Abstract: In a method of and apparatus for heating circulating air, particularly circulating air in drying equipment, a portion of the circulating air is exhausted from the drying equipment and conveyed to a combustion chamber for the thermal incineration therein. Prior to entry into the combustion chamber, the exhaust portion of the circulating air is preheated by a transfer of heat with oxidyzed gases produced in the combustion chamber. Thereupon, an outlet channel conveys all or part of still-heated incinerated gases either directly to the remainder of the circulating air in the drying chamber, or indirectly to an air-lock, or alternatively to a heat exchanger to heat the remaining circulating air in the drying chamber.