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 by-products of combustion pass through the tube and is vented to the atmosphere through the chimney system, unlike a direct-fired system, which circulates the by-products of combustion through the product load.

The burner is directed straight into the air stream within the drying chamber, causing the by-products of combustion to mix with the recirculated air. This means that the recirculated air, now carrying the by- products of combustion, comes into contact with the product load, introducing potential challenges and considerations in the drying process.