Geothermal heating and cooling system

In a geothermal system for conditioning air in an enclosed space by selective transfer of heat between such air and the subterranean water system of the earth including a heat pump of the liquid-to-air type, an air circulation system for circulating air through said heat pump in heat exchange relationship with a refrigerant therein and for directing such air into the enclosed space, and a liquid circulating system for circulating a liquid through said heat pump in heat exchange relationship with said refrigerant, and a heat sink in heat exchange relationship with the subterranean water system of the earth and connected to said liquid circulating system, the improvement therein wherein said heat sink comprises

• (a) an elongate, generally cylindrical liquid container of a material having high thermal conductivity, said container having a length of at least about forty times its diameter to provide a large amount of surface contact with the earth for the volume of liquid contained therein, said container being buried in the earth in a generally vertical orientation and at a depth providing a good heat transfer relationship with the subterranean water system of the earth, said container having an inlet conduit communicating with the interior of the container at the top thereof and an outlet conduit extending generally longitudinally of and within said container and communicating with the interior of said container adjacent the bottom thereof so that liquid enters at the top of said container, travels downwardly therein in heat transfer relationship with the thermally conductive material of the container and is withdrawn from the bottom portion of the container, means surrounding and thermally insulating said outlet conduit substantially throughout its length from the liquid in said container, and means for maintaining said outlet conduit substantially centered within said container and for stabilizing said outlet conduit therein, said centering and stabilizing means including a plurality of positioning devices spaced along said outlet conduit, said positioning devices extending between the interior of said container and said outlet conduit and permitting the liquid to travel downwardly around said outlet conduit,
• (b) said liquid circulating system providing a temperature gradient of approximately 20 degrees F. between the liquid being withdrawn from said container and the subterranean water for maximizing the heat transfer rate between said heat sink and the subterranean water and also providing a predetermined liquid dwell time sufficient for at least about a 10 degree F. change in temperature of the liquid within said heat sink and a BTU per hour capacity rating of at least 20,000.