Abstract: A hot air induction box is shown which includes an enclosure surrounding the point at which seed cotton or other fibrous material is sucked up from a belt conveyor or chute. The entrance into the enclosure through which the fibrous material passes is restricted by a horizontally pivoted door. This door is counterweighted in such a manner that it restricts the necessary entrance of the air used for conveying and induces a partial vacuum within the enclosure. The partial vacuum thus formed is adequate to pull hot air from an air heater into the enclosure where it becomes a substantial portion of the conveying air.