Abstract:
A system is disclosed which utilizes air conditioning waste to heat a second fluid such as swimming pool water. The second condenser for pool water heating is connected in parallel with the air conditioning condenser. An accumulator is connected between the condensers and the expansion valve to absorb fluctuations in refrigerant level due to different operating conditions caused by the pool water heating, thereby ensuring that liquid refrigerant is always supplied to the expansion valve. A controller reads the ambient air temperature at the air conditioning condenser and reads the air conditioning system condensing pressure and uses an algorithm to compute ambient air fan speed at the air conditioning condenser based on these two inputs to maintain a consistent heated pool water temperature. 
     An alternate system includes first and second condensers connected in series with an accumulator connected between the second condenser and the expansion valve and a pressure equalization line connected between the compressor and the accumulator. A controller reads the ambient air temperature at the air conditioning condenser and reads the air conditioning system condensing pressure and uses an algorithm to compute ambient air fan speed at the air conditioning condenser based on these two inputs to maintain a consistent heated pool water temperature.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to the recovery of waste heat from a refrigeration or an air conditioning system, to provide a heated fluid at a controlled, consistent temperature. 
       BACKGROUND 
       [0002]    The use of a heater to warm swimming pool water is quite common among swimming pool owners. Many existing systems use electric, gas, or fuel oil-heating units, which are costly to operate. Attempts to utilize air conditioning waste heat to provide a safe, economical, and low energy consuming pool water heating system, such as shown in U.S. Pat. No. 3,976,123 issued to Davies, have not been commercially successful as previous systems did not maintain a constant discharge temperature, were inefficient to operate, and could cause equipment damage. 
       SUMMARY OF THE INVENTION 
       [0003]    It is a general object of the present invention to provide a pool water heater that uses the waste heat from a refrigeration or an air conditioning system to heat pool water, or other fluids, to useful and desired temperatures, and to do such water heating with consistent, controlled output water temperatures, with optimum air conditioning system efficiency, and without equipment damage. 
         [0004]    This and other objects and features are provided, in accordance with one aspect of the present invention, by an air conditioning system comprising a compressor connected to a first condenser and to a second condenser, connected in parallel or in series. The condensers and the compressor are connected to an accumulator, the accumulator connected to an expansion valve, the expansion valve connected to an evaporator, and the evaporator connected to the compressor. A pump draws water from a pool of water and supplies the water to the first condenser and then the water is returned to the pool. A control system adjusts the thermal performance of the second condenser to increase or decrease the condensing pressure and condensing temperature to heat the water to the desired temperature, based on the readings of two sensors, pressure and/or temperature, while the accumulator supplies the proper amount of liquid refrigerant to the expansion valve during all phases of operation. Other applications are presented for hot water heating and clothes drying. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1A  shows a prior art air conditioning waste heat recovery system for heating pool water;  FIG. 1B ,  1 C, and  1 D show a partial enlargement of  FIG. 1A  and show the condition of the hot high temperature gaseous and liquid refrigerant with no pool water heating, partial pool water heating with the system charged with no pool water heating, and partial pool water heating with system charged with full pool water heating, respectively; 
           [0006]      FIG. 1E  shows Theoretical Outlet Water Temperature, Air Conditioning System Condensing Pressure, Condenser Fan ON/OFF, and Hot Water Requirements at various Operational Conditions; 
           [0007]      FIG. 2A  shows a first embodiment of the present invention air conditioning waste heat recovery system for heating pool water where the condensers are connected in series to an accumulator with a pressure equalization line between the compressor and accumulator, and the thermal performance of refrigerant-to-air condenser is controlled by adjusting its fan speed;  FIG. 2B ,  2 C, and  2 D show a partial enlargement of  FIG. 2A , and show the condition of the hot high temperature gaseous and liquid refrigerant with no pool water heating, partial pool water heating, and maximum pool water heating, respectively; 
           [0008]      FIG. 3A  shows a second embodiment of the present invention air conditioning waste heat recovery system for heating pool water Where the condensers are connected in parallel between the compressor and accumulator and the thermal performance of refrigerant-to-air condenser is controlled by adjusting its fan speed;  FIG. 3B ,  3 C, and  3 D show a partial enlargement of  FIG. 3A , and show the condition of the hot high temperature gaseous and liquid refrigerant with no pool water heating, partial pool water heating, and maximum pool water heating, respectively; 
           [0009]      FIG. 3E  is similar as  FIG. 3A  except the pool water heater is replaced by domestic or commercial hot water heating; 
           [0010]      FIG. 3F  is similar as  FIG. 3A  except the pool water heater is replaced by clothes dryer heating; 
           [0011]      FIG. 4A and 4B  show the control graphs for controlling the water temperature from the refrigerant-to-water condenser using ambient air temperature at the refrigerant-to-air condenser and exit water temperature at the refrigerant-to-water condenser to modulate fan motor speed in  FIG. 2A and 3A  and associated Figures; 
           [0012]      FIG. 5A and 5B  show the control graphs for controlling the water temperature from the refrigerant-to-water condenser using ambient air temperature at the refrigerant-to-air condenser and the system condensing pressure to modulate fan motor speed in  FIG. 2A and 3A  and associated Figures; 
           [0013]      FIG. 6A  shows Theoretical Outlet Water Temperature, Air Conditioning System Condensing Pressure, Condenser Fan Speed, and Hot Water Requirements at various Operational Conditions. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    The use of air conditioning waste heat to heat swimming pool water has been demonstrated and is well know in the art. Davies discloses a system for controlled heating of pool water using waste heat of an air conditioner where the refrigerant-to-air condenser fan is cycled on and off in response to a sensor monitoring the temperature of the water exiting the refrigerant-to-water condenser. If the water temperature is below the Fan Off Set Point, the air conditioning condenser fan will be turned off, increasing the condensing pressure and temperature, increasing the amount of heat going into the refrigerant-to-water condenser, increasing the temperature of the water exiting refrigerant-to-water condenser. When the water temperature reaches the Fan On Set Point, which is higher than the Fan Off Set Point, the air conditioning fan will be turned on, decreasing the condensing pressure and temperature, reducing the amount of heat going into the refrigerant-to-water condenser, lowering the temperature of the water exiting refrigerant-to-water condenser. However, there are a number of inherent disadvantages present in this and other prior art systems. The cycling of the condenser fan is a poor practice as the rate of cycling can become too high, burning out the condenser fan motor. Cycling of the condenser fan increases as the water heating BTU/hr load decreases as when the inlet water temperature approaches the Fan Off Set Point. Increasing the temperature separation between the Condenser Fan On and Off Set Points will reduce the instances of motor burn out but increases the temperature swing in the outlet temperature of the water exiting the refrigerant-to-water condenser which is unacceptable in many applications like domestic hot water heating. 
