Much of the heat produced by fuel combustion is unavailable for productive use. Figure 1 shows the flow of product and heat for a typical process. Previous columns showed that hot offgas contains much of the combustion heat, while a lesser but still significant amount is lost through the walls of the furnace.[1,2] Only the remaining heat is available for raw-material processing. A main objective of combustion management is to maximize the available heat. Here, we define the gross available heat is the heat of combustion minus the heat carried out in the offgas, while the net available heat is the gross available heat minus the heat loss. Both are expressed as a percent of the combustion heat.