Defrost system for heat pump pool heater

Abstract

A heat pump pool heater (HPPH) system is disclosed which may include a heat pump, a water temperature sensor, one or more evaporator sensors, and one or more supplemental heat sources. The HPPH system can determine that frost is forming on an evaporator coil and can transition from a normal pool water heating mode to a defrost mode to remove frost from the evaporator coil. During the defrost mode, the HPPH system can operate the one or more supplemental heat sources to provide heat to the pool water.

1 . A heat pump pool heater system comprising:
 a heat pump comprising a refrigerant circuit fluidly connecting a compressor, a condenser coil, a thermal expansion valve, and an evaporator coil via refrigerant conduit such that refrigerant can pass therethrough;   one or more supplemental heat sources configured to output heat;   a water pump configured to draw water from a pool, pass the water across the condenser coil and the one or more supplemental heat sources, and flow heated water from the condenser coil and/or the one or more supplemental heat sources to the pool;   a controller configured to selectively transition the heat pump between a water heating mode and a defrost mode, the defrost mode comprising ceasing a flow of refrigerant through the condenser coil and engaging the one or more supplemental heat sources to output heat to the water.   
     
     
         2 . The heat pump pool heater system of  claim 1 , wherein the water heating mode comprises (i) refrigerant flowing sequentially through the compressor, the condenser coil, the thermal expansion valve, and the evaporator coil and (ii) the one or more supplemental heat sources being deactivated such that heat is provided to the water solely by the heat pump. 
     
     
         3 . The heat pump pool heater system of  claim 1 , further comprising a water temperature sensor configured to measure a temperature of water associated with the pool, wherein the controller is further configured to:
 receive water temperature data from the water temperature sensor; and   determine that a current water temperature is less than a target water temperature; and   output instructions for at least one of the heat pump or the one or more supplemental heat sources to provide heat to the water.   
     
     
         4 . The heat pump pool heater system of  claim 3 , further comprising one or more sensors configured to measure one or more corresponding characteristics at or near the evaporator coil, wherein the controller is further configured to:
 receive sensor data from the one or more sensors;   determine that a current sensor value fails to satisfy a corresponding target value; and   transition the heat pump to the defrost mode.   
     
     
         5 . The heat pump pool heater system of  claim 4 , wherein:
 the one or more sensors comprises a coil temperature sensor configured to measure a temperature of the refrigerant in or near the evaporator coil,   the current sensor value is a current coil temperature,   the corresponding target value is a coil temperature threshold, and   determining that the current sensor value fails to satisfy the corresponding target value comprises determining that the current coil temperature is less than the coil temperature threshold.   
     
     
         6 . The heat pump pool heater system of  claim 4 , wherein:
 the one or more sensors comprises an ambient temperature sensor configured to measure a temperature of ambient air at or near the evaporator coil,   the current sensor value is a current ambient temperature,   the corresponding target value is an ambient temperature threshold, and   determining that the current sensor value fails to satisfy the corresponding target value comprises determining that the current ambient temperature is less than the ambient temperature threshold.   
     
     
         7 . The heat pump pool heater system of  claim 4 , wherein:
 the one or more sensors comprises an ambient temperature sensor configured to measure a humidity of ambient air at or near the evaporator coil,   the current sensor value is a current ambient humidity,   the corresponding target value is an ambient humidity threshold, and   determining that the current sensor value fails to satisfy the corresponding target value comprises determining that the current ambient humidity is less than the ambient humidity threshold.   
     
     
         8 . The heat pump pool heater system of  claim 4 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for the compressor to cease operation. 
     
     
         9 . The heat pump pool heater system of  claim 4 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for a reversing valve to reverse a direction of the flow of refrigerant through the heat pump. 
     
     
         10 . The heat pump pool heater system of  claim 4 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for a valve to open and direct the flow of refrigerant directly from the compressor to the evaporator coil, thereby bypassing the condenser coil. 
     
     
         11 . The heat pump pool heater system of  claim 4 , further comprising:
 a supplemental defrost heat source; and   a fan configured to pass air across the evaporator coil,   wherein transitioning the heat pump to the defrost mode comprises outputting instructions for the supplemental defrost heat source to output heat and for the fan to pass air across the evaporator coil.   
     
     
         12 . The heat pump pool heater system of  claim 1 , wherein the one or more supplemental heat sources comprises an electrical resistance heating element. 
     
     
         13 . The heat pump pool heater system of  claim 1 , wherein the one or more supplemental heat sources comprises a combustion-type heating device. 
     
     
         14 . A non-transitory, computer readable medium having instructions stored thereon that, when executed by one or more processors, cause a controller to:
 receive water temperature data from a water temperature sensor of a heat pump pool heating (HPPH) system;   determine that a current water temperature is less than a target water temperature;   output instructions for at least one of a heat pump of the HPPH system or a supplemental heat source of the HPPH system to provide heat to the water;   receive sensor data from one or more sensors configured to measure one or more corresponding characteristics at or near an evaporator coil of the HPPH system;   determine that a current sensor value fails to satisfy a corresponding target value; and   transition the HPPH system to a defrost mode by:
 outputting instructions for ceasing a flow of refrigerant through a condenser coil of the HPPH system; and 
 outputting instructions for the one or more supplemental heat sources to generate heat for heating pool water. 
   
     
     
         15 . The non-transitory, computer readable medium of  claim 14 , wherein:
 the one or more sensors comprises a coil temperature sensor configured to measure a temperature of the refrigerant in or near the evaporator coil,   the current sensor value is a current coil temperature,   the corresponding target value is a coil temperature threshold, and   determining that the current sensor value fails to satisfy the corresponding target value comprises determining that the current coil temperature is less than the coil temperature threshold.   
     
     
         16 . The non-transitory, computer readable medium of  claim 14 , wherein transitioning the HPPH system to the defrost mode comprises outputting instructions for a compressor of the HPPH system to cease operation. 
     
     
         17 . The non-transitory, computer readable medium of  claim 14 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for a reversing valve of the HPPH system to reverse a direction of the flow of refrigerant through the heat pump. 
     
     
         18 . The non-transitory, computer readable medium of  claim 14 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for a valve of the HPPH system to open and direct the flow of refrigerant directly from a compressor of the HPPH system to the evaporator coil, thereby bypassing the condenser coil. 
     
     
         19 . The non-transitory, computer readable medium of  claim 14 , wherein transitioning the heat pump to the defrost mode comprises outputting instructions for (i) a supplemental defrost heat source of the HPPH system to output heat and (ii) a fan of the HPPH system to pass heated air from the supplemental defrost heat source across the evaporator coil.