Abstract:
Water heater apparatus includes a tank for storing water; a heat exchanger associated with the tank and being operative to receive refrigerant and transfer heat therefrom to the tank, the heat exchanger representatively being a heat conductive tube externally wrapped around the tank in heat conductive contact therewith; air conditioning apparatus operative to utilize refrigerant flowing through a refrigerant circuit portion of the air conditioning apparatus, the refrigerant circuit portion being in fluid communication with the heat exchanger; and a control system operative to selectively cause a portion of the flowing refrigerant to pass through the heat exchanger, or cause essentially the entire flow of the refrigerant to bypass the heat exchanger.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of the filing date of provisional U.S. patent application No. 61/779,087 filed Mar. 13, 2013. The entire disclosure of the provisional application is hereby incorporated herein by this reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Various apparatus and methods have previously been proposed for preheating water in a water heater tank using refrigerant from air conditioning apparatus such as an air conditioner with a non-reversible refrigerant circuit, or a heat pump having a reversible refrigerant circuit. However, such previously proposed apparatus and methods have often proven to be undesirably complex and expensive for use in many applications. It would be desirable to provide such apparatus and methods that efficiently utilize air conditioning apparatus refrigerant heat to preheat water. It is to this goal that the present invention is primarily directed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an air conditioner/water heater circuit embodying principles of the present invention, with the air conditioner providing only conditioned space air cooling; 
         FIG. 2  is a schematic diagram similar to that in  FIG. 1 , but with the air conditioner being in its air cooling mode and also providing refrigerant heat to a single water heater; 
         FIG. 3  is a schematic diagram similar to that in  FIG. 2 , but with the air conditioner providing refrigerant heat to one of the water heater tanks in a two water heater tank arrangement; 
         FIG. 4  is a schematic diagram of a heat pump/water heater circuit embodying principles of the present invention, with the heat pump being in its air cooling mode; 
         FIG. 5  is a schematic diagram similar to that in  FIG. 4 , but with the heat pump being in its air cooling mode and also providing refrigerant heat to the water heater; 
         FIG. 6  is a schematic diagram similar to that in  FIG. 4 , but with the heat pump being in its air heating mode without also providing refrigerant heat to the water heater; and 
         FIG. 7  is a schematic diagram similar to that in  FIG. 4 , but with the heat pump being in its air heating mode and also providing refrigerant heat to the water heater. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, the term “air conditioning apparatus” encompasses apparatus useable to change the temperature of air being delivered to a conditioned space and having an associated refrigerant circuit. Thus, “air conditioning apparatus” may comprise (1) an air conditioning unit (or “air conditioner”) having a non-reversible refrigerant circuit that may be used to cool air delivered to a conditioned space, or (2) a heat pump having a reversible refrigerant circuit that may be used to heat or cool air delivered to a conditioned space. 
     Typical residential air conditioning apparatus removes heat from a house and transfers it to the environment outside the house. In carrying out principles of the present invention, a portion of that heat may be captured and used to pre-heat water in the home&#39;s water heater to a temperature below the set point temperature of the water heater. The electric element(s) or gas burner in the water heater provides additional heat to bring the water temperature up to the set point temperature of the water heater. A heat pump in either its heating or cooling mode may also be used to pre-heat water in a water heater in accordance with principles of the present invention. 
     An air conditioner/water heater circuit  10  embodying principles of the present invention is schematically depicted in  FIGS. 1 and 2  and includes (1) an air conditioner  12  having an outdoor condensing unit  14  and an indoor coil unit  16 , and (2) an associated water heater  18  which, representatively, may be a gas-fired or electric water heater. In  FIG. 1  the air conditioner  12  is in an air cooling only mode, and in  FIG. 2  is in an air cooling mode and further provides supplemental, refrigerant-based heat to the water heater  18 . The various functions of the air conditioner/water heater circuit  10  are controlled by a schematically depicted electronic control circuit  20  (shown only in  FIG. 1 ) which operates various subsequently described components of the overall circuit  10 . 
     Referring initially to  FIG. 1 , the outdoor condensing unit  14  includes a condenser coil  22  and associated condenser fan  24 , and a compressor  26 . The condenser coil  22  and compressor  26  are coupled, as shown, by a refrigerant tubing circuit  28  having suction and liquid line portions  30  and  32 , to the indoor unit evaporator coil  34  and to a heat conductive refrigeration tube spiral-wrapped around a metal tank portion  36  of the water heater  18  and serving as a refrigerant-to-tank water heat exchanger  38  for the water heater  18 . 