         [0015]    Davies states “In operation, the transfer of heat to the pool water does not interfere with the refrigeration and cooling capabilities of refrigeration loop”. This is a common false belief, because it is assumed that the air conditioning system is more efficient due to the additional condensing capacity of the refrigerant-to-water condenser. But in fact, a 15% degradation has been observed with a small, 1-ton pool water refrigerant-to-water condenser installed on a 3-ton air conditioning system. The degradation is caused by the refrigerant-to-water condenser, which when in operation takes liquid refrigerant from the refrigerant-to-air condenser, disrupting the balance of liquid refrigerant in the system, allowing hot gaseous refrigerant to reach the air conditioner&#39;s expansion valve and evaporator. Larger degradations will occur if larger refrigerant-to-water condensers are used, which is one reason why prior air pool water heaters use smaller refrigerant-to-water condensers. The air conditioning system is usually charged with refrigerant without pool water heating. With just the refrigerant-to-air condenser running, refrigerant is added until a solid column of liquid exits the refrigerant-to-air condenser. The solid column of refrigerant liquid can be seen in a sight glass installed after the condenser and the solid column of refrigerant liquid keeps high pressure gaseous refrigerant out of the evaporator, which would degrade the operation of the evaporator. When the pool water is turned on, refrigerant is condensed in the refrigerant to-water condenser and this amount of liquid is removed from the refrigerant-to-air condenser allowing high pressure gaseous refrigerant to reach the expansion valve and evaporator. Gaseous refrigerant will now be seen in the sight glass. The result is the operational efficiency of the air conditioning system is lowered. The amount of gaseous refrigerant reaching the expansion valve and evaporator is dependent upon the amount of refrigerant being condensed in the refrigerant-to-water condenser. Charging the air conditioner when the pool heater is running will keep the refrigerant liquid column up to the expansion valve and evaporator while water is being heated by the refrigerant-to-water condenser. But when the pool heater is turned off excess liquid refrigerant will pass thru the evaporator to the compressor, destroying the compressor, as the compressor cannot compress a liquid. A larger pool water refrigerant-to-water condenser will increase the risk of compressor damage, which is why they are sized to the small side. Air conditioning inefficiency due to high pressure gaseous refrigerant reaching the evaporator and compressor damage risks are additional problems that have limited the use of air conditioning waste heat to heat pool water or other fluids. 
         [0016]    Referring now to  FIG. 1A , a prior art air conditioning waste heat recovery system for heating pool water is shown generally as  100 . The air conditioning waste heat recovery system comprises a compressor  101 , a pool water condenser  102 , a refrigerant-to-air condenser  103 , an expansion valve  104 , an air to refrigerant evaporator  105  and refrigerant-to-air fan motor controller  108 . The refrigerant flow is shown by arrows  110 . Compressor  101  is connected to and supplies gaseous high pressure refrigerant-to-water condenser  134  condensing line  114  with refrigerant line  112 , the refrigerant-to-water condenser  134  condensing line  114  is connected to and supplies high pressure gaseous and/or liquid refrigerant to refrigerant-to-air condenser  103  refrigerant line  118  with refrigerant line  116 , the refrigerant-to-air condenser  103  refrigerant line  118  supplies high pressure liquid refrigerant to expansion valve  104  with refrigerant line  121 , the expansion valve  104  supplies low pressure liquid refrigerant to evaporator  105  refrigerant line  124 , the evaporator  105  refrigerant line  124  supplies low pressure gaseous refrigerant to compressor  101  with refrigerant line  128 . The pool water flow is shown by arrows  130 . Pump  131  is connected to and draws pool water  138  from pool  137  with line  139 , pump  131  is connected to and supplies the pool water  138  to the refrigerant-to-water condenser  134  with water line  132 , the water condenser  134  puts pool water  138  in contact for heat exchange with refrigerant line  114  which heats the pool water  138 , the water condenser  134  supplies heated water to the pool  137  with water line  136 . The waste heat recovery system refrigerant-to-air condenser  103  consists of a refrigerant line  118  with thermally connected fins  164 , fan motor  160  with fan blades  166  that blow ambient air  162  across the fins  164 , heating the ambient air  162 . The waste heat recovery system expansion valve  104  causes the high pressure liquid refrigerant to become low pressure liquid refrigerant. The waste heat recovery system air to refrigerant evaporator  105  consists of a refrigerant line  124  with thermally connected fins  184 , fan motor  180  with fan blades  186  which blow interior home air  182  across fins  184 , cooling the interior home air  186 , supplying low pressure gaseous refrigerant  141  to compressor  201 . Refrigerant-to-air fan motor controller  108  reads the temperature of the exit water at sensor  175  with electrical line  173  and turns fan motor  160  off once the predefined exit water temperature is reached with electrical line  171 . Now, all of the condensing must happen at the refrigerant-to-water condenser  134  refrigerant line  114  which increases the condensing pressure and temperature, heating the pool water  138  to a higher temperature. Fan motor controller  108  continues to read the exit water temperature with sensor  175  and will turn fan motor  160  back on when the exit water temperature increases to the predefined Fan ON temperature. Condensing will now occur in both condensers, lowering the condensing pressure and temperature, heating the pool water  138  to a lower temperature. If the pool water  138  temperature drops below the predefined Fan OFF set point, the OFF/ON cycle will repeat. The in home thermostat  172  tells fan motor controller  108  when system  100  is running. 
