Patent Publication Number: US-9885486-B2

Title: Heat pump humidifier and dehumidifier system and method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of and claims priority from U.S. patent application Ser. No. 12/870,545 titled “Heat Pump Humidifier and Dehumidifier System and Method” filed Aug. 27, 2010, the complete subject matter of which is hereby expressly incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     The subject matter herein relates generally to heat pumps and, more particularly, to a heat pump humidifier and dehumidifier system and method. 
     Heat pumps are used to condition air supplied to a building or structure. Typically, the supply air passes through a first heat exchanger to adjust a temperature and humidity of the supply air. The supply air is then channeled to a desiccant wheel to humidify or dehumidify the air prior to discharging the air into the space. Generally, return air is utilized to regenerate the desiccant wheel by humidifying or dehumidifying the regeneration air. When the supply air is humidified, the regeneration air is dehumidified. When the supply air is dehumidified, the regeneration air is humidified. Generally, the regeneration air also passes through a second heat exchanger prior to passing through the desiccant wheel. The first and second heat exchangers usually transfer energy between the supply air and the regeneration air. 
     Typically, the regeneration air is supplied from inside the space. As such, outside air generally lacks sufficient energy to properly regenerate the desiccant wheel. Accordingly, known heat pump systems may operate at reduced efficiencies when using outside air to regenerate the desiccant wheel. Because of the reduced efficiency of the heat pump, the heat pump may not be capable of conditioning some outside air. In particular, known heat pumps generally lack the capability of conditioning outside air having extreme hot or extreme cold temperatures. 
     A need remains for a more efficient heat pump system or method that utilizes the energy of return air to regenerate the desiccant wheel, increase effectiveness of the heat pump and provides considerable humidification load reductions to building operation. Another need remains for a heat pump that pre-processes supply air to enable the heat pump to operate in extreme weather conditions without significant reduction in efficiency. 
     SUMMARY OF THE INVENTION 
     In one embodiment, a heat pump system for conditioning air supplied to a space is provided. The system includes a pre-processing module that pre-conditions supply air. A supply air heat exchanger is in flow communication with the pre-processing module. The supply air heat exchanger receives air from the pre-processing module and at least one of heats or cools the air from the pre-processing module. A processing module is in flow communication with the supply air heat exchanger. The processing module receives and conditions air from the supply air heat exchanger. A regeneration air heat exchanger is provided to at least one of heat or cool regeneration air. The regeneration air heat exchanger and the supply air heat exchanger are fluidly coupled by a refrigerant system. 
     In another embodiment, a method for conditioning air supplied to a space is provided. The method includes pre-conditioning supply air with a pre-processing module. The method also includes at least one of heating or cooling the air from the pre-processing module with a supply air heat exchanger in flow communication with the pre-processing module. The method also includes conditioning air from the supply air heat exchanger with a processing module in flow communication with the supply air heat exchanger. The method also includes at least one of heating or cooling regeneration air with a regeneration air heat exchanger that is fluidly coupled to the supply air heat exchanger by a refrigerant system. 
     In another embodiment, a method for conditioning air supplied to a space is provided. The method includes conditioning supply air with a processing module. The method also includes at least one of heating or cooling the air prior to or after the processing module with one or more supply air heat exchangers in flow communication with the processing module. The method also includes at least one of heating or cooling the regeneration air with one or more regeneration air heat exchanger that is fluidly coupled to the supply air heat exchangers by a refrigerant system. 
     In another embodiment, a method for conditioning air supplied to a space is provided. The method includes conditioning supply air with a processing module. The method also includes at least one of heating or cooling the air prior to or after the processing module with one or more supply air heat exchangers in flow communication with the processing module. The method also includes at least one heat exchanger switch in flow communication with the supply air heat exchangers that is fluidly coupled to a refrigerant system. 
     In another embodiment, a method for conditioning air supplied to a space is provided. The method includes conditioning supply air with a processing module. The method also includes at least one of heating or cooling the air prior to or after the processing module with one or more supply air heat exchangers in flow communication with the processing module. The method also includes at least one heat exchanger switch in flow communication with the supply air heat exchangers that is fluidly coupled to a refrigerant system and a control method that allows the space sensible load and latent load to be maintained independently. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view of a heat pump system formed in accordance with an embodiment and operating in a summer mode. 
         FIG. 2  is a schematic view of the system shown in  FIG. 1  operating in a winter mode. 
         FIG. 3  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 4  is a psychrometric chart of the return air of a heat pump system operating in a summer mode. 
         FIG. 5  is a psychrometric chart of the supply air of a heat pump system operating in a winter mode. 
         FIG. 6  is a psychrometric chart of the return air of a heat pump system operating in a winter mode. 
         FIG. 7  is a schematic view of another heat pump system formed in accordance with an embodiment and operating in a winter mode. 
         FIG. 8  is a psychrometric chart of the heat pump system shown in  FIG. 7  operating in a winter mode. 
         FIG. 9  is a schematic view of another heat pump system formed in accordance with an embodiment and operating in a winter mode. 
         FIG. 10  is a schematic view of another heat pump system formed in accordance with an embodiment and operating in a summer mode. 
         FIG. 11  is a schematic view of the heat pump system shown in  FIG. 10  and operating in a summer mode. 
         FIG. 12  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 13  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 14  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 15  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 16  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 17  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 18  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 19  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 20  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 21  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 22  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 23  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 24  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 25  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 26  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 27  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 28  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 29  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 30  is a psychrometric chart of the supply air of a heat pump system operating in a summer mode. 
         FIG. 31  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 32  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 33  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 34  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 35  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 36  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 37  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 38  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 39  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 40  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 41  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 42  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 43  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 44  is a schematic view of another heat pump system formed in accordance with an embodiment. 
         FIG. 45  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 46  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a summer mode. 
         FIG. 47  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 48  is a psychrometric chart of the supply air and regeneration air of a heat pump system operating in a winter mode. 
         FIG. 49  is a schematic view of another heat pump system formed in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The foregoing summary, as well as the following detailed description of certain embodiments will be better understood when read in conjunction with the appended drawings. As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property. 
       FIG. 1  is a schematic view of a heat pump system  100  formed in accordance with an embodiment and operating in a summer mode  130 .  FIG. 2  is a schematic view of the system  100  operating in a winter mode  132 . The system  100  is configured to condition supply air flowing into a building or space and return air channeled from within the building or space. When in the summer mode  130 , among other things, the system  100  dehumidifies the supply air flowing into the building. When in the winter mode  132 , among other things, the system  100  humidifies the supply air flowing into the building. The system  100  is capable of switching between the summer mode  130  and the winter mode  132  without the need to reconfigure the components of the system  100 . 
     First, the operation of system  100  is described in connection with the summer mode  130 , as illustrated in  FIG. 1 . In the summer mode  130 , the system includes a supply air flow path  112  and a return air flow path  120 . The supply air flow path  112  travels between a supply air inlet  108  and a supply air outlet  110 . In one embodiment, the system  100  may include at least one fan to draw air into and move air through the supply air flow path  112 . Outside air flows through the supply air inlet  108  and into an outside air region  101 . 
     A pre-processing module  102  is positioned downstream of the outside air region  101 . In one embodiment, the pre-processing module  102  may include an energy recovery device, such as, an enthalpy wheel, a fixed enthalpy plate, an enthalpy pump and/or any other suitable heat exchanger that transfers both sensible heat and latent heat. In one embodiment the pre-processing module  102  is formed as a fixed body heat exchanger, an air to air heat exchanger, an air to liquid heat exchanger, a liquid to air heat exchanger, or liquid to liquid heat exchanger. The pre-processing module  102  includes a supply air side  109  and a return air side  111 . The supply air side  109  is positioned within the supply air flow path  112 . The return air side  111  is positioned within the return air flow path  120 . 
     Outside air passes through the supply air side  109  of the pre-processing module  102 . The pre-processing module  102  is configured to transfer latent energy and sensible energy between the supply air flow path  112  and the return air flow path  120 . The latent energy includes moisture in the flow paths  112  and  120 . The pre-processing module  102  transfers heat from a warmer flow path to a cooler flow path. The pre-processing module  102  also transfers humidity from a high humidity flow path to a low humidity flow path. The outside air is cooled as the outside air passes through the pre-processing module  102 . The cooled air from the pre-processing module  102  is discharged into a pre-processed air region  103  positioned downstream from the pre-processing module  102 . 
     A supply air heat exchanger  106  is positioned downstream from the pre-processed air region  103 . The supply air heat exchanger  106  operates as an evaporator coil or cooling coil in the summer mode  130 . As an evaporator coil, the supply air heat exchanger  106  conditions the cooled air and further removes heat from the cooled air to produce saturated air that is discharged into a conditioned air region  105 . The amount of energy required to saturate air is proportional to the temperature and humidity of the air conditions in the pre-processed air region. Generally cooler air requires less energy to become saturated than warmer air. Because the supply air is first cooled by the pre-processing module  102 , the energy expended by the supply air heat exchanger  106  to saturate the supply air to the desired saturated conditions is reduced, thereby increasing an efficiency of the supply air heat exchanger  106  as the supply air heat exchanger  106  saturates or cools the air. In the summer mode  130 , the system  100  is capable of operating at extreme temperatures. For example, in the summer mode  130 , the pre-processing module is capable of conditioning outside air having a dry bulb temperature over 90° F. Additionally, the supply air heat exchanger  106  is capable of conditioning air having a dry bulb temperature over 80° F. 
     A processing module  104  is positioned downstream from the conditioned air region  105 . The saturated air passes through the processing module  104 . In one embodiment, the processing module  104  may include a desiccant wheel, liquid desiccant system or any other suitable exchanger that removes and/or transfers moisture from the air. The processing module  104  may utilize any one of, or a combination of drierite, silica gel, calcium sulfate, calcium chloride, montmorillonite clay, activated aluminas, zeolites and/or molecular sieves to absorb moisture in the air. Other components that may also be used by the processing module are halogenated compounds such as halogen salts including chloride, bromide and fluoride salts, to name a few examples. In one embodiment, the processing module  104  is formed as a fixed body heat exchanger, an air to air heat exchanger, an air to liquid heat exchanger, a liquid to air heat exchanger, or liquid to liquid heat exchanger. The processing module  104  includes a supply air side  113  and a return air side  115 . The supply air side  113  is positioned within the supply air flow path  112  and the return air side  115  is positioned within the return air flow path  120 . The saturated air passes through the supply air side  113  to remove moisture therefrom and produce conditioned supply air that has been further dehumidified. Because the air is first saturated by the supply air heat exchanger  106 , the efficiency of the processing module  104  is increased when dehumidifying the air. The dehumidified supply air flows downstream into a processed air region  107 . From the processed air region  107 , the dehumidified supply air flows through the supply air outlet  110  and into the space. 
     Regeneration air in the form of return air leaves the space at return air inlet  116  and traverses a return air flow path  120 . The return air flow path  120  is defined between the return air inlet  116  and a return air outlet  118 . In one embodiment, the system  100  may include at least one fan to draw air into and move air through the return air flow path  120 . Return air enters through the return air inlet  116  and flows downstream into the return air region  117 . 
     The return air side  111  of the pre-processing module  102  is positioned downstream from the return air region  117 . The return air passes through the return air side  111  of the pre-processing module  102 . The pre-processing module  102  transfers heat and moisture into the return air passing through the return air side  111 , thereby removing heat from the supply air passing through the supply air side  109 . The heated air flows into a pre-processed air region  119  and through a series of dampers  125 ,  127 ,  129 , and  131 . In the summer mode  130  dampers  125  and  129  are opened and dampers  127  and  131  are closed to direct the heated air to a regeneration air heat exchanger  114  positioned downstream from the damper  125 . 
     The regeneration air heat exchanger  114  operates as a condenser coil in the summer mode  130  to heat and lower a relative humidity of conditioned air. The heat exchanger  114  uses the heat from the supply air heat exchanger  106  to lower the relative humidity of the heated air thus increasing the air&#39;s capacity to absorb water downstream. The heated air flows into a conditioned air region  121 . The lowered relative humidity air in the conditioned air region  121  is channeled downstream to the return air side  115  of the processing module  104 . 
     The lowered relative humidity air passing through the return air side  115  of the processing module  104  regenerates the processing module  104  by receiving moisture from the saturated air in the supply air side  113  and adding humidity to the exhaust air that flows into a processed air region  123 . The exhaust air is channeled through the open damper  129 , through return air outlet  118 , and is exhausted from the space. 
     In one embodiment, the heat pump system  100  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the pre-processing module  102 , the processing module  104 , the supply air heat exchanger  106 , and/or the regeneration air heat exchanger  114  to achieve a pre-determined dehumidification in the summer mode  130  and pre-determined humidification in a winter mode  130 . 
     In another embodiment, the heat pump system  100  senses a condition of at least one of the supply or return air from the space to control an output of at least one of the pre-processing module  102 , the processing module  104 , the supply air heat exchanger  106 , and/or the regeneration air heat exchanger  114  to achieve a pre-determined performance of the system  100 . 
     In another embodiment, the heat pump system  100  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the pre-processing module  102 , the processing module  104 , the supply air heat exchanger  106 , and/or the regeneration air heat exchanger  114  to limit frost formation in the pre-processing module  102  and/or the regeneration air heat exchanger  114  in the winter mode  132 . 
     In another embodiment, the heat pump system  100  senses a condition of at least one of the supply air or the return air from the space to control an output of at least one of the pre-processing module  102  or the processing module  104 . 
     In another embodiment, at least one of the pre-processing module  102  or processing module  104  is formed as a rotating body. The rotating body is rotated with at least one of a pre-determined speed or a predetermined range to achieve a pre-determined amount of at least one of moisture transfer or heat transfer to limit frost formation in the pre-processing module  102  and/or the regeneration air heat exchanger  114 . A rotational speed of at least one of the pre-processing module  102  and/or the processing module  104  may be adjusted to a predetermined range, such that the pre-processing module  102  operates as at least one of a sensible wheel, a enthalpy wheel or a desiccant wheel based on variations in the outside air or return air from the space. 
     In another embodiment, the heat pump system  100  senses a condition of at least one of a supply air stream or a return air stream to control the output of at least one of a single compressor or variable compressor to limit frost formation in the pre-processing module and or the heat exchanger in winter mode. 
     In another embodiment, the heat pump system  100  senses a condition of at least one of a supply air stream or a return air stream to control the output of at least one of a single compressor or variable compressor to achieve a pre-determined performance of the system  100 . 
     It should be noted that the system  100  is exemplary only and may include any number of pre-processing modules  102 , processing modules  104 , supply air heat exchangers  106  and/or regeneration air heat exchangers  114 . Additionally, the arrangement of the components may be varied. The components described herein are arranged to provide a balance in energy between the supply air flow path  112  and the return air flow path  120 . 
     The system  100  includes a refrigerant system  133  having piping  135  that fluidly couples the supply air heat exchanger  106  and the regeneration air heat exchanger  114 . The refrigerant system  133  pumps a refrigerant between the supply air heat exchanger  106  and the regeneration air heat exchanger  114 . In the summer mode  130 , the refrigerant system  133  pumps cooled refrigerant to the supply air heat exchanger  106  to cool the air flowing through the supply air heat exchanger  106 . The cooled refrigerant is heated by the air in the supply air heat exchanger  106  to form heated refrigerant. The heated refrigerant flows through the piping  135  to the regeneration air heat exchanger  114  to heat the air flowing through the regeneration air heat exchanger  114 . The refrigerant is cooled by the air in the regeneration air heat exchanger  114  to form cooled refrigerant that is pumped back to the supply air heat exchanger  106 . 
     In the winter mode  132 , the refrigerant system  133  pumps heated refrigerant to the supply air heat exchanger  106  to heat the air flowing through the supply air heat exchanger  106 . The heated refrigerant is cooled by the air in the supply air heat exchanger  106  to form cooled refrigerant. The cooled refrigerant flows through the piping  135  to the regeneration air heat exchanger  114  to cool the air flowing through the regeneration air heat exchanger  114 . The refrigerant is heated by the air in the regeneration air heat exchanger  114  to form heated refrigerant that is pumped back to the supply air heat exchanger  106 . 
