What does CO stand for in furnace flue gas measurements?

In the context of furnace flue gas measurements, CO stands for Carbon Monoxide. This is a critical component to monitor in heating systems because it is a colorless, odorless gas that can be harmful or even fatal in high concentrations. Carbon Monoxide is produced during incomplete combustion of fossil fuels, including natural gas, propane, and heating oil, which are commonly used in heating systems.

Maintaining proper combustion efficiency in a furnace is essential to minimize the production of Carbon Monoxide and ensure safe operation. Thus, monitoring CO levels helps technicians assess the performance and safety of the heating system. In contrast, the other substances listed in the choices either do not relate to furnace flue gas measurements or do not have the abbreviation CO in their standard chemical nomenclature.