Reznor HVAC North America Home - Reznor® began producing the first gas heating units for residential application in 1888. Since then, we have focused on the use of natural gas for heating commercial & industrial spaces. Our products provide comfort and protection for factories, warehouses, greenhouses, garages and countless other applications where robust, reliable heat are required. We supply the premier Unit Heaters, Duct Furnaces, Infrared, and indirect fired units to serve these applications. Many applications have need for more than just heating units. In these applications, Reznor® brand products are available in Direct Expansion (DX), Chilled Water, and Evaporative Cooling. Our specialty with these products is to supply high amounts of outside air for improving Indoor Air Quality.