Deadly Carbon Monoxide - How To Do Venting Test. A simple method to test your gas water heater or gas appliances. Carbon monoxide could and can be deadly. This is only a test if you don't have a CO detector in your home. Warning ! this test is NOT to measure the exact amount or how much CO or CO2 is in your home and should not be relied on for safety. A Carbon Monoxide Detector should be used in your home. This Test is only a guide to show if the airflow in your venting system is working correctly. And please if in doubt or not sure what you are doing please call a certified repair company on this. Thank you for watching and please check out some of my older videos. Peace to all of you.