Heat pump water heater with external inlet tube

Abstract

A heat pump water heater system includes a water storage tank and a sealed heat pump cycle with a compressor, a condenser or gas cooler, an evaporator, and a refrigerant. The condenser/gas cooler is disposed in a heat exchange relationship with at least a portion of the water storage tank for heating water within the tank. The tank includes an outlet through which hot water is discharged, and a cold water inlet that is disposed so as to introduce cold water into the tank at a location of a bottommost portion of the condenser/gas cooler. The cold water introduced into the tank is not pre-heated by hot water in the tank so as to establish a thermodynamically efficient temperature differential between the cold water and hot water in the tank.

What is claimed is: 
     
         1 . A heat pump water heater system, comprising:
 a water storage tank;   a sealed heat pump cycle, comprising a compressor, a condenser/gas cooler, an evaporator, and a refrigerant, wherein said condenser is disposed in a heat exchange relationship with at least a portion of said water storage tank for heating water within said tank; and   said tank further comprising an outlet through which hot water is discharged, and a cold water inlet that is disposed so as to introduce cold water into said tank at a location of a bottommost portion of said condenser/gas cooler;   wherein cold water introduced into said tank is not pre-heated by hot water in said tank so as to establish a thermodynamically efficient temperature differential between the cold water and hot water within said tank.   
     
     
         2 . The heat pump water system as in  claim 1 , further comprising an inlet pipe that is disposed externally of said tank, said cold water inlet disposed proximate to a bottom of said tank, and said inlet pipe connected to said cold water inlet. 
     
     
         3 . The heat pump water system as in  claim 1 , wherein said condenser/gas cooler comprises a coiled heat exchanger wrapped around said tank, said heat exchanger comprising a refrigerant inlet disposed proximate to said cold water inlet and a refrigerant outlet disposed proximate to a top of said tank. 
     
     
         4 . The heat pump water system as in  claim 1 , further comprising a generally horizontally disposed cold water discharge pipe within said tank connected to said cold water inlet, said discharge pipe comprising outlets disposed along the length thereof. 
     
     
         5 . The heat pump water system as in  claim 4 , wherein said outlets are oriented towards a bottom of said tank. 
     
     
         6 . The heat pump water system as in  claim 1 , further comprising at least one supplemental electric resistive heating element within said tank. 
     
     
         7 . A water storage tank apparatus for a heat pump water heater system, comprising:
 a tank in which cold water introduced into said tank is heated and discharged as hot water;   a refrigerant condenser/gas cooler configured in a heat exchange relationship with at least a portion of said tank; and   said tank further comprising an outlet through which hot water is discharged, and a cold water inlet that is disposed so as to introduce cold water into said tank at a location of a bottommost portion of said condenser/gas cooler;   wherein cold water introduced into said tank is not pre-heated by hot water in said tank so as to establish a thermodynamically efficient temperature differential between the cold water and hot water within said tank.   
     
     
         8 . The water storage tank apparatus as in  claim 7 , further comprising an inlet pipe that is disposed externally of said tank, said cold water inlet disposed proximate to a bottom of said tank, and said inlet pipe connected to said cold water inlet. 
     
     
         9 . The water storage tank apparatus as in  claim 7 , wherein said condenser/gas cooler comprises a coiled heat exchanger wrapped around said tank, said heat exchanger comprising a refrigerant inlet disposed proximate to said cold water inlet and a refrigerant outlet disposed proximate to a top of said tank. 
     
     
         10 . The water storage tank apparatus as in  claim 7 , further comprising a generally horizontally disposed cold water discharge pipe within said tank connected to said cold water inlet, said discharge pipe comprising outlets disposed along the length thereof. 
     
     
         11 . The water storage tank apparatus as in  claim 10 , wherein said outlets are oriented towards a bottom of said tank. 
     
     
         12 . The water storage tank apparatus as in  claim 7 , further comprising at least one supplemental electric resistive heating element within said tank.