Abstract: In order to guarantee that the floor space be kept to a minimum and nevertheless render a closed circuit system possible with a device for absorbing the heat of the earth, particularly for operating a heat pump which at the same time affords high, steady final temperatures of the medium to be heated, a probe with a tube body extending into the ground like a column is used. The end of the probe pointing to the ground is sealed, and in the interior thereof an inner tube is arranged, the diameter of which is smaller than the inside diameter of the tube body, so as to form a circulation jacket. The inner tube is provided at its bottom end with an overflow opening into the circulation jacket. It is advantageous to seal the tube body at its end that points to the ground by means of a removable piston. This enables the tube body to be inserted into the ground as a permanently implanted boring rod during a wash boring operation.