Abstract: A semi-convective forced air system for heating glass sheets during a heating cycle. The system has a heating chamber, and a longitudinal conveyor extending lengthwise through the heating chamber. A plurality of longitidinally-extending air manifolds are located within the chamber and are in fluid connection with a compressed air source. The manifolds are arranged in at least one widthwise-extending column. Each of the manifolds are oriented parallel to the length of the conveyor and are constructed and arranged to create a downward flow of heated air toward the conveyor to convectively heat the entire length of selected widthwise portions of a sheet of glass on the conveyor. A controller supplies or restricts the flow of compressed air to selected manifolds within a column at predetermined times during the heating cycle.