     The refrigerant system  133  may include a metering device and check valve system  137  to control a flow of the refrigerant between the supply air heat exchanger  106  and the regeneration air heat exchanger  114 . Additionally, a switch  139  may be provided to reverse a flow of the refrigerant through the refrigerant system  133 . For example, the flow of the refrigerant may be reversed when the system  100  is switched between the summer mode  130  and the winter mode  132 . A compressor  141  is provided to compress the refrigerant. In the summer mode  130 , the refrigerant passes through the compressor  141  after exiting the supply air heat exchanger  106  and before entering the regeneration air heat exchanger  114 . In the winter mode  132 , the refrigerant passes through the compressor  141  after exiting the regeneration air heat exchanger  114  and before entering the supply air heat exchanger  106 . 
       FIGS. 3 and 4  illustrate psychrometric charts  350  and  400  for the system  100  when operating in the summer mode  130 . It should be noted that the charts  350  and  400  are exemplary only and illustrate a single operating point for the summer mode  130  conditions. The charts  350  and  400  include an x-axis  300  that illustrates a dry bulb temperature of the air in degrees Fahrenheit and a y-axis  302  that illustrates vapor pressure in inches of mercury. A second y-axis  304  illustrates a humidity ratio in grains of moisture per pound of dry air. Curve  306  illustrates a saturation point of the air and lines  308  illustrate an enthalpy of the air in BTU per pound of dry air. Lines  310  illustrate a wet bulb temperature of the air in degrees Fahrenheit. A sensible heat ratio is illustrated on line  312  and a dew point temperature in degrees Fahrenheit is illustrated on line  314 . A relative humidity of the air is illustrated on curves  316  and a volume of the air in cubic feet per pound of dry air is illustrated on curves  318 . 
       FIG. 3  is a psychrometric chart  350  illustrating the condition of the air in the supply air flow path  112  when the system  100  is operating in the summer mode  130  and when the supply air enters the outside air region  101  at point  352  on chart  350 . The supply air has a dry bulb temperature of approximately 95° F. and a wet bulb temperature of approximately 78° F. The enthalpy of the supply air is approximately 42 BTU per pound of dry air and the humidity ratio is approximately 120 grains of moisture per pound of dry air. 
     The supply air passes through the supply air side  109  of the pre-processing module  102 . The pre-processing module  102  cools the supply air to generate cooled air that is discharged into the pre-processed air region  103  of the system  100 . Point  354  of chart  350  illustrates the conditions of the cooled air within the pre-processed air region  103 . The cooled air has a dry bulb temperature of approximately 80° F. and a wet bulb temperature of approximately 68.5° F. The enthalpy of the cooled air is approximately 33 BTU per pound of dry air and the humidity ratio is approximately 86 grains of moisture per pound of dry air. 
     The cooled air flows downstream to the supply air heat exchanger  106  and is conditioned to near the saturation curve  306 . The supply air heat exchanger  106  operates as an evaporator coil to further reduce the temperature of the cooled air and generate saturated air. The cooled saturated air is discharged into the conditioned air region  105 . Point  356  of chart  350  illustrates the conditions of the saturated air within the conditioned air region  105 . At point  356  the saturated air has a dry bulb temperature of approximately 52° F. and a wet bulb temperature of approximately 52° F. The enthalpy of the saturated air is approximately 22 BTU per pound of dry air and the humidity ratio is approximately 58 grains of moisture per pound of dry air. 
     Next the saturated air is channeled through supply air side  113  of the processing module  104 . The processing module  104  removes moisture from the saturated air to generate dehumidified supply air within the processed air region  107 . Point  358  of chart  350  illustrates the conditions of the supply air. The supply air has a dry bulb temperature of approximately 74° F. and a wet bulb temperature of approximately 57° F. The enthalpy of the supply air is approximately 24.5 BTU per pound of dry air and the humidity ratio is approximately 42 grains of moisture per pound of dry air. The supply air is discharged through the supply air outlet  110  and into the space. 
       FIG. 4  is a psychrometric chart  400  illustrating the condition of the air in the return air flow path  120  when the system  100  is operating in the summer mode  130 . The return air enters the system  100  through the return air inlet  116 . Point  402  of chart  400  illustrates the condition of the return air within the return air region  117 . The return air has a dry bulb temperature of approximately 74° F. and a wet bulb temperature of approximately 62.5° F. The enthalpy of the return air is approximately 28 BTU per pound of dry air and the humidity ratio is approximately 66 grains of moisture per pound of dry air. 
     The return air flows through the return air side  111  of the pre-processing module  102 . The heat and moisture removed from the supply air on the supply air side  109  of the pre-processing module  102  is transferred into the return air on the return air side  111  of the pre-processing module  102  to generate heated air. The heated air flows into the pre-processed air region  119 . Point  404  of chart  400  illustrates the conditions of the heated air. At point  404  the heated air has a dry bulb temperature of approximately 88° F. and a wet bulb temperature of approximately 73° F. The enthalpy of the heated air is approximately 36 BTU per pound of dry air and the humidity ratio is approximately 98 grains of moisture per pound of dry air. 
     The heated air passes through the regeneration air heat exchanger  114 . In the summer mode  130 , the regeneration air heat exchanger  114  operates as a condenser coil and transfers the heat from the supply air heat exchanger  106  to the return air flow path  120 . The heat exchanger  114  also lowers a relative humidity of the air to increase the air&#39;s capacity to absorb water downstream. The dry air is discharged into the conditioned air region  121 . Point  406  of chart  400  illustrates the conditions of the dry air within the conditioned air region  121 . At point  406  the dry air has a dry bulb temperature of approximately 110° F. and a wet bulb temperature of approximately 79° F. The enthalpy of the dry air is approximately 42 BTU per pound of dry air and the humidity ratio is approximately 98 grains of moisture per pound of dry air. 
     The dry air travels downstream to the return air side  115  of the processing module  104 . The processing module  104  transfers moisture from the cooled saturated air in the supply air side  113  to the heated dry air in the return air side  115 . Point  408  of chart  400  illustrates the conditions of the exhaust air. The exhaust air has a dry bulb temperature of approximately 87° F. and a wet bulb temperature of approximately 77° F. The enthalpy of the exhaust air is approximately 41 BTU per pound of dry air and the humidity ratio is approximately 125 grains of moisture per pound of dry air. The exhaust air is discharged from the space through the return air outlet  118 . 
     Next, the operation of system  100  is described in connection with the winter mode  132 , as illustrated in  FIG. 2 . In the winter mode  132 , the supply air flow path  112  follows the same path as defined in the summer mode  130 . In the winter mode  132 , the function of the system components may differ from the function of the system components in the summer mode  130 . 
     Outside air flows through the supply air inlet  108  and into the outside air region  101 . The outside air in the outside air region  101  travels downstream through the supply air side  109  of the pre-processing module  102 . The outside air is heated by the pre-processing module  102  to generate heated and humidified air that is discharged into the pre-processed air region  103 . 
     The heated and humidified air in the pre-processed air region  103  passes through the supply air heat exchanger  106 . The supply air heat exchanger  106  operates as a condenser coil in the winter mode  132  to lower a relative humidity of the heated air and increase the air&#39;s capacity to absorb water downstream. The supply air heat exchanger  106  generates dry air that is discharged into the conditioned air region  105 . When processing air having extreme cold temperatures, the supply air heat exchanger will be operating in a very inefficient matter. Because the outside air is first heated by the pre-processing module  102 , the supply air heat exchanger  106  is capable of heating outside air having extreme cold temperatures very efficiently. For example, the pre-processing module  102  is capable of conditioning air having a temperature below 32° F. Using the components illustrated in  FIG. 2 , the pre-processing module  102  is capable of conditioning air having a temperature between −10° F. and 32° F. With additional components, the pre-processing module  102  is capable of conditioning air having temperature between −30° F. and 32° F. Moreover, the supply air heat exchanger  106  is capable of conditioning air having a temperature below 50° F., in the winter mode  132 . 
     The lowered relative humidity heated air travels from the supply air heat exchanger  106  through the supply air side  113  of the processing module  104 . The processing module adds moisture to the conditioned air to produce humidified supply air. The humidified supply air flows into the processed air region  107 . From the processed air region  107 , the supply air flows through the supply air outlet  110  and into the space. 
     The return air flow path  140  of the winter mode  132  differs from the return air flow path  120  of the summer mode. The dampers  125 ,  127 ,  129 , and  131  may be opened and/or closed to change the return air flow path  120  of the summer mode  130  to return air flow path  140  of the winter mode  132 . Additionally, the functions of at least some of the system components may change in the winter mode  132 . The return air flow path  140  is defined between the return air inlet  116  and a return air outlet  142 . 
     Return air flows through the return air inlet  116  and into the return air region  117 . The return air then flows into the return air side  111  of the pre-processing module  102 . The pre-processing module  102  transfers heat and moisture from the return air into the supply air passing through the supply air side  109  of the pre-processing module  102 , thereby cooling the air in the return air flow path  140 . The cooled air flows into the pre-processed air region  119  and is channeled through dampers  125 ,  127 ,  129 , and  131 . In the winter mode  132  dampers  125  and  129  are closed and dampers  127  and  131  are opened to direct the cooled air to the return air side  115  of the processing module  104 . 
     The processing module  104  is regenerated by the supply air. The processing module  104  removes moisture from the cooled air in the return air side  115  and discharges the moisture into the dry air in the supply air side  113 . The processing module  104  dehumidifies air in the return air flow path  140  while humidifying the supply air flow. The dehumidified air is discharged into a processed air region  144 . The dehumidified air in the processed air region  144  is channeled to the regeneration air heat exchanger  114 . 
     The regeneration air heat exchanger  114  operates as an evaporator coil in the winter mode  130  to cool the dehumidified air. The regeneration air heat exchanger  114  also removes heat from the return air and discharges the heat to the supply air heat exchanger  106 . The heat exchanger  114  cools the dehumidified air to generate cooled exhaust air. When cooling air having extreme cold temperatures, the regeneration air heat exchanger  114  is susceptible to freezing. Because the return air is first dehumidified by the processing module  104 , the dehumidified air in the processed air region  144  is able to be cooled by the regeneration air heat exchanger  114  to very cold temperatures without the risk of freezing. Furthermore, as the return air is dried by the processing module  104 , the air&#39;s dry bulb condition in the processed air region  144  is raised, thus enabling additional heat transfer to the supply air heat exchanger  106  improving efficiency of the system. The cooled exhaust air flows into a conditioned air region  146  and is channeled through return air outlet  142  and exhausted from the building. 
       FIGS. 5 and 6  illustrate psychrometric charts  450  and  500  for the system  100  when operating in the winter mode  132 . It should be noted that the charts  450  and  500  are exemplary only and illustrate a single operating point for the winter mode  132  operating conditions. The charts  450  and  500  include an x-axis  300  that illustrates a dry bulb temperature of the air in degrees Fahrenheit and a y-axis  302  that illustrates vapor pressure in inches of mercury. A second y-axis  304  illustrates a humidity ratio in grains of moisture per pound of dry air. Curve  306  illustrates a saturation point of the air and lines  308  illustrate an enthalpy of the air in BTU per pound of dry air. Lines  310  illustrate a wet bulb temperature of the air in degrees Fahrenheit. A sensible heat ratio is illustrated on line  312  and a dew point temperature in degrees Fahrenheit is illustrated on line  314 . A relative humidity of the air is illustrated on curves  316  and a volume of the air in cubic feet per pound of dry air is illustrated on curves  318 . 
       FIG. 5  is a psychrometric chart  450  illustrating the condition of the outside air in the supply air flow path  112 , when the system  100  is operating in the winter mode  132  and when the outside air enters the system  100  through the supply air inlet  108  and flows into the outside air region  101 . Point  452  of chart  450  illustrates the conditions of the outside air. At point  452 , the outside air has a dry bulb temperature of approximately −10° F. and a wet bulb temperature of approximately −10° F. The enthalpy of the outside air is approximately −2 BTU per pound of dry air and the humidity ratio is approximately 3 grains of moisture per pound of dry air. 
     The outside air passes through the supply air side  109  of the pre-processing module  102  where the air is heated and discharged into the pre-processed air region  103 . Point  454  of chart  450  illustrates the conditions of the heated air in the pre-processed air region  103 . At point  454 , the heated air has a dry bulb temperature of approximately 30° F. and a wet bulb temperature of approximately 27° F. The enthalpy of the heated air is approximately 9.5 BTU per pound of dry air and the humidity ratio is approximately 16 grains of moisture per pound of dry air. 
     The heated air passes through the supply air heat exchanger  106 . In the winter mode  132 , the supply air heat exchanger  106  operates as a condenser coil to heat the air using heat discharged from the regeneration air heat exchanger  114 . The supply air heat exchanger  106  also lowers a relative humidity of the air to increase the air&#39;s capacity to absorb water downstream. The supply air heat exchanger  106  lowers the relative humidity of heated air that is discharged into the conditioned air region  105 . Point  456  illustrates the conditions of the heated air. At point  456  the heated air has a dry bulb temperature of approximately 90° F. and a wet bulb temperature of approximately 56.7° F. The enthalpy of the dried air is approximately 24 BTU per pound of dry air and the humidity ratio is approximately 16 grains of moisture per pound of dry air. 
     The heated air travels downstream through the supply side  113  of the processing module  104  where humidity from the return air in the return side  115  is discharged into the lower relative humidity air in the supply side  113 . The humidified supply air is discharged into the processed air region  107 . Point  458  of chart  450  illustrates the conditions of the supply air. At point  458 , the supply air has a dry bulb temperature of approximately 70° F. and a wet bulb temperature of approximately 53° F. The enthalpy of the supply air is approximately 22 BTU per pound of dry air and the humidity ratio is approximately 33 grains of moisture per pound of dry air. The supply air is discharged through the supply air outlet  110  and into the building. 
       FIG. 6  is a psychrometric chart  500  illustrating the condition of the air in the return air flow path  140  when the system  100  is operating in the winter mode  132  and when the return air enters the system  100  through the return air inlet  116  and flows into the return air region  117 . Point  502  of chart  500  illustrates the conditions of the return air. The return air has a dry bulb temperature of approximately 70° F. and a wet bulb temperature of approximately 53° F. The enthalpy of the return air is approximately 22 BTU per pound of dry air and the humidity ratio is approximately 33 grains of moisture per pound of dry air. 
     The return air flows through the return air side  111  of the pre-processing module  102  where heat is removed from the return air and discharged into the outside air in the supply air side  109  of the pre-processing module  102 . The pre-processing module  102  produces cooled air in the return air flow path  140  that is discharged into the pre-processed air region  119 . Point  504  of chart  500  illustrates the conditions of the cooled air in the pre-processed air region  119 . The cooled air has a dry bulb temperature of approximately 28° F. and a wet bulb temperature of approximately 27° F. The enthalpy of the cooled air is approximately 10 BTU per pound of dry air and the humidity ratio is approximately 20 grains of moisture per pound of dry air. 
     The cooled air passes through return air side  115  of the processing module  104 . The processing module  104  transfers humidity from the cooled air in the return air side  115  to the dry air in the supply air side  113  of the processing module  104 . Dehumidified air is discharged from the processing module  104  into the processed air region  144 . Point  506  of chart  500  illustrates the conditions of the dehumidified air in the processed air region  144 . The dehumidified air in the processed air region  144  has a dry bulb temperature of approximately 49° F. and a wet bulb temperature of approximately 34° F. The enthalpy of the dehumidified air is approximately 13 BTU per pound of dry air and the humidity ratio is approximately 7 grains of moisture per pound of dry air. 
     The dehumidified air then passes through the regeneration air heat exchanger  114 . In the winter mode  132 , the regeneration air heat exchanger  114  operates as an evaporator coil to cool the dehumidified air. The regeneration air heat exchanger  114  removes heat from the dehumidified air. The heat is discharged into the supply air heat exchanger  106  to heat the supply air traveling through the supply air heat exchanger  106 . Cooled exhaust air is discharged from the regeneration air heat exchanger  114  into the conditioned air region  146 . Point  508  of chart  500  illustrates the conditions of the exhaust air. At point  508 , the exhaust air has a dry bulb temperature of approximately 10° F. and a wet bulb temperature of approximately 9° F. The enthalpy of the exhaust air is approximately 3 BTU per pound of dry air and the humidity ratio is approximately 7 grains of moisture per pound of dry air. The exhaust air is discharged from the space through the return air outlet  142 . 
