Abstract:
A service valve assembly that is designed to minimize leakage by reducing the number of leakage paths from the valve assembly. In addition, the service valve assembly is designed to permit connection to many different refrigeration systems and has higher flow capacity. The valve assembly is engageable by current servicing tools so that purchase of new service tools is not required. In the valve assembly, the service connection is designed as part of the shut-off valve and communicates with the condenser side port. Therefore, initial processing through the condenser side port and subsequent processing through the evaporation side port occur through the combined service connection and shut-off valve structure. Once installed, the described valve assembly has one leak path versus two leak paths in known valve assemblies.

Description:
[0001]    This application is a Continuation of application Ser. No. 12/985,598 filed on Jan. 6, 2011, which claims the benefit of U.S. Provisional Application Ser. No. 61/299425, filed on Jan. 29, 2010, which applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    A service valve assembly is described for use in a refrigeration system that includes a condenser unit and an evaporation unit located away from the condenser unit. 
       BACKGROUND 
       [0003]    In certain refrigeration systems, for example a split system air conditioning unit, a service valve assembly is used to provide access to various parts of the system during manufacture as well as after installation of the system. A split system air conditioning unit is a unit that has the condenser unit mounted in a different location than the evaporation unit. The central air conditioning system in most homes is an example of a split system, with the condenser unit located outside of the home, and the evaporation unit located in the furnace. 
         [0004]      FIG. 1  illustrates a conventional service valve assembly  2  that has a housing  4 , a condenser side port  6 , and an evaporation side port  8 . A piston  10  is disposed inside the housing and is used to isolate the condenser side of the refrigeration system or allow a flow path between the evaporation side and the condenser side. A removable cap  12  is secured to the housing  4  and is removed to provide access to the piston  10  so the piston can be rotated to change the position of the piston in the housing between the isolation position shown in  FIG. 1  to a position permitting flow between the evaporation side and the condenser side. An access valve  14  provides access to the interior of the housing  4  for use in servicing the refrigeration system to which the assembly  2  is connected. 
         [0005]    In typical use, the condenser side port  6  of the valve assembly  2  is connected to the condenser unit at the factory. The piston  10  is actuated outward to provide a flow path between the evaporation side and the condenser side. The manufacturer will attach to the evaporation side port  8  using suitable tooling and test for leaks, evacuate the system of air/contaminants, and charge with refrigerant. The piston  10  is then closed to isolate the condenser side and the tooling is removed. Processing can occur through the access valve  14 , but it is more typical to process through the evaporation side port  8 . Once the system is ready for installation, the evaporation side port  8  is connected to the evaporation coil. The installer and downstream service personnel can then attach servicing tools to the access valve  14  to evacuate the system or perform other servicing functions, and the piston  10  opened again to allow the flow of refrigerant between the condenser and evaporator side. 
       SUMMARY 
       [0006]    A service valve assembly is described that is designed to minimize leakage by reducing the number of leakage paths from the valve assembly. In addition, the service valve assembly is designed to permit connection to many different refrigeration systems and has higher flow capacity. The valve assembly is engageable by current field tools so that purchase of new service tools is not required. 
         [0007]    In the described valve assembly, the service connection is designed as part of the shut-off valve and has a default configuration that communicates with the condenser side port. Therefore, initial processing through the condenser side port and subsequent processing through the evaporation side port occur through the combined service connection and shut-off valve structure. Once installed, the described valve assembly has one leak path versus two leak paths in the valve assembly shown in  FIG. 1 . 
         [0008]    In one embodiment, a service valve assembly is provided for a refrigeration system that includes a condenser unit and an evaporation unit. The valve assembly includes a housing having a passageway, a condenser side port in communication with the passageway for connection to the condenser unit, an evaporation side port in communication with the passageway for connection to the evaporation unit, and a service port in communication with the passageway. A valve unit is disposed within the passageway of the housing. The valve unit includes a shut-off valve and a control valve, where the shut-off valve controls flow through the housing and has a first position that permits flow communication between the condenser side port and the service port, and a second position that prevents flow communication between the condenser side port and the evaporation side port and the service port but permits flow communication between the evaporation side port and the service port. The control valve controls flow through the service port and has a first position preventing flow past the control valve and thereby preventing flow through the service port, and a second position that permits flow past the control valve and thereby permits flow through the service port. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a conventional service valve assembly. 
           [0010]      FIG. 2  is a perspective, partial cross-sectional view of the service valve assembly described in the detailed description. 
