What role does combustion air play in the function of a chimney?

Combustion air is essential for the fire to ignite and continue burning. For proper combustion of fuel, a sufficient supply of air is required. This air, rich in oxygen, combines with the fuel when ignited, producing heat and combustion gases. Without adequate combustion air, fires may burn inefficiently, leading to incomplete combustion and the production of harmful byproducts, including carbon monoxide.

Thus, in the context of a chimney, without the necessary combustion air, the fire could go out or produce insufficient heat, and the flow of exhaust gases could be disrupted. This makes it imperative for a functioning chimney to have a proper and consistent supply of combustion air for effective operation.