Abstract: A device for controlling air having a thermal differential between a higher and a lower location, having a tube with two ends and a length that traverses the distance between the higher and lower locations, with one end of the tube at the higher location and one end of the tube at the lower location, for the transfer of air therebetween and having openings at each of the ends for the air to pass at both the higher and lower locations inwardly and outwardly, a bi-directional fan for moving the air through the tube inwardly and outwardly as necessary, a switch or thermostat for switching the bi-directional fan on and off for determining the inward and outward direction and velocity of the air flow; and power for powering the bi-directional fan.