The drying capacity is increased because cooling is not done in the dryer, the grain is not completely dried and another heater for drying can be added to what was previously the cooling section of the dryer. Plan for the increased drying capacity when selecting the airflow and fan required for dryeration. Air is moved upward in a dryeration bin, so the first grain delivered to the bin is the first grain cooled. If the air was pulled down, the cooled grain would be reheated each time hot grain was added. Also, condensation on the grain would be likely if warm moist air from the hot grain came in contact with cooled grain.
Spoilage is a concern if the cooling air is pulled down through the grain.
Air in the bin is warm and damp during dryeration. Condensation will form when this warm, damp air comes in contact with the cooler bin wall or roof. More condensation will occur when there is a large difference between grain temperature and outdoor temperature. To reduce the roof condensation, provide at least 1 square foot of opening in the roof for each 1000 cfm of airflow. Adding fans and insulation may help but will not eliminate condensation.