A forced convection heating apparatus and process for heating glass sheets therewithin. The apparatus includes at least one gas burner for producing hot combustion gases which is to be distributed toward and into contact with the top and/or bottom surfaces of a glass sheet within the apparatus housing. The velocity of the distributed hot combustion gases which eventually impinges upon the top surface of the glass sheet is controllable independently of the impingement velocity of the hot combustion gases being distributed, and, in turn, directed toward and into contact with the bottom surface of the glass sheet.