Furnaces are used in refineries and petrochemical plants to break down hydrocarbon fluids, converting them into fuels or chemicals such as gasoline, diesel, ethylene, and propylene. Furnaces can account for more than 50% of the total plant energy consumption, therefore small improvements in efficiency could have large financial returns. Continuously evolving federal and local environmental laws mandate refineries and petrochemical plants to carefully monitor and reduce cumulative CO & NOx emissions. The effects of controlling fuel consumption, flame shape, excess O2, CO & NOx emission are well understood. Often overlooked are the gains associated with better draft control by utilizing accurate stack damper control.