As the amount of excess air increases, what happens to heat?

When the amount of excess air increases in a combustion process, it can lead to more heat being carried away through the flue to the outdoors. This occurs because excess air can dilute the combustion gases, resulting in lower combustion temperatures. The additional air enhances the heat losses by carrying away more heat with the flue gases.

In an ideal combustion scenario, the amount of air would be balanced to provide just enough oxygen for the complete combustion of the fuel, thereby maximizing efficiency. However, as excess air increases, it not only reduces the temperature of the combustion products but also leads to an increase in the volume of flue gases, which further carries away more heat.

This concept is crucial in HVACR where optimizing combustion efficiency is essential for ensuring systems operate within their specified ranges and perform effectively.