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How to Test Your Carbon Monoxide Detector: A Denver Electrician Explains

So, there are 2 different ways to “test” your carbon monoxide detector. You can test it for:

  1. Battery/electrical power: Is the detector getting enough power to sound off in the presence of CO?
  2. Functionality: Is the detector properly detecting CO in the first place?

So, really, the way that you test your detector depends on what you’re trying to test. We’ll walk you through the steps for both tests below.

Want a professional to test or replace your CO detector?

Testing for battery/electrical power? Follow these steps

  1. Locate your CO detector(s).
    In Colorado, code requires that you have a CO detector placed “near” any room that has a fuel-burning heater/appliance or fireplace and within 15 feet of any sleeping room. If you have an attached garage, you should have a CO detector installed there as well. See specific code details regarding CO detector placement in Colorado here.
  2. Hold down the test button until the detector beeps.
    The test button should be located on the front of the detector and is usually labeled “test/reset”. The beeping should be loud enough to hear throughout the house.
  3. Repeat step #2 for every CO detector in your home.
    If you find that one or more CO detectors don’t beep when you hold the test button down, try changing out the batteries.

    If the unit still isn’t beeping after you’ve changed out the batteries, you may need to replace the unit or you may have an electrical issue (if the unit is hardwired).

Testing for functionality? Follow these steps

  1. Locate your CO detector.
    Determine if you have a CO detector with a digital display. If so, continue to step #2. If not, skip to step #3.
  2. Wave a lit incense stick 8 inches from the CO detector.
    This is a good way to test CO detectors with digital displays because these detectors can detect and read very low levels of CO (like those produced by an incense stick). So, when you wave the incense stick, watch the digital display for any change in reading.
  3. Purchase and use a CO detector testing kit.
    Don’t worry, these kits typically aren’t too expensive. You can find them online for under $10. The kits provide a device that encircles the alarm and a gas container that holds a high concentration of CO gas. You spray the gas into the device containing the detector.

    After 5-10 minutes, if the detector is working properly, it will sound an alarm (be prepared as the alarm will be very loud).

    Note: Step #2 only tests for very low, safe levels of CO and doesn’t test whether your unit can sound an alarm quickly in the event of higher, more dangerous levels of CO. Additionally, step #3 only tests for very high amounts of CO levels.

Need help? Ask a Denver electrician

Whether you want to test your unit or think your CO detector needs to be replaced, our expert electricians can help.

Need help from a Colorado Plumbing, Heating, Cooling, or Electrical Specialist? 

For your convenience, you can request an appointment in one of two ways:

  • Call us at (303) 436-2525 for immediate assistance.
  • Click on the button below to schedule your appointment online.


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