         [0017]    Referring now to  FIG. 1B ,  1 C, and  1 D, partial enlargements of  FIG. 1A , where refrigerant lines  112 ,  114 ,  116 ,  118 , and  121  are shown coming to, through, and exiting pool water and refrigerant-to-air condenser  103  at various operational conditions. Refrigerant flow direction is shown by arrows  110 . 
         [0018]    Referring now to  FIG. 1B  where the pool water condenser is not being used and there is no pool water flow. Only the refrigerant-to-air condenser  103  is in operation and it is supporting the full air conditioning load. Liquid refrigerant  144  is only condensed in the refrigerant-to-air condenser  103 . Condensing starts at point  118   a  when the gaseous high pressure, high temperature refrigerant  141  comes in contact for heat exchange with the portion of refrigerant line  118  that is in contact for heat exchange with the thermally conductive fins  164  that are cooled by ambient air  162 . Condensing basically ends at point  118   b  as refrigerant line  118  continues past thermally conductive fins  164 . Approximately one half of the condenser volume between point&#39;s  118   a  and  118   b  are filled with liquid refrigerant  144 . The air conditioning system is normally charged with refrigerant with just the refrigeration to air condenser running, and charging is stopped when the outlet of the refrigerant-to-air condenser is solid liquid as seen in sight glass  119 . 
         [0019]    Referring now to  FIG. 1C , where both the pool water condenser  102  and refrigerant-to-air condenser  103  are in operation. Pool water flow is shown by arrows  130 . Liquid refrigerant  144  is condensed in both condensers. Condensing starts at point  114   a  when the gaseous high pressure, high temperature refrigerant comes in contact for heat exchange with the portion of refrigerant line  114  that is in contact for heat exchange with and cooled by pool water  138 . Now there is liquid refrigerant in both condensers and since the system was charged with only the refrigeration to air condenser  103  running, there is not enough refrigerant in the system to allow a solid column of liquid exiting the refrigerant-to-air condenser  103  as seen in sight glass  119 . Now both gaseous high pressure refrigerant  141  and liquid refrigerant  144  reach the expansion valve  104  and air to refrigerant evaporator  105 , reducing system efficiency 
         [0020]    Referring now to  FIG. 1D , where the air conditioning system has been charged with both the pool water condenser  102  and the refrigerant-to-air condenser  103  running. Now there is a solid column of liquid refrigerant  144  exiting the refrigerant-to-water condenser  134  and there is no high pressure gas  141  reaching the expansion valve  104  or the air to refrigerant evaporator  105 , as shown in sight glass  119 , for proper operational efficiency. However, when the pool water is turned off, the refrigerant liquid volume will revert to that of  FIG. 1B  and the liquid refrigerant volume difference between  FIG. 1D  and  FIG. 1B  will go into the air to refrigerant evaporator  105  and on to the compressor  101 . Any liquid refrigerant  144  reaching the compressor  101  will cause severe damage and is dangerous. 
         [0021]    Referring now to  FIG. 1E , where theoretical Outlet Water Temperature, Air Conditioning System Condensing Pressure, Condenser Fan ON/OFF, and Hot Water Requirements at various Operational Conditions are shown for  FIG. 1A . Five Operational Conditions are presented. The No.  1  Condition is for no pool water heating and the Hot Water requirement is zero. The air conditioning system is working normally as shown is  FIG. 1B . The No.  5  Condition is for full pool water heating and the Hot Water requirement is 100%. Refrigerant condensing is taking place only in the refrigerant-to-water condenser. There is very little cycling of fan motor  160  under this condition and if the system was charged with refrigerant under this operating condition, the liquid refrigerant distribution would be as shown in  FIG. 1D . If the system was charged with refrigerant under operation condition No.  1 , the liquid refrigerant distribution would be as shown in  FIG. 1C  and hot gaseous refrigerant would reach the expansion valve, degrading air conditioning performance. The No.  2 , No.  3 , and No.  4  conditions are for 25%, 50% and 75% Hot Water requirements. Fan motor cycling decreases as the Hot Water requirements increase. Fan motor cycling at the lower Hot Water requirements will damage the typical refrigerant-to-air condenser fan motor. Fan motor cycling can be reduced by increasing the difference between the Fan ON and Fan OFF set points but this causes higher hot water temperature differences between Fan ON and Fan OFF operation, which is unacceptable to other applications like hot water heating. If the system was charged with refrigerant under operating condition No  5 , the liquid refrigerant distribution would be as shown in  FIG. 1E , but excess liquid refrigerant, the liquid difference between  FIG. 1D and 1E , would be available to damage the compressor. Under these conditions, the lower the hot water requirements, the more liquid refrigerant is available to damage the compressor. If the system was charged with refrigerant under operation condition No.  1 , the liquid refrigerant distribution would be as shown in  FIG. 1C  and hot gaseous refrigerant would reach the expansion valve, degrading air conditioning performance. If the system is charged under conditions  2 ,  3 , or  4 , the system will only operate correctly at these specific operating conditions. 
         [0022]    Accordingly, it is desirable to have an air conditioning waste heat system capable of heating pool water to desired temperatures with good operational efficiency, consistent output temperatures, and no equipment damage. 
