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How To Replace a Carbon Monoxide Detector

Carbon monoxide can kill you. In every home there should be at least one carbon monoxide detector to determine CO levels and alarm the occupants when CO or carbon monoxide reaches a dangerous point. Every fuel-burning appliance gives off carbon monoxide as a byproduct of combustion. In a properly designed and installed ventilation system carbon monoxide gases are expelled to the atmosphere but system components wear out or become damaged allowing carbon monoxide gases to escape. That is where carbon monoxide detectors come in handy. They sense the presence of carbon monoxide gas and activate an alarm.

There are three basic types of carbon monoxide detectors. Biometric, also known as colorimetric detectors operate on the basis of a detected disc color change. Semi-conductor detectors utilize electronic circuitry to detect the presence of carbon monoxide and trigger an alarm. Safe Air Sentry detectors utilize a chemical process for detection. They are the most efficient but they are also typically very expensive. Carbon monoxide detectors operate with batteries or can be plugged into a wall outlet. There are also hard-wired models with a battery back up. The best bet for carbon monoxide detectors are the combination smoke and carbon monoxide detectors.


Combination smoke and carbon monoxide detectors are the best bet for performance and efficiency

Combination smoke and carbon monoxide detectors are the best bet for performance and efficiency

  1. Carbon monoxide has a specific gravity of .9667 and thus is lighter than air, which has a specific gravity of 1 so carbon monoxide will rise to the ceiling.
  2. So, the most appropriate location for carbon monoxide detectors is near or on the ceiling and close to sleeping areas or bedrooms.
  3. Avoid mounting carbon monoxide detectors near the floor, near or above boilers, furnaces, gas-fired hot water heaters, cooking stoves, freestanding heaters or fireplaces, or within fifteen feet of any cooking or fuel-burning appliance.


  1. If you have purchased a battery operated carbon monoxide detector, you can mount it anyplace that is near a sleeping area. Simply mark the location of the mount bracket, drill two holes and attach the mount bracket to the surface with the supplied screws. If mounting the detector to sheetrock without using wall studs, insert hollow wall anchors through the holes in the sheetrock and drive the mount screws into them.
  2. Wall outlet detectors simply need to be plugged into a wall outlet. They typically recalibrate themselves automatically.
  3. Hard-wired detectors will be mounted to a surface such as a ceiling and connected to a dedicated electrical circuit that originates at the electrical panel.
  4. You will need to run two conductors and a ground from the electrical panel either through the attic or under the floor and route them up to the detector location. Connect one end of one conductor to a circuit breaker in the electrical panel. The second conductor, usually a white one, will be connected to the neutral buss bar in the panel. Connect the ground to the ground bar in the panel.
  5. At the detector location, connect the conductors to the matching leads in the detector with wire nuts or by utilizing the terminals in the detector itself. Be sure to connect the ground in the detector.
  6. Turn the power on at the electrical panel and test the carbon monoxide detector with a test kit to ensure it is hooked up properly and functions as designed.


Maintain your detector in accordance with the manufacturer’s instructions. Most detectors need to be replaced at least every five years, if not more frequently.

Change the batteries in your detector at least twice a year.

Some say to change the sensor in your detector annually. It may be a better solution to simply change the carbon monoxide detector regularly instead.

Be sure to test your detector regularly to ensure that it is functioning properly.

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