           [0011]      FIG. 3  is a close-up view of a portion of the service valve assembly shown in  FIG. 2 . 
           [0012]      FIG. 4  is a view similar to  FIG. 2  but with the cap removed. 
           [0013]      FIG. 5  is a cross-sectional view of the service valve assembly of  FIG. 2  with the shut-off valve open and the control valve open to the condenser side. 
           [0014]      FIG. 6  is a view similar to  FIG. 5  but with the shut-off valve closed and the control valve closed. 
           [0015]      FIG. 7  is a view similar to  FIG. 6  but with the control valve opened. 
           [0016]      FIG. 8  is a view similar to  FIG. 5  showing to flow path between the condenser side port and the evaporation side port. 
           [0017]      FIG. 9  is a view similar to  FIG. 8  but showing the cap. 
           [0018]      FIG. 10  is a view of an alternative embodiment of a service valve assembly with the shut-off valve open and the control valve open. 
           [0019]      FIG. 11  is a view similar to  FIG. 10  but with the shut-off valve closed and the control valve closed. 
           [0020]      FIG. 12  is a view similar to  FIG. 10  with the shut-off valve open and the control valve closed. 
           [0021]      FIG. 13  is a view of an alternative embodiment of a service valve assembly with the shut-off valve open and the control valve open. 
           [0022]      FIG. 14  is a view similar to  FIG. 13  but with the control valve closed. 
           [0023]      FIG. 15  is a view similar to  FIG. 13  with the shut-off valve at a second position and the control valve open. 
           [0024]      FIG. 16  is a view similar to  FIG. 13  showing a flow path between the condenser side port and the evaporation side port and the control valve closed. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    With reference initially to  FIGS. 2-4 , a service valve assembly  20  that incorporates the concepts described herein is illustrated. The service valve assembly  20  will be described in this application as being used in a split system refrigeration unit that includes a condenser unit mounted in a separate location that the evaporation unit. Examples of refrigeration systems in which the concepts described herein can be used include, but are not limited to, an air conditioning system or a refrigerator for foodstuffs. The concepts described herein can be used on other types of split systems as well. 
         [0026]    The service valve assembly  20  includes a housing  22  having a condenser side port  24 , an evaporation side port  26 , a service port  28  and a cap  30  that is removably disposable over the service port. The components of the service valve assembly  20  can be made primarily of metal or a metal alloy, for example bronze, that is compatible with the fluid used in the refrigeration system incorporating the service valve assembly, although other materials, including plastics for some of the components, could be used if it is determined that the material used is compatible with the refrigeration system fluid. 
         [0027]    The housing  22  is illustrated as being generally rectangular in shape and having a fluid passageway  32  formed therein. The fluid passageway  32  is a generally hollowed-out internal section of the housing. 
         [0028]    The condenser side port  24  comprises an opening  34  (visible in  FIG. 5 ) formed in one of the side walls of the housing  22  that communicates with the fluid passageway  32 , and a tube  36  that has a first end that is brazed, welded or otherwise secured into the opening  34  and projects from the housing to a second, opposite end. In use of the service valve assembly  20 , the condenser side port  24 , in particular the second end of the tube  36 , is connected to a condenser unit of the refrigeration system at the factory. Within the housing  22  is a flow port  37  that places the condenser side port  24  in communication with the passageway  32 . 
         [0029]    The evaporation side port  26  comprises an opening  38  formed in a side wall of the housing  22  opposite the side wall containing the opening  34  and that communicates with the fluid passageway  32 , and a tube  40  that has a first end that is brazed, welded or otherwise secured into the opening  38  and projects from the housing to a second, opposite end. The longitudinal axis of the tube  36  is illustrated as being substantially parallel to the longitudinal axis of the tube  40 , with the axes of the tubes  36 ,  40  being offset from one another along the length of the housing  22 . The tubes  36 ,  40  could also have other orientations, for example the axes of the tubes could be aligned (i.e. inline) with no offset. In use of the service valve assembly, the evaporation side port, in particular the second end of the tube  40 , is connected to an evaporation unit of the refrigeration system when the service valve assembly is fully installed. 
