - Check the date and learn the beeps
Find the “replace-by” date printed on the back of the device, or the manufacturer’s user guide so you know when it expires, and learn how its emergency beeps sound distinctly different from your smoke alarms. - Test today
Press the test button to ensure the alarm has power and you recognize its specific sound. - Learn the symptoms
Know that CO poisoning symptoms (like sleepiness, dizziness, nausea, headache, and coughing) can easily look like the flu. Trust the alarm.
Don’t
Don’t assume you will wake up to the smell of smoke. Toxic smoke puts you into a deeper sleep; a loud alarm is your only reliable warning.
Alarm Types
Why it matters
Carbon monoxide alarms come in different power styles and combination units. Choosing the right type ensures your device works during power outages and complies with Illinois law.What to know: You have choices for how your carbon monoxide alarms are powered. You can also purchase combination units that detect both smoke and CO, but state law requires these to use distinctly different alarm sounds so you know exactly which hazard is present.
Illinois State Law Requirement
Since January 1, 2007, Illinois law requires carbon monoxide alarms in any home that uses fossil fuels (such as a gas furnace, gas stove, or gas water heater) or has an attached garage.
What this means for you:
- Where to put them
You must install an approved CO alarm within 15 feet of every bedroom door. You must also have at least one on every level of a multi-level home (including basement). - Exemptions
You do not need a CO alarm if your home meets all three of these conditions: 1. Entirely electric (does not burn fossil fuels for cooking, heat, or hot water). 2. Not connected to a garage in any way. 3. Not close to any outside sources of carbon monoxide.
Do this now:
- Measure the distance
Confirm you have a working CO alarm within 15 feet of every bedroom door. - Check every level
Ensure you have a working CO alarm on every level of your home (including the basement). - Check your power type
Look at your current alarms so you know exactly what maintenance they require, especially making sure that plug-in and hardwired models have fresh backup batteries. - Check the date and learn the beeps
Find the “replace-by” date printed on the back of the device so you know when it expires, and learn how its emergency beeps sound distinctly different from your smoke alarms
Don’t
Don’t ignore the end-of-life signal. CO alarms do not last forever. If the alarm chirps to tell you it has expired, replacing the battery will not fix it (especially if you have a 10-year sealed model). Do not take the battery out to silence it; you must replace the entire alarm to stay protected.
Type Overview
Replaceable-Battery Alarms
Why it matters
Battery-powered CO alarms are easy to install exactly where you need them without worrying about open electrical outlets.
What to know
These alarms run entirely on batteries. Just like smoke alarms, their sensors wear out over time. Because they don’t plug into the wall, they rely 100% on you keeping fresh batteries inside them.
Do this now:
- Test
Press the test button once a month. - Change batteries
Replace the batteries at least once a year (unless it is a 10-year sealed model). - Replace at end-of-life
Check the date on the back and replace the entire unit when it expires.
Don’t
Don’t remove the batteries. It is illegal in Illinois to tamper with or remove CO alarm batteries. If the alarm chirps, replace the batteries or the entire unit immediately.
10-Year Sealed Battery Alarms
Why it matters
These alarms prevent the most common reason battery-powered alarms fail: dead or missing batteries.
What to know
These alarms use a built-in, “long-life” battery designed to last for the entire life of the device (often up to 10 years). You never have to change the battery, but the sensor still wears out over time. When the alarm reaches the end of its life, it will begin to chirp, and you must replace the entire unit.
Do this now:
- Test
Press the test button once a month to ensure the sealed battery is still powering the device. - Change the date
Look at the “replace-by” date on the back of the device so you know what year it will expire. - Replace at end-of-life
Replace the entire alarm immediately when the end-of-life chirp begins.
Don’t
Don’t try to open the alarm. Never try to pry the alarm open to replace the sealed battery. When the battery dies or the unit expires, you must replace
Plug-in Alarms with Battery Backup
Why it matters
Plug-in alarms are convenient, but they will fail during a power outage if you forget to maintain their backup battery.
What to know
These alarms plug directly into a standard household wall outlet. Because power outages are a major risk for CO poisoning (due to people running generators or alternative heaters).
Do this now:
- Secure the plug
Make sure the alarm is plugged into a wall outlet that is not controlled by a light switch so it cannot be accidentally turned off. - Test
Press the test button once a month. - Change the backup battery
Check and replace the backup battery regularly so the alarm is ready for the next severe storm or power outage.
Don’t
Don’t rely entirely on the wall plug. Never use a plug-in CO alarm with a dead or missing backup battery.
Hardwired Alarms
Why it matters
Hardwired alarms connect directly to your home’s electricity, but just like plug-in models, they rely on a backup battery to keep you safe when the power goes out.
What to know
These alarms are wired into your home’s electrical system and are often interconnected (so when one sounds, they all sound). Illinois law mandates that hardwired CO alarms must include a secondary battery backup.
Do this now:
- Test
Press the test button once a month. - Change the backup battery
Replace the backup battery at least once a year. - Replace at end-of-life
Replace the entire unit when it reaches its expiration date.
Don’t
Don’t assume hardwired alarms last forever. Even though they are wired into your home, the sensors still wear out. The entire unit must be completely replaced based on the manufacturer’s user manual.
