The chiller basically removes heat from the water. It is used as a refrigerant to remove heat from the building. The chilled water circulates through a chilled water loop and through coils located in air handlers. Chilled water systems include other HVAC equipment designed to exchange heat such as computer room air conditioners. The chilled water absorbs the heat from the building. It then returns to the chiller where the chiller removes the heat from the water using the refrigeration process. Some chilled water loop arrangements are very complex while others are simple. Control of the chilled water from pressure to velocity, to volume, is up to the control system controlling the pumps and valve actuators in the system.