         [0030]    The second end of the tube  40  is illustrated as being closed so that fluid cannot escape through the second end of the tube  40  until the closure is removed. The closure can be integrally formed with the tube  40  as in the illustrated example, or the closure can comprise a temporary blockage means removably installed in the tube such as a brazed cap or a sealed plug. The tube  40  is also illustrated as having at least one step  42 , or multiple steps, so that the tube  40  has sections  40   a,    40   b  of different diameters, with the diameter of section  40   b  being less than the diameter of section  40   a.  In another configuration, the tube  40  could be configured to have steps that increase in size such that section  40   b  would be larger than section  40   a.  The use of one or more steps on the tube  40  provides different tube diameters, allowing the tube to be cut at the appropriate tube diameter during installation for connection with the evaporation unit. Therefore, the tube  40  can fit many different systems. 
         [0031]    With reference to  FIGS. 4 and 5 , the service port  28  comprises an opening  44  formed through an end of the housing  22  and that communicates with the fluid passageway  32 . The exterior surface of the service port is provided with a threaded section  46 , an annular groove  48 , and a cap scaling surface  50 . 
         [0032]    A valve unit  60  is disposed within the service port  28  and the passageway  32  of the housing, and projects from the housing. The valve unit  60  controls flow through the housing  22  by controlling flow between the condenser side port  24 , the service port  28 , and the evaporation side port  26 , as well as controlling flow through the service port. To accomplish these tasks, the valve unit  60  includes a shut-off valve  62  and a control valve  64 . 
         [0033]    As shown in  FIG. 3-5 , the shut-off valve  62  is in the form of a piston valve with a piston body  70  having one end disposed within the service port  26  and a second end extending from the housing. The piston body  70  is generally cylindrical and includes a central passageway  72  extending from one end to the other end. 
         [0034]    The exterior of the piston body  70  includes a first threaded section  74  that engages with internal threads formed on the inside of the service port  28 . The threaded section  74  permits the piston body to be screwed in and out of the service port, thereby adjusting the position of the piston body depending upon the desired flow path. A sealing groove formed between two shoulders  76   a,    76   b  is also formed in the exterior of the piston body  70 , and a seal  78  is disposed in the sealing groove. The seal  78  seals with the interior surface of the service port to prevent fluid leaks past the piston body. 
         [0035]    The portion of the piston body  70  that extends from the housing includes a second threaded section  80  for connection with a standard service connection tool, and a hex surface  82  for engagement with a tool for rotating the piston body  70  to adjust the position thereof. 
         [0036]    The piston body  70  also includes a piston head  84  that extends from the first end thereof and which is fixed to the piston body via circumferentially spaced standoffs  86  (best seen in  FIG. 3 ) that extend from the piston head to the interior of the piston body. The piston head  84  moves with the piston body  70  as the piston body  70  is actuated into and from the service port. Gaps are defined between the standoffs  86  and the head  84  is spaced from the end of the piston body  70  to define a flow path (shown by the line in  FIG. 5 ) past the piston head to and from the central passageway  72 . 
         [0037]    A stem  88  is placed with the piston head  84  and extends within the central passageway  72  toward the second end of the piston body  70 . The control valve  64  comprises a poppet  90  with a sleeve  92  that is disposed over and is slideable on the end of the stem  88  and a poppet head  94  having a diameter greater than the diameter of the sleeve  92 . An elastomeric seal  96  is fixed to the poppet head  94  for sealing engagement with a sealing surface  98  on the inside of the piston body  70  formed by a reduced diameter section of the passageway  72 . 
         [0038]    A coil spring  100  is disposed around the stem  88  and has one end engaged with the ends of the stand-offs  86  and a second end engaged with the poppet head  94 . The spring  100  normally biases the poppet head  94  into sealing engagement with the sealing surface  98  as shown in  FIG. 3  preventing fluid flow through the passageway  72  and through the piston body  70 . In this position, there is a gap between the end of the stem  88  and the end of the sleeve  92 . This permits the poppet  90  to be actuated to the left in  FIG. 3  by a pin or other suitable projection on a service connection tool, to an open position shown in  FIG. 5  where the poppet head  94  is unseated from the sealing surface  98 , allowing fluid flow through the piston body. 
         [0039]    Returning to  FIGS. 2-4 , the cap  30  has internal threads  110  that engage with the threaded section  46  for securing the cap  30  over the service port  28 . A hex surface  112  facilitates installation and removal of the cap  30  using a suitable tool or by hand. The interior of the cap  30  also includes a sealing surface  114  that forms a metal-to-metal seal with the cap sealing surface  50  when the cap is fully installed. 
         [0040]    Use and operation of the service valve assembly  20  will now be described with reference to  FIGS. 2-4  along with  FIGS. 5-9 . The service valve assembly  20 , with or without the cap installed, would be provided. At this time, the second end of the rube  40  is closed as shown in  FIGS. 2 and 4 , and the poppet  90  is biased by the spring to a first, closed position. 
