Whichever way the thermostat turns, it generates cool cash for AAON. Its subsidiaries make and sell rooftop air conditioning and heating equipment for commercial and industrial buildings, primarily in the US. Its units range in size from one ton to 230 tons. (Typical commercial buildings require one ton of cool air for every 300 to 400 sq. ft.) The company also makes air handlers, condensing units, chillers, coils, and boilers; it has recently begun marketing a limited number of residential products. AAON's business is about evenly split between the new construction and replacement markets.