Abstract: A portable heating unit comprising a heater and a low velocity blower, an elongated lightweight collapsible flexible heat carrying duct and an intermediate high velocity intake fan unit for mixing the low velocity heated air from said portable heater with ambient air and introducing the mixed air streams into the inlet end of said flexible duct. The intake fan unit includes a venturi for assuring adequate mixing of the air within the elongated flexible collapsible tube to provide a high velocity flow of air at a substantially constant temperature level along the length of the flexible tube. The tube is provided with a plurality of openings arranged in spaced intervals to eject high velocity jets of heated air at locations where they may be used most effectively.The unit is designed to be positioned upon the ground and the remote end is sealed and preferably staked or otherwise held to the ground to prevent undue movement.