Sterling HVAC Equipment, A Mestek Company, is proudly "Made in the USA". Sterling has been a major producer of A.G.A/C.G.A. certified Unit Heaters for over four decades.High and Low Intensity Infrared, Air Curtains, Rooftop Furnaces, Evaporative Cooling Units, Packaged HVAC Rooftop and Indoor Units, Direct Fird and Air Turnover Units enhance Sterling's complete line of HVAC equipment.