Placement
Where to Install
Why it matters
Because carbon monoxide can spread anywhere in the home, you need alarms placed where they will successfully wake you up from a deep sleep.
What to know
To comply with state law and ensure you wake up during an emergency, CO alarms must be placed near sleeping areas, on every level of the home, and kept away from areas that cause false alarms. Do not install a CO detector near your kitchen or garage, or in a room with a furnace.
Do this now
- Measure the distance
Confirm you have a CO alarm within 15 feet of every bedroom door. - Check every level
Ensure you have a working CO alarm on every level of your home (including the basement). - Relocate if needed
Move alarms away from kitchens, garages, or furnace rooms to prevent false alarms.
Don’t
Don’t run engines or burn fuel inside. Never heat your home with a gas range or oven, never burn charcoal inside your home or garage, and never run a combustion engine (like a car, lawn mower, snow blower, or generator) in enclosed areas.
Maintenance
Testing & Replacement
Why it matters
An expired CO alarm cannot protect you from this invisible gas.
What to know
Carbon monoxide sensors degrade over time. Unlike smoke alarms, which have a standard 10-year lifespan, CO alarms vary based on the brand and model. Many need to be replaced after 5 to 7 years, some after 10 years.
Know your specific alarm
Always read your manufacturer’s user manual or search it online to know exactly how long your alarm is designed to last and when it expires. Also, check the “replace-by” date printed on the back of the device.
Do this now
- Test
Press the test button on your CO alarms once a month to ensure they are working. - Check the date
Find your alarm’s manufacture date or “replace-by” date printed on the device. - Set a reminder
Replace the entire unit according to the manufacturer’s instructions or when the end-of-life signal sounds.
Don’t
Don’t remove the battery. Never take the battery out of your CO alarm to stop a chirp. If it chirps, check the date on the back and either replace the battery or replace the entire expired unit immediately. CO alarms do not last forever, sensors go bad.
What the Beep Means
Why it matters
Because you cannot see or smell carbon monoxide, your survival depends entirely on reacting immediately when the alarm sounds. Knowing the exact difference between a smoke alarm, a CO alarm, and a dying battery tells you exactly how to save your life in those critical first seconds.
Important Disclaimer
Know Your Specific Alarm. Exact beep and chirp patterns vary by brand and model. By law, combination smoke/carbon monoxide alarms must sound different for a fire hazard versus a CO hazard. While many standard CO alarms use a four-beep pattern, you must always read the label on the back of your unit or check your manufacturer’s user manual so you know exactly what your specific alarm is programmed to tell you.
What to Know
While standard smoke alarms usually sound three loud beeps, many standard CO alarms use a different pattern: four loud beeps and a pause. If your alarm sounds a loud, continuous emergency pattern, you must assume dangerous levels of carbon monoxide are actively filling your home. Alternatively, a single periodic “chirp” is a maintenance signal for a dying battery, malfunction, or expired unit.
Do this now
- Learn the sound
Press the test button on your CO alarm today so your whole family knows exactly what its emergency pattern sounds like. - Evacuate for the emergency alarm
If you hear the loud repeating emergency alarm, move everyone (including pets) to fresh air outside right away. - Call 911 and stay outside
Call 911 or the local fire department from outside in the fresh air. Do not go back inside until emergency personnel evaluate the home and specifically tell you it is safe. - Fix chirps fast
If the alarm sounds a single chirp, check the manufacture date and replace the battery (unless it has a 10-year sealed battery) or replace the entire expired alarm immediately.
Don’t
- Don’t wait to see how you feel.
Because CO poisoning symptoms like sleepiness, headache, dizziness and nausea mimic the flu, never wait for someone to feel sick before reacting to the emergency alarm. Trust the alarm, get outside immediately, and call 911 - Don’t open windows to “air it out.”
Opening windows before calling 911 puts you in danger by keeping you inside longer, and it removes the gas that firefighters need to trace in order to find the deadly leak.
Special Situations
Accessibility & False Alarms
Why it matters
Every person in your home must be able to wake up to the alarm, regardless of their hearing ability. Additionally, if your CO alarm constantly goes off due to poor placement, you may start ignoring the alarm, which can be deadly.
What to know
- Accessibility
Standard high-pitched CO alarms may not wake people who are deaf, hard of hearing, or who are heavy sleepers. Specialized alerting devices are available to ensure everyone is warned. - False Alarms
A CO alarm can trigger a false alarm if it is placed too close to an appliance that safely burns fossil fuels. To prevent this, CO alarms should never be installed near your kitchen or garage, or inside a room with a furnace.
Do this now
- Adapt for hearing
If someone in your home has trouble hearing standard alarms, install visual strobe lights, vibrating pads, bed shakers, or low-frequency tone alarms in their sleeping area. - Relocate for false alarms
If your CO alarm frequently sounds when you pull a vehicle into the garage or use your stove, move the alarm further away from those areas to comply with the manufacturer’s placement instructions.
Don’t
Don’t unplug the alarm to stop the noise. Disconnecting or removing the batteries from a CO alarm removes your only protection from deadly Carbon Monoxide. If you are getting false alarms, relocate the device; never disable it.