DX geothermal ground loops are large loops of copper tubing buried in the earth that circulates refrigerant, which exchanges heat with the surrounding soil. The ground loop is the only difference between a traditional geothermal system and a DX system. A traditional system uses a large earth loop of polyurethane tubing that circulates a water-antifreeze mixture to exchange heat with the earth, then that water loop exchanges heat with the refrigerant loop inside the heat pump. DX systems just remove that large external water loop, and extend the refrigerant loop to exchange heat directly with the earth. Because the large water loop is removed, the copper refrigerant loop of a DX system takes up less space in the earth to exchange the same amount of heat.