A furnace for heating glass sheets that each have a coated surface and an oppositely facing uncoated surface, comprising: a housing defining a heating chamber and having entrance and exit ends (20, 22); a roll conveyor for conveying glass sheets to be heated within the heating chamber along a horizontal conveying plane between the entrance and exit ends (20,22) of the housing with the coated surface facing upwardly and with the uncoated surface facing downwardly and supported by the roll conveyor; electric resistance elements for heating the housing within the heating chamber below and above the conveying plane; a hot air distributing system that that is located within the heating chamber between the entrance and exit ends (20, 22) above the roll conveyor and supplies hot air jets downwardly toward the upwardly facing coated glass surface of each conveyed glass sheet, and the hot air jets entrain hot air within the heating chamber and the combined flow of hot air provides convective heating of the coated glass surface in addition to the radiant heating thereof by the electric resistance elements; characterised in that the hot air distribution system includes horizontal delivery tubes located only above the conveyor spaced along the direction of conveyance extending laterally with respect thereto and supplying only downwardly directed hot air jets to the coated surface of the glass sheet, and the hot air distribution system also including: a control that increases the forced convection heating of the coated surface of the glass sheet by the downwardly directed hot air jets from the hot air distributing system during the glass sheet conveyance along the direction of conveyance to balance the heating and the resultant temperature of the upwardly facing coated surface and the downwardly facing uncoated surface of each conveyed glass sheet being heated. a housing defining a heating chamber and having entrance and exit ends (20, 22); a roll conveyor for conveying glass sheets to be heated within the heating chamber along a horizontal conveying plane between the entrance and exit ends (20,22) of the housing with the coated surface facing upwardly and with the uncoated surface facing downwardly and supported by the roll conveyor; electric resistance elements for heating the housing within the heating chamber below and above the conveying plane; a hot air distributing system that that is located within the heating chamber between the entrance and exit ends (20, 22) above the roll conveyor and supplies hot air jets downwardly toward the upwardly facing coated glass surface of each conveyed glass sheet, and the hot air jets entrain hot air within the heating chamber and the combined flow of hot air provides convective heating of the coated glass surface in addition to the radiant heating thereof by the electric resistance elements; characterised in that the hot air distribution system includes horizontal delivery tubes located only above the conveyor spaced along the direction of conveyance extending laterally with respect thereto and supplying only downwardly directed hot air jets to the coated surface of the glass sheet, and the hot air distribution system also including: a control that increases the forced convection heating of the coated surface of the glass sheet by the downwardly directed hot air jets from the hot air distributing system during the glass sheet conveyance along the direction of conveyance to balance the heating and the resultant temperature of the upwardly facing coated surface and the downwardly facing uncoated surface of each conveyed glass sheet being heated.