Rooftop heaters combine a furnace and air conditioner into one package. The typical rooftop unit uses natural gas for heating and electricity for cooling.
Rooftop heaters are used most commonly for space heating in commercial and small industrial settings.
Despite the name, rooftop heaters may be installed on ground-level concrete pads for buildings with multiple stories or a pitched roof.
Gas furnaces are available in sizes ranging from 30,000 to 500,000 BTU, although the most common commercial rooftop heaters have a capacity around 250,000 BTU. The size of a unit will generally be determined by the desired air conditioning load.