How do I know if my fire alarm detects carbon monoxide?

Author: Lexus Moore  |  Last update: Tuesday, July 1, 2025

In our latest video, we asked the National Fire Protection Association what the noises mean and how to stay safe from fires and carbon monoxide. Here's a simple guide: Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps.

Does my fire alarm detect carbon monoxide?

Fires can produce carbon monoxide, so a smoke alarm won't always detect this gas. On the other hand, carbon monoxide can be present without any visible smoke or flames, making a smoke alarm insufficient for protection.

How to know if a smoke alarm is going off for carbon monoxide?

Smoke alarms typically sound with 3 beeps in a row, while carbon monoxide detectors usually sound with 4 beeps. Press and hold the button on the front of the detector to test the alarm, and make note of how many beeps it produces.

What will my alarm do if it detects carbon monoxide?

When the carbon monoxide alarm senses a dangerous level of CO gas, the unit will emit a loud alarm pattern. The alarm pattern is four short beeps – followed by five seconds of silence – followed by four short beeps.

How can I be sure my carbon monoxide detector is working?

How to test your carbon monoxide detectors to ensure they are working properly? To test your carbon monoxide detectors, press and hold the test button on the alarm. The detector will sound 4 beeps, a pause, then 4 beeps for 5-6 seconds. Refer to the user manual for your specific model.

Know the Difference between the Sounds of Your Smoke Alarms and Carbon Monoxide Alarm

Does the fire department charge to check for carbon monoxide?

In most areas, the fire department does not charge to respond to carbon monoxide alarms or to check for the presence of CO in a residence. However, policies can vary depending on the jurisdiction or specific fire department. It's always a good idea to contact your local fire department for specifics on their policies.

What are two warning signs of carbon monoxide poisoning?

The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” If you breathe in a lot of CO, it can make you pass out or kill you.

What if the carbon monoxide alarm goes off but no fire?

False or nuisance alarms are when your smoke detector or CO alarm goes off, but there is no presence of smoke or carbon monoxide in your home. However, if your smoke or carbon monoxide detector sounds indicating an emergency and you are not certain it is a nuisance alarm, evacuate the home and call 9-1-1.

How much carbon monoxide before alarm goes off?

"According to UL Standard 2034, home carbon monoxide detectors must sound a warning before carbon monoxide levels reach 100 parts per million over 90 minutes, 200 parts per million over 35 minutes or 400 parts per million over 15 minutes.

How to tell if carbon monoxide is in your house?

It is also a good idea to know the signs of a potential CO problem:
  1. Streaks of soot around fuel-burning appliances, or fallen soot in a fireplace.
  2. Absence of an upward draft in your chimney.
  3. Excess moisture and condensation on windows, walls and cold surfaces.
  4. Rusting on flue pipes or appliance jacks.

Should I be worried if my smoke alarm goes off for no reason?

Sometimes, smoke detectors will keep going off for no reason when they have reached the end of their life span. Fire alarms have a lifespan of about 10 years, after which they will need to be replaced. Smart smoke detectors can help eliminate some of the annoyances related to false alarms.

What to do if a carbon monoxide alarm goes off and then stops?

If you have a carbon monoxide detector chirping and then it stops, it's important to take the situation seriously, even if the alarm is no longer sounding. Even if the alarm has stopped, get everyone out of the home to a place with fresh air.

Would a carbon monoxide alarm go off in a fire?

Carbon monoxide alarms do not detect fire, so you should make sure you also have a working smoke alarm on every level of your home.

Why did my fire alarm randomly go off in the middle of the night?

Why did my fire alarm randomly go off in the middle of the night? This is likely due to one of the common causes like low battery, dirt buildup, humidity, or insects interfering with the sensor. Test the alarm and clean it thoroughly to try and resolve the issue. Make sure batteries are fresh and secure.

Why is my fire detector blinking red?

Your alarm manufacturer may have included a blinking red light to let you know it's time to test the alarm again. The Batteries are Low: Usually accompanied by a loud beep, a blinking red light could mean the batteries in the unit are low. Consider adding fresh batteries and running a test to make sure it's working.

How do I know if my fire alarm is going off for carbon monoxide?

In our latest video, we asked the National Fire Protection Association what the noises mean and how to stay safe from fires and carbon monoxide. Here's a simple guide: Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps.

Will opening a window help with carbon monoxide?

If you experience symptoms that you think could be from CO poisoning: DO GET FRESH AIR IMMEDIATELY. Open doors and windows, turn off combustion appliances and leave the house.

How to tell if your smoke detector is also a carbon monoxide detector?

CO alarms and combination CO alarms are always clearly labeled even though many smoke detectors are not. Another way to verify whether your devices can detect both CO gas and smoke is by pressing their test buttons. Modern, hard-wired units will issue verbal alerts such as “Warning!

How to test a carbon monoxide alarm?

How to test a carbon monoxide detector:
  1. Hold the “test” button until you hear two beeps sound off.
  2. Once you hear these beeps, release your finger off the test button.
  3. Repeat this process but hold the test button until you hear four beeps.

How do you know if there is carbon monoxide without a detector?

Signs of a carbon monoxide leak in your house or home

Sooty or brownish-yellow stains around the leaking appliance. Stale, stuffy, or smelly air, like the smell of something burning or overheating. Soot, smoke, fumes, or back-draft in the house from a chimney, fireplace, or other fuel burning equipment.

Who can test my home for carbon monoxide?

Some municipal fire departments and utility companies will come to your home and check for carbon monoxide for free or at reduced rates. The main tool used in these tests is an electronic portable toxic multi-gas monitor.

Do fire alarms pick up carbon monoxide?

But even though you have a comprehensive smoke detection system, it isn't enough to protect against the threat of carbon monoxide. Carbon monoxide is an odorless, tasteless, and invisible gas that can make inhabitants sick or even lead to death.

How much does it cost to get your house checked for carbon monoxide?

Professional carbon monoxide testing can cost from $100 to $200+. But, most homeowners usually have carbon monoxide detectors which can range from $20 to $150+, according to Home Advisor, depending on the detector type.

How do firemen check for carbon monoxide?

Using Carbon Monoxide Meters to Detect and Monitor Carbon Monoxide Levels. The Sensorcon Inspector is a trusted tool used by firefighters and emergency medical technicians in detecting and identifying the source of carbon monoxide (CO) during fire and rescue activities.

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