Abstract: Rotary regenerative total heat energy exchanger having an asbestos-free heat exchange media formed by spirally winding flat and corrugated webs of aluminum foil and/or fully bleached, 45 lb. Kraft paper constituted by 84% fibres and 16% salts. The contained salts are 90% ammonium sulfide and 10% diammonium phosphate. Wheel thickness for efficient transfer of both sensible heat and latent heat with minimal air pressure drop across the wheel is a multiple of from 100 to 400, preferably 125 to 200, times the flute height of the corrugation web of the media. Although media may be substantially all-paper, preferred embodiments provide media having both a flat web and a corrugated web of aluminum foil, a pair of paper webs being disposed respectively on the opposite surfaces of either the flat foil web or the corrugated foil web.