       FIG. 7  is a schematic view of another heat pump system  200  formed in accordance with an embodiment and operating in a winter mode. The heat pump system  200  includes many of the elements of the heat pump system  100 . The elements of the heat pump system  200  that are the same as the elements of the heat pump system  100  are denoted using the same reference numerals. The heat pump system  200  includes a reheat coil  202  positioned upstream from the regeneration air heat exchanger  114  that is operational in the winter mode  132 . The reheat coil  202  is positioned downstream from the return air side  115  of the processing module  104  in the winter mode  132 . The reheat coil  202  adds heat, lowers the relative humidity of the return air exiting the return air side  115  of the processing module  104  prior to entering the regeneration air heat exchanger  114 . The reheat coil  202  may prevent frost formation on the regeneration air heat exchanger  114  during the winter mode  132 . 
     The reheat coil  202  is fluidly coupled to the refrigeration system  133  through piping  204 . The piping  204  is joined to the compressor  141  to receive heated refrigerant therefrom. A refrigerant flow control device  206  may be provided to control a flow of refrigerant to the reheat coil  202 . 
       FIG. 8  is a psychrometric chart  210  of the heat pump system  200  operating in a winter mode  132 . Point  212  of chart  210  illustrates the conditions of the return air. The return air has a dry bulb temperature of approximately 70° F. and a wet bulb temperature of approximately 53° F. The enthalpy of the return air is approximately 22 BTU per pound of dry air. 
     The return air flows through the return air side  111  of the pre-processing module  102  where heat is removed from the return air and discharged into the outside air in the supply air side  109  of the pre-processing module  102 . The pre-processing module  102  produces cooled air in the return air flow path  140  that is discharged into the pre-processed air region  119 . Point  214  of chart  210  illustrates the conditions of the cooled air in the pre-processed air region  119 . The cooled air has a dry bulb temperature of approximately 28° F. and a wet bulb temperature of approximately 27° F. The enthalpy of the cooled air is approximately 10 BTU per pound of dry air. 
     The cooled air passes through return air side  115  of the processing module  104 . The processing module  104  transfers humidity from the cooled air in the return air side  115  to the dry air in the supply air side  113  of the processing module  104 . Dehumidified air is discharged from the processing module  104  into the processed air region  144 . Point  216  of chart  210  illustrates the conditions of the dehumidified air in the processed air region  144 . The dehumidified air in the processed air region  144  has a dry bulb temperature of approximately 49° F. and a wet bulb temperature of approximately 34° F. The enthalpy of the dehumidified air is approximately 13 BTU per pound of dry air. 
     The dehumidified air then passes through the reheat coil  202 . Point  218  of the chart  210  illustrates the conditions of the reheated air discharged from the reheat coil  202 . The reheated air has a dry bulb temperature of approximately 63° F. and a wet bulb temperature of approximately 42° F. The enthalpy of the dehumidified air is approximately 16 BTU per pound of dry air. 
     The reheated air then passes through the regeneration air heat exchanger  114 . The regeneration air heat exchanger  114  removes heat from the dehumidified air. The heat is discharged into the supply air heat exchanger  106  to heat the supply air traveling through the supply air heat exchanger  106 . Cooled exhaust air is discharged from the regeneration air heat exchanger  114  into the conditioned air region  146 . Point  220  of chart  210  illustrates the conditions of the exhaust air. At point  220 , the exhaust air has a dry bulb temperature of approximately 10° F. and a wet bulb temperature of approximately 9° F. The enthalpy of the exhaust air is approximately 3 BTU per pound of dry air and the humidity ratio is approximately 7 grains of moisture per pound of dry air. The exhaust air is discharged from the space through the return air outlet  142 . 
       FIG. 9  is a schematic view of another heat pump system  250  formed in accordance with an embodiment and operating in a winter mode. The heat pump system  250  includes many of the elements of the heat pump system  100 . The elements of the heat pump system  250  that are the same as the elements of the heat pump system  100  are denoted using the same reference numerals. The heat pump system  250  includes a sub-cooling coil  252  positioned upstream from the regeneration air heat exchanger  114 . The sub-cooling coil  252  is positioned downstream from the return air side  115  of the processing module  104 . The sub-cooling coil  252  adds heat, lowers the relative humidity of the return air exiting the return air side  115  of the processing module  104  prior to entering the regeneration air heat exchanger  114 . The sub-cooling coil  252  may prevent frost formation on the regeneration air heat exchanger  114  during the winter mode  132 . 
     The sub-cooling coil  252  is fluidly coupled to the refrigeration system  133  through piping  254 . The piping  254  includes a pair of flow control devices  256  to control a flow of refrigerant to the sub-cooling coil  252 . In one embodiment, the refrigerant system  133  may also include an additional metering device and check valve system  258  to control the flow of refrigerant therethrough. 
       FIG. 10  is a schematic view of another heat pump system  150  operating in a summer mode  180 .  FIG. 11  is a schematic view of the system  150  operating in a winter mode  182 . In the summer mode  180 , a supply air flow path  162  and a return air flow path  170  flow through the system  150 . In the winter mode  182 , the supply air flow path  162  follows the same path as defined in the summer mode  180  and return air follows a return air flow path  190 . In the winter mode  182  the function of the system components may differ from the function of the system components in the summer mode  180 . The system  150  includes dampers  171 ,  172 ,  173 , and  174  to redirect the return air path  170  of the summer mode  180  into the return air path  190  of the winter mode  182 . 
     Referring to the summer mode  180  illustrated in  FIG. 10 , outside air flows through the supply air inlet  158  and downstream to a supply air side  151  of a pre-processing module  152 . The pre-processing module  152  removes heat from the outside air. The outside air discharged from the pre-processing module  152  flows into a pair supply air heat exchangers  156  and  157 . In the summer mode  180 , the supply air heat exchangers  156  and  157  operate as evaporator coils to saturate the outside air. The outside air then flows downstream to a supply air side  155  of a processing module  154 . The processing module  154  removes moisture from the outside air to generate dehumidified supply air that is discharged through the supply air outlet  160  and into the space. At least one fan (not shown) may be positioned within the supply air flow path  162  to move the supply air from the supply air inlet  158  downstream to the supply air outlet  160 . 
     In the summer mode  180 , regeneration air in the form of return air flows through the return air inlet  166  and through a return air side  153  of the pre-processing module  152 . The pre-processing module  152  removes heat from the outside air in the supply air side  151  and transfers the heat to the return air in the return air side  153 . The return air is then channeled to a regeneration air heat exchanger  164 , which preferably is shut off. The return air travels through the regeneration air heat exchanger  164  unchanged and into a regeneration air heat exchanger  165 . In the summer mode  180 , the regeneration air heat exchanger  165  operates as a condenser coil to lower a relative humidity of the return air to increase the air&#39;s capacity to absorb water downstream. The regeneration air heat exchanger  165  uses the heat removed from the supply air by the supply air heat exchanger  157  to dry the return air. The heated return air then flows to a return air side  159  of the processing module  154  and receives moisture from the supply air side  155 . The return air discharged from the processing module  154  flows through a regeneration air heat exchanger  167 , which operates as a condenser coil to further heat the return air using the heat from the supply air heat exchanger  156 . The return air is then discharged through a return air outlet  168 . It is understood that heat exchangers in the supply and return air flow paths could be matched differently then that stated previously. For instance, the regeneration air heat exchanger  165  could also be coupled with the supply air heat exchanger  156 . Likewise the regeneration air heat exchanger  167  could also be coupled with the supply air heat exchanger  157 . 
     Referring to  FIG. 11 , the winter mode  182  of the system  150  is illustrated. The supply air flow path  162  follows the same path as defined in the summer mode  180 . In the winter mode  182  the function of the system components may differ from the function of the system components in the summer mode  180 . Supply air enters the supply air inlet  158  and flows downstream to the pre-processing module  152  where the supply air receives heat from the return air flow path  190 . The supply air discharged from the pre-processing module  152  flows into the supply air heat exchangers  156  and  157 . In the winter mode  182 , the supply air heat exchangers  156  and  157  operate as condenser coils to heat, lower a relative humidity of the supply air and increase the air&#39;s capacity to absorb water downstream. The dried supply air then travels to the processing module  154  where the supply air receives moisture from the return air flow path  190  to generate humidified supply air. The humidified supply air is discharged through the supply air outlet  160  and into the space. 
     The return air flow path  190  of the winter mode  182  differs from the return air flow path  170  of the summer mode  180 . The dampers  171 ,  172 ,  173 , and  174  of the system  150  are open and/or closed to change the return air flow path  170  of the summer mode  180  to the return air flow path  190  of the winter mode  182 . Additionally, the functions of at least some of the system components may change in the winter mode  182 . Return air enters the return air flow path  190  through the return air inlet  166 . The return air flows through the pre-processing module  152  where heat is removed from the return air. The heat is discharged into the supply air flow path  162 . The return air then flows to the processing module  154  where moisture is removed from the return air. The moisture from the return air is discharged into the supply air flow path  162 . The return air discharged from the processing module  154  travels to the regeneration air heat exchangers  165  and  164 . In the winter mode  182 , the regeneration air heat exchangers  165  and  164  operate as evaporator coils to cool the return air prior to the return air being discharged through the return air outlet  192 . It is understood that the return air flow path  190  of the winter mode could alternatively flow through the regeneration air heat exchanger  167 , which is preferably shut off, and then to the process module  154  depending on the damper (not shown) location and operation. 
     In one embodiment, the heat pump system  150  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the pre-processing module  152 , the processing module  154 , the supply air heat exchangers  156  and/or  157 , and/or the regeneration air heat exchangers  164 ,  165 , and/or  167  to achieve a pre-determined dehumidification of the supply air in summer mode  180  and a pre-determined humidification of the supply air in the winter mode  182 . 
     In another embodiment, the heat pump system  150  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the pre-processing module  152 , the processing module  154 , the supply air heat exchangers  156  and/or  157 , and/or the regeneration air heat exchangers  164 ,  165 , and/or  167  to achieve a pre-determined performance of the system  150 . 
     In another embodiment, the heat pump system  150  senses a condition of at least one of the supply air or return air from the space to and control an output of at least one of the pre-processing module  152 , the processing module  154 , the supply air heat exchangers  156  and/or  157 , and/or the regeneration air heat exchangers  164 ,  165 , and/or  167  to limit frost formation in at least one of the pre-processing module  152  and/or regeneration air heat exchangers  164 ,  165 , and/or  167  in the winter mode  182 . 
     In another embodiment, the heat pump system  150  senses a condition of at least one of the supply air stream or the return air stream from the space to control an output of at least one of a single compressor, multiple compressors and/or variable compressor to limit frost formation in at least one of the pre-processing module  152  and/or regeneration air heat exchangers  164 ,  165  and/or  167  in the winter mode  182 . 
     In another embodiment, the heat pump system  150  senses a condition of at least one of the supply air stream or the return air stream from the space to control an output of at least one of a single compressor, multiple compressors and/or variable compressor to achieve a pre-determined performance of the system  150 . 
     Referring to  FIGS. 10 and 11 , the heat pump system  150  includes a first refrigerant system  143  and a second refrigerant system  145 . The first refrigerant system  143  includes piping  147  that fluidly couples the supply air heat exchanger  156 , the regeneration air heat exchanger  164 , and the regeneration air heat exchanger  167 . The first refrigerant system  143  pumps a refrigerant between the supply air heat exchanger  156  and at least one of the regeneration air heat exchanger  164  or the regeneration air heat exchanger  167 . A heat exchanger switch  149  controls the flow of refrigerant to the regeneration air heat exchanger  164  and the regeneration air heat exchanger  167 . In the summer mode  180 , the first refrigerant system  143  pumps cooled refrigerant to the supply air heat exchanger  156  to cool the air flowing through the supply air heat exchanger  156 . The cooled refrigerant is heated by the air in the supply air heat exchanger  156  to form heated refrigerant. The heated refrigerant flows through the piping  147  to at least one of the regeneration air heat exchanger  164  or the regeneration air heat exchanger  167  to heat the air flowing through the regeneration air heat exchanger  164  and/or the regeneration air heat exchanger  167 . The refrigerant is cooled by at least one of the regeneration air heat exchanger  164  or the regeneration air heat exchanger  167  to form cooled refrigerant that is pumped back to the supply air heat exchanger  156 . 
     In the winter mode  182 , the first refrigerant system  143  pumps heated refrigerant to the supply air heat exchanger  156  to heat the air flowing through the supply air heat exchanger  156 . The heated refrigerant is cooled by the air in the supply air heat exchanger  156  to faun cooled refrigerant. The cooled refrigerant flows through the piping  147  to at least one of the regeneration air heat exchanger  164  or the regeneration air heat exchanger  167  to cool the air flowing through the regeneration air heat exchanger  164  and/or the regeneration air heat exchanger  167 . The refrigerant is heated by the air in at least one of the regeneration air heat exchanger  164  or the regeneration air heat exchanger  167  to form heated refrigerant that is pumped back to the supply air heat exchanger  156 . 
     The first refrigerant system  143  may include a metering device and check valve system  161  to control a flow of the refrigerant between the supply air heat exchanger  156  and the regeneration air heat exchanger  164  and/or the regeneration air heat exchanger  167 . Additionally, a switch  163  may be provided to reverse a flow of the refrigerant through the first refrigerant system  143 . For example, the flow of the refrigerant may be reversed when the system  150  is switched between the summer mode  180  and the winter mode  182 . A compressor  169  is provided to compress the refrigerant. In the summer mode  180 , the refrigerant passes through the compressor  169  after exiting the supply air heat exchanger  156  and before entering the regeneration air heat exchangers  164  and/or  167 . In the winter mode  182 , the refrigerant passes through the compressor  169  after exiting the regeneration air heat exchangers  164  and/or  167  and before entering the supply air heat exchanger  156 . 
     The second refrigerant system  145  includes piping  175  that fluidly couples the supply air heat exchanger  157  and the regeneration air heat exchanger  165 . The second refrigerant system  145  pumps a refrigerant between the supply air heat exchanger  157  and the regeneration air heat exchanger  165 . In the summer mode  180 , the refrigerant system  145  pumps cooled refrigerant to the supply air heat exchanger  157  to cool the air flowing through the supply air heat exchanger  157 . The cooled refrigerant is heated by the air in the supply air heat exchanger  157  to form heated refrigerant. The heated refrigerant flows through the piping  175  to the regeneration air heat exchanger  165  to heat the air flowing through the regeneration air heat exchanger  165 . The refrigerant is cooled by the air in the regeneration air heat exchanger  165  to form cooled refrigerant that is pumped back to the supply air heat exchanger  157 . 
     In the winter mode  182 , the second refrigerant system  145  pumps heated refrigerant to the supply air heat exchanger  157  to heat the air flowing through the supply air heat exchanger  157 . The heated refrigerant is cooled by the air in the supply air heat exchanger  157  to form cooled refrigerant. The cooled refrigerant flows through the piping  175  to the regeneration air heat exchanger  165  to cool the air flowing through the regeneration air heat exchanger  165 . The refrigerant is heated by the air in the regeneration air heat exchanger  165  to form heated refrigerant that is pumped back to the supply air heat exchanger  157 . 
     The second refrigerant system  145  may include a metering device and check valve system  177  to control a flow of the refrigerant between the supply air heat exchanger  157  and the regeneration air heat exchanger  165 . Additionally, a switch  179  may be provided to reverse a flow of the refrigerant through the second refrigerant system  145 . For example, the flow of the refrigerant may be reversed when the system  150  is switched between the summer mode  180  and the winter mode  182 . A compressor  181  is provided to compress the refrigerant. In the summer mode  180 , the refrigerant passes through the compressor  181  after exiting the supply air heat exchanger  157  and before entering the regeneration air heat exchanger  165 . In the winter mode  182 , the refrigerant passes through the compressor  181  after exiting the regeneration air heat exchanger  165  and before entering the supply air heat exchanger  157 . 
       FIG. 12  is a schematic view of another heat pump system  600  formed in accordance with an embodiment. The system  600  is capable of switching between a summer mode and a winter mode without the need to reconfigure the components of the system  600 . 
     The system  600  includes a supply air flow path  602 , a return air flow path  604 , and an outside air flow path  606 . The supply air flow path  602  travels between a supply air inlet  608  and a supply air outlet  610 . In one embodiment, the system  600  may include at least one fan to draw air into and move air through the supply air flow path  602 . Outside air flows through the supply air inlet  608  and through a pre-processing module  612  positioned downstream of the supply air inlet  608 . 
