Does combustion air always include dilution air?

Combustion air refers to the air that is required to support the combustion process in fuel gas systems. It is essential for the efficient operation of combustion appliances, as it provides the oxygen necessary for the chemical reactions that occur when fuel is burned.

Dilution air, on the other hand, is the air that is mixed with the products of combustion before they are exhausted from the appliance or system. This is often necessary to ensure that combustion gases are adequately dispersed and do not reach harmful concentrations. The inclusion of dilution air can also assist in achieving proper functioning of venting systems, particularly in preventing backdrafts and ensuring that combustion products are expelled safely.

In many systems, combustion air does indeed include dilution air because they often work together to ensure efficient and safe combustion. The air supplied for combustion needs to be balanced with the air that dilutes the exhaust gases to prevent issues like backdrafting, incomplete combustion, and the accumulation of harmful gases. Thus, combustion processes are generally designed to integrate both types of air to optimize performance and safety standards across different applications, regardless of whether they are commercial or residential.