         [0023]    Referring now to  FIG. 2A , an air conditioning waste heat recovery system for heating pool water according to the present invention is shown generally as  200 , and comprises a compressor  201 , a pool water condenser  202 , a refrigerant-to-air condenser  203  where the condensers are connected in series; a pressure equalization line  206 , an accumulator  207 , a fan speed control  208  for the refrigerant-to-air condenser  203  fan motor  260 , an expansion valve  204 , and an air to refrigerant evaporator  205 . Arrows  210  show the refrigeration flow. Compressor  201  is connected to and supplies gaseous high pressure refrigerant to refrigerant line tee  215  with refrigerant line  213 , the refrigeration tee  215  is connected to and supplies gaseous high pressure, high temperature refrigerant to refrigerant-to-water condenser  234  condensing line  214  with refrigerant line  212 , the refrigerant-to-water condenser  234  condensing line  214  is connected to and supplies gaseous and or liquid refrigerant-to-air condenser  203  refrigerant line  218  with refrigerant line  216 , the refrigerant-to-air condenser  203  refrigerant line  218  supplies high pressure liquid refrigerant to accumulator  207  with refrigerant line  220 . The tee  215  also supplies gaseous high pressure refrigerant to accumulator  207  with pressure equalization line  206 . The accumulator  207  is connected to and supplies high pressure liquid refrigerant to expansion valve  204  with refrigerant line  221 , the expansion valve  204  supplies low pressure liquid refrigerant to evaporator  205  refrigerant line  224 , the evaporator  205  refrigerant line  224  supplies low pressure gaseous refrigerant to the compressor  201  with refrigerant line  228 . The pool water condenser  202  water flow is shown by arrows  230 . Pump  231  is connected to and draws pool water  238  from pool  237  with line  239 , the pump  231  is connected to and supplies the pool water  238  to the refrigerant-to-water condenser  234  with water line  232 , the water condenser  234  puts the pool water  238  in contact for heat exchange with the refrigerant line  214  which heats the pool water  238 , the water condenser  234  supplies heated pool water  238  to the pool  237  with water line  236 . The waste heat recovery system refrigerant-to-air condenser  203  consists of a refrigerant line  218  with thermally connected fins  264 , fan motor  260  with fan blades  266  that blow ambient air  262  across the fins  264 , heating the ambient air  262 . Fan speed controller  208  is connected to and adjusts fan motor  260  speed from zero to 100%, which controls the amount of condensation taking place in the refrigerant-to-air condenser  203  and raises or lowers the condensing pressure in both condensers to obtain the desired water temperature exiting the refrigerant-to-water condenser  234 . The waste heat recovery system expansion valve  204  causes the high pressure liquid refrigerant to become low pressure liquid refrigerant. The waste heat recovery system air to refrigerant evaporator  205  consists of a refrigerant line  224  with thermally connected fins  284 , fan motor  280  with fan blades  286  which blow interior home air  282  across the fins  284 , cooling the interior home air  286  and supplying gaseous refrigerating to compressor  201  by refrigerant line  228 . The control system  208  that modulates the refrigerant-to-air condenser  203  fan  206  will be discussed in detail later. 
         [0024]    Referring now to  FIG. 2B ,  2 C,  2 D, partial enlargements of  FIG. 2A , where refrigerant lines  213 ,  212 ,  214 ,  215 ,  216 ,  218 , and  221  are shown coming to, through, and exiting pool water condenser  202 , refrigerant-to-air condenser  203  and accumulator  207 ; and pressure equalization line  206  is connected between tee  215  a head of pool water refrigerant-to-water condenser  202  and the accumulator  207 . Arrows  210  show refrigerant flow direction. 
         [0025]    Referring now to  FIG. 2B , the pool water condenser  202  is not being used and there is no pool water flow. The refrigerant-to-air condenser  203  is in operation and its condensing capacity is controlled by fan motor controller  208  running fan motor  280  at 100 percent of fan capacity, because water heating is not desired. Liquid refrigerant  244  is condensed only in the refrigerant-to-air condenser  203 . Condensing starts at point  218   a  when the gaseous high pressure, high temperature refrigerant  241  comes in contact for heat exchange with the portion of refrigerant line  218  that is in contact for heat exchange with the cooling fins  264 . Condensing basically ends at point  218   b  as refrigerant line  218  continues past thermally conductive fins  264 . The condensing volume between point&#39;s  218   a  and  218   b  are approximately one half filled with liquid refrigerant. The air conditioning system has been charged with the refrigerant with just the pool water condenser  202  running as shown in  FIG. 2D , which is the maximum liquid refrigerant condition and charging, stopped when the outlet of the refrigerant-to-air condenser  203  is solid liquid as seen in sight glass  119 . The accumulator  207  has the capacity to receive the unneeded liquid refrigerant when the pool water condenser is not in operation and pressure equalization line  206  allows accumulator volume changes without forcing the excess liquid refrigerant through the system, to avoid compressor damage. 
         [0026]    Referring now to  FIG. 2C , where both the pool water condenser  202  and refrigerant-to-air condenser  203  are both in operation. Arrows  230  show pool water flow. Condensing starts at point  214   a  when the gaseous high pressure, high temperature refrigerant  241  comes in contact for heat exchange with the portion of refrigerant line  214  that is in contact for heat exchange with and cooled by the pool water  238 . Now there is liquid refrigerant in both condensers and since the system was charged with only the pool water condenser  202  running, there is enough liquid refrigerant  244  in the accumulator  207  to supply liquid refrigerant  244  so that a continuous column of liquid exits the accumulator  207  as seen in sight glass  219 . Now only liquid refrigerant  244  reaches the expansion valve  204  and air to refrigerant evaporator  205 , maintaining system efficiency. Fan motor controller  208  adjusts fan motor  260  speed between zero and 100%, which increases or decreases the condensing pressure and temperature to maintain the desired water temperature at the point  214   b  in the pool water refrigerant-to-water condenser  202 . 
