In the case of direct heating systems used for dryers and curing ovens, Maxon air ducts, grid shaped or line burners  with large heating surface are used to heat up the airflow directly in the air duct without a heat exchanger.  This requires no smoke-flue, therefore, direct burners operate with virtually 100% efficiency.

Cycle times are shorter, temperature regulation is more stable and faster, maintenance costs drop and a significant energy saving can be achieved.