Method of installing geothermal heat pump system and device for installation
View Patent ↗An installation tool for installation of earth loops includes a cylindrical body with slots in its outer surface, for receiving of tubes of the earth loops, and a central passage extending therethrough from a grout fitting to a central opening at a leading end face of the cylindrical body. An anchor fits over the end face and includes a face plate with tube apertures extending therethrough, a retainer ring which serves to hold the earth loops in place within the slots during insertion of the tool into the borehole, and a pair of flexible plates extending from opposing positions on the retainer ring, approximately in parallel with the longitudinal axis of the cylindrical body. In use, a plurality of straight (linear) boreholes are drilled at an angle relative to the horizontal of 5° to less than 90°, preferably 5° to 45°, at least two coupled tube pairs are inserted into each borehole and then grout is injected to force the anchor away from the cylindrical body, to fill the boreholes surrounding the earth loops and to form a seal for heat exchange between the earth loops the surrounding earth.
1. An installation tool for installation of at least one coupled pair of tubes in a borehole, to a blind end of the borehole, the installation tool comprising:
a cylindrical body presenting a cylindrical outer surface;
a central passage extending along a central, longitudinal axis of the cylindrical body, from a grout fitting for connecting a grout hose to a central opening at a leading end face of the cylindrical body;
at least two slots formed in and extending along the length of the cylindrical outer surface, each slot being open at the cylindrical outer surface of the cylindrical body for receiving therein a portion of the length, including a leading end, of one tube of the coupled pair; and
an anchor which fits over the cylindrical body, wherein the anchor comprises:
a face plate having tube apertures for receiving the tubes extending therethrough;
a retainer ring which is integral with the face plate and which removably fits over one end of the cylindrical body to hold, in cooperation with the face plate, the coupled tube pair within the slots during insertion of the tool into the borehole; and
a pair of flexible plates integral with the retainer ring and extending from opposing positions on the retainer ring, approximately in parallel with the longitudinal axis of the cylindrical body.
2. The installation tool according to claim 1 wherein the flexible plates cover leading end portions of the tubes of the coupled pair.
3. The installation tool according to claim 2 wherein the flexible plates extend from the retainer ring beyond the grout fitting.
4. An installation tool according to claim 1 wherein the opening of each slot is narrowed adjacent the leading end face, relative to the remainder of the opening along the length of the slot.
5. An installation tool according to claim 1 having four of said slots arranged around the central passage.
6. A method for installation of a geothermal heat exchange loop using an installation tool according to claim 1 , the method comprising:
forming a borehole with a blind end in the earth at an angle slanted relative to the horizontal but significantly less than 90° relative to the horizontal;
coupling ends of a pair of tubes together, leaving opposing ends of the paired tubes free;
inserting the free ends of the paired tubes through the tube apertures of the face plate and sliding the face plate along the tubes to their coupled ends;
mounting at least one pair of tubes having ends coupled together, for service as the geothermal heat exchange loop, in the slots of the cylindrical body;
fitting the retainer ring over the forward end of the cylindrical body to hold the coupled pair within the slots during insertion into the borehole;
inserting the installation tool to the blind end of the borehole;
injecting grout through the grout fitting and out the central opening to force the face plate away from the forward end of the cylindrical body, to spread apart the flexible plates and to force the coupled pair of tubes out of the slots;
withdrawing the cylindrical body from the borehole whereby distal ends of the flexible plates engage the earth to hold the anchor with the borehole, adjacent the blind end, and to cause the cylindrical body to separate from the anchor as the cylindrical body is withdrawn from the borehole; and
filling the borehole with the grout.
7. A method according to claim 6 wherein the borehole is formed along an approximately straight line.
8. A method according to claim 7 wherein a trailing end of the tool is coupled to a guidable drillstring and the tool is guided straight along a linear path to the blind end of the borehole during insertion.
9. A method according to claim 6 wherein the angle of the borehole relative to the horizontal is 30° to 45°.