The chiller basically removes heat from the water so that it may 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 and other HVAC equipment designed to exchange heat such as computer room air conditioners or other specialized equipment. The chilled water absorbs the heat from the building and 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. Chillers range in size from smaller than 5 tons all the way up to several hundred tons and can be found in residential applications, commercial buildings, and industrial process applications.
Many chillers have cooling towers where the heat removed in the chiller barrel is transferred to another barrel. It is the condenser barrel where the refrigerant is condensed and sent back to the evaporator barrel to remove the heat. The process is in reverse in the condenser barrel. The water absorbs heat from the refrigerant and allows it to condense.
The water is then transferred to a cooling tower where the heat in this water is removed to the atmosphere. Once the heat is removed from the water it is pumped back to the chiller barrel to absorb more heat from the refrigerant. Some chillers do not have a condenser barrel to remove the heat. The refrigerant is pumped into a condenser coil where a fan blows across the coil and removes the heat. These chillers are cheaper to purchase upfront but not as efficient to run as those with the condenser barrels. The upfront costs are less but the energy costs are more over the long run. One bonus to an air cooled chiller is that it does not require a cooling tower and therefore the maintenance costs associated with maintaining a cooling tower.