Thus, inefficient chillers can waste significant amounts of electricity, and even modest improvements in efficiency may yield substantial energy savings and attractive paybacks. It is also important to remember that chillers are actually part of a complicated system, and any inefficiencies or over-efficiencies in pumps, cooling towers, and controls also have the potential to waste as much, if not more, money than the wrong chiller. To maximize cost-effectiveness, we recommend that you analyze the entire chilled water system in addition to exercising care in specifying the efficiency of the chiller itself. Therefore, they usually offer high reliability and low maintenance requirements. A centrifugal compressor acts very much like a centrifugal fan, compressing the vapor flowing through it by spinning it from the center of an impeller wheel radially outward so that centrifugal forces compress the vapor.
Some machines use multiple impellers to compress the refrigerant in stages.
This chilled water is pumped to one or more air handlers, where the coolness of the chilled water is transferred to indoor air. The cool air is distributed around the building through a network of ducts. The ducts run to terminal units, which control the flow of air to diffusers. The chilled water plant also requires several additional devices, known as auxiliaries, to move chilled water between the chilled water plant and the air handlers, as well as reject heat from the chilled water plant to the outside world. Auxiliary devices generally include pumps and cooling towers.