     The pre-processing module  612  includes a supply air side  614  and a regeneration air side  616 . The supply air side  614  is positioned within the supply air flow path  602 . The regeneration air side  616  is positioned within the return air flow path  604 . Outside air passes through the supply air side  614  of the pre-processing module  612 . The pre-processing module  612  is configured to transfer latent energy and sensible energy between the supply air flow path  602  and the return air flow path  604 . The latent energy includes moisture in the flow paths  602  and  604 . The pre-processing module  612  transfers heat from a warmer flow path to a cooler flow path. The pre-processing module  612  also transfers humidity from a high humidity flow path to a low humidity flow path. The outside air is cooled as the outside air passes through the pre-processing module  612 . 
     The cooled air from the pre-processing module  612  is discharged into a supply air heat exchanger  618  positioned downstream from the pre-processing module  612 . The supply air heat exchanger  618  discharges air into another supply air heat exchanger  620  positioned downstream from the supply air heat exchanger  618 . The supply air heat exchangers  618  and  620  operate as evaporator coils or cooling coils in the summer mode. As evaporator coils, the supply air heat exchangers  618  and  620  condition the cooled air and further remove heat from the cooled air to produce saturated air. 
     A processing module  622  is positioned downstream from the supply air heat exchangers  618  and  620 . The saturated air passes through the processing module  622 . The processing module  622  includes a supply air side  624  and an outside air side  626 . The supply air side  624  is positioned within the supply air flow path  602  and the outside air side  626  is positioned within the outside air flow path  606 . The saturated air passes through the supply air side  624  to remove moisture therefrom and produce conditioned supply air that has been further dehumidified. Because the air is first saturated by the supply air heat exchangers  618  and  620 , the efficiency of the processing module  622  is increased when dehumidifying the air. The dehumidified supply air flows downstream through the supply air outlet  610  and into the space. 
     Regeneration air in the form of return air leaves the space at a return air inlet  628  and traverses the return air flow path  604 . The return air flow path  604  is defined between the return air inlet  628  and a return air outlet  630 . In one embodiment, the system  600  may include at least one fan to draw air into and move air through the return air flow path  604 . 
     The regeneration air side  616  of the pre-processing module  612  is positioned downstream from the return air inlet  628 . The return air passes through the regeneration air side  616  of the pre-processing module  612 . The pre-processing module  612  transfers heat and moisture into the return air passing through the regeneration air side  616 , thereby removing heat from the supply air passing through the supply air side  614 . The heated air flows into a regeneration air heat exchanger  632  positioned downstream from the regeneration air side  616  of the pre-processing module  612 . 
     The regeneration air heat exchanger  632  operates as a condenser coil in the summer mode to heat and lower a relative humidity of the conditioned air. The regeneration air heat exchanger  632  is fluidly coupled to the supply air heat exchanger  618  by a refrigerant system  634 . The refrigerant system  634  pumps a refrigerant between the regeneration air heat exchanger  632  and the supply air heat exchanger  618 . The regeneration air heat exchanger  632  uses the heat from the supply air heat exchanger  618  to lower a relative humidity of the heated air thus increasing the air&#39;s capacity to absorb water downstream. In one embodiment, a compressor  636  may be provided in the refrigerant system  634  to condition the refrigerant flowing between the supply air heat exchanger  618  and the regeneration air heat exchanger  632 . The heated air from the regeneration air heat exchanger  632  is discharged from the return air outlet  630 . 
     Regeneration air in the form of outside air enters the system  600  at an outside air inlet  638  and traverses the outside air flow path  606 . The outside air flow path  606  is defined between the outside air inlet  638  and an outside air outlet  640 . In one embodiment, the system  600  may include at least one fan to draw air into and move air through the outside air flow path  606 . The outside air flows into a regeneration air heat exchanger  642  positioned downstream from the outside air inlet  638 . 
     The regeneration air heat exchanger  642  operates as a condenser coil in the summer mode to heat and lower a relative humidity of conditioned air. The regeneration air heat exchanger  642  is fluidly coupled to the supply air heat exchanger  620  by a refrigerant system  644 . The refrigerant system  644  pumps a refrigerant between the regeneration air heat exchanger  642  and the supply air heat exchanger  620 . The regeneration air heat exchanger  642  uses the heat from the supply air heat exchanger  620  to lower the relative humidity of the heated air thus increasing the air&#39;s capacity to absorb water downstream. In one embodiment, a compressor  646  may be provided in the refrigerant system  644  to condition the refrigerant flowing between the supply air heat exchanger  620  and the regeneration air heat exchanger  642 . The heated air from the regeneration air heat exchanger  642  is discharged into the outside air side  626  of the processing module  622 . 
     The processing module  622  transfers heat and moisture into the supply air passing through the supply air side  624 , thereby removing heat from the outside air passing through the outside air side  626 . The outside air is discharged from the processing module  622  through the outside air outlet  640 . 
     In a winter mode, the system  600  may be configured to heat and humidify the supply air flowing into the building. For example, the supply air heat exchangers  618  and  620  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  632  and  642  may be reversed in the winter mode to operate as evaporator coils. 
       FIG. 13  is a schematic view of an alternative embodiment of the heat pump system  600 . In  FIG. 12  the outside air flow path  606  is configured to flow in a counter-flow direction with respect to the supply air flow path  602 . In  FIG. 13 , the regeneration air heat exchanger  642  is positioned on an opposite side of the processing module  622 , in comparison to  FIG. 12 . Accordingly, the outside air flow path  606  illustrated in  FIG. 13  is reversed and flows parallel to the supply air flow path  602 . Parallel air flow of the outside air flow path  606  and the supply air flow path  602  may improve the transfer of heat and moisture between the outside air side  626  and the supply air side  624  of the processing module  622 . 
       FIG. 14  is a schematic view of another alternative embodiment of the heat pump system  600 . The heat pump system  600  includes an additional heat source  601  positioned between the supply air heat exchanger  620  and the supply air side  624  of the processing module  622 . The additional heat source  601  is positioned downstream of the supply air heat exchanger  620  and upstream from the processing module  622 . In one embodiment, the additional heat source  601  may be located downstream of the processing module  622 . The additional heat source  601  may be a hot water coil, steam coil, electric heater, gas burner, or the like. The additional heat source  601  may be configured for operation in the winter mode. Accordingly, the additional heat source  601  may be shut-off in the summer mode so that the supply air passes through the additional heat source  601  unchanged. In one embodiment, the supply air may by-pass the additional heat source  601  in the summer mode and travel directly from the supply air heat exchanger  620  to the processing module  624 . 
     In the winter mode, the system  600  may have multiple modes of operation. In one embodiment, the system  600  may utilize the additional heat source  601  with the processing module  622  turned off and the pre-processing module  612  turned on to heat and humidify the supply air passing therethrough. In such an embodiment, the supply air heat exchanger  618  and  620  may also be shut off so that only the additional heating source  601  would provide heat after the pre-processing module  612 . 
     In another embodiment, the additional heat source  601  may be operated with either one or both of the supply air heat exchangers  618  and  620 . In such an embodiment, the supply air heat exchangers  618  and  620  are operated as condensers to heat the supply air in the supply air flow path  602 . Additionally, either one or both of the regeneration air heat exchangers  632  and  642  operate as evaporators to cool the air in the return air flow path  604  and the outside air flow path  606 , respectively. In such an embodiment, the processing module  622  may be operated. Accordingly, supply air leaving the supply air heat exchanger  620  could be heated further by the additional heating source  601  before entering the processing module  622  where the supply air is humidified. The outside air flow path  606  is then heated and dehumidified as it passes through the processing module  622 . 
       FIG. 15  is a schematic view of another alternative embodiment of the heat pump system  600 . The heat pump system  600  includes the additional heat source  601  (as illustrated in  FIG. 14 ) and a pair of pre-heat coils  603  and  605 . The pre-heat coil  603  is positioned in the return air flow path  604  between the regeneration air heat exchanger  632  and the pre-processing module  612 . The pre-heat coil  603  is positioned downstream from the regeneration air side  616  of the pre-processing module  612  and upstream from the regeneration air heat exchanger  632 . The pre-heat coil  605  is positioned in the outside air flow path  606  upstream of the regeneration air heat exchanger  642  and the processing module  622 . The pre-heat coils  603  and  605  may be hot water coils, steam coils, electric heaters, gas burners, heat exchangers tied to the refrigeration system or the like. 
     In the winter mode, the supply air in the supply air flow path  602  is heated and humidified by the pre-processing module  612  and then heated by supply air heat exchangers  618  and  620 . The supply air may also be heated by the additional heat source  601  prior to being cooled and humidified by the processing module  622 . The return air in the return air flow path  604  is cooled and dehumidified by the pre-processing module  612 . The return air is then pre-heated by the pre-heat coil  603  and cooled by the regeneration air heat exchanger  632 . The outside air in the outside air flow path  606  is pre-heated by the pre-heat coil  605  and then cooled by the regeneration air heat exchanger  642 . The outside air is then reheated and dehumidified by the processing module  622 . 
     The pre-heat coil  603  offsets a saturation point of the return air stream so that heat absorbed by the pre-processing wheel and transferred to the return air stream is recaptured by the regeneration air heat exchanger  632  without energy being lost. Optionally, a supply pre-heating coil (not shown) may be located upstream of the pre-processing module  612 . 
       FIG. 16  is a schematic view of another heat pump system  700  formed in accordance with an embodiment capable of operating in a summer mode or a winter mode. 
     The system  700  includes a supply air flow path  702 , a return air flow path  704 , a first outside air flow path  706 , and a second outside air flow path  701 . The supply air flow path  702  travels between a supply air inlet  708  and a supply air outlet  710 . Outside air flows through the supply air inlet  708  and through a pre-processing module  712  positioned downstream of the supply air inlet  708 . The pre-processing module  712  includes a supply air side  714  positioned within the supply air flow path  702 . Outside air passes through the supply air side  714  of the pre-processing module  712 . The pre-processing module  712  is configured to transfer latent energy and sensible energy between the supply air flow path  702  and the return air flow path  704 . The supply air is cooled as the supply air passes through the pre-processing module  712 . 
     The cooled air from the pre-processing module  712  is discharged into a supply air heat exchanger  718  positioned downstream from the pre-processing module  712 . The supply air heat exchanger  718  discharges air into a second supply air heat exchanger  719  positioned downstream from the supply air heat exchanger  718 . The supply air heat exchanger  719  discharges air into a third supply air heat exchanger  720  positioned downstream from the supply air heat exchanger  719 . The supply air heat exchangers  718 ,  719 , and  720  operate as evaporator coils or cooling coils in the summer mode. 
     A processing module  722  is positioned downstream from the supply air heat exchangers  718 ,  719 , and  720 . The air passes through the processing module  722 . The processing module  722  includes a supply air side  724  positioned within the supply air flow path  702 . The air passes through the supply air side  724  to remove moisture therefrom and produce conditioned supply air that has been dehumidified. The dehumidified supply air flows downstream through the supply air outlet  710  and into the space. 
     Regeneration air in the form of return air leaves the space at return air inlet  728  and traverses the return air flow path  704 . The return air flow path  704  is defined between the return air inlet  728  and a return air outlet  730 . A return air side  716  of the pre-processing module  712  is positioned downstream from the return air inlet  728 . The return air passes through the return air side  716  of the pre-processing module  712 . The pre-processing module  712  transfers heat and moisture into the return air passing through the return air side  716 , thereby removing heat from the supply air passing through the supply air side  714 . The heated air flows into a regeneration air heat exchanger  732  positioned downstream from the return air side  716  of the pre-processing module  712 . 
     The regeneration air heat exchanger  732  operates as a condenser coil in the summer mode to heat and lower a relative humidity of conditioned air. The regeneration air heat exchanger  732  is fluidly coupled to the supply air heat exchanger  719  by a refrigerant system  734 . The refrigerant system  734  pumps a refrigerant between the regeneration air heat exchanger  732  and the supply air heat exchanger  719 . In one embodiment, a compressor  736  may be provided in the refrigerant system  734  to condition the refrigerant flowing between the supply air heat exchanger  719  and the regeneration air heat exchanger  732 . The heated air from the regeneration air heat exchanger  732  is discharged from the return air outlet  730 . 
     Regeneration air in the form of outside air enters the system  700  at an outside air inlet  738  and traverses the outside air flow path  706 . The outside air flow path  706  is defined between the outside air inlet  738  and an outside air outlet  740 . The outside air flows into a regeneration air heat exchanger  742  positioned downstream from the outside air inlet  738 . The regeneration air heat exchanger  742  operates as a condenser coil in the summer mode to heat and lower relative humidity of conditioned air. The regeneration air heat exchanger  742  is fluidly coupled to the supply air heat exchanger  720  by a refrigerant system  744 . The refrigerant system  744  pumps a refrigerant between the regeneration air heat exchanger  742  and the supply air heat exchanger  720 . In one embodiment, a compressor  746  may be provided in the refrigerant system  744  to condition the refrigerant flowing between the supply air heat exchanger  720  and the regeneration air heat exchanger  742 . The heated air from the regeneration air heat exchanger  742  is discharged into an outside air side  726  of the processing module  722 . 
     The processing module  722  transfers heat and moisture into the supply air passing through the supply air side  724 , thereby removing heat from the outside air passing through the outside air side  726 . The outside air is discharged from the processing module  722  through the outside air outlet  740 . 
     Regeneration air in the form of outside air enters the system  700  at an outside air inlet  703  and traverses the outside air flow path  701 . The outside air flow path  701  is defined between the outside air inlet  703  and an outside air outlet  705 . The outside air flows into a regeneration air heat exchanger  707  positioned downstream from the outside air inlet  703 . 
     The regeneration air heat exchanger  707  operates as a condenser coil in the summer mode to heat and lower relative humidity of conditioned air. The regeneration air heat exchanger  707  is fluidly coupled to the supply air heat exchanger  718  by a refrigerant system  709 . The regeneration air heat exchanger  707  extracts the heat from the supply air heat exchanger  718 . In one embodiment, a compressor  711  may be provided in the refrigerant system  709  to condition the refrigerant flowing between the supply air heat exchanger  718  and the regeneration air heat exchanger  707 . The heated air from the regeneration air heat exchanger  707  is discharged through the outside side air outlet  705 . 
     In a winter mode, the system  700  may be configured to humidify the supply air flowing into the building. For example, the supply air heat exchangers  718 ,  719 , and  720  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  707 ,  732  and  742  may be reversed in the winter mode to operate as evaporator coils. 
       FIG. 17  is a schematic view of an alternative embodiment of the heat pump system  700 . In  FIG. 16 , the outside air flow path  706  is configured to flow in a counter-flow direction with respect to the supply air flow path  702 . In  FIG. 17 , the regeneration air heat exchanger  742  is positioned on an opposite side of the processing module  722 , in comparison to  FIG. 16 . Accordingly, the outside air flow path  706  illustrated in  FIG. 17  is reversed and flows parallel to the supply air flow path  702 . Parallel air flow of the outside air flow path  706  and the supply air flow path  702  may improve the transfer of heat and moisture between the outside air side  726  and the supply air side  724  of the processing module  722 . 
       FIG. 18  is a schematic view of another heat pump system  800  formed in accordance with an embodiment that operates in a summer mode or a winter mode. The system  800  includes a supply air flow path  802 , a return air flow path  804 , a first outside air flow path  806 , a second outside air flow path  801 , and third outside air flow path  821 . The supply air flow path  802  travels between a supply air inlet  808  and a supply air outlet  810 . Outside air flows through the supply air inlet  808  and through a pre-processing module  812  positioned downstream of the supply air inlet  808 . 
     The outside air passes through a supply air side  814  of the pre-processing module  812 . The supply air is cooled as the supply air passes through the pre-processing module  812 . The cooled air from the pre-processing module  812  is discharged into a supply air heat exchanger  818  positioned downstream from the pre-processing module  812 . The supply air heat exchanger  818  discharges air into a second supply air heat exchanger  819  positioned downstream from the supply air heat exchanger  818 . The supply air heat exchanger  819  discharges air into a third supply air heat exchanger  820  positioned downstream from the supply air heat exchanger  819 . The supply air heat exchangers  818 ,  819 , and  820  operate as evaporator coils or cooling coils in the summer mode. 
     A processing module  822  is positioned downstream from the supply air heat exchangers  818 ,  819 , and  820 . The saturated air passes through a supply air side  824  of the processing module  822  that is positioned within the supply air flow path  802 . The air passes through the supply air side  824  to remove moisture therefrom and produce conditioned supply air that has been further dehumidified. The dehumidified supply air flows downstream through the supply air outlet  810  and into the space. 
