Install the 9-volt backup battery into the unit -- this will be used in the event of a power outage. Lay the alarm face-down on a flat surface. Press the battery door lock in and swing the door open. Pull the battery connector slightly out of the compartment for better access. Snap the 9-volt battery into the connector, making sure to match the polarity as indicated. Place the battery and connector back into the compartment and replace the battery door, press on the door until the lock clicks.
Decide on the best location for your carbon monoxide alarm. Choose a place that is close to the bedrooms. If there is more than one level in your home, or the bedrooms are far apart, install additional alarms to protect the entire house. Place one of the adhesive labels on the alarm and add the phone number to your local emergency provider. Place the other adhesive label next to the front door with an emergency number.
Set the alarm on a table or flat surface. Plug the power cord into an electrical outlet. Allow the alarm to properly warm up. You will see either a flashing red dot, or "888" flashing on the display screen indicating that the alarm is on and warming up. In 20 seconds, the display screen will read "0."
Test the alarm to make sure it is working properly. Press and release the "Test/Reset" button. After 15 seconds, there will be four quick beeps followed by five seconds of silence. The alarm will sound four more quick beeps -- you should be able to clearly hear the alarm in the event of an emergency. This indicates that the alarm is set and working. Press the "Test/Reset" button to turn the alarm off and reset it after it sounds.
Press the "Peak Level" button to display the highest reading of carbon monoxide in a home.