The CWMC (Chilled Water Master Controller) is a microprocessor based controller designed for the precise monitoring and coordination of DDC controllers for multiple chilled water systems. The control unit provides central control for up to six chillers via interfaces with the individual Digital Diagnostic Controllers (DDC)* on each chiller. It controls all of the heating and cooling functions for each chiller, as well as operation of the seawater and chilled water pumps. It optimizes compressor operation by automatically changing the lead compressor to evenly distribute run time.