         [0027]    Referring now to  FIG. 2D , where the pool water condenser  202  is running at 100% and carrying the full air conditioning load. Refrigerant-to-air condenser  203  fan motor  280  has been turned off by motor controller  208 . This is the maximum water heating capability of the waste heat recovery system  200  and all of the condensing energy is going into heating the pool water. Arrows  230  show pool water flow. Condensing starts at point  214   a  when the gaseous high pressure, high temperature refrigerant  241  comes in contact for heat exchange with that portion of refrigerant line  214  that is in contact for heat exchange with and cooled by the pool water  238 . Now there is the maximum liquid refrigerant in both condensers and this is the operational condition for proper charging of the air conditioning waste heat recovery system for heating pool water. Now there is enough liquid refrigerant  244  in the accumulator  207  to supply liquid refrigerant  244  to allow a solid column of liquid to exit the accumulator  207  when pool water condenser  202  is not in operation and there is enough accumulator capacity to accept unneeded liquid refrigerant when pool water condenser  202  is running up to 100% of capacity. Since the accumulator maintains a constant liquid refrigerant supply to expansion valve  204  and the accumulator has the capacity to hold unneeded liquid refrigerant  244 , the system works at peak efficiency and there is no risk of compressor damage. 
         [0028]    Referring now to  FIG. 2A  again, fan  260  controller  208  receives inputs or sends outputs from water exit temperature sensor  275  by electrical line  273 , from condensing pressure sensor  277  at accumulator  207  by electrical line  278 , from ambient air temperature sensor  276  at refrigerant-to-air condenser  203  by electrical line  272 , and controls fan motor  260  speed with control line  271 . Controller  208  determines if water heating is needed and controller  208  turns on the air conditioning system by electrical line  274  to in home thermostat  272 . Controller then adjusts the speed of fan  260  per control graphs shown in  FIG. 4A and 4B  to maintain the selected water exit temperature from refrigerant-to-water condenser  234  as read at sensor  275 . 
         [0029]    The size of the accumulator is dependent upon the sizes of the system condensers  234  and  203 . Typically the accumulator volume must be at least equal to the volume delta between the liquid volume shown in  FIG. 2B  and the liquid volume shown in  FIG. 2D  between point  214   a  and the point where line  221  enters accumulator  207 . This will guarantee that the expansion valve only sees liquid refrigerant under all stated operating conditions. A 5 to 10% additional accumulator volume is usually added as a safety factor. 
         [0030]    Referring now to  FIG. 3A , an air conditioning waste heat recovery system for heating pool water accordingly to the present invention is shown generally as  300  where the condensers are connected in parallel and the refrigerant-to-air condenser capacity is controlled by ambient air flow  362 . The assembly  300  comprises a compressor  301 , a pool water condenser  302 , a refrigerant-to-air condenser  303 , an accumulator  307 , a fan speed control  308  for the refrigerant-to-air condenser  303 , an expansion valve  304 , and an air to refrigerant evaporator  305 . Arrows  310  show the refrigeration flow. Compressor  301  is connected to and supplies gaseous high pressure refrigerant to refrigerant line tee  315  with refrigerant line  313 , the refrigeration tee  315  is connected in parallel to and supplies gaseous high pressure refrigerant to both refrigerant-to-water condenser  334  condensing line  314  with refrigerant line  312 , and refrigerant-to-air condenser  303  condensing line  318  with refrigerant line  316 . Both condensers supply high pressure gaseous and/or liquid refrigerant to accumulator  307  with refrigerant lines  317  and  320 . Accumulator  307  supplies liquid refrigerant to expansion valve  305  and evaporator  304  with refrigerant line  321 . Evaporator  304  supplies low pressure gaseous refrigerant to compressor  301  with refrigerant line  328 . The pool water condenser  302  water flow is shown by arrows  330 . Pump  331  is connected to and draws pool water  338  from pool  337  with line  339 , the pump  331  is connected to and supplies the pool water  338  to the refrigerant-to-water condenser  334  with water line  332 , the refrigerant-to-water condenser  334  puts the pool water  338  in contact for heat exchange with the refrigerant line  314  which heats the pool water  338 , the refrigerant-to-water condenser  334  supplies heated water to the pool  337  with water line  336 . The waste heat recovery system refrigerant-to-air condenser  303  consists of a refrigerant line  318  with thermally connected fins  364 , fan motor  360  with fan blades  366  that blow ambient air  362  across the fins  364 , heating the ambient air  362  and fan speed controller  308  which controls the amount of condensation taking place in the refrigerant-to-air condenser  303  by adjusting the amount of ambient air  362  blowing over the fins  364 . The waste heat recovery system expansion valve  304  and air to refrigerant evaporator  305  operate in the conventional manner supplying low pressure gaseous refrigerating to compressor  301  by refrigerant line  328 . 
         [0031]    Referring now to  FIG. 3B ,  3 C, and  3 D, partial enlargements of  FIG. 3A , where refrigerant lines  315 ,  313 ,  312 ,  314 ,  317 ,  316 ,  318 ,  320  and  321  are shown coming to, through, and exiting pool water condenser  302 , refrigerant-to-air condenser  303  and accumulator  307 . Both condensers are connected in parallel. Refrigerant flow is show with arrows  310 . 
