Heating is provided by Ribbon Pipe burners and adjustable balancing burners which are transversely placed above and below the baking band. The burners work on Zero pressure system. Each burner is provided with gas line as zero pressure and a low pressured combustion air line. Air and Gas are mixed at each burner by a proportional mixing device which utilize the air pressure to entertain the combustible gas and deliver the mixture to the burner. The ratio of air and gas can be adjusted to provide with optimum combustion.