Coaxial ground heat exchanger and method for installing said ground heat exchanger in the ground

A coaxial ground heat exchanger mounted within a ground heat exchanger hole, comprising:

• a central core tube;
• and
• an expandable jacket tube which encloses said central core tube, wherein an inner wall of said expandable jacket tube and an outer wall of said central core tube delimit an annular gap, the annular gap extending along a central axis of said coaxial ground heat exchanger and being adapted to accommodate a heat transfer medium, wherein the heat transfer medium circulates from the annular gap through a length of the central core tube or vice versa,
• wherein the expandable jacket tube is formed by an expandable hose covering that will expand radially in response to an elevated internal pressure in said annular gap, the expandable hose covering encasing the central core tube in a folded state, the expandable hose covering arranged to be brought into a stable end shape by the heat transfer medium when the heat transfer medium is fed into said annular gap with overpressure,
• wherein the expandable hose covering in the stable end shape encloses said central core tube along an entire circumference of the expandable hose covering, and an outer wall of said expandable hose covering adjoins an inner wall of the ground heat exchanger hole along an entire internal circumference of the ground heat exchanger hole in said stable end shape, and
• wherein the expandable hose covering comprises an unfolded diameter that is selected to be larger than a diameter of the ground heat exchanger hole.