Abstract: A geothermal fill material composed of one or more high heat conductivity materials alone or in combination to produce a fill that can be used to cover and encapsulate geothermal ground coils to improve heat transfer between the ground and the fluid inside the coils and to improve the rate of heat recovery of the fill in contact and in the vicinity of the coils. These materials can be in the form of particulates, rods or wire mesh and in any combination. Further enhancements are to cover this high conductivity material with low conductivity materials near the surface of the ground or to install the coils in a ground coil field below a structure in order to reduce ground heat loss to the atmosphere in the winter and to reduce heat gain from the atmosphere in the summer.

Abstract: Geothermal ground coils are installed and embedded in fill at the bottom of excavations, made for drainage fields associated with septic and other effluent systems, prior to the addition of the drainage field sanitary fill. This configuration eliminates the need for expensive bore holes and provides a ground heat source that is at a higher temperature than natural ground formations due to the supplemental heat imparted to the ground by the drain field effluent Fouling of the outside heat transfer surfaces of the ground coils is also avoided because of the clarifying and filtering action of the drain field fill. This provides an improved ground source heat pump system wherein the installation costs are reduced arid the capacity and efficiency of the system are improved.