     Regeneration air in the form of return air leaves the space at return air inlet  828  and traverses the return air flow path  804  defined between the return air inlet  828  and a return air outlet  830 . The return air passes through a return air side  816  of the pre-processing module  812 . The pre-processing module  812  transfers heat and moisture into the return air passing through the return air side  816 , thereby removing heat from the supply air passing through the supply air side  814 . The heated air is discharged from the return air outlet  830 . 
     Regeneration air in the form of outside air enters the system  800  at an outside air inlet  838  and traverses the outside air flow path  806  that is defined between the outside air inlet  838  and an outside air outlet  840 . The outside air flows into a regeneration air heat exchanger  842  positioned downstream from the outside air inlet  838 . The regeneration air heat exchanger  842  operates as a condenser coil in the summer mode to heat and lower relative humidity of conditioned air. The regeneration air heat exchanger  842  is fluidly coupled to the supply air heat exchanger  820  by a refrigerant system  844 . In one embodiment, a compressor  846  may be provided in the refrigerant system  844  to condition the refrigerant flowing between the supply air heat exchanger  820  and the regeneration air heat exchanger  842 . The heated air from the regeneration air heat exchanger  842  is discharged into the outside air side  826  of the processing module  822 . 
     The processing module  822  transfers heat and moisture into the supply air passing through the supply air side  824 , thereby removing heat from the outside air passing through the outside air side  826 . The outside air is discharged from the processing module  822  through the outside air outlet  840 . 
     Regeneration air in the form of outside air enters the system  800  at an outside air inlet  803  and traverses the outside air flow path  801  defined between the outside air inlet  803  and an outside air outlet  805 . The outside air flows into a regeneration air heat exchanger  807  positioned downstream from the outside air inlet  803 . The regeneration air heat exchanger  807  operates as a condenser coil in the summer mode. The regeneration air heat exchanger  807  is fluidly coupled to the supply air heat exchanger  818  by a refrigerant system  809 . The refrigerant system  809  pumps a refrigerant between the regeneration air heat exchanger  807  and the supply air heat exchanger  818 . In one embodiment, a compressor  811  may be provided in the refrigerant system  809  to condition the refrigerant flowing between the supply air heat exchanger  818  and the regeneration air heat exchanger  807 . The heated air from the regeneration air heat exchanger  807  is discharged through the outside side air outlet  805 . 
     Regeneration air in the form of outside air enters the system  800  at an outside air inlet  823  and traverses the outside air flow path  821  defined between the outside air inlet  823  and the outside air outlet  805 . The outside air flows into a regeneration air heat exchanger  825  positioned downstream from the outside air inlet  823 . 
     The regeneration air heat exchanger  825  operates as a condenser coil in the summer mode to heat and lower relative humidity of conditioned air. The regeneration air heat exchanger  825  is fluidly coupled to the supply air heat exchanger  819  by a refrigerant system  827 . In one embodiment, a compressor  829  may be provided in the refrigerant system  827  to condition the refrigerant flowing between the supply air heat exchanger  819  and the regeneration air heat exchanger  825 . The heated air from the regeneration air heat exchanger  825  is discharged through the outside side air outlet  805 . 
     In a winter mode, the system  800  may be configured to humidify the supply air flowing into the building. For example, the supply air heat exchangers  818 ,  819 , and  820  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  807 ,  825  and  842  may be reversed in the winter mode to operate as evaporator coils. 
       FIG. 19  is a schematic view of an alternative embodiment of the heat pump system  800 . In  FIG. 18 , the outside air flow path  806  is configured to flow in a counter-flow direction with respect to the supply air flow path  802 . In  FIG. 19 , the regeneration air heat exchanger  842  is positioned on an opposite side of the processing module  822 , in comparison to  FIG. 18 . Accordingly, the outside air flow path  806  illustrated in  FIG. 19  is reversed and flows parallel to the supply air flow path  802 . Parallel air flow of the outside air flow path  806  and the supply air flow path  802  may improve the transfer of heat and moisture between the outside air side  826  and the supply air side  824  of the processing module  822 . 
       FIG. 20  is a schematic view of another heat pump system  900  formed in accordance with an embodiment. The system  900  includes a supply air flow path  902 , a first outside air flow path  906 , a second outside air flow path  901 , and third outside air flow path  921 . The supply air flow path  902  includes return air  939  that enters the supply air flow path  902  through a return air inlet  908 . A portion  931  of the return air is discharged through a return air outlet  930  as exhaust air. Another portion  933  of the return air enters a mixing box  935 . The supply air flow path  902  also includes outside air  941  that enters an outside air inlet  937  and mixes with the portion  933  of the return air to form the supply air. 
     The supply air flows into a supply air heat exchanger  918 . The supply air heat exchanger  918  discharges air into a second supply air heat exchanger  919  positioned downstream from the supply air heat exchanger  918 . The supply air heat exchanger  919  discharges air into a third supply air heat exchanger  920  positioned downstream from the supply air heat exchanger  919 . The supply air heat exchangers  918 ,  919 , and  920  operate as evaporator coils or cooling coils in the summer mode. The air passes through a supply air side  924  of the processing module  922  and then flows downstream through a supply air outlet  910  and into the space. 
     Regeneration air in the form of outside air enters the system  900  at an outside air inlet  938  and traverses the outside air flow path  906  that is defined between the outside air inlet  938  and an outside air outlet  940 . The outside air flows into a regeneration air heat exchanger  942  positioned downstream from the outside air inlet  938 . 
     The regeneration air heat exchanger  942  operates as a condenser coil in the summer mode. The regeneration air heat exchanger  942  is fluidly coupled to the supply air heat exchanger  920  by a refrigerant system  944 . In one embodiment, a compressor  946  may be provided in the refrigerant system  944  to condition the refrigerant flowing between the supply air heat exchanger  920  and the regeneration air heat exchanger  942 . The heated air from the regeneration air heat exchanger  942  is discharged into an outside air side  926  of the processing module  922 . 
     The processing module  922  transfers heat and moisture into the supply air passing through the supply air side  924 , thereby removing heat from the outside air passing through the outside air side  926 . The outside air is discharged from the processing module  922  through the outside air outlet  940 . 
     Regeneration air in the form of outside air enters the system  900  at an outside air inlet  903  and traverses the outside air flow path  901  defined between the outside air inlet  903  and an outside air outlet  905 . The outside air flows into a regeneration air heat exchanger  907  positioned downstream from the outside air inlet  903 . 
     The regeneration air heat exchanger  907  operates as a condenser coil in the summer mode. The regeneration air heat exchanger  907  is fluidly coupled to the supply air heat exchanger  918  by a refrigerant system  909  having a compressor  911  to condition the refrigerant flowing between the supply air heat exchanger  918  and the regeneration air heat exchanger  907 . The heated air from the regeneration air heat exchanger  907  is discharged through the outside side air outlet  905 . 
     Regeneration air in the form of outside air enters the system  900  at an outside air inlet  923  and traverses the outside air flow path  921  defined between the outside air inlet  923  and the outside air outlet  905 . The outside air flows into a regeneration air heat exchanger  925  positioned downstream from the outside air inlet  923  and fluidly coupled to the supply air heat exchanger  919  by a refrigerant system  927  having a compressor  929 . The heated air from the regeneration air heat exchanger  925  is discharged through the outside side air outlet  905 . 
     In a winter mode, the system  900  may be configured to humidify the supply air flowing into the building. For example, the supply air heat exchangers  918 ,  919 , and  920  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  907 ,  925  and  942  may be reversed in the winter mode to operate as evaporator coils. 
       FIG. 21  is a schematic view of an alternative embodiment of the heat pump system  900 . In  FIG. 20 , the outside air flow path  906  is configured to flow in a counter-flow direction with respect to the supply air flow path  902 . In  FIG. 21 , the regeneration air heat exchanger  942  is positioned on an opposite side of the processing module  922 , in comparison to  FIG. 20 . Accordingly, the outside air flow path  906  illustrated in  FIG. 21  is reversed and flows parallel to the supply air flow path  902 . Parallel air flow of the outside air flow path  906  and the supply air flow path  902  may improve the transfer of heat and moisture between the outside air side  926  and the supply air side  924  of the processing module  922 . 
       FIG. 22  is a schematic view of another heat pump system  1000  formed in accordance with an embodiment. The system  1000  includes a supply air flow path  1002 , a first outside air flow path  1006 , a second outside air flow path  1001 , and third outside air flow path  1021 . The supply air flow path  1002  includes return air  1039  that enters the supply air flow path  1002  through a return air inlet  1008 . A portion  1031  of the return air is discharged through a return air outlet  1030  as exhaust air. Another portion  1033  of the return air enters a mixing box  1035 . The supply air flow path  1002  also includes outside air  1041  that enters an outside air inlet  1037  and mixes with the portion  1033  of the return air to form the supply air. 
     The supply air flows into a supply air heat exchanger  1018 . The supply air heat exchanger  1018  discharges air into a second supply air heat exchanger  1019  positioned downstream from the supply air heat exchanger  1018 . The supply air heat exchanger  1019  discharges air into a third supply air heat exchanger  1020  positioned downstream from the supply air heat exchanger  1019 . The supply air heat exchangers  1018 ,  1019 , and  1020  operate as evaporator coils or cooling coils in the summer mode. The air passes through a supply air side  1024  of the processing module  1022  and then flows downstream to a fourth supply air heat exchanger  1080 . The supply air heat exchanger  1080  also operates as evaporator coils or cooling coils in the summer mode. The air passes from the supply air heat exchanger  1080  to a reheat coil  1060  that reheats the supply air during the winter mode. 
     Regeneration air in the form of outside air enters the system  1000  at an outside air inlet  1038  and traverses the outside air flow path  1006  that is defined between the outside air inlet  1038  and an outside air outlet  1040 . The outside air flows into a regeneration pre-reheat coil  1062  positioned downstream from the outside air inlet  1038 . The air leaving the regeneration pre-reheat coil  1062  then passes into a regeneration air heat exchanger  1042  positioned downstream from the regeneration pre-reheat coil  1062 . 
     The regeneration air heat exchanger  1042  operates as a condenser coil in the summer mode. The regeneration air heat exchanger  1042  is fluidly coupled to the supply air heat exchanger  1020  and the supply air heat exchanger  1080  by a refrigerant system  1044 . In one embodiment, a compressor  1046  may be provided in the refrigerant system  1044  to condition the refrigerant flowing between the supply air heat exchangers  1020  and  1080 , and the regeneration air heat exchanger  1042 . The heated air from the regeneration air heat exchanger  1042  is discharged into an outside air side  1026  of the processing module  1022 . 
     The refrigerant system  1044  includes a node branch  1068  located downstream, along the fluid flow path, from the compressor  1046 . At the node branch  1068 , the fluid path splits along parallel refrigerant branches  1064  and  1066 . The refrigerant branch  1064  extends to and from the heat exchanger  1020  that is located upstream of the process module  1022 , while the refrigerant branch  1066  extends to and from the heat exchanger  1080  that is located downstream of the process module  1022 . Valves  1074  and  1076  are located along the branches  1064  and  1066 , respectively, to permit and inhibit flow of the coolant fluid through one or both of the branches  1064  and  1066 . The outlets of the valves  1074  and  1076  merge again at node  1078  and re-circulate to the heat exchanger  1042 . The valves  1074  and  1076  may be automatically controlled by a controller module. The valves  1074  and  1076  may be adjusted between fully open, fully closed, partially open and partially closed positions to vary the amount of coolant fluid that flows along each of the branches  1064  and  1066 . The valves  1074  and  1076  may be adjusted based upon summer versus winter mode. 
     The processing module  1022  transfers heat and moisture into the supply air passing through the supply air side  1024 , thereby removing heat from the outside air passing through the outside air side  1026 . The outside air is discharged from the processing module  1022  through the outside air outlet  1040 . 
     Regeneration air in the form of outside air enters the system  1000  at an outside air inlet  1003  and traverses the outside air flow path  1001  defined between the outside air inlet  1003  and an outside air outlet  1005 . The outside air flows into a regeneration air heat exchanger  1007  positioned downstream from the outside air inlet  1003 . 
     The regeneration air heat exchanger  1007  operates as a condenser coil in the summer mode. The regeneration air heat exchanger  1007  is fluidly coupled to the supply air heat exchanger  1018  by a refrigerant system  1009  having a compressor  1011  to condition the refrigerant flowing between the supply air heat exchanger  1018  and the regeneration air heat exchanger  1007 . The heated air from the regeneration air heat exchanger  1007  is discharged through the outside side air outlet  1005 . 
     Regeneration air in the form of outside air enters the system  1000  at an outside air inlet  1023  and traverses the outside air flow path  1021  defined between the outside air inlet  1023  and the outside air outlet  1005 . The outside air flows into a regeneration air heat exchanger  1025  positioned downstream from the outside air inlet  1023  and fluidly coupled to the supply air heat exchanger  1019  by a refrigerant system  1027  having a compressor  1029 . The heated air from the regeneration air heat exchanger  1025  is discharged through the outside side air outlet  1005 . 
     In a winter mode, the system  1000  may be configured to humidify the supply air flowing into the building. For example, the supply air heat exchangers  1018 ,  1019 ,  1020  and  1080  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  1007 ,  1025  and  1042  may be reversed in the winter mode to operate as evaporator coils. 
       FIGS. 23-30  illustrates psychrometric charts for the system  1000  when operating in various configurations.  FIGS. 23-30  illustrate exemplary data points representative of the air condition when passing between designated regions within system  1000 .  FIG. 23  illustrates the system  1000  when using 100% return air as the entering air while configured to perform pre-cooling with postdehumidification and sensible cooling. In this configuration, the outside air inlet  1037  is closed such that return air through return air inlet  1008  provides all of the supply air. The supply air heat exchangers  1018  and  1019  are turned off and only the supply air heat exchanger  1020  is active.  FIG. 23  illustrates outside air at data point  2301  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 74° F. and a relative humidity of approximately 78%.  FIG. 23  also illustrates return air at data point  2302  with a dry bulb temperature of 65° F., a wet bulb temperature of approximately 52° F. and a relative humidity of approximately 40%. As the air passes through the supply air heat exchanger  1020 , the humidity and temperature of the return air is changed to data point  2303 , and as the air passes through the processing module  1022 , the air conditions are adjusted to data point  2304  (dry bulb temperature of 65° F., wet bulb temperature of 50° F. and 31% relative humidity). As the air passes through the supply air heat exchanger  1080 , the conditions are further changed to data point  2305  and supplied to the controlled space (dry bulb temperature of 52° F., wet bulb temperature of 44° F. and relative humidity 50%). The heat exchanger  1080  performs post-dehumidification sensible cooling only without changing the humidity of the supply air. 
       FIG. 24  illustrates a psychrometric chart for the system  1000  when operating with 100% return air as the entering supply air. In this configuration, the outside air inlet  1037  is closed such that return air through return air inlet  1008  provides all of the supply air. The supply air heat exchangers  1018  and  1019  are turned off and only the supply air heat exchanger  1020  is active. The supply air heat exchanger  1020  changes the supply air condition from the data point  2402  (dry bulb temperature of 65° F., wet bulb temperature of 52° F. relative humidity 40%) to the conditions at data point  2403  (dry bulb temperature of 46° F., wet bulb temperature of 43° F. relative humidity 80%). Next as the air passes downstream from the heat exchanger  1020  through the processing module  1022 , the conditions of the supply air are moved from data point  2403  to the conditions at data point  2404  (dry bulb temperature of 60° F., wet bulb temperature of 47° F. and relative humidity approximately 36%). There is no post-dehumidification sensible cooling. 
