Abstract: A system and method for using multiple ClimateTalk™ compliant thermostats in a zoned HVAC system are provided. The system may include a first ClimateTalk™ thermostat in a first zone, a second ClimateTalk™ thermostat in a second zone, a third ClimateTalk or 24v AC thermostat in a third zone, and a ClimateTalk™ HVAC unit and/or 24v AC HVAC unit, for servicing the demands in the first, second and third zones. A controller in the zoned HVAC system may establish a ClimateTalk™ network between the controller and the HVAC unit, where the controller may identify itself as the sole ClimateTalk™ thermostat in this network. The controller may also establish additional ClimateTalk™ networks between the controller and each of the first, second and third thermostats, by identifying the controller as a distinct ClimateTalk™ HVAC unit in each of the respective additional networks.

Abstract: An interface circuit for detecting, filtering and conditioning alternating current (AC) voltage input signals from external controllers to be received by a microcontroller. Coupled between the outputs of the external controllers and the inputs of the microcontroller of the interface circuit are RS232 receivers, which are used to detect and condition AC voltage input signals. A voltage divider having specific value resistors may be coupled between the outputs of the external controllers and the inputs of the RS232 receivers to reduce the operational voltage to a narrow detection range, the combination allowing the microcontroller to interpret the status of the AC voltage input signal.

Abstract: A damper assembly having adjustable damper vanes and a motor mechanically coupled for moving the damper vanes is operatively associated with an electro-optical controller for repositioning the damper vanes between a normally open and a closed position and vice versa. The electro-optical control has an opaque disk connected and movable with the damper vanes with a first bore corresponding to the open position, and a second bore corresponding to the closed position of the damper vanes. Each of the respective bores is operatively associated with a pair of coacting electronic elements consisting of a light emitting diode and a phototransistor. Each of the phototransistors communicates with an electronic system having logic circuitry so that when the light signals are detected by the phototransistor and signaled, the electronic system will actuate or stop the motor as programmed in the control logic circuitry to reposition the damper vanes.