NOVELTY - The casing support has a base support element (30) which is arranged to be supported by a ground surface around a borehole. An annular orientation guide element comprises a central conduit communicating with an aperture (36). The orientation guide element (58) comprises an upper surface (59) at a selected angle relative to a lower support surface (57) of the base element. A casing support ring (54) is coupled to the orientation element to support the casing in the borehole. The outer casing is extended through the ring, the conduit and the aperture.    USE - Casing support mounted on chamber (claimed) of geothermal borehole heat exchanger (BHE) of geothermal energy system.    ADVANTAGE - The low cost modular system enables the outer casing of a geothermal BHE to be supported from an upper surface, so that the coaxial geothermal BHE can be suspended or hung from the bottom wall of the chamber rather than supported by the base of the borehole. The orientation of the borehole and inclination of the borehole can eliminate the possibility of human error during set up of the drilling process. Since common set of components can be used for various borehole depths and inclinations, the modular system allows ease of manufacturing and installation. The connections between the well heads and the flow lines can be standardized and manufactured off site, so that the installation time and installed costs can be reduced. The orientation guide elements are sealed using a sealing compound to ensure that surface water coming up from the borehole cannot enter the chamber, so that the well head and associated connections and flow lines can be protected against corrosion. The use of multiple boreholes in a single chamber reduces the surface area of the ground required for the boreholes.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) chamber of geothermal BHE; and    (2) a method of installing casing support of geothermal BHE.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of the coaxial geothermal BHE during installation.    Base support element (30)    Aperture (36)    Casing support ring (54)    Lower support surface (57)    Orientation guide element (58)    Upper surface of orientation guide element (59)