       FIG. 25  illustrates a psychrometric chart for the system  1000  when operating in the summer mode with 50% return air and 50% outside air combined as the entering air at the mixing box  1035 . The psychrometric chart of  FIG. 25  is representative of the supply air processing when the system  1000  performs pre-cooling with post-dehumidification and sensible cooling. As shown in  FIG. 25 , the outside air conditions may begin at data point  2501  (dry bulb temperature of 80° F., wet bulb temperature of 74° F. and relative humidity of 78%), while the return air begins with the conditions at data point  2502  (dry bulb temperature of 65° F., wet bulb temperature of 52° F. and relative humidity of 40%). When the outside air and return air are mixed at the mixing box  1035 , the air conditions are representative of data point  2503  (dry bulb temperature of 72° F., wet bulb temperature of 64° F. and relative humidity of 67%). In the example of  FIG. 25 , the system  1000  operates supply air heat exchanges  1019  and  1020 , as well as heat exchanger  1080 . The air passing from the mixing box  1035  is conditioned by the heat exchanger  1019  to change the conditions of the air to data point  2504  (dry bulb temperature of 57° F., wet bulb temperature of 57° F. and approximately 100% relative humidity, mainly at saturation), as the air exits downstream of the heat exchanger  1019 . The heat exchanger  1020  then further processes the supply air to the conditions denoted at data point  2505  (dry bulb temperature of 46° F., wet bulb temperature of 46° F. and 100% relative humidity, mainly at saturation). The air exiting the heat exchanger  1020  passes through the processing module  1022  and is conditioned to the state denoted at data point  2506  when discharged from the processing module  1022  (dry bulb temperature of 59° F., wet bulb temperature of 47° F. and relative humidity of 37%). Next, the air on the discharge side of the processing module  1022  passes through the heat exchanger  1080  and its condition is changed to the state denoted at data point  2507  (dry bulb temperature of 53° F., wet bulb temperature of 44° F. and relative humidity 44%). The heat exchanger  1080  performs post-dehumidification sensible cooling. 
       FIG. 26  illustrates a psychrometric chart for the operation of the system  1000  when utilizing 100% return air as the entering air and without using any pre-cooling from any of heat exchangers  1018 ,  1019  and  1020 , but while using post-dehumidification sensible cooling at heat exchanger  1080 . The outside air conditions are the same as denoted in previous examples at data point  2601 , while the return air conditions are as denoted at data point  2602 . The supply air with the conditions of data point  2602  are passed through the processing module  1022  and adjusted to the state denoted at data point  2603  (dry bulb temperature of 72° F., wet bulb temperature of 54° F. and relative humidity 28%). Next the supply air at the discharge side of the processing module  1022  passes through the heat exchanger  1080  at which post-dehumidification sensible cooling is performed to reduce the state of the supply air to the point denoted at data point  2604  (dry bulb temperature of 60° F., wet bulb temperature of 49° F. and relative humidity 42%). 
       FIG. 27  illustrates a psychrometric chart for the operation of the system  1000  when utilizing 100% outside air and no return air at entering air. The psychrometric chart of  FIG. 27  reflects the operation of the system  1000  when performing pre-cooling at each of heat exchangers  1018 ,  1019  and  1020 , and while performing post-dehumidification sensible cooling at heat exchanger  1080 . Beginning at data point  2701 , the conditions of the entering air are changed at heat exchangers  1018 ,  1019  and  1020  as denoted at data point  2702 ,  2703  and  2704 , respectively. The air conditions at the discharge side of heat exchanger  1020  (as denoted at data point  2704 ) are at a humidity saturation point (e.g. 100% relative humidity). The air discharged from heat exchanger  1020  then passes through the processing module  1022  where the condition of the air is changed to the conditions at data point  2705  (60° F. dry bulb temperature, 47° F. wet bulb temperature and 38% relative humidity). The air discharged from the processing module  1022  then passes through the heat exchanger  1080  at which post-dehumidification sensible cooling is performed to change the conditions of the air to the conditions state denoted at data point  2706  (dry bulb temperature of 54° F., wet bulb temperature of 44° F. and relative humidity 42%). 
       FIG. 28  illustrates a psychrometric chart of the operation of the processing module  1000  when using 100% outside air and no return air at the entering air. The psychrometric chart of  FIG. 28  illustrates the configuration of the system  1000  when each of heat exchangers  1018 ,  1019  and  1020  are operated, but while heat exchanger  1080  is turned off and does not perform any post-dehumidification sensible cooling. As shown in  FIG. 28 , the outside air conditions begin at data point  2801  and are changed to correspond to data point  2802 ,  2803  and  2804  when passing through each of the heat exchangers  1018 ,  1019  and  1020 , respectively. The conditions at the downstream side of the heat exchanger  1020  (data point  2804 ) have a dry bulb temperature of 46° F., wet bulb temperature of 46° F. and is saturated along the moisture saturation line. As the air passes through the processing module  1022 , the conditions of the air are changed to the state denoted at data point  2805  (dry bulb temperature of 59° F., wet bulb temperature of 47° F. and relative humidity of 37%). The air conditions at the discharge side of the processing module  1022  remain steady as the air is passed into the conditioned space without any further post-dehumidification sensible cooling. 
       FIG. 29  illustrates a configuration in which the system  1000  utilizes 100% return air as the entering air with no outside air being introduced. In  FIG. 29 , the system  1000  is configured to perform pre-cooling, only utilizing the heat exchanger  1020 , while the heat exchangers  1018  and  1019  are turned off. The system  1000  is also configured in the example of  FIG. 29  to perform post-dehumidification sensible cooling at heat exchanger  1080 . As shown in  FIG. 29  the entering air beings at the conditions denoted at data point  2901  corresponding to the conditions of return air. As the entering air passes through the heat exchanger  1020 , the conditions are changed to the state denoted at data point  2902  (dry bulb temperature of 47° F., wet bulb temperature of 43° F. and relative humidity 80%). As the air passes from the heat exchanger in  1020  through the processing module  1022 , the conditions of the air are changed to the state denoted at data point  2903  (dry bulb temperature of 60° F., wet bulb temperature of 47° F. and relative humidity 27%). As the air passes from the discharge side of the processing module at  1022  through the heat exchanger  1080 , the conditions of the air are changed to the state denoted at data point  2904  (dry bulb temperature of 54° F., wet bulb temperature of 44° F. and relative humidity 43%). 
       FIG. 30  illustrates a psychrometric chart for the operation of the system  1000  when utilizing 50% outside air and 50% return air as the entering air at the mixing box  1035 . Once the desired portions of outside and return air are mixed at the mixing box, the mixed air has the conditions denoted at data point  3001  (dry bulb temperature of 73° F., wet bulb temperature of 64° F. and relative humidity 67%). In the example of  FIG. 30 , the system  1000  utilizes the heat exchangers  1019  and  1020  to perform pre-cooling and turns off the heat exchanger  1080  to perform no post-dehumidification sensible cooling (e.g. without post-dehumidification sensible cooling). The entering air is adjusted from the conditions at data point  3001  to the conditions denoted at data point  3002  and then  3003  as the entering air passes through the heat exchanger  1019  and then  1020 , respectively. The air discharged from the heat exchanger  1020  has a dry bulb temperature of 47° F. and has a saturation moisture content. As the air passes from the heat exchanger  1020  through the pre-processor  1022 , the conditions of the air are adjusted to the state at  3004  (dry bulb temperature of 59° F., wet bulb temperature of 47° F. and relative humidity 38%). 
     The embodiments described herein utilize a pre-processing module in both summer and winter modes for energy recovery. The embodiments further utilize a processing module for both dehumidification in the summer mode and humidification in the winter mode. Additionally, in the winter mode the processing module dehumidifies the return air, by reduction of grains in moisture and an increase in sensible dry bulb temperature, prior to the return air entering the cooling coil in the air source heat pump. The return air is first dehumidified by entering the pre-processing module, where the source air is heated and humidified. The return air is further dehumidified prior to entering the evaporator coil by the processing module. Additionally, as the return air is dehumidified by the processing module, the dry bulb temperature of the return air is increased which increases the efficiency of the heat pump. The evaporator can then run at lower temperatures without freezing the evaporator fins. In winter mode the energy in the return air is used in the reverse air source heat pump cycle. 
     Additionally, in the embodiments described herein, supply air is humidified by both the pre-processing module and the processing module to reduce humidification load requirements and energy consumption for the buildings in the winter mode. The embodiments also provide an efficient air source heat pump for winter heating in lieu of electric, gas, HW, or stream. The return air also provides stable and optimum regenerative air temperatures and conditions for the processing module reactivation in the summer mode. 
       FIG. 31  is a schematic view of another heat pump system  1100  formed in accordance with an embodiment. The system  1100  is configured to condition supply air flowing into a building or space and return air channeled from within the building or space. When in the summer, among other things, the system  1100  dehumidifies the supply air flowing into the building. When in the winter mode, among other things, the system humidifies the supply air flowing into the building. The system  1100  is capable of switching between the summer mode and the winter mode without the need to reconfigure the components of the system  1100 . The system includes a supply air flow path  1102  and a regeneration air flow path  1106 . The supply air flow path  1102  includes return air flow path  1139  that enters the supply air flow path  1102  through a return air inlet  1108 . A portion  1131  of the return air may be discharged through a return air outlet  1130  as exhaust air. Another portion  1133  of the return air enters a mixing box  1135 . The supply air flow path  1102  also includes outside air  1141  that enters an outside air inlet  1137  and mixes with the portion  1133  of the return air to form the supply air. 
     The supply air flows into a supply air heat exchanger  1120 . The supply air heat exchanger  1120  operates as an evaporator coil or cooling coil in the summer mode. As an evaporator coil, the supply air heat exchanger  1120  conditions the air and removes heat from the air to produce saturated air that is discharged into a conditioned air region  1111 . A processing module  1122  is positioned downstream from the conditioned air region  1111 . The saturated air passes through a supply air side  1124  of the processing module  1122  to remove moisture there from and produce supply air that has been further dehumidified and heated. Because the air is first saturated by the supply air heat exchanger  1120 , the efficiency of the processing module  1122  is increased when dehumidifying the air. The dehumidified supply air then flows downstream into a processed air region  1129 . The supply air heat exchanger  1180  also operates as an evaporator coil or cooling coil in the summer mode. From the processed air region  1129 , the dehumidified supply air flows through the second supply air heat exchanger  1180  that further conditions the air and removes heat from the air to produce conditioned supply air. The conditioned air passes from the supply air heat exchanger  1180  to the supply air outlet  1160  and into the space. 
     Regeneration air flow path  1106  includes return air flow path  1139  that enters the regeneration air flow path  1106  through a return air inlet  1108 . A portion  1131  of the return air may be discharged through a return air outlet  1130  as exhaust air. Another portion  1133  of the return air enters a mixing box  1185 . The regeneration air flow path  1106  also includes outside air  1186  that enters an outside air inlet  1103  and mixes with the portion  1133  of the return air to form the regeneration air. 
     The regeneration air flows into a regeneration air heat exchanger  1142 . The regeneration air heat exchanger  1142  operates as a condenser coil in the summer mode to heat and lower a relative humidity of the air. The heat exchanger  1142  uses the heat from the supply air heat exchangers  1120  and  1180  to lower the relative humidity of regeneration air thus increasing the air&#39;s capacity to absorb water downstream. The heated air flows into a conditioned air region  1112 . The lowered relative humidity air in the conditioned air region  1112  is channeled downstream to the regeneration air side  1126  of the processing module  1122 . The lowered relative humidity air passing through the regeneration air side  1126  of the processing module  1122  regenerates the processing module  1122  by receiving moisture from the saturated air in the supply air side  1124  and adding humidity to the regeneration air that flows into a processed air region  1113 . The regeneration air flows from the processed air region  1113  to the second regeneration air heat exchanger  1162 . The second regeneration air heat exchanger  1162  operates as a very efficient condenser coil in the summer mode to dissipate heat from the refrigeration system  1144  in which heat was absorbed by the supply heat exchangers  1120  and  1180 . The regeneration air passes from the regeneration air heat exchanger  1162  into a processed air region  1114 . The regeneration air flows from the processed air region  1114  to the regeneration air outlet  1105 . The regeneration air heat exchangers  1142  and  1162  are fluidly coupled to the supply air heat exchangers  1120  and  1180  by a refrigerant system  1144 . In one embodiment, a compressor  1146  may be provided in the refrigerant system  1144  to condition the refrigerant flowing between the supply air heat exchangers  1120  and  1180 , and the regeneration air heat exchangers  1142  and  1162 . 
     The refrigerant system  1144  includes a node branch  1191  located downstream, along the fluid flow path, from the compressor  1146 . At the node branch  1191 , the fluid path splits along parallel refrigerant branches  1195  and  1196 . The refrigerant branch  1195  extends to and from the heat exchanger  1162  that is located downstream of the process module  1122  in the regeneration air stream, while the refrigerant branch  1196  extends to and from the heat exchanger  1142  that is located upstream of the process module  1122  in the regeneration air stream. Valves  1190  and  1192  permit and inhibit flow of the coolant fluid through one or both of the branches  1195  and  1196 . The outlet of the valve  1192  merges at node  1193  along branch  1197 . Branch  1197  includes a metering device and check valve system  1194  to control a flow of the refrigerant between the supply air heat exchangers  1120  and  1180  and the regeneration air heat exchangers  1142  and  1162 . At the node branch  1178 , the fluid path splits again along parallel refrigerant branches  1164  and  1166 . The refrigerant branch  1164  extends to and from the heat exchanger  1120  that is located upstream of the process module  1122  in the supply air stream, while the refrigerant branch  1166  extends to and from the heat exchanger  1180  that is located downstream of the process module  1122  in the supply air stream. Valves  1176  and  1174  permit and inhibit flow of the coolant fluid through one or both of the branches  1164  and  1166 . The outlet of the valve  1174  merges at node  1168  along branch  1198 . Branch  1198  includes a switch  1199  to permit reversing the flow of the refrigerant through the refrigerant system  1144 . For example, the flow of the refrigerant may be reversed between the summer mode and the winter mode. The valves  1174 ,  1176 ,  1190  and  1192  may be automatically controlled by a controller module. The valves  1174 ,  1176 ,  1190  and  1192  may be adjusted between fully open, fully closed, partially open and partially closed positions to vary the amount of coolant fluid that flows along each of the branches  1164 ,  1166 ,  1195  and  1196 . The valves  1174 ,  1176 ,  1190  and  1192  may be adjusted independently one from the other based upon summer versus winter mode. 
     The heat pump system  1100  includes a refrigerant system  1144  which includes a series of pipes, branches, metering devices, check valves and switching device that fluidly couples the supply air heat exchanger  1120 , the supply air heat exchanger  1180 , the regeneration air heat exchanger  1142  and the regeneration air heat exchanger  1162 . The refrigerant system  1144  pumps a refrigerant between at least one of the supply air heat exchanger  1120  or the supply air exchanger  1180  and at least one of the regeneration air heat exchanger  1142  or the regeneration air heat exchanger  1162 . Alternatively, the refrigerant system  1144  pumps a refrigerant between the supply air heat exchanger  1120  and both the regeneration air heat exchanger  1142  and the regeneration heat exchanger  1162 . Heat exchanger switches  1190  and  1192  controls the flow of refrigerant to the regeneration air heat exchangers  1142  and  1162 . Whereas heat exchanger switches  1174  and  1176  controls the flow of refrigerant to the supply air heat exchangers  1120  and  1180 . In the summer mode, the refrigerant system  1144  pumps cooled refrigerant to at least one of the supply air heat exchanger  1120  or the supply air heat exchanger  1180  to cool the air flowing through the supply air heat exchanger  1120  and/or the supply air heat exchanger  1180 . The cooled refrigerant is heated by the air in at least one of the supply air heat exchangers  1120  or the supply air heat exchanger  1180  to form heated refrigerant. The heated refrigerant flows through the piping to at least one of the regeneration air heat exchanger  1142  or the regeneration air heat exchanger  1162  to heat the air flowing through the regeneration air heat exchanger  1142  and/or the regeneration air heat exchanger  1162 . The refrigerant is cooled by the air in at least one of the regeneration air heat exchanger  1142  or the regeneration air heat exchanger  1162  to form cooled refrigerant that is pumped back to the supply air heat exchangers  1120  and/or  1180 . 
     In the winter mode, the refrigerant system  1144  pumps heated refrigerant to at least one of the supply air heat exchanger  1120  or the supply air heat exchanger  1180  to heat the air flowing through the supply air heat exchanger  1120  and/or the supply air heat exchanger  1180 . The heated refrigerant is cooled by the air in at least one of the supply air heat exchanger  1120  or the supply air heat exchanger  1180  to form cooled refrigerant. The cooled refrigerant flows through the piping to at least one of the regeneration air heat exchanger  1142  or the regeneration air heat exchanger  1162  to cool the air flowing through the regeneration air heat exchanger  1142  and/or the regeneration air heat exchanger  1162 . The refrigerant is heated by the air in at least one of the regeneration air heat exchanger  1142  or the regeneration air heat exchanger  1162  to form heated refrigerant that is pumped back to the supply air heat exchangers  1120  and/or  1180 . 