         [0041]    The condenser side port  24  is then connected to the condenser side of the refrigeration system by attaching the tube  36  to the condenser unit. The cap, if present, is also removed. If not already in position, the piston body  70  is actuated to a first position shown in  FIG. 5  which provides flow communication between the condenser side port and the service port. 
         [0042]    Suitable process tooling known in the art is then connected to the service port. This actuates the poppet  90  to a second position shown in  FIG. 5  which opens a flow path past the control valve and thereby permits flow through the service port with the condenser side as shown by the flow path line. 
         [0043]    Once the processing of the condenser side is completed, the process tooling is removed and the poppet will be biased back to the closed position by the spring. The piston body  70  is then actuated into the housing  22  by rotating the piston body  70 , until the piston head  84  reaches a second position where the piston head engages and seals with the flow port  37  as shown in  FIG. 6 . The piston head and the flow port form a metal-to-metal seal that hermetically seals the system by preventing flow communication between the condenser side port and the evaporation side port and the service port. However, flow communication between the evaporation side port and the service port is permitted. Installing the cap  30  adds a secondary seal via the metal-to-metal seal of the surfaces  50 ,  114  to provide a leak-proof system. 
         [0044]    At this point, the condenser unit and attached service valve assembly  20  are stored and/or shipped for installation. During this delay period, fluid leakage tends to be the biggest concern which is prevented by the seals discussed above. 
         [0045]    When the condenser unit is ready for installation, the installer will cut-off the tube  40  at a diameter that is appropriate for the system as shown in  FIG. 7 . Because of the steps  42 , one tube  40  can fit many different systems. Alternatively, the removable plug is removed from the tube  40 . The now open end of the tube is attached to the evaporation side of the refrigeration system. The installer then connects to the service port  28  of the valve assembly  20  using a standard service connection tool. This opens the poppet as shown in  FIG. 7 , and the installer processes the evaporation side of the system via the illustrated flow path. Once processing is complete, the service connection tool is removed, and the poppet is biased back to the closed position. 
         [0046]    The piston body  70  is then actuated to move the piston body back out to the first position as illustrated in  FIG. 8  which unseats the piston head from the flow port and allows the condenser side and the evaporator side to communicate with each other as shown by the flow path. The cap  30  can then be re-installed over the service port as indicated in  FIG. 9  to seal the system. 
         [0047]    For ongoing maintenance of the system, for example adding refrigerant, taking readings, etc, the cap  30  can be removed and the system can be accessed through the service port via the control valve  64 . The service port is designed to interface with existing service connection tools, eliminating the need to purchase new service equipment. 
         [0048]    With reference to  FIGS. 10-12 , an alternative embodiment of a service valve assembly  200  is illustrated. The assembly  200  includes a housing  202  having a passageway  204 , a condenser side port  206  in communication with the passageway for connection to the condenser unit, an evaporation side port  208  in communication with the passageway for connection to the evaporation unit, and a service port  210  in communication with the passageway. The evaporation side port  208  can have one or more steps similar to the valve assembly  20  of  FIGS. 2-9 . 
         [0049]    In this embodiment, the condenser side port  206  and the evaporation side port  208  are integrally formed with the housing  202 , for example from a one-piece forged construction. Further, the condenser side port  206  and the evaporation side port  208  are aligned with each other thereby providing a straight flow path. As with the valve assembly  20 , the evaporation side port  208  initially has a closed end  212 . 
         [0050]    A valve unit  214  is disposed within the service port  210  and the passageway  204 . The valve unit  214  controls flow through the housing  202  by controlling flow between the condenser side port  206 , the service port  210 , and the evaporation side port  208 , as well as controlling flow through the service port. To accomplish these tasks, the valve unit  214  includes a shut-off valve  216  and a control valve  218 . 
         [0051]    The shut-off valve  216  is in the form of a piston valve with a piston body  220  having one end disposed within the service port and a second end extending from the housing. The piston body  220  is generally cylindrical and includes a central passageway  222  extending from one end to the other end. 
         [0052]    The exterior of the piston body  220  includes a first threaded section  224  that engages with internal threads formed on the inside of the service port  210 . The threaded section  224  permits the piston body to be screwed in and out of the service port, thereby adjusting the position of the piston body depending upon the desired flow path. A sealing groove formed between two shoulders  226   a,    226   b  is also formed in the exterior of the piston body  220 , and a seal  228  is disposed in the sealing groove. The seal  228  seals with the interior surface of the service port to prevent fluid leaks past the piston body. 
