Heat of Compression Dryers 1088/23 703 m3 / hr, 677-14,743 cfm for Dew Points at -40 ° C Heat of Compression dryers use twin tower dryer technology and the most energy efficient design available for oil-free applications. Dryers recover heat, which is a natural byproduct of the compression process, to offset virtually all of your energy costs. The HC Series provides a constant supply of -40 ° F (-40 ° C) dew point air under all load conditions at operating costs significantly less than conventional desiccant dryers.