     Operatively linked to the electronic control system  20  are (1) an electronically controlled regulator valve  40  with an associated refrigerant temperature sensor  42  installed as shown in the refrigerant tubing circuit  28  within the condensing unit  14 , (2) an electronically controlled regulator valve  44  and an associated refrigerant temperature sensor  46  installed as shown in the refrigerant tubing circuit  28  adjacent the refrigerant inlet  48  of the coiled heat exchanger  38 , and (3) a normally open solenoid valve  50  installed in a refrigerant bypass line  32   a  between the heat exchanger inlet  48  and the heat exchanger refrigerant outlet  52 . As illustrated in  FIG. 1 , water to be heated is flowed into the water heater tank  36  via a water inlet pipe  54 , and, in response to a heated water demand, is discharged from the tank  36  via a hot water supply pipe  56 . 
     Still referring to  FIG. 1 , with the air conditioner  12  in its air cooling only mode, without the water heater  18  needing refrigerant heat to be transferred to the water in its tank  36  via the heat exchanger  38 , gaseous refrigerant if transferred from the evaporator coil  34  to the compressor  26  via the suction line  30 , with the compressor  26  causing hot refrigerant liquid to flow through and be cooled by the condenser coil  22 . The electronic control system  20  maintains the solenoid valve  50  in its normally open position, and holds the regulator valves  40 , 44  in closed positions such that liquid exiting the condenser coil  22  flows through the open solenoid valve  50 , bypassing the water heater heat exchanger  38 , and flows, via tubing portion  32 , through the expansion valve  58  into and through the evaporator coil  34 . Cooled gaseous refrigerant discharged from the evaporator coil  34  is then returned to the compressor  26  via suction line  30 . Air (not shown) flowed over the evaporator coil  34  is cooled and flowed to a conditioned space served by the air conditioner  12 . 
     Turning now to  FIG. 2 , when the water heater  18  requires refrigerant heat (as determined by a non-illustrated temperature sensor in a bottom portion of the tank  36 ), the control system  20  ( FIG. 1 ) appropriately positions the various previously described valves  40 , 44 , 50  to which it is linked to cause a portion of the hot refrigerant traversing the tubing circuit  28  to pass through the heat exchanger  38 , thereby adding refrigerant heat to the water in the water heater tank  36 , before joining the hot refrigerant flow exiting the valve  50  and bypassing the heat exchanger  38  for flow therewith to the evaporator coil  34 . When the control system  20  detects that the water heater  18  no longer needs refrigerant heat, it returns the air conditioner  12  to its  FIG. 1  air cooling mode in which all of the refrigerant flow traversing the tubing circuit  28  bypasses the water heater coiled tube heat exchanger  38  for the additional electric or gas-fired water heater  18   a.    
     The overall air conditioner/water heater circuit  10   a  schematically depicted in  FIG. 3  is identical to the previously described air conditioner/water heater circuit  10  with the exceptions that (1) an additional water heater  18   a , having either electric or gas heating apparatus associated therewith, but without an associated coiled tube refrigerant-to-water heat exchanger, is connected in series with the previously described water heater  18  such that water exiting the water heater  18  via pipe  56  is flowed through the additional water heater  18   a  and then discharged therefrom through a hot water outlet pipe  56   a , and (2) the water heater  18  is not provided with electric or gas heat, but receives only refrigerant heat via its tubing heat exchanger portion  38 , thus functioning solely as a water preheating device. 
     This two tank configuration allows hot water to be stored when the air conditioner unit  12  (or a heat pump as later described herein) is running during times when there is little or no demand for hot water, thereby providing additional low cost hot water capacity during periods of time when the demand for hot water is high. It also improves the efficiency of the air conditioning unit or heat pump compared to the previously described single tank arrangement since the water in the preheater tank  18  will usually be at a lower temperature than the water temperature in the main tank  18   a  during periods of time when there is little or demand for hot water. 
     A heat pump/water heater circuit  60  embodying principles of the present invention is schematically depicted in  FIGS. 4-7  and includes (1) a heat pump  62  having an outdoor unit  64  and an indoor coil unit  66 , and (2) an associated water heater  68  which, representatively, may be a gas-fired or electric water heater. In  FIG. 4  the heat pump  62  is in an air cooling only mode. In  FIG. 5  the heat pump  62  is in an air cooling mode and further provides supplemental, refrigerant-based water preheating to the water heater  68 . In  FIG. 6  the heat pump  62  is in an air heating only mode. In  FIG. 7  the heat pump  62  is in an air heating mode and further provides supplemental, refrigerant-based water preheating to the water heater  68 . The various functions of the heat pump/water heater circuit  60  are controlled by a schematically depicted electronic control circuit  70  (shown only in  FIG. 4 ) which operates various subsequently described components of the circuit  60 . 
     As shown in  FIGS. 4-7 , the outdoor unit  64  includes a condenser coil  72  and associated fan  74 , and a compressor  76 . The condenser coil  72  and compressor  76  are coupled, as shown, by a refrigerant tubing circuit  78  having line portions  80  and  82 , to the indoor unit evaporator coil  84  and to a heat conductive copper tube spiral-wrapped around a metal tank portion  86  of the water heater  68  and serving as a refrigerant-to-tank water heat exchanger  88  for the water heater  68 . 