         [0032]    Referring now to  FIG. 3B , pool water condenser  302  is not in operation and all condensing is occurring at the refrigerant-to-air condenser. Compressor  301  is connected to and supplies gaseous high pressure refrigerant  341  to refrigerant line tee  315  with refrigerant line  313 , the refrigeration tee  315  is connected in parallel to and supplies gaseous high pressure refrigerant  341  to both refrigerant-to-water condenser  334  condensing line  314  with refrigerant line  312 , and refrigerant-to-air condenser  303  condensing line  318  with refrigerant line  316 . Both condensers supply high pressure gaseous  341  and liquid refrigerant  344  to accumulator  307  with refrigerant line  317  and  320 , respectively. Accumulator  307  supplies liquid refrigerant  344  to expansion valve  305  and evaporator  304  with refrigerant line  321 . The pool water condenser  302  is not being used and there is no pool water flow. The refrigerant-to-air condenser  303  is in operation and its condensing capacity is controlled by fan motor controller  308  running fan motor  360  at 100 percent of fan capacity. Liquid refrigerant  344  is condensed only in the refrigerant-to-air condenser  303 . Condensing starts at point  318   a  when the gaseous high pressure, high temperature refrigerant  341  comes in contact for heat exchange with the portion of refrigerant line  318  that is in contact for heat exchange with the cooling fins  364 . Condensing basically ends at point  318   b  as refrigerant line  318  continues past thermally conductive fins  364 . Accumulator  307  accepts or supplies liquid refrigerant  344  as required, maintaining a constant liquid refrigerant flow to expansion valve  304  as shown in sight glass  319 . 
         [0033]    Referring now to  FIG. 3C , where both the pool water condenser  302  and refrigerant-to-air condenser  303  are both in operation. Arrows  330  show pool water flow. Condensing starts at point  314   a  when the gaseous high pressure, high temperature refrigerant comes in contact for heat exchange with the portion of refrigerant line  314  that is in contact for heat exchange with and cooled by the pool water  338 . Now there is liquid refrigerant in both condensers and since the system was charged with only the larger volume condenser running, there is enough liquid refrigerant  344  in the accumulator  307  to allow a solid column of liquid to exit the accumulator  307  as seen in sight glass  319 . Now only liquid refrigerant  344  reaches the expansion valve  304  and air to refrigerant evaporator  305 , maintaining system efficiency. Fan motor controller  308  adjusts fan motor  380  speed between zero and 100%, which increases or decreases the condensing pressure and condensing temperature to maintain the desired water temperature at the point  314   b  in the pool water condenser  302 . 
         [0034]    Referring now to  FIG. 3D  where only the pool water condenser  302  is running. Arrows  330  show pool water flow and refrigerant low is shown by arrows  310 . Condensing starts at point  314   a  when the gaseous high pressure, high temperature refrigerant comes in contact for heat exchange with the portion of refrigerant line  314  that is in contact for heat exchange with and cooled by the pool water  338 . Fan motor controller  308  running fan motor  280  at zero percent of fan capacity, which makes all condensing take place in the pool water condenser  302 . This is the maximum water heating condition. Accumulator  307  accepts or supplies liquid refrigerant as required, maintaining a constant liquid refrigerant flow to expansion valve  304  as shown in sight glass  319 . 
         [0035]    Referring now to  FIG. 3E , which is similar to  FIG. 3A  except the pool water source has been replaced with a hot water heater. Fan  360  controller  308  receives inputs or sends outputs from water exit temperature sensor  375  by electrical line  373 , from refrigerant-to-water condenser  334 , from water heater control module  381 E by electrical line  379 E, from condensing sensor  377  at accumulator  307  by electrical line  378 , from ambient air temperature sensor  376  at refrigerant-to-air condenser  303  by electrical line  372 , and controls fan motor  360  speed with control line  371 . Water heater control module  381  tells controller  308  that water heating is needed and the air conditioning system is turned on by electrical line  374  to in home thermostat  372 . Controller then adjusts the speed of fan  360  per control graphs shown in  FIG. 4A and 4B  or  FIG. 5A and 5B  to maintaining the selected water exit temperature from refrigerant-to-water condenser  334  as read at sensor  375  or  377 . 
         [0036]    Referring now to  FIG. 3F , which is similar to  FIG. 3A  except the pool water source has been replaced with a clothes dryer condenser. Fan  360  controller  308  receives inputs or sends outputs from refrigerant-to-air clothes dryer sensor  379 F by electrical line  373 F, from clothes dryer control module  381  F by electrical line  379 F, from condensing pressure sensor  377  at accumulator  307  by electrical line  378 , from ambient air temperature sensor  376  at refrigerant-to-air condenser  303  by electrical line  372 , and controls fan motor  360  speed with control line  371 . Clothes dryer control module  381  tells controller  308  that air heating is needed and the air conditioning system is turned on by electrical line  374  to in home thermostat  372 . Controller  308  then adjusts the speed of fan  360  per control graphs shown in  FIG. 4A and 4B  or  5 A and  5 B to maintaining the selected air exit temperature from clothes dryer condenser  309 F as read at sensor  375 F. Note that charts  4 A,  4 B,  5 A and  5 B are for controlling the water exit temperature and that these water exit temperatures must be replaced with the wanted clothes dryer air exit temperatures for proper control and operation. 
         [0037]    Other applications could be to Pasteurize milk or beer using the waste heat from a Dairy or Brewery&#39;s refrigeration systems or Hospital hot water heating using the Hospital&#39;s air conditioning waste heat. These applications could be met year round as their refrigeration or air conditioning systems run year round. Most air conditioned factory or office complexes could have their fluid heating needs met using their refrigeration or air conditioning waste heat. 
         [0038]    System charging of two condensers in parallel is done with only the condenser with the larger liquid requirement running. Typically, this is the refrigerant-to-air condenser  303  in  FIG. 3A . However, there are instances where the other condensers may have the larger liquid requirement and in those cases, system charging must be done with only that condenser running. Charging is complete when the sight glass  319  is full of liquid. 
         [0039]    The size of the accumulator for condensers connected in parallel is determined by subtracting the liquid requirements of each condenser when it alone is running as shown in  FIG. 3B  and  FIG. 3D  and plus an additional safety factor amount such as 1% of the system&#39;s liquid refrigerant volume. For the refrigerant-to-water condenser  334  the volume is typically equal to ½ of the volume between points  314   a  and  314   b  and the volume between points  314   b  and  317   a  as shown in  FIG. 3D . For the refrigerant-to-air condenser  303 , the refrigerant liquid volume is typically equal to ½ the volume between points  318   a  and  318   b  and the volume between points  318   b  and  321   a  as shown in  FIG. 3B . 
