Abstract: An apparatus for achieving heat exchange between a liquid medium and the earth for insertion into a borehole in the earth, the apparatus having a casing, a cap closing the casing lower end, a dip tube of external diameter smaller than the interior diameter of the casing and positioned within the casing providing an annular area between the dip tube and the interior of the casing and a top manifold cap providing a first port connected to the upper end of casing and a second port connected to the upper end of the dip tube and flow channels within the manifold cap connecting the casing and dip tube to flow lines so that fluid may flow downward in the dip tube and upwardly within the annular area in the casing to exchange heat with the earth. A vent hole is provided to communicate with the upper end of the dip tube to prevent air lock.

Abstract: A system for exchanging thermal energy between a fluid medium and the earth is provided employing a number of boreholes drilled vertically in the earth spaced apart by adjacent intervals. An upflow conduit and a downflow conduit are placed in parallel relationship within the boreholes and connected at their lower ends. At the top of each borehole there is a header providing means to conduct fluid through the conduits in each borehole in a parallel or series arrangement. In each of the headers there is a partition dividing the flow of fluid passing downwardly into the borehole from the flow of fluid passing upwardly out of the borehole with a vent in the partition so that air which might otherwise be trapped in the verical conduits can by vented to prevent airlock of the system.