Systems and Methods for Passive and Active Hybrid Defrost Control for Pool/Spa Heat Pumps

Abstract

Systems and methods for passive and active hybrid defrost control for a pool/spa heat pump are provided. The system monitors the temperature of the evaporator coil of the heat pump and, as required, operates the heat pump in a passive defrost mode if the temperature is less than or equal to a first predetermined temperature value. The system operates the heat pump in an active defrost mode if the temperature of the evaporator coil remains below the first predetermined temperature value and a first time period has expired. The system can stop operation of the active defrost mode when the temperature of the evaporator coil is greater than a second predetermined temperature value. Additionally, the system can stop operation of the passive defrost mode or the active defrost mode upon expiration of a timeout timer.

What is claimed is: 
     
         1 . A system for passive/active hybrid defrosting of a heat pump, comprising:
 a controller in communication with a heat pump; and   a memory storing control logic executed by the controller, the control logic causing the controller to:   determine a temperature of an evaporator coil of the heat pump;   operate the heat pump in a passive defrost mode if the temperature of the evaporator coil is less than or equal to a first predetermined temperature value; and   operate the heat pump in an active defrost mode if the temperature of the evaporator coil remains below the first predetermined temperature value and a first time period has expired.   
     
     
         2 . The system of  claim 1 , wherein the control logic causes the controller to operate the heat pump in the passive defrost mode for the first time period. 
     
     
         3 . The system of  claim 2 , wherein the control logic causes the controller to stop operation of the passive defrost mode when the first time period has elapsed and the temperature of the evaporator coil remains below the first predetermined temperature value. 
     
     
         4 . The system of  claim 1 , wherein the control logic causes the heat pump to stop operation of the active defrost mode when the temperature of the evaporator coil is greater than a second predetermined temperature value. 
     
     
         5 . The system of  claim 1 , wherein the control logic causes the controller to operate the heat pump in the active defrost mode for a second time period. 
     
     
         6 . The system of  claim 5 , wherein the control logic causes the controller to stop operation of the active defrost mode if the temperature of the evaporator coil is greater than the second predetermined temperature value. 
     
     
         7 . The system of  claim 1  where the control logic causes the controller to stop operation of the passive defrost mode or the active defrost mode upon expiration of a timeout timer. 
     
     
         8 . The system of  claim 1 , wherein the first predetermined temperature value is 29 degrees fahrenheit. 
     
     
         9 . The system of  claim 1 , wherein the first predetermined temperature value falls in a range of 22-32 degrees fahrenheit. 
     
     
         10 . The system of  claim 1 , wherein the second predetermined temperature value is 42 degrees fahrenheit. 
     
     
         11 . The system of  claim 1 , wherein the second predetermined temperature value falls in a range of 40-50 degrees fahrenheit. 
     
     
         12 . The system of  claim 1 , wherein the heat pump is operated in the passive defrost mode by turning off a compressor of the heat pump and turning on a fan of the heat pump. 
     
     
         13 . The system of  claim 1 , wherein the heat pump is operated in the active defrost mode by turning off a fan of the heat pump and turning on a compressor of the heat pump.