An encasement assembly for installing sub-surface refrigerant tubing in a direct exchange heating/cooling system includes a weighted and protective encasement tube for lowering the bottom distal U-bend portion of the refrigerant tubing into a well/borehole. The encasement tube has a main body portion and a rounded or cone-shaped nose. The U-bend portion of the distal end of the refrigerant transport lines is encased within a cementitious grout inside the tube. The grout inside the encasement tube has a flat top portion to prevent upward flotation and at least one eyebolt for securing a trimmie tube with an expendable wire during installation. An optional nose ring is attached to the lower distal end of the tube for marker float attachment in water.