Temperature control of unoccupied living spaces

Apparatus for controlling, during unoccupied periods, the operation of an HVAC providing temperature conditioned air to a living space having occupied and unoccupied periods, the HVAC including heating and cooling apparatus for conditioning mixed air, including outside air and return air from the space, presented in heat exchange relationship therewith by a fan from a mixed air chamber, the fan being energized by connection to a voltage source, the heating and cooling apparatus providing heat and cold air at a discharge temperature in dependence on hot and cold space temperature error signals presented thereto at a magnitude equal to the temperature difference between an actual space temperature and corresponding space heat and cool reference temperatures, the HVAC presenting mixed air to the space in the absence of space temperature error signals, the mixed air chamber including outside air and return air dampers for providing the mixed air through position modulation of the dampers in response to a mixed air space temperature error signal presented thereto at a magnitude equal to the temperature difference between the actual space temperature and a space mixed air reference temperature, the apparatus comprising:

• HVAC temperature sensor means for providing an actual hot air discharge temperature signal, an actual cold air discharge temperature signal, and an actual mixed air temperature signal;
• space temperature sensor means for providing an actual space temperature signal;
• outside temperature sensor means for providing an actual outside air temperature signal;
• electronic processing means, providing an actual time of day signal, and having means for storing signals including real time signals establishing a plurality of real time intervals, each interval representative of an associated one of the space occupied and unoccupied periods , said processing means comparing said actual time of day signal with said real time intervals for providing an unocupied signal manifestation in response to said actual time of day signal indicating a present unoccupied period, said means for storing signals further including occupid space heat and cool reference temperature signals, and unoccupied space heat and cool reference temperature signals at a lower and higher temperature value, respectively, than the corresponding occupied reference signals, said processing means being responsive to said sensor means for providing, in the presence of said unoccupied signal manisfestation, a comparison of said actual space temperature signal to said unoccupied space heat and cool reference temperature signals to provide unoccupied space heat and cool temperature error signals, respectively, in response to a temperature difference therebetween, said processing means providing hot air and cold air reference discharge temperature signals in response to the presence of a related one of said unoccupied space heat and cool temperature error signals, each at a magnitude in dependence on the associated one of said unococupied space heat and cool temperature error signals, said processing means presenting said reference discharge temperature signals to the heating and cooling apparatus to provide modulation of the respective discharge temperatures in dependence on the magnitude thereof, said processing means further providing, in the presence of said unoccupied signal manifestation in the absence of both of said unoccupied space heat and cool temperature error signals, a fan turn-off gate signal;
• and
• gated switch means, interconnected between the voltage source and the fan, and responsive to said fan turn-off gate signal presented at a gate input thereof, said switch means providing connection of the fan to the voltage source in the absence of said turn-off gate signal, said switch means not providing connection of the fan to the voltage source in the presence of said turn-off gate signal.