Abstract: An improved geothermal heat exchange unit, which can be placed in ground and/or water, has a rigid hollow core about which is formed a helical winding of thermally conductive tube. The return section of the tube extends vertically along a central axis of the core, separated from the inner wall of the core by thermal insulating material. The heat exchange unit is optionally encased in a solid thermally conductive casing and may have a small diameter oil return tube from the lowermost portion of the unit to the suction intake port of a gas compressor. An optional high pressure water hose is attached for installation assistance in wet sand or wet soils.