         [0040]    Referring now to  FIG. 4A , a graph is shown of ambient temperature measured at sensor  276  or  376  at the refrigerant-to-air condenser  203  or  303  vs. refrigerant-to-air condenser fan speed for maintaining controlled exit water temperature from the pool water condenser  202  or  302  by controller  208  or  308  in  FIG. 2A  or  FIG. 3A , respectively. As shown in the previous sentence, the last two digits of an item number are the same between  FIG. 2A  and  FIG. 3A , and the first digit is either 2 or 3, respectively. From this point forward, this convention will apply unless otherwise noted. The graph in  FIG. 4A  is for an exit water temperature set point of 120° F. as read by sensor  275  at the pool water condenser  202  and an operational ambient temperature range from 60 to 120° F. as read by sensor  276 . The 120° F. exit water temperature set point is chosen by the system operator. The operational ambient temperature range is the expected ambient temperature range at the refrigerant-to-air condenser. As the ambient temperature moves from 60 to 120° F., the fan speed will change from zero fan speed to 100% fan speed with a defined constant exit water temperature from the refrigerant-to-water condenser of 120° F. 
         [0041]    Referring now to  FIG. 4B , a graph is shown of exit water temperature from the refrigerant-to-water condenser as read at sensor  275  vs. refrigerant-to-air condenser fan speed for maintaining controlled exit water temperature from the refrigerant-to-water condenser as read at sensor  275 . This graph is for the mid point ambient of 90° F. at the refrigerant-to-air condenser as read by sensor  276  and an exit water temperature from the refrigerant-to-water condenser range of 10° F. centered about the 120 degree set point. As the exit water temperature from the refrigerant-to-water condenser moves from 115 to 125° F., the fan speed control will change from zero fan speed to 100% fan speed at a constant 90° F. ambient temperature at the refrigerant-to-air condenser. 
         [0042]    The control formula for graphs  4 A and  4 B can be represented by the following mathematical formula: 
         [0000]      [25+( T   ambMP   −T   amb ) K   amb ]+[25+( T   wSP   −T   wact ) K   w ]=% fan speed at the refrigerant-to-air condenser. 
       Where: 
       [0000]    
       
         All temperatures are in ° F. 
         T amb  equals the ambient air temperature at the refrigerant-to-air condenser  276 . 
         T ambMP  equals the mid point of expected ambient air temperatures at the refrigerant-to-air condenser. 
         T wact  equals the actual exit water temperature from the refrigerant-to-water condenser at sensor  275 . 
         T wSP  equals exit water temperature set point desired from the refrigerant-to-water condenser. 
         K amb  equals a constant that sets the control sensitivity to changes in ambient temperature at the refrigerant-to-air condenser. The ambient air temperature at the refrigerant-to-air condenser has a second order effect on the actual exit water temperature from the refrigerant-to-water condenser and Kamb is set at −1.66, a relatively insensitive number. 
       
     
         [0049]    K w  equals a constant that sets the control sensitivity to changes in exit water temperature from the refrigerant-to-water condenser. Since controlling the exit water temperature from the refrigerant-to-water condenser is the goal of this control and by definition is the first order effect, K w  is set at −10 for these graphs. The higher the K amb  and K w  values, the higher the control reaction to changes in temperature. In the values above, K w  is 16.66 times more sensitive to its temperature changes than K amb . If the system has problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser, Kw should be increased. If Kw is too high,-the control will be too sensitive, causing rapid oscillations in fan speed. If Kw is too low, the control will be too insensitive, causing problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser. Kw values from −10 to −20 are usually acceptable. 
         [0050]    The exit water temperature at sensor  275  should run within 2 degrees of the T wSP  temperature. If the exit water temperature at sensor  275  runs to the low side, increase T wSP . If, the exit water temperature at sensor  275  runs to the high side, decrease T wSP . 
         [0051]    Referring again to  FIG. 4A  and  FIG. 4B , it is possible to change sensor  275  or  375  from reading the water exit temperature to reading the system condensing temperature and to get similar control results with all other conditions being the same. 
         [0052]    The control formula for graphs  4 A and  4 B for using system condensing temperature instead of water exit temperature can be represented by the following mathematical formula: 
         [0000]      [25+( T   ambMP   −T   amb ) K   amb ]+[25+( T   conT SP   −T   conT act ) KconT ]=% fan speed at the refrigerant-to-air condenser. 
       Where: 
       [0000]    
       
         All temperatures are in ° F. 
         T amb  equals the ambient air temperature at the refrigerant-to-air condenser  276 . 
         T ambMP  equals the mid point of expected ambient air temperatures at the refrigerant-to-air condenser. 
         T ConT act  equals the actual system condensing temperature from the refrigerant-to-water condenser at sensor  275 . 
         T ConT SP  equals system condensing temperature set point need to produce the desired exit water temperature from the refrigerant-to-water condenser. 
         K amb  equals a constant that sets the control sensitivity to changes in ambient temperature at the refrigerant-to-air condenser. The ambient air temperature at the refrigerant-to-air condenser has a second order effect on the actual exit water temperature from the refrigerant-to-water condenser and K amb  is set at −1.66, a relatively insensitive number. 
       
     
         [0059]    K conT  equals a constant that sets the control sensitivity to changes in system condensing temperature which affects exit water temperature at the refrigerant-to-water condenser. Since controlling the exit water temperature from the refrigerant-to-water condenser is the goal of this control and by definition is the first order effect, K conT  is set at −10 for these graphs. The higher the K amb  and K conT  values, the higher the control reaction to changes in temperature. In the values above, K conT  is 16.66 times more sensitive to its temperature changes than K amb . If the system has problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser, K conT  should be increased. If K conT  is too high, the control will be too sensitive, causing rapid oscillations in fan speed. If K conT  is too low, the control will be too insensitive, causing problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser. Kw values from −10 to −20 are usually acceptable. 
