Ground Source Heat Pump: Natea, the direct condensation and evaporation system (D/X Heat Pump). Heat is transferred by means of the refrigerant operating inside a closed circuit, in a network of collectors buried beneath the surface of the ground outside, at a depth of between 60 and 100 cm, and an underfloor heating system inside the house. Sofath® : Natural Heating - Geothermal Energy - Renewable Energy - Heat Pump - Thermodynamics - Buried loops - Reversible - Heating - Air conditioning - Renewable energy. Heat is captured from the ground via a collector made of polyethylene-coated copper pipes, buried horizontally, inside which the refrigerant circulates. Useable heat is transmitted inside the house via an underfloor heating system – also made up of polyethylene-coated copper pipes.