         [0053]    The portion of the piston body  220  that extends from the housing includes a second threaded section  230  for connection with a standard service connection tool, and a hex surface  232  for engagement with a tool for rotating the piston body  220  to adjust the position thereof. 
         [0054]    The piston body  220  also includes a piston head  234  at the first end thereof. The piston head  234  moves with the piston body  220  as the piston body  220  is actuated into and from the service port. A stem  236  extends from the piston head and a flow path is defined between the stem  236  and the interior of the piston body  220 . Radial openings  238  are formed in the piston body  220  adjacent the head  234  to provide communication between the flow path and the exterior of the piston body. 
         [0055]    The control valve  218  comprises a poppet  240  with a stem  242  that is slideably disposed within a channel in the stem  236  and a poppet head  244  having a diameter greater than the diameter of the stem  242 . The poppet head  244  has an elastomeric seal  245  fixed to the surface thereof for sealing engagement with a sealing surface  246  on the inside of the piston body  220  formed by a reduced diameter section of the passageway  222 . 
         [0056]    A coil spring  248  is disposed around the stem  242  and has one end engaged with the end of the stem  236  and a second end engaged with the poppet head  244 . The spring  248  normally biases the poppet head  244  into sealing engagement with the sealing surface  246  as shown in  FIG. 11  preventing fluid flow through the passageway  222  and through the piston body  220 . An extension stem  250  extends from the poppet head  244  into a position to be engaged by a pin or other suitable projection on a service connection tool, to an open position shown in  FIG. 10  where the poppet head  244  is unseated from the sealing surface  246 , allowing fluid flow through the piston body. 
         [0057]    Assuming that the valve assembly  200  is installed to the condenser side.  FIG. 10  shows the shutoff valve  216  at a first position that permits flow communication between the condenser side port and the service port, and with the control valve  218  at a second position that permits flow past the control valve and thereby permits flow through the service port. The stage shown in  FIG. 10  is similar to the stage shown in  FIG. 5  for the valve assembly  20 . 
         [0058]    Once the processing of the condenser side is completed, the process tooling is removed and the poppet  240  will be biased back to the closed position by the spring  248 . The piston body  220  is then actuated into the housing by rotating the piston body until the piston head  234  reaches a second position where the piston head engages and seals with the interior of the housing as shown in  FIG. 11 . The piston head and the housing form a metal-to-metal seal that hermetically seals the system by preventing flow communication between the condenser side port and the evaporation side port and the service port. However, flow communication between the evaporation side port and the service port is permitted. Installing a cap similar to the cap  30  adds a secondary seal via a metal-to-metal seal between the cap and the service port to provide a leak-proof system. 
         [0059]    When the condenser unit is ready for installation, the installer will cut-off the tube of the evaporation side port  208  at a diameter that is appropriate for the system. The now open end of the tube is attached to the evaporation side of the refrigeration system. The installer then connects to the service port  210  of the valve assembly  200  using a standard service connection tool. This opens the poppet and the installer processes the evaporation side of the system. Once processing is complete, the service connection tool is removed, and the poppet is biased back to the closed position. 
         [0060]    The piston body  220  is then actuated to move the piston body back out to the first position as illustrated in  FIG. 12  which unseats the piston head and allows the condenser side and the evaporator side to communicate with each other. The cap can then be re-installed over the service port to seal the system. 
         [0061]    For ongoing maintenance of the system, for example adding refrigerant, taking readings, etc, the cap can be removed and the system can be accessed through the service port via the control valve. The service port is designed to interface with existing service connection tools, eliminating the need to purchase new service equipment. 
         [0062]      FIGS. 13-16  illustrate another alternative embodiment of a service valve assembly  300  that uses a ball valve as a shut-off valve. The assembly  300  includes a housing  302  having a passageway  304 , a condenser side port  306  in communication with the passageway for connection to the condenser unit, an evaporation side port  308  in communication with the passageway for connection to the evaporation unit, and a service port  310  in communication with the passageway. The evaporation side port  308  can have one or more steps similar to the valve assembly  20  of  FIGS. 2-9 . 
         [0063]    In this embodiment, the condenser side port  306  and the evaporation side port  308  are aligned with each other thereby providing a straight flow path. The evaporation side port  308  can have a closed end, or as shown in  FIG. 13 , the end can be open. 
