Zone of greatest demand controller, apparatus, and method

A controller, multiple zone control apparatus, and method for controlling temperature independently in each zone for use in a structure having an interior divided into a plurality of zones. The controller is constructed and arranged to control the temperature in each zone by actuating a temperature effecting device to communicate a temperature conditioned fluid to the zone. The controller is constructed and arranged to determine a zone temperature error for each of the zones based upon the difference between a predetermined temperature and the temperature represented by a signal sent from a sensor located in the zone in which the error is to be determined. The controller also is constructed and arranged to compare the errors of a plurality of zones to determine the zone of greatest error. The controller has a predetermined on/off cycle for each zone for actuating the temperature effecting device such that when the cycle is in an "on" condition, the temperature effecting device communicates fluid to the zone and when the cycle is in an "off" condition, then the device does not communicate fluid to the zone. The controller is constructed and arranged to actuate the temperature effecting device when the on/off cycle of the zone of greatest error dictates such actuation. The controller also has a synchronizing mechanism to synchronize the on/off cycles of each zone when a predetermined triggering event occurs.