Heat pump water heater

Abstract

A heat pump water heater that includes a compressor, a condenser, an expansion device, and an evaporator. The condenser is in a heat exchange relationship with a water storage tank and includes a heat exchange coil with a first section and a second section. The first section has a first flow area. The second section has a second flow area that is less than the first flow area and the second section is downstream from the first section. The compressor, the condenser, the expansion device, and the evaporator are connected in series.

What is claimed is: 
     
         1 . A heat pump water heater comprising:
 a compressor;   a condenser in a heat exchange relationship with a water storage tank, the condenser including a heat exchange coil with a first section and a second section, the first section has a first flow area, the second section has a second flow area that is less than the first flow area, and the second section is downstream from the first section;   an expansion device; and   an evaporator;   wherein the compressor, the condenser, the expansion device, and the evaporator are connected in series.   
     
     
         2 . The heat pump water heater of  claim 1 , wherein a flow area ratio comparing the first flow area to the second flow area is greater than or equal to two and less than or equal to four. 
     
     
         3 . The heat pump water heater of  claim 1 , wherein the first section has a first section length;
 wherein the second section has a second section length; and   wherein a length ratio comparing the first section length to the second section length is greater than or equal to 0.8 and less than or equal to one.   
     
     
         4 . The heat pump water heater of  claim 1 , wherein the first section has a first section outer diameter; and
 wherein the second section has a second section outer diameter that is less than the first section outer diameter.   
     
     
         5 . The heat pump water heater of  claim 4 , wherein the first section has a first section wall thickness; and
 wherein the second section has a second section wall thickness that is equal to the first section wall thickness.   
     
     
         6 . The heat pump water heater of  claim 1 , wherein the heat exchange coil is positioned within the water storage tank. 
     
     
         7 . The heat pump water heater of  claim 1 , wherein the heat exchange coil is wound around the outside of the storage tank 
     
     
         8 . The heat pump water heater of  claim 2 , wherein the first section has a first section length;
 wherein the second section has a second section length; and   wherein a length ratio comparing the first section length to the second section length is greater than or equal to 0.8 and less than or equal to one.   
     
     
         9 . The heat pump water heater of  claim 8 , wherein the first section has a first section outer diameter; and
 wherein the second section has a second section outer diameter that is less than the first section outer diameter.   
     
     
         10 . The heat pump water heater of  claim 9 , wherein the first section has a first section wall thickness; and
 wherein the second section has a second section wall thickness that is equal to the first section wall thickness.   
     
     
         11 . The heat pump water heater of  claim 9 , wherein the heat exchange coil is positioned within the water storage tank. 
     
     
         12 . The heat pump water heater of  claim 9 , wherein the heat exchange coil is wound around the outside of the storage tank 
     
     
         13 . The heat pump water heater of  claim 10 , wherein the heat exchange coil is positioned within the water storage tank. 
     
     
         14 . The heat pump water heater of  claim 10 , wherein the heat exchange coil is wound around the outside of the storage tank 
     
     
         15 . The heat pump water heater of  claim 8 , wherein the heat exchange coil is positioned within the water storage tank. 
     
     
         16 . The heat pump water heater of  claim 8 , wherein the heat exchange coil is wound around the outside of the storage tank 
     
     
         17 . The heat pump water heater of  claim 2 , wherein the first section has a first section outer diameter; and
 wherein the second section has a second section outer diameter that is less than the first section outer diameter.   
     
     
         18 . The heat pump water heater of  claim 2 , wherein the heat exchange coil is positioned within the water storage tank. 
     
     
         19 . The heat pump water heater of  claim 2 , wherein the heat exchange coil is wound around the outside of the storage tank 
     
     
         20 . The heat pump water heater of  claim 3 , wherein the first section has a first section outer diameter; and
 wherein the second section has a second section outer diameter that is less than the first section outer diameter.