What is the effect of too much excess air in a combustion system?

In a combustion system, using too much excess air means that there is more air supplied than what is necessary for the complete combustion of the fuel. This leads to a phenomenon where the additional air carries away a significant amount of heat that could have otherwise been used in the heating process.

When the combustion process includes excess air, the combustion gases that exit through the stack are typically cooler because they are diluted with additional nitrogen from the air, which does not participate in the combustion reaction. Consequently, a larger portion of the generated heat escapes with these cooler exhaust gases, resulting in lower overall efficiency of the heating process.

Utilizing excessive amounts of air also contributes to potential issues within the combustion chamber, such as increased formation of nitrogen oxides (NOx) due to high combustion temperatures caused by the incomplete combustion of fuel. However, in this specific context, the most pertinent effect is the increased heat loss through the stack, which undermines the system's efficiency and effectiveness.