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How to test carbon monoxide detection in a combination smoke detector?

Learn how to safely test the carbon monoxide detection function in your combination smoke detector. Follow these easy steps to ensure your home stays protected.

Reviewed by Content Team

Head of Content, D. Gorenko

Updated June, 5

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How to test carbon monoxide detection in a combination smoke detector?

 

Understanding Your Device: Confirm It's a Combination Detector

 

Before testing the carbon monoxide (CO) detection feature of your combination smoke and CO detector, ensure that your device indeed combines both functionalities. Combination detectors typically have clear labeling or indicators on their face or packaging stating they detect both smoke and carbon monoxide. Review the user manual provided by the manufacturer carefully to verify the presence of this dual capability.

 

Use the Manufacturer-Test Button for a Preliminary Check

 

Combination smoke and carbon monoxide alarms include a standard 'test' button to ensure basic electrical function. Pressing and holding this button for several seconds should produce a loud sound, triggering both the smoke and carbon monoxide audible signals sequentially. Listen carefully to distinguish two different alarm tones: smoke alarms usually sound with a series of rapid beeps, while carbon monoxide warnings often produce a continuous set of short or longer continuous beeps. Check the alarm’s instruction manual for specific beep patterns or voice warnings relevant to carbon monoxide.

 

Testing Carbon Monoxide Detection Functionality: Specialized CO Tester Kits

 

While the test button confirms electrical functionality, it doesn't fully validate the sensor's reaction to actual carbon monoxide gas. To thoroughly test carbon monoxide functionality, it's advisable to utilize a specialized carbon monoxide detector testing spray or canned CO test gas, which simulates the conditions under which your detector would sense real carbon monoxide.

For accurate and safe testing, follow these detailed guidelines:

  • Purchase a professional-grade carbon monoxide detector tester spray or canned CO tester gas. These products are readily available online, in home improvement stores, or from safety supply providers.
  • Read and follow all safety instructions provided by the test gas manufacturer very carefully.
  • Position yourself directly under or next to the CO detector, and spray the tester gas gently toward the sensor from approximately six inches distance for the recommended duration indicated on the product’s instructions (usually 15–20 seconds).
  • Wait and observe carefully; the detector should respond within several seconds to a minute or two after exposure to the gas, sounding its specific carbon monoxide alarm audible and/or voice warning clearly and distinctly.
  • If no response is observed within the period established by the tester manufacturer's guidelines, repeat the test carefully once more. Continued absence of response means your detector may have a fault or expired sensor requiring immediate replacement.

Never test carbon monoxide detection using car exhaust, combustion appliances, or household CO sources; these sources pose serious health hazards during testing.

 

Maintenance and Resetting After Testing

 

After testing is complete, open windows in the test area momentarily to dissipate test gases effectively. Your detector may require reset procedures outlined in the manual. Typically, the device automatically resets after sensing clean air or after you press the reset button for several seconds. Ensure the device status properly returns to 'Ready' or 'Normal' operation conditions after testing.

Testing should take place regularly, typically each month, to ensure that the device is working optimally and your house stays safe.

 

Replacing the CO Detector According to Manufacturer Guidelines

 

Carbon monoxide sensors do expire over time, often needing replacement every five to seven years, depending on the manufacturer's recommendations printed within your manual or on a sticker on the detector itself. If the device fails to respond during a test or if the designated expiration date has passed, promptly replace the unit with a new one to maintain protective coverage.

 

When Additional Help May Be Needed

 

While routine testing is often straightforward, situations occasionally arise where professional advice and assistance are beneficial. If your combination CO and smoke detector repeatedly fails testing or raises other concerns, contacting a professional is advisable. Expanding residential and commercial properties in cities like St Louis and Nashville often benefit significantly from professional maintenance as part of a comprehensive safety strategy.

Routine professional maintenance can include:

  • Inspection and thorough cleaning of detectors and sensors
  • Expert evaluation and replacement of expired or faulty detectors
  • Advice on ideal placement for carbon monoxide detectors within your home or commercial building to properly address safety and building codes

Remember, periodically verifying carbon monoxide detection within your combination detector is critically important for the safety and health of yourself, family members, visitors, and those around you.

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