         [0060]    The exit water temperature at sensor  275  should run within 2 degrees of the T conT SP  depending upon the size of the refrigerant-to-water condenser. If the exit water temperature at sensor  275  runs to the low side, increase T conT SP . If the exit water temperature at sensor  275  runs to the high side, decrease T conT SP . 
         [0061]    Referring now to  FIG. 5A , a graph is shown of ambient temperature at the refrigerant-to-air condenser vs. refrigerant-to-air condenser fan speed for maintaining controlled exit water temperature from the refrigerant-to-water condenser by controller  208  in  FIG. 2A and 308  in  FIG. 3A . This graph is for a condensing pressure set point of 253 psi and an operational ambient temperature range from 60 to 120° F. As the ambient temperature moves from 60 to 120° F., the fan speed control will change from zero fan speed to 100% fan speed with a defined constant condensing pressure of 253 psi. 
         [0062]    Referring now to  FIG. 5B , a graph is shown of exit water temperature from the refrigerant-to-water condenser vs. condensing for maintaining controlled exit water temperature from the refrigerant-to-water condenser. This graph is for the mid point condensing pressure of 253 psi and a condensing pressure range of 6 psi centered about the 253 psi set point. These pressures are for R-22 and must be representative of the refrigerant being used by the system. As the condensing pressure moves from 250 to 256 psi, the fan speed control will change from zero fan speed to 100% fan speed at a constant 90 degree F. ambient temperature at the refrigerant-to-air condenser. 
         [0063]    The control formula for these two graphs can be represented by the following mathematical formula: 
         [0000]      [25+( T   ambMP   −T   amb ) K   amb ]+[25+( P   conSP   −P   act )2.5  K   con ]=% refrigerant-to-air condenser fan speed. 
       Where: 
       [0000]    
       
         T amb  equals the ambient air temperature at the refrigerant-to-air condenser. 
         T ambMP  equals the mid point of expected ambient air temperatures at the refrigerant-to-air condenser. 
         P act  equals the actual condensing pressure at the refrigerant-to-water condenser and is selected based on the refrigerant used and the desired exit temperature of the refrigerant-to-water condenser. In this case the pressure is measured at the accumulator. 
         P conSP  equals condensing pressure set point desired from the refrigerant-to-water condenser. 
         K amb  equals a constant that sets the control sensitivity to changes in ambient temperature at the refrigerant-to-air condenser. The ambient air temperature at the refrigerant-to-air( condenser has a second order effect on the actual exit water temperature from the refrigerant-to-water condenser and Kamb is set at −1.66, a relatively insensitive number. 
       
     
         [0069]    K con  equals a constant that sets the control sensitivity to changes in condensing pressure at the refrigerant-to-water condenser and thereby the exit water temperature from the refrigerant-to-water condenser. Since controlling the exit water temperature from the refrigerant-to-water condenser is the goal of this control and by definition K con  is the first order effect, K con  is set at −10 for these graphs. The higher the K amb  and K con  values, the higher the control reaction to changes in temperature and pressure, respectively. In the values above, K con  is 16.66 times more sensitive to its changes than K amb . If the system has problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser, K con  should be increased. If K con  is too high, the control will be too sensitive, causing rapid oscillations in fan speed. If Kw is too low, the control will be too insensitive, causing problems maintaining accurate exit water temperatures from the refrigerant-to-water condenser. Kw values from −10 to −20 are usually acceptable. 
         [0070]    The exit water temperature at sensor  275  should run within 2 degrees of the P conSP  based on the pressure-temperature of the refrigerant being used. If the exit water temperature at sensor  275  runs to the low side, increase P conSP . If the exit water temperature at sensor  275  runs to the high side, decrease P conSP . 
         [0071]    Referring now to  FIG. 6A , where Theoretical Outlet Water Temperature, Air Conditioning System Condensing Pressure, Condenser Fan Speed, and Hot Water Requirements at various Operational Conditions are shown for  FIG. 2A and 3A . Five Operational Conditions are presented. The No.  1  Condition is for no pool water heating and the Hot Water requirement is zero. The air conditioning system is working normally as shown in  FIG. 2B  or  FIG. 3B  and the refrigerant-to-air fan motor  260  is running at 100%. The No.  5  Condition is for full pool water heating and the Hot Water requirement is 100%. Refrigerant condensing is taking place only in the refrigerant-to-water condenser as shown in  FIG. 2D and 3D  and the refrigerant-to-air fan motor  250  is not running, forcing all condensing to take place at the refrigerant-to-water condenser  234 . The No.  2 , No.  3 , and No.  4  conditions are for 25%, 50% and 75% Hot Water requirements. Fan motor  260  is controlled by controller  208  per control graphs  4 A and  4 B or  5 A and  5 B. The ambient air temperature at sensor  276  is 90° F. and has the fan motor  260  running at 50%. Sensor  275  gives the exit temperature of the heated pool water and controller  208  reads this sensor and adjusts fan  260  speed up or down from the 50% level set by ambient sensor  275  per the control formula given previously or control graphs in  FIG. 4A and 4B . Since the control formula is 16.66 times more sensitive to the exit water temperature than the ambient air temperature, slight changes in exit water temperature will be corrected by significant changes in refrigerant-to-air condenser fan speed allowing consistent water temperature control over a wide range of operating conditions. 
         [0072]    The same results can be reached by replacing Sensor  275  or  375  readings with condenser pressure sensor  277  or  377  and using control graphs shown in  FIG. 5   a  and  5 B and their formula presented previously. 
         [0073]    While the invention has been particularly shown and described with reference to preferred embodiments thereof it is well understood by those skilled in the art that various changes and modifications can be made in the invention without departing from the spirit and scope of the invention as defined by the appended claims.