Image Number 2 for United States Patent #5361982.
Disclosed herein is a temperature control system for multi-zone temperature control with setback control. The system includes a thermostat associated with each zone of a building, and a central control unit which communicates with each thermostat to send temperature setpoint values to each thermostat for the purpose of conserving energy and reducing energy consumption during certain times of the day. Each thermostat is associated with either a heating or cooling device, where setup temperature values are sent from the central control unit to the thermostats where cooling devices are used in place of heating devices. The thermostats are designed to operate as stand-alone units which control the temperature within a zone based upon a temperature setpoint stored at the unit. The temperature setpoint values are replaced by the higher or lower temperature setpoint values transmitted to the thermostats by the control units during setback or setup time periods. To avoid the requirement of installing communication wires between the central control unit and thermostat, each thermostat and the central control unit includes communications circuitry which allows the thermostats and control unit to communicate over the power conductors within the building.