What test should be performed to verify that CO is not leaking into living spaces?

• A. Visual inspection of the venting.
• B. Use a CO detector test and, if possible, a post-start combustion analysis to ensure CO levels are within safe limits.
• C. Check the flame appearance only.
• D. Measure duct static pressure.

Answer: (B)

CO is colorless and odorless, so the safest way to confirm it isn’t leaking into living spaces is to directly monitor ambient CO and verify proper combustion and venting. A CO detector test checks the actual environment, ensuring there are no elevated CO levels where people live. If possible, a post-start combustion analysis should be performed as well; this tests the appliance’s exhaust gases right after ignition to confirm combustion is clean and the venting path is working, meaning CO production is minimized and properly vented. Visual checks of venting or flame appearance can miss hidden leaks, and measuring duct static pressure doesn’t assess CO presence. Together, these tests provide direct evidence that CO is not entering living spaces and that the appliance is operating safely.