Abstract: A vertical column type evaporator for ice manufacture formed of inner and outer tubular members defining an evporation chamber has separate refrigerant and hot gas lines extending into the bottom region of the evaporator and has a suction line at the top region. A conduit connecting a discharge of a compressor to an expansion valve leading to the refrigerant line is wrapped around an upper exterior end of an outer tubular member of the chamber. The upper end of the chamber is thereby preheated by compressed refrigerant in the conduit wrap so that ice formed along upper wall portions in the evaporator chamber is rapidly released during the ice harvesting cycle.