     The outdoor unit  64  has a reversing valve  90 , an electronically controlled regulator valve  92 , and a normally closed solenoid valve  94  connected as shown in the tubing circuit  78  and operatively linked to the electronic control system  70 . The indoor coil unit  66  has a normally closed solenoid valve  98  and a normally open solenoid valve  100  connected as shown in the tubing circuit  78  and operatively linked to the electronic control system  70 . The water heater  68  has a temperature sensor  102 , an electronically controlled regulator valve  104 , a normally open solenoid valve  106 , and a normally closed solenoid valve  108  connected as shown in the tubing circuit  78  and operatively linked to the electronic control system  70 . 
     Turning now to  FIG. 4 , with the heat pump/water heater system  60  in an air cooling only mode, the electronic control system sets the previously described valve components in the tubing circuit  78  in a manner such that the compressor  76  causes refrigerant discharged therefrom to flow, via tubing portion  80  of the tubing circuit  78 , sequentially through the condenser coil  72  to the water heater  68  where the refrigerant, due to the closure of the regulator valve  104 , bypasses the heat exchanger  88  through the open solenoid valve  106 . The liquid refrigerant then flows through tubing portion  80  through the expansion valve  110  into and through the evaporator coil  84 , and finally (as gaseous refrigerant) flows back to the compressor  76 . Air (not shown) flowed over the evaporator coil  84  is cooled and flowed to a conditioned space served by the heat pump  62 . 
     When a temperature sensor (not shown) of the water heater  68  calls for refrigerant heat while the heat pump  62  is in a cooling mode thereof, the electronic control system  70  appropriately repositions the water heater regulator valve  104  and the normally open solenoid valve  106  such a portion of the hot refrigerant flows through the heat exchanger  88  and back into the tubing portion  80 , thereby adding refrigerant heat to the tank water, with the remainder of the hot refrigerant approaching the water heater  68  bypassing it and flowing with the refrigerant exiting the heat exchanger  88  through the expansion valve  110  and the evaporator coil  84  back to the compressor  76  via the tubing portion  82 . 
     With the heat pump/water heater system  60  switched to its air heating only mode as shown in  FIG. 6 , the electronic control system  70  ( FIG. 4 ) switches the reversing valve  90 , and adjusts other tubing circuit valve components, in a manner such that hot refrigerant discharged from the compressor  76  initially flows, via tubing portion  82  of the tubing circuit  78 , to the evaporator coil  84  (now functioning as an air heating coil). A portion of this refrigerant flow bypasses the coil  84  (through partially opened valve  98 ) and enters tubing portion  80  downstream of the coil  84 , with the refrigerant flow exiting the coil  84  via the expansion valve  110  mixing with the bypassing refrigerant for delivery therewith to the water heater  68  via the tubing portion  80 . This mixed refrigerant flow, via the closure of the valve  104 , entirely bypasses the heat exchanger  88 , via the open solenoid valve  106 , and then sequentially flows, via the tubing portion  80  and the opened valve  94 , through the expansion valve portion (not shown) of the condenser coil  72 , the condenser coil  72  (which extracts heat from outside air), and then back to the compressor  76 . 
     Finally, as shown in  FIG. 7 , if the electronic control system  70  ( FIG. 4 ) detects that the water heater  68  needs refrigerant heat when the heat pump  62  is in an air heating mode, the control system  70  appropriately adjusts the water heater valves  104 , 106 , 108  in a manner such that a portion of the mixed refrigerant flow to the water heater  68  flows through the coiled tubing heat exchanger  88  to add refrigerant heat to the tank water, with the balance of the mixed refrigerant flow bypassing the heat exchanger  88  via the valve  106 . 
     In the case of either the previously described air conditioning unit  12  or the heat pump  62 , when the temperature of the water in the lower portion of the water heater tank reaches a predetermined temperature, appropriate ones of the valve components in the outdoor unit and water heater are positioned by the electronic control system ( 20  or  70  as the case may be) to return the air conditioning unit or heat pump system to its normal operational mode (cooling or heating without refrigerant heat transfer to the water heater tank water). 
     In optional constructions of the air conditioning and heat pump systems  10 , 60  described above, the electronically controlled regulator valves may be replaced with fixed orifice solenoid valves, and the flow of hot refrigerant to the water heater refrigerant-to-water heat exchanger coils may instead be regulated by the compressor discharge (head) pressure using an outdoor or indoor fan speed controller which is, in turn, controlled by the sensed water temperature in the water heater tank. 
     The foregoing detailed description is to be clearly understood as being given by way of illustration and example only, the spirit and scope of the present invention being limited solely by the appended claims.