What do we call the air that mixes with flue gases in a draft hood or regulator?

The correct term for the air that mixes with flue gases in a draft hood or regulator is dilution air. This air plays a crucial role in reducing the concentration of potentially harmful flue gases before they are vented into the atmosphere. By diluting the flue gases with fresh air, the overall emissions are minimized, thus promoting better safety and compliance with environmental standards.

The significance of dilution air lies in its ability to enhance the efficiency of the ventilation process in heating systems. It ensures that any noxious gases that may be produced during combustion are sufficiently mixed with fresh air, thereby reducing their toxicity and ensuring safer discharge into the atmosphere.

While combustion air refers specifically to the air that is necessary for the combustion process itself, and intake air generally denotes the air that enters the combustion system, neither of these terms accurately describes the air that specifically mixes with flue gases in this context. Excess air pertains to the air supplied to the combustion process beyond what is needed for complete combustion, which is different from the function of dilution air.