The burner directs the combustible process into a radiant tube which acts as a heat exchanger. Air passing over the tube is heated before coming into contact with the product load. The byproducts of combustion pass through the tube and are vented to the atmosphere through the chimney system, unlike a direct-fired system, which circulates the byproducts of combustion through the product load.
The burner is fired directly into the air stream within the drying chamber where the byproducts of combustion mix with the recirculated air. This same recirculated air, which has been exposed to the byproducts of combustion. Then, it comes into contact with the product load.