Abstract: A thermostat receives setpoint information from a system in communication with the thermostat. The thermostat is operative to modify any locally entered setpoints by a predefined amount dictated by the setpoint information received from the system in communication with the thermostat. The thermostat is preferably operative to continually display the time remaining during which it will be under the control of the system in communication with the thermostat. This affords an occupant of the room viewing the displayed time with an opportunity to elect to either continue or to override the control by the system in communication with the thermostat at any time.

Abstract: A thermostat monitors the indoor air temperature indicated by the thermostat's indoor air temperature sensor. The monitored indoor air temperature must be within a predefined range of acceptable temperatures to be considered valid. In the event the monitored temperature is outside this predefined range, the thermostat proceeds to read the outdoor air temperature and activate a heating system if the outdoor air temperature reading is below a predefined level.

Abstract: Apparatus and method for controlling an air distribution system of the type which includes a motor drivingly associated with a blower and a duct system, and further including a target air flow rate signal which represents a target air flow for the air distribution system. The apparatus and method provide control of the motor speed to maintain a rate of air flow in the system at substantially the target air flow rate regardless of the status pressure therein. The apparatus provides a speed signal representative of the speed of the motor, and a control signal in response to the target air flow rate signal and the speed signal, and controls the motor speed in response to the control signal. The central signal is provided independent of the duct system. Motor speed is controlled by applying a voltage to the motor which varies in accordance with the control signal for maintaining the rate of air flow in the system at substantially the target air flow rate regardless of the static pressure therein.

Abstract: A process is disclosed for controlling the operative setpoint of a thermostat during transition from a currently scheduled setpoint temperature to the next scheduled setpoint temperature. The operative setpoint is changed by small amounts at calculated time intervals. The time intervals are a function of the transition periods allocated for different types of systems for air conditioning air that may be operatively connected to the thermostat as well as the difference between the currently scheduled setpoint temperature and the next scheduled setpoint temperature.

Abstract: A setback control for an HVAC system is selectable by depressing a switch on a control panel associated with a programmed microprocessor. The programmed microprocessor is operative to thereafter change the setpoint temperature by a predefined amount each hour until a predetermined number of hours have passed. The set point temperature is thereafter held for a further hourly count before being returned to the starting setpoint temperature. The directional change in setpoint temperature is a function of whether the HVAC system is in a heating or cooling mode of operation.

Abstract: In an outdoor unit of a heat pump having a variable speed compressor, the fan speed is controlled in response to both the speed of the compressor and the temperature of the outdoor refrigerant such that the operating efficiency of the fan and its driving motor can be optimized over a full range of compressor operating speeds.