Abstract: Devices and methods for adjusting the physical properties of air used in the combustion of carbon based fuels are described. Parameters such as air temperature, pressure and moisture content are adjusted before the air is delivered to a combustion chamber of devices such as furnaces, boiler and the like. The physical properties of the air may be are adjusted such that a predetermined amount of oxygen and/or water are delivered to the combustion chamber. In one embodiment the amount of oxygen and/or moisture delivered by the intake air is optimized to increase the efficiency of the carbon fuel burned in combustion and/or to minimize the production of compounds such as NOX SO2, CO, CO2 and the like.