DX coil cools the air by transferring the heat taken from the air passing through the evaporator to refrigerant with the help of compressor. To simply describe the system, a direct expansion cooling coil is adapted to an air handling unit and required number of VRF outdoor needed by this coil is connected. While performing this operation, the refrigerant is evaporated at the source (AHU) where the heat transfer is made. During the heat transfer by conventional cooling groups (chiller / hot water boiler), heat is transferred to water first and then the heat transfer is done inside the AHU via pipes and pumps. AHU with DX coil provides air conditioning in the place without need for hot water boilers.