Reduced energy heat pump defrost for unoccupied space

Abstract

Embodiments are directed to determining, by a controller comprising a processor, that a coil associated with a heat pump is subjected to a defrost cycle, determining, by the controller, that at least one of: a conditioned space is occupied, and a thermostat associated with the conditioned space indicates that an energy saving mode is not in use, and enabling, by the controller, an auxiliary heat source based on the determination that the coil is subject to the defrost cycle and the determination that the conditioned space is occupied or the thermostat indicates that the energy saving mode is not in use.

What is claimed is: 
     
         1 . A method comprising:
 determining, by a controller comprising a processor, that a coil associated with a heat pump is subjected to a defrost cycle;   determining, by the controller, that at least one of:   
       a conditioned space is occupied, and 
       a thermostat associated with the conditioned space indicates that an energy saving mode is not in use; and
 enabling, by the controller, an auxiliary heat source based on the determination that the coil is subject to the defrost cycle and the determination that the conditioned space is occupied or the thermostat indicates that the energy saving mode is not in use. 
 
     
     
         2 . The method of  claim 1 , wherein an indication that the energy saving mode is in use is expressed as being at least one of: setback, away, on vacation, and sleep. 
     
     
         3 . The method of  claim 1 , wherein the indication that the energy saving mode is not in use is based on a schedule entered at the thermostat. 
     
     
         4 . The method of  claim 1 , wherein the conditioned space is determined to be occupied when a motion in an amount greater than a first threshold is detected by a sensor within a second threshold amount of time. 
     
     
         5 . The method of  claim 1 , wherein the coil is located outside of a building. 
     
     
         6 . The method of  claim 1 , wherein the thermostat comprises a device configured to selectively pass a request for auxiliary heat based on the determination that the conditioned space is occupied or the thermostat indicates that the energy saving mode is not in use. 
     
     
         7 . The method of  claim 6 , wherein the thermostat receives the request for auxiliary heat from the heat pump. 
     
     
         8 . The method of  claim 6 , wherein the device comprises a relay or a switching device. 
     
     
         9 . The method of  claim 6 , wherein the thermostat receives the request for auxiliary heat in accordance with serial communications. 
     
     
         10 . The method of  claim 1 , further comprising:
 disabling, by the controller, the auxiliary heat source following the completion of the defrost cycle.   
     
     
         11 . An apparatus comprising:
 at least one processor; and   memory having instructions stored thereon that, when executed by the at least one processor, cause the apparatus to:   
       determine that a coil associated with a heat pump is subjected to a defrost cycle, 
       determine that at least one of: 
       a conditioned space is occupied, and 
       an energy saving mode is not in use in association with the conditioned space, and 
       enable an auxiliary heat source based on the determination that the coil is subject to the defrost cycle and the determination that the conditioned space is occupied or that the energy saving mode is not in use. 
     
     
         12 . The apparatus of  claim 11 , wherein a determination that the energy saving mode is not in use is based on at least one input received at a thermostat. 
     
     
         13 . The apparatus of  claim 11 , wherein the conditioned space is determined to be occupied when a motion in an amount greater than a first threshold is detected by a sensor within a second threshold amount of time. 
     
     
         14 . The apparatus of  claim 11 , wherein the auxiliary heat source is enabled using a control signal on a dedicated wire. 
     
     
         15 . The apparatus of  claim 14 , wherein the instructions, when executed by the at least one processor, cause the apparatus to:
 receive a request for auxiliary heat from the heat pump on a second dedicated wire,   wherein the enabling of the auxiliary heat source is based on the received request.   
     
     
         16 . The apparatus of  claim 11 , wherein the auxiliary heat source is enabled based on a control value included as part of a two-wire serial communication. 
     
     
         17 . A system comprising:
 a sensor configured to provide an indication of whether a motion in an amount greater than a first threshold is detected within a second threshold amount of time; and   
       a processor configured to: 
       determine whether a coil associated with a heat pump is subjected to a defrost cycle, 
       determine whether a conditioned space is occupied based on the indication provided by the sensor, and 
       enable an auxiliary heat source that is located within the conditioned space when the coil is subject to the defrost cycle and when the conditioned space is occupied. 
     
     
         18 . The system of  claim 17 , further comprising:
 a thermostat configured to receive an input that indicates whether an energy saving mode is entered,   wherein the processor is configured to enable the auxiliary heat source when the coil is subject to the defrost cycle and when the input indicates that the energy saving mode is not entered.   
     
     
         19 . The system of  claim 18 , wherein the thermostat is configured to receive the input via at least one of: a key, a button, a switch, a menu, a slider bar, and a voice recognition device. 
     
     
         20 . The system of  claim 18 , wherein the thermostat is configured to receive the input via a slider bar, and wherein the energy saving mode comprises a plurality of levels corresponding to positions of the slider bar, and wherein when the slider bar is pushed to a comfort level the auxiliary heat source is enabled with every defrost, and wherein when the slider bar is pushed to an efficiency level the auxiliary heat source is disabled during defrost.