A Chilled water coil manages the flow obviously of chilled water. This chilled water is supplied from a chiller that can be sometimes located very far away, but a refrigerant must be obtained by a very near condensing unit. The cooling coil is actually the evaporator in a vapor-compression refrigeration cycle when a refrigerant is used. HVAC coils that operate with this direct refrigerant expansion are most popularly known as DX coils.