     The refrigerant system  1144  may include a metering device and check valve system  1194  to control a flow of the refrigerant between the supply air heat exchanger  1120  and/or the supply air heat exchanger  1180  and the regeneration air heat exchanger  1142  and/or the regeneration air heat exchanger  1162 . Additionally, a switch  1199  may be provided to reverse a flow of the refrigerant through the refrigerant system  1144 . For example, the flow of the refrigerant may be reversed when the system  1100  is switched between the summer mode and the winter mode. A compressor  1146  is provided to compress the refrigerant. In the summer mode, the refrigerant passes through the compressor  1146  after exiting the supply air heat exchangers  1120  and/or  1180  and before entering the regeneration air heat exchangers  1142  and/or  1162 . In the winter mode, the refrigerant passes through the compressor  1146  after exiting the regeneration air heat exchangers  1142  and/or  1162  and before entering the supply air heat exchangers  1120  and/or  1180 . 
     In a winter mode, the system  1100  may be configured to humidify and heat the supply air flowing into the building. For example, the supply air heat exchanger  1120  and the supply air heat exchanger  1180  may be reversed in the winter mode to operate as condenser coils. Additionally, the regeneration air heat exchangers  1142  and  1162  may be reversed in the winter mode to operate as evaporator coils. 
       FIGS. 32-43  illustrates psychrometric charts for the system  1100  when operating in various configurations.  FIGS. 32-43  illustrate exemplary data point&#39;s representative of the air condition when passing between designated regions within system  1100 .  FIG. 32  illustrates the system  1100  in the summer mode when using 100% return air as the entering supply air while configured to perform pre-cooling, dehumidification and sensible cooling. In this configuration, the outside air inlet  1137  is closed, the return air outlet  1130  is closed, the mixing box damper  1135  is open, the mixing box damper  1185  is closed and the outside air inlet  1103  is closed such that all the return air through return air inlet  1108  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% outside air.  FIG. 32  illustrates return air at data point  3202  with a dry bulb temperature of 75° F., a wet bulb temperature of approximately 63° F. and a relative humidity of approximately 50%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the return air is changed to data point  3203  (dry bulb temperature of 52° F., wet bulb temperature of 52° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3204  (dry bulb temperature of 66° F., wet bulb temperature of 54° F. and 45% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  3205  and supplied to the controlled space (dry bulb temperature of 61° F., wet bulb temperature of 52° F. and relative humidity 55%). The heat exchanger  1180  performs sensible cooling only without changing the humidity of the supply air. The regeneration air is also illustrated in  FIG. 32 , where outside air at data point  3201  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3206  (dry bulb temperature of 103° F., wet bulb temperature of 76° F. and 30% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3207  (dry bulb temperature of 88° F., wet bulb temperature of 74° F. and 53% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3208  and discharges to ambient (dry bulb temperature of 112° F., wet bulb temperature of 81° F. and relative humidity 27%). Because the heat absorbed in the refrigeration system is released in two separate condenser coils, with the second condenser coil located after the processing module  1122  where the temperature is reduced this substantially improves the performance of the refrigeration system  1144  because operation discharge pressures are lowered. 
       FIG. 33  illustrates the system  1100  in the summer mode when using 100% return air as the entering supply air while configured to perform pre-cooling, dehumidification and no post-dehumidification sensible cooling. In this configuration, the outside air inlet  1137  is closed, the return air outlet  1130  is closed, the mixing box damper  1135  is open, the mixing box damper  1185  is closed and the outside air inlet  1103  is closed such that all the return air through return air inlet  1108  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% outside air.  FIG. 33  illustrates return air at data point  3302  with a dry bulb temperature of 75° F., a wet bulb temperature of approximately 63° F. and a relative humidity of approximately 50%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the return air is changed to data point  3303  (dry bulb temperature of 49° F., wet bulb temperature of 49° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3304  (dry bulb temperature of 63° F., wet bulb temperature of 51° F. and 45% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 33 , where outside air at data point  3301  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3306  (dry bulb temperature of 103° F., wet bulb temperature of 76° F. and 30% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3307  (dry bulb temperature of 88° F., wet bulb temperature of 74° F. and 53% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3308  and discharges to ambient (dry bulb temperature of 112° F., wet bulb temperature of 81° F. and relative humidity 27%). Because the heat absorbed in the refrigeration system is released in two separate condenser coils, with the second condenser coil located after the processing module  1122  where the temperature is reduced this substantially improves the performance of the refrigeration system  1144  because operation discharge pressures are lowered. 
       FIG. 34  illustrates the system  1100  in the summer mode when using 50% return air and 50% outside air as the mixed entering supply air while the system is configured to perform pre-cooling, dehumidification and post-dehumidification sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is closed, the mixing box damper  1135  is half open, the mixing box damper  1185  is half open and the outside air inlet  1103  is open such that both the supply air and the regeneration is comprised of 50% return air and 50% outside air. Once the desired portions of outside and return air are mixed at the mixing boxes, the mixed air has the conditions denoted at data point  3409  (dry bulb temperature of 77° F., wet bulb temperature of 66° F. and relative humidity 57%). As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the air is changed to data point  3403  (dry bulb temperature of 54° F., wet bulb temperature of 54° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3404  (dry bulb temperature of 68° F., wet bulb temperature of 55° F. and 43% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  3405  and supplied to the controlled space (dry bulb temperature of 63° F., wet bulb temperature of 53° F. and relative humidity 52%). The heat exchanger  1180  performs sensible cooling only without changing the humidity of the supply air. The regeneration air is also illustrated in  FIG. 34 , where the mixed regeneration air at data point  3409  with a dry bulb temperature of 77° F., a wet bulb temperature of approximately 66° F. and a relative humidity of approximately 57%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3406  (dry bulb temperature of 100° F., wet bulb temperature of 73° F. and 25% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3407  (dry bulb temperature of 85° F., wet bulb temperature of 71° F. and 52% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3408  and discharges to ambient (dry bulb temperature of 108° F., wet bulb temperature of 78° F. and relative humidity 32%). 
       FIG. 35  illustrates the system  1100  in the summer mode when using 50% return air and 50% outside air as the mixed entering supply air while the system is configured to perform pre-cooling, dehumidification and no post-dehumidification sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is closed, the mixing box damper  1135  is half open, the mixing box damper  1185  is half open and the outside air inlet  1103  is open such that both the supply air and the regeneration is comprised of 50% return air and 50% outside air. Once the desired portions of outside and return air are mixed at the mixing boxes, the mixed air has the conditions denoted at data point  3509  (dry bulb temperature 77° F., wet bulb temperature 66° F. and relative humidity 57%). As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the air is changed to data point  3503  (dry bulb temperature of 51° F., wet bulb temperature of 51° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3504  (dry bulb temperature of 66° F., wet bulb temperature of 54° F. and 43% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 35 , where the mixed regeneration air at data point  3509  with a dry bulb temperature of 77° F., a wet bulb temperature of approximately 66° F. and a relative humidity of approximately 57%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3506  (dry bulb temperature of 100° F., wet bulb temperature of 73° F. and 25% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3507  (dry bulb temperature of 85° F., wet bulb temperature of 71° F. and 52% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3508  and discharges to ambient (dry bulb temperature of 108° F., wet bulb temperature of 78° F. and relative humidity 32%). 
       FIG. 36  illustrates the system  1100  in the summer mode when using 100% outside air as the entering supply air while configured to perform pre-cooling, dehumidification and sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is close, the mixing box damper  1135  is close, the mixing box damper  1185  is close and the outside air inlet  1103  is close such that all the outside air through supply air inlet  1137  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% return air.  FIG. 36  illustrates outside air at data point  3601  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  3603  (dry bulb temperature of 56° F., wet bulb temperature of 56° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3604  (dry bulb temperature of 72° F., wet bulb temperature of 57° F. and 40% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  3605  and supplied to the controlled space (dry bulb temperature of 66° F., wet bulb temperature of 55° F. and relative humidity 50%). The heat exchanger  1180  performs sensible cooling only without changing the humidity of the supply air. The regeneration air is also illustrated in  FIG. 36 , where return air at data point  3602  with a dry bulb temperature of 75° F., a wet bulb temperature of approximately 62° F. and a relative humidity of approximately 50%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3606  (dry bulb temperature of 98° F., wet bulb temperature of 69° F. and 28% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3607  (dry bulb temperature of 82° F., wet bulb temperature of 68° F. and 50% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3608  and discharges to ambient (dry bulb temperature of 105° F., wet bulb temperature of 75° F. and relative humidity 25%). Because the regeneration air is 100% return air (which is typically drier then the outside air in the summer) the system  1100  is able to improve the performance of the processing module to extract additional moisture from the supply air stream and further dry the supply air in the summer mode. The performance of the refrigeration system is also improved as the discharge pressures are lowered. 
       FIG. 37  illustrates the system  1100  in the summer mode when using 100% outside air as the entering supply air while configured to perform pre-cooling, dehumidification and no post dehumidification sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is close, the mixing box damper  1135  is close, the mixing box damper  1185  is close and the outside air inlet  1103  is close such that all the outside air through supply air inlet  1137  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% return air.  FIG. 37  illustrates outside air at data point  3701  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  3703  (dry bulb temperature of 55° F., wet bulb temperature of 55° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3704  (dry bulb temperature of 70° F., wet bulb temperature of 57° F. and 42% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 37 , where return air at data point  3702  with a dry bulb temperature of 75° F., a wet bulb temperature of approximately 62° F. and a relative humidity of approximately 50%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3706  (dry bulb temperature of 98° F., wet bulb temperature of 70° F. and 28% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3707  (dry bulb temperature of 82° F., wet bulb temperature of 68° F. and 50% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3708  and discharges to ambient (dry bulb temperature of 105° F., wet bulb temperature of 75° F. and relative humidity 25%). Because the regeneration air is 100% return air (which is typically drier then the outside air in the summer) the system  1100  is able to improve the performance of the processing module to extract additional moisture from the supply air stream and further dry the supply air in the summer mode. The performance of the refrigeration system is also improved as the discharge pressures are lowered. 
       FIG. 38  illustrates the system  1100  in the winter mode when using 100% return air as the entering supply air while configured to perform pre-heating, humidification and post sensible heating. In this configuration, the outside air inlet  1137  is closed, the return air outlet  1130  is closed, the mixing box damper  1135  is open, the mixing box damper  1185  is closed and the outside air inlet  1103  is closed such that all the return air through return air inlet  1108  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% outside air.  FIG. 38  illustrates return air at data point  3802  with a dry bulb temperature of 70° F., a wet bulb temperature of approximately 53° F. and a relative humidity of approximately 30%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the return air is changed to data point  3803  (dry bulb temperature of 92° F., wet bulb temperature of 62° F. and 15% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3804  (dry bulb temperature of 77° F., wet bulb temperature of 59° F. and 33% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  3805  and supplied to the controlled space (dry bulb temperature of 100° F., wet bulb temperature of 67° F. and relative humidity 16%). The heat exchanger  1180  performs post sensible heating. The regeneration air is also illustrated in  FIG. 38 , where outside air at data point  3801  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 37° F. and a relative humidity of approximately 40%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3806  (dry bulb temperature of 26° F., wet bulb temperature of 25° F. and 90% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3807  (dry bulb temperature of 41° F., wet bulb temperature of 31° F. and 28% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3808  and discharges to ambient (dry bulb temperature of 23° F., wet bulb temperature of 20° F. and relative humidity 60%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. 
       FIG. 39  illustrates the system  1100  in the winter mode when using 100% return air as the entering supply air while configured to perform pre-heating, humidification and no post sensible heating. In this configuration, the outside air inlet  1137  is closed, the return air outlet  1130  is closed, the mixing box damper  1135  is open, the mixing box damper  1185  is closed and the outside air inlet  1103  is closed such that all the return air through return air inlet  1108  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% outside air.  FIG. 39  illustrates return air at data point  3902  with a dry bulb temperature of 70° F., a wet bulb temperature of approximately 53° F. and a relative humidity of approximately 30%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the return air is changed to data point  3903  (dry bulb temperature of 105° F., wet bulb temperature of 66° F. and 9% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3904  (dry bulb temperature of 87° F., wet bulb temperature of 63° F. and 25% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 39 , where outside air at data point  3901  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 37° F. and a relative humidity of approximately 40%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  3906  (dry bulb temperature of 26° F., wet bulb temperature of 25° F. and 90% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  3907  (dry bulb temperature of 45° F., wet bulb temperature of 32° F. and 20% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  3908  and discharges to ambient (dry bulb temperature of 26° F., wet bulb temperature of 21° F. and relative humidity 45%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Furthermore, because the refrigeration system  1144  includes heat exchanger switches  1174  and  1176  that control the flow of refrigerant independently to the supply air heat exchangers  1120  and  1180  this allows to the system to control the space sensible load independently from the latent load. 
       FIG. 40  illustrates the system  1100  in the winter mode when using 50% return air and 50% outside air as the mixed entering supply air while the system is configured to perform pre-heating, humidification and post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is closed, the mixing box damper  1135  is half open, the mixing box damper  1185  is half open and the outside air inlet  1103  is open such that both the supply air and the regeneration is comprised of 50% return air and 50% outside air. Once the desired portions of outside and return air are mixed at the mixing boxes, the mixed air has the conditions denoted at data point  4009  (dry bulb temperature of 57° F., wet bulb temperature of 45° F. and relative humidity 37%). As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the air is changed to data point  4003  (dry bulb temperature of 80° F., wet bulb temperature of 55° F. and 17% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4004  (dry bulb temperature of 68° F., wet bulb temperature of 53° F. and 36% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  4005  and supplied to the controlled space (dry bulb temperature of 90° F., wet bulb temperature of 61° F. and relative humidity 17%). The heat exchanger  1180  performs sensible heating. The regeneration air is also illustrated in  FIG. 40 , where the mixed regeneration air at data point  4009  with a dry bulb temperature of 57° F., a wet bulb temperature of approximately 45° F. and a relative humidity of approximately 37%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4006  (dry bulb temperature of 38° F., wet bulb temperature of 35° F. and 70% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4007  (dry bulb temperature of 51° F., wet bulb temperature of 38° F. and 24% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4008  and discharges to ambient (dry bulb temperature of 32° F., wet bulb temperature of 26° F. and relative humidity 50%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. 
       FIG. 41  illustrates the system  1100  in the winter mode when using 50% return air and 50% outside air as the mixed entering supply air while the system is configured to perform pre-heating, humidification and no post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is closed, the mixing box damper  1135  is half open, the mixing box damper  1185  is half open and the outside air inlet  1103  is open such that both the supply air and the regeneration is comprised of 50% return air and 50% outside air. Once the desired portions of outside and return air are mixed at the mixing boxes, the mixed air has the conditions denoted at data point  4109  (dry bulb temperature of 57° F., wet bulb temperature of 45° F. and relative humidity 37%). As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the air is changed to data point  4103  (dry bulb temperature of 92° F., wet bulb temperature of 60° F. and 12% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4104  (dry bulb temperature of 77° F., wet bulb temperature of 52° F. and 28% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 41 , where the mixed regeneration air at data point  4109  with a dry bulb temperature of 57° F., a wet bulb temperature of approximately 45° F. and a relative humidity of approximately 37%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4106  (dry bulb temperature of 38° F., wet bulb temperature of 35° F. and 70% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4107  (dry bulb temperature of 55° F., wet bulb temperature of 39° F. and 17% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4108  and discharges to ambient (dry bulb temperature of 36° F., wet bulb temperature of 28° F. and relative humidity 38%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Furthermore, because the refrigeration system  1144  includes heat exchanger switches  1174  and  1176  that control the flow of refrigerant independently to the supply air heat exchangers  1120  and  1180  this allows to the system to control the space sensible load independently from the latent load. 
