What causes carbon monoxide to be produced in gas furnaces?

The production of carbon monoxide in gas furnaces is chiefly attributed to incomplete combustion of gas. When natural gas or propane is burned, it ideally combines with oxygen to produce carbon dioxide and water as byproducts. However, if the combustion process is not complete—due to insufficient oxygen supply, improper burner alignment, or other factors—carbon monoxide, a dangerous byproduct, can be formed instead.

This is a significant safety concern, as carbon monoxide is a colorless, odorless gas that can accumulate in enclosed spaces and pose serious health risks. Ensuring proper combustion by maintaining adequate airflow and optimizing burner function is essential to minimizing carbon monoxide emissions in gas furnaces.

The other options, while they may contribute to broader operational issues, do not directly lead to the formation of carbon monoxide in the same primary manner as incomplete combustion does. For instance, excess moisture can affect combustion efficiency but is not the fundamental cause of carbon monoxide production. Similarly, a faulty ignition system and blocked exhaust venting can lead to other performance problems but are not the main contributors to incomplete combustion that specifically results in carbon monoxide.