Air conditioning apparatus including a heat pump

Apparatus for conditioning the air within an indoor space comprising:

• a. a housing including first heat transfer means for selectively heating air passing therethrough;
• b. duct means connected to said housing for providing communication between said housing and said indoor space;
• c. indoor fan means for circulating air through said housing and said duct means to said indoor space;
• d. a heat pump selectively operable in at least a heating mode including a compressor, indoor heat exchange coil, expansion means, outdoor heat exchange coil, and conduit means for connecting same in a closed refrigerant circuit whereby said indoor heat exchange coil may operate as a condenser to remove heat from compressed refrigerant and said outdoor heat exchange coil may operate as an evaporator to transfer heat to expanded refrigerant, said indoor heat exchange coil being disposed within one of said housing and said duct means at a location downstream from said first heat transfer means in heat exchange relationship with said circulated air and said outdoor heat exchange coil being disposed in heat exchange relationship with an ambient heat sink;
• and
• e. control means for selectively operating said first heat transfer means and said heat pump comprising
• i. means for sensing the demand for heat within said indoor space and for producing a first signal in response to a relatively low demand for heat and a second signal in response to satisfaction of said relatively low demand for heat, and for producing a third signal in response to a relatively high demand for heat;
• ii. first means for initiating operation of said heat pump in said heating mode in response to said first signal and terminating operation thereof in response to said second signal;
• iii. second means for initiating operation of said first heat transfer means and terminating operation of said heat pump in response to said third signal, and for terminating operation of said first heat transfer means in response to said second signal;
• iv. means for sensing the temperature of said ambient heat sink and for producing an override signal when said ambient temperature drops below a predetermined level;
• v. fourth means responsive to said override signal for preventing operation of said heat pump in response to said first signal;
• and
• vi. fifth means responsive to said override signal for effecting operation of said first heat transfer means in response to said first signal and terminating operation thereof in response to said second signal.