Abstract: Air chambers underlie the perforated floor of the grain storage chamber of a grain tower. Fans propel air from outside the grain tower into such air chambers. The fans are contained within the tower at bulkheads which divide ones of the air chambers each into a relatively larger air distribution chamber and a relatively smaller air intake chamber. The distribution chamber communicates through the perforations in the perforate floor to aerate grain within the grain compartment. The intake chamber is partly bounded by a portion of the peripheral wall of the tower. The fans draw outside air through limited openings in the tower peripheral wall into such intake chambers.