A convection heating furnace for a glass sheet, into which oven glass sheet (3) arrives along a hauling track, as on moving rolls (4), and said furnace further comprises of heating elements (12), in order to heat the air, which is blasted against glass sheet (3), a blaster and blast air channelling in order to blast said air against the glass sheet, and the blast air channelling has, elongated channels (1), into which at least a part of the blast air heating elements 12 are fitted, and each channel comprises air blasting means on its flank directed against the glass sheet (3). As air blast elements there are nozzle groups fixed on the channel (1) flank, where the nozzle group formed of sheet metal, as of two, into shape formed sheets joined together to form a casing, whereby said casing comprises one or several for blast air directed discharge channels (6), and the direction of air flow in said casing (2) is essentially in the same direction as in said discharge channels (6).