What is flue gas?

Flue gas is the mixture of gases produced by the combustion of fuel, which typically includes a variety of products depending on the fuel type. When fuels such as natural gas, propane, or oil are burned, they release gases that can include carbon dioxide, water vapor, nitrogen oxides, and potentially harmful substances like carbon monoxide. Understanding flue gas is crucial for ensuring compliance with safety and environmental regulations, as well as for assessing the efficiency of heating systems.

The other options suggest alternative interpretations of gases associated with cooking or heating, but they do not accurately describe the complex mixture that results from combustion processes. For instance, cooking gases are specifically processed for household energy needs, while the notion of a natural gas byproduct having no environmental effects is misleading, as all combustion processes release some form of emissions that can impact air quality. Heating water in residential units typically utilizes a fuel source, which would also produce flue gas during combustion.