A grain dryer has a heated drying section with an upper plenum and a cooling section. A heater is positioned between the lower plenum and the upper plenum, wherein air is heated by the heater as air in the lower plenum is pulled through the heater and into the upper plenum. A fan takes a suction from a ductwork on the heated drying section to draw a vacuum in the upper and lower plenums. Grain enters the dryer and flows into the drying section where the grain is exposed to heated air being pulled from the upper plenum into the ductwork. Grain flows from the drying section into the cooling section where the grain is exposed to cooling air being pulled through outer walls of the cooling section into the lower plenum. Grain flows from the cooling section into the unloading section.