       FIG. 42  illustrates the system  1100  in the winter mode when using 100% outside air as the entering supply air while configured to perform pre-heating, humidification and post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is close, the mixing box damper  1135  is close, the mixing box damper  1185  is close and the outside air inlet  1103  is close such that all the outside air through supply air inlet  1137  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% return air.  FIG. 42  illustrates outside air at data point  4201  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4203  (dry bulb temperature of 67° F., wet bulb temperature of 48° F. and 18% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4204  (dry bulb temperature of 59° F., wet bulb temperature of 47° F. and 38% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  4205  and supplied to the controlled space (dry bulb temperature of 82° F., wet bulb temperature of 56° F. and relative humidity 17%). The heat exchanger  1180  performs post sensible heating. The regeneration air is also illustrated in  FIG. 42 , where return air at data point  4202  with a dry bulb temperature of 70° F., a wet bulb temperature of approximately 53° F. and a relative humidity of approximately 30%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4206  (dry bulb temperature of 52° F., wet bulb temperature of 45° F. and 58% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4207  (dry bulb temperature of 60° F., wet bulb temperature of 45° F. and 30% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4208  and discharges to ambient (dry bulb temperature of 41° F., wet bulb temperature of 36° F. and relative humidity 60%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Furthermore, the system utilizes return air from the space to regenerate the processing module improving yet further the overall performance of system  1100 . 
       FIG. 43  illustrates the system  1100  in the winter mode when using 100% outside air as the entering supply air while configured to perform pre-heating, humidification and no post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is close, the mixing box damper  1135  is close, the mixing box damper  1185  is close and the outside air inlet  1103  is close such that all the outside air through supply air inlet  1137  provides all of the supply air. Correspondingly the entering regeneration air is comprised of 100% return air.  FIG. 43  illustrates outside air at data point  4301  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4303  (dry bulb temperature of 88° F., wet bulb temperature of 56° F. and 9% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4304  (dry bulb temperature of 73° F., wet bulb temperature of 54° F. and 28% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The heat exchanger  1180  performs no post sensible heating. The regeneration air is also illustrated in  FIG. 43 , where return air at data point  4302  with a dry bulb temperature of 70° F., a wet bulb temperature of approximately 53° F. and a relative humidity of approximately 30%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4306  (dry bulb temperature of 52° F., wet bulb temperature of 45° F. and 58% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4307  (dry bulb temperature of 66° F., wet bulb temperature of 47° F. and 18% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4308  and discharges to ambient (dry bulb temperature of 48° F., wet bulb temperature of 37° F. and relative humidity 35%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Additionally, because the refrigeration system  1144  includes heat exchanger switches  1174  and  1176  that control the flow of refrigerant independently to the supply air heat exchangers  1120  and  1180  this allows to the system to control the space sensible load independently from the latent load. Furthermore, the system utilizes return air from the space to regenerate the processing module improving yet further the overall performance of system  1100 . 
     In one embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , the mixing boxes  1135  and/or  1185  to achieve a pre-determined dehumidification in the summer mode and pre-determined humidification in a winter mode. 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , the mixing boxes  1135  and/or  1185  to achieve a pre-determined performance of the system  1100 . 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or return air from the space to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , the mixing boxes  1135  and/or  1185  to limit frost formation in the regeneration air heat exchangers  1142  and/or  1162  in the winter mode. 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of a supply air stream or a return air stream to control the output of at least one of a single compressor or variable compressor to limit frost formation in the regeneration heat exchangers  1142  and/or  1162  in winter mode. 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of a supply air stream or a return air stream to control the output of at least one of a single compressor or variable compressor to achieve a pre-determined performance of the system  1100 . 
     In another embodiment, the heat pump system  1100  is used for conditioning air supplied to a space. The system includes conditioning supply air with a processing module. The system also includes at least one of heating or cooling the air prior to or after the processing module with one or more supply air heat exchangers in flow communication with the processing module. The system  1100  also includes at least one heat exchanger switch in flow communication with the supply air heat exchangers that is fluidly coupled to a refrigerant system and a control system that allows the space sensible load and latent load to be maintained independently. 
     In another embodiment, the heat pump system  1100  described herein utilizes a plurality of heat exchangers and a refrigeration system in both summer and winter modes for energy recovery. The embodiment further utilizes a plurality of heat exchanger switches to control the flow of cold and hot refrigerant in the refrigeration system. Additionally, as the return air is dehumidified by the processing module, the dry bulb temperature of the return air is increased which increases the efficiency of the heat pump. The evaporator can then run at lower temperatures without freezing the evaporator fins. In winter mode the energy in the return air is used in the reverse air source heat pump cycle. 
     In another embodiment, the heat pump system  1100  described herein, supply air is humidified by the processing module to reduce humidification load requirements and energy consumption for the buildings in the winter mode. The embodiments also provide an efficient air source heat pump for winter heating in lieu of electric, gas, HW, or stream. The return air also provides stable and optimum regenerative air temperatures and conditions for the processing module reactivation in both the summer and winter mode. 
       FIG. 44  is a schematic view of an alternative embodiment of the heat pump system  1100 . In  FIG. 31 , the return air flow path  1139  is configured to flow in either one of or both mixing box dampers  1135  and/or  1185  depending on the different operation mode of system  1100  to form the portion of the return air flow path  1133 . In  FIG. 44 , the portion return air flow paths  1133  are none existent. Accordingly, the return air flow path  1139  is configured to flow completely through the return air opening  1130  forming the exhaust air flow path  1131 . In  FIG. 31 , the mixing box damper  1135  and/or mixing box damper  1185  can be open, whereas in  FIG. 44  both the mixing box dampers  1135  and  1185  are closed. In  FIG. 44 , both the outside air inlet  1137  and outside air inlet  1103  are fully open providing 100% outside air to both the supply air flow path  1102  and the regeneration air flow path  1106 . Providing 100% outside air to both the supply air flow path  1102  and the regeneration air flow path  1106  may improve the transfer of heat and moisture between the supply air side  1124  and the regeneration air side  1126  of the processing module  1122 . Additionally, providing 100% outside air to both the supply air flow path  1102  and the regeneration air flow path  1106  may improve the coefficient of performance (COP) of the system as the suction pressure may be increased and the discharge pressure may be decreased. Furthermore, because the refrigeration system  1144  includes and switch  1199 , heat exchanger switches  1174 ,  1176 ,  1190  and  1192  that are all in flow communication with compressor  1146  as well as heat exchangers  1120 ,  1180 ,  1142  and  1162  positioned on the upstream side and downstream side of the processing module  1122  also in flow communication with compressor  1146  the overall system  1100  can be controlled very efficiently to maintain building heating, cooling, humidification and dehumidification loads through the year. While it is preferred in most instances to include a return air flow path, it is also understood that system  1100  in  FIG. 44  may not contain a return air inlet  1108 , return air flow path  1139 , a return air outlet  1130 , an exhaust air flow path  1131  and mixing boxes  1135  and  1185  and system  1100  would still function as described herein. 
       FIGS. 45-48  illustrates psychrometric charts for the system  1100  when operating in various configurations.  FIGS. 45-48  illustrate exemplary data point&#39;s representative of the air condition when passing between designated regions within system  1100 .  FIG. 45  illustrates the system  1100  in the summer mode when using 100% outside air as the entering supply air while configured to perform pre-cooling, dehumidification and sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is open, the mixing box damper  1135  is close, the mixing box damper  1185  is closed and the outside air inlet  1103  is open such that all the outside air through outside air inlet  1137  provides all of the supply air and all the outside air through outside air inlet  1103  provides all of the regeneration air.  FIG. 45  illustrates outside air at data point  4501  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4503  (dry bulb temperature of 56° F., wet bulb temperature of 56° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4504  (dry bulb temperature of 71° F., wet bulb temperature of 58° F. and 47% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  4505  and supplied to the controlled space (dry bulb temperature of 65° F., wet bulb temperature of 56° F. and relative humidity 56%). The heat exchanger  1180  performs sensible cooling only without changing the humidity of the supply air. The regeneration air is also illustrated in  FIG. 45 , where outside air at data point  4501  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4506  (dry bulb temperature of 103° F., wet bulb temperature of 76° F. and 30% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4507  (dry bulb temperature of 88° F., wet bulb temperature of 75° F. and 53% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4508  and discharges to ambient (dry bulb temperature of 115° F., wet bulb temperature of 81.5° F. and relative humidity 24%). Because the heat absorbed in the refrigeration system is released in two separate condenser coils, with the second condenser coil located after the processing module  1122  where the temperature is reduced this substantially improves the performance of the refrigeration system  1144  because operation discharge pressures are lowered. Furthermore, since the supply heat exchanger  1180  is active the sensible load and latent load of the space can be maintained independently. 
       FIG. 46  illustrates the system  1100  in the summer mode when using 100% outside air as the entering supply air while configured to perform pre-cooling, dehumidification and no post-sensible cooling. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is open, the mixing box damper  1135  is close, the mixing box damper  1185  is closed and the outside air inlet  1103  is open such that all the outside air through outside air inlet  1137  provides all of the supply air and all the outside air through outside air inlet  1103  provides all of the regeneration air.  FIG. 46  illustrates outside air at data point  4601  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4603  (dry bulb temperature of 55° F., wet bulb temperature of 55° F. and 100% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4604  (dry bulb temperature of 70° F., wet bulb temperature of 57° F. and 43% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The regeneration air is also illustrated in  FIG. 46 , where outside air at data point  4601  with a dry bulb temperature of 80° F., a wet bulb temperature of approximately 70° F. and a relative humidity of approximately 60%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4606  (dry bulb temperature of 105° F., wet bulb temperature of 77° F. and 28% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4607  (dry bulb temperature of 89° F., wet bulb temperature of 75° F. and 52% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4608  and discharges to ambient (dry bulb temperature of 115° F., wet bulb temperature of 81.5° F. and relative humidity 24%). Because the heat absorbed in the refrigeration system is released in two separate condenser coils, with the second condenser coil located after the processing module  1122  where the temperature is reduced this substantially improves the performance of the refrigeration system  1144  because operation discharge pressures are lowered. Furthermore, since the supply heat exchanger  1180  is inactive the sensible load and latent load of the space can be maintained independently. 
       FIG. 47  illustrates the system  1100  in the winter mode when using 100% outside air as the entering supply air while configured to perform pre-heating, humidification and post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is open, the mixing box damper  1135  is close, the mixing box damper  1185  is closed and the outside air inlet  1103  is open such that all the outside air through outside air inlet  1137  provides all of the supply air and all the outside air through outside air inlet  1103  provides all of the regeneration air.  FIG. 47  illustrates outside air at data point  4701  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4703  (dry bulb temperature of 68° F., wet bulb temperature of 48° F. and 18% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4704  (dry bulb temperature of 57° F., wet bulb temperature of 46° F. and 40% relative humidity). As the air passes through the active supply air heat exchanger  1180 , the conditions are further changed to data point  4705  and supplied to the controlled space (dry bulb temperature of 81° F., wet bulb temperature of 56° F. and relative humidity 18%). The heat exchanger  1180  performs post sensible heating. The regeneration air is also illustrated in  FIG. 47 , where outside air at data point  4701  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4706  (dry bulb temperature of 26° F., wet bulb temperature of 25° F. and 85% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4707  (dry bulb temperature of 37° F., wet bulb temperature of 29° F. and 35% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4708  and discharges to ambient (dry bulb temperature of 18° F., wet bulb temperature of 17° F. and relative humidity 90%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Furthermore, because the refrigeration system  1144  includes heat exchanger switches  1174  and  1176  that control the flow of refrigerant independently to the supply air heat exchangers  1120  and  1180  the sensible load and latent load of the space can be maintained independently. 
       FIG. 48  illustrates the system  1100  in the winter mode when using 100% outside air as the entering supply air while configured to perform pre-heating, humidification and no post-sensible heating. In this configuration, the outside air inlet  1137  is open, the return air outlet  1130  is open, the mixing box damper  1135  is close, the mixing box damper  1185  is closed and the outside air inlet  1103  is open such that all the outside air through outside air inlet  1137  provides all of the supply air and all the outside air through outside air inlet  1103  provides all of the regeneration air.  FIG. 48  illustrates outside air at data point  4801  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the supply air passes through the active supply air heat exchanger  1120 , the humidity and temperature of the outside air is changed to data point  4803  (dry bulb temperature of 88° F., wet bulb temperature of 56° F. and 9% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4804  (dry bulb temperature of 72° F., wet bulb temperature of 54° F. and 28% relative humidity). As the air passes through the inactive supply air heat exchanger  1180 , the supply air conditions are unchanged. The heat exchanger  1180  performs no post-sensible heating. The regeneration air is also illustrated in  FIG. 48 , where outside air at data point  4801  with a dry bulb temperature of 45° F., a wet bulb temperature of approximately 36° F. and a relative humidity of approximately 40%. As the regeneration air passes through the active regeneration air heat exchanger  1142 , the humidity and temperature of the regeneration air is changed to data point  4806  (dry bulb temperature of 26° F., wet bulb temperature of 25° F. and 85% relative humidity), and as the air passes through the processing module  1122 , the air conditions are adjusted to data point  4807  (dry bulb temperature of 43° F., wet bulb temperature of 30° F. and 22% relative humidity). As the air passes through the second active regeneration air heat exchanger  1162 , the conditions are further changed to data point  4808  and discharges to ambient (dry bulb temperature of 24° F., wet bulb temperature of 19° F. and relative humidity 50%). Because the refrigeration system  1144  includes heat exchanger switches  1190  and  1192  that control the flow of refrigerant independently to the regeneration air heat exchangers  1142  and  1162  this improved the performance of the processing module  1122  to absorb moisture and heat the regeneration air stream thus substantially improving the performance of the refrigeration system  1144  because the suction pressures are higher, improving the coefficient of performance (COP) of the system. Additionally the processing module offsets humidification load requirement in the space. Furthermore, because the refrigeration system  1144  includes heat exchanger switches  1174  and  1176  that control the flow of refrigerant independently to the supply air heat exchangers  1120  and  1180  the sensible load and latent load of the space can be maintained independently. 
     In one embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or regeneration air to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , to achieve a pre-determined dehumidification in the summer mode and pre-determined humidification in a winter mode. 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or regeneration air to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , to achieve a pre-determined performance of the system  1100 . 
     In another embodiment, the heat pump system  1100  senses a condition of at least one of the supply air or regeneration air to control an output of at least one of the supply air heat exchangers  1120  and/or  1180 , the supply heat exchanger switches  1174  and/or  1176 , the regeneration air heat exchangers  1142  and/or  1162 , the regeneration heat exchanger switches  1190  and/or  1192 , the processing module  1122 , to limit frost formation in the regeneration air heat exchangers  1142  and/or  1162  in the winter mode. 
     In another embodiment, the heat pump system  1100  is used for conditioning air supplied to a space. The system includes conditioning supply air with a processing module using only outside air. The system also includes at least one of heating or cooling the air prior to or after the processing module with one or more supply air heat exchangers in flow communication with the processing module. The system  1100  also includes at least one heat exchanger switch in flow communication with the supply air heat exchangers that is fluidly coupled to a refrigerant system and a control system that allows the space sensible load and latent load to be maintained independently. 
     In another embodiment, the heat pump system  1100  described herein utilizes a plurality of heat exchangers and a refrigeration system in both summer and winter modes for energy recovery. The embodiment further utilizes a plurality of heat exchanger switches to control the flow of cold and hot refrigerant in the refrigeration system. Additionally, as the outside air is dehumidified by the processing module, the dry bulb temperature of the outside air is increased which increases the efficiency of the heat pump. The evaporator can then run at lower temperatures without freezing the evaporator fins. In winter mode the energy in the outside air is used in the reverse air source heat pump cycle. 
     In another embodiment, the system  1100  may include at least one fan to draw air into and move air through the supply air flow path  1102 . Outside air flows through the supply air inlet  1137  and through supply heat exchanger  1120 , a pre-processing module  1122  positioned downstream of the supply air inlet  1137 . 
     In another embodiment additional compressors, additional refrigerant systems, pre-cooling, pre-heating supply heat exchangers and energy recovery devices (not shown) can be added to system  1100  further performance of the system. 
     In another embodiment, the heat pump system  1100  described herein, supply air is humidified by the processing module to reduce humidification load requirements and energy consumption for the buildings in the winter mode while using only outside air. The embodiments also provide an efficient air source heat pump for winter heating in lieu of electric, gas, HW, or stream. 
       FIG. 49  is a schematic view of another heat pump system  600  formed in accordance with an embodiment capable of operating in a summer mode or a winter mode. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments of the invention without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments of the invention, the embodiments are by no means limiting and are exemplary embodiments. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. 
     This written description uses examples to disclose the various embodiments of the invention, including the best mode, and also to enable any person skilled in the art to practice the various embodiments of the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the various embodiments of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if the examples have structural elements that do not differ from the literal language of the claims, or if the examples include equivalent structural elements with insubstantial differences from the literal languages of the claims.