AAON, Inc. is engaged in the engineering, manufacturing, marketing and sale of air conditioning and heating equipment consisting of standard, semi-custom and custom rooftop units, chillers, packaged outdoor mechanical rooms, air handling units, makeup air units, energy recovery units, condensing units, geothermal/water-source heat pumps and coils. Its products serve the commercial and industrial new construction and replacement markets. Its rooftop and condensing unit markets consist of units installed on commercial or industrial structures of less than 10 stories in height. Its air handling units, self-contained units, geothermal/water-source heat pumps, chillers, packaged outdoor mechanical rooms and coils are applicable to all sizes of commercial and industrial buildings. The replacement market consists of products installed to replace existing units/components that are worn or damaged.