PDF Improve Your Boiler's Combustion Efficiency Energy
(MMBtu) of natural gas while producing 45,000 lb/hour of 150psig steam. Stack gas measurements indicate an excess air level of % with a flue gas minus combustion air temperature of 400°F. From the table, the boiler combustion efficiency is % (E1). Tuning the boiler reduces the excess air to % with a flue gas minus combustion