         [0064]    A valve unit  312  is disposed within the service port  310  and the passageway  304 . The valve unit  312  controls flow through the housing  302  by controlling flow between the condenser side port  306 , the service port  310 , and the evaporation side port  308 , as well as controlling flow through the service port. To accomplish these tasks, the valve unit  312  includes a shut-off valve  316  and a control valve  318 . 
         [0065]    The shut-off valve  316  is in the form of a ball valve with a right angle flow path  320  as shown in  FIGS. 13-15  and a straight flow path  322  as shown in  FIG. 16 . The ball valve is fixed to a sleeve  326  that is rotatably disposed within the housing such that rotation of the sleeve  326  causes rotation of the ball valve. The sleeve  326  includes flats  327  at the end thereof for engagement with a tool for rotating the sleeve  326 . 
         [0066]    The control valve  318  is in the form of a piston that includes a first threaded section  324  that engages with internal threads formed on the inside of a sleeve  326  disposed within the service port  310 . The threaded section  324  permits the control valve piston to be screwed in and out to adjust the position of the piston. A sealing groove formed between two shoulders is also formed in the exterior of the control valve  118 , and a seal  328  is disposed in the sealing groove. The seal  328  seals with the interior surface of the sleeve  326  to prevent fluid leaks past the piston body. 
         [0067]    The portion of the control valve  318  that extends from the housing includes a second threaded section  330  for connection with a standard service connection tool, and a hex surface  332  for engagement with a tool for rotating the control valve  318  to adjust the position thereof. 
         [0068]    The control valve  318  is generally hollow with an open end  334 , defining an internal flow path. The opposite end of the control valve  318  defines a piston head  336 . Radial openings  338  are formed in the control valve  318  adjacent the head  336  to provide communication between the internal flow path and the exterior. The piston head  336  is designed to form a metal-to-metal seal with a sealing surface  339  on the inside of the sleeve  326 . 
         [0069]    Operation of the valve assembly  300  is as follows. Assuming that the valve assembly  300  is installed to the condenser side,  FIG. 13  shows the shut-off valve  316  at a first position that permits flow communication between the condenser side port and the service port, and with the control valve  318  at a second position that permits flow past the control valve and thereby permits flow through the service port. The stage shown in  FIG. 13  is similar to the stage shown in  FIG. 5  for the valve assembly  20 . 
         [0070]    Once the processing of the condenser side is completed, the sleeve  326 , which is fixed to the shut-off valve  316 , is rotated so that the right angle flow path  320  connects the evaporation side and the service port as shown in  FIG. 15 . The process tooling is then removed. The control valve  318  is then actuated into the housing by rotating the valve  318  until the piston head  336  reaches a position where the piston head engages and seals with the sealing surface  339  as shown in  FIG. 14 . The piston head and the sealing surface forms a metal-to-metal seal sealing the system by preventing flow communication between the condenser side port and the evaporation side port and the service port. Alternatively, the control valve  318  can first be actuated to seal with the surface  339  as shown in  FIG. 14 , followed by rotation of the sleeve and shut-off valve to the position shown in  FIG. 15 . 
         [0071]    Installing a cap similar to the cap  30  adds a secondary seal via a metal-to-metal seal between the cap and the service port to provide a leak-proof system. The cap can include threads on the outer diameter that engage with inner diameter threads on the housing  302 , and can include a metal to metal seal like the cap  30 . Alternatively, the cap can include inner diameter threads that engage with outer diameter threads on the housing, as well as a metal-to-metal seal with the housing like the cap  30 . 
         [0072]    When the condenser unit is ready for installation, the evaporation side port  308  is attached to the evaporation side of the refrigeration system. The control valve  318  is then actuated out to unseat the piston head  336  from the sealing surface  339 , thereby placing the evaporation side in communication with the service port. The installer then connects to the service port and processes the evaporation side of the system. Once processing is complete, the ball valve is then rotated so that the straight flow path  322  places the condenser side and the evaporator side in direct communication with each other as shown in  FIG. 16 . The control valve is threaded into the housing to engage the piston head with the sealing surface and the service connection tool is removed. 
         [0073]    The cap can then be re-installed over the service port to seal the system. 
         [0074]    For ongoing maintenance of the system, for example adding refrigerant, taking readings, etc, the cap can be removed and the system can be accessed through the service port via the control valve  318 . The service port is designed to interface with existing service connection tools, eliminating the need to purchase new service equipment. 
         [0075]    The described and illustrated features of the valve assembly  20 , the valve assembly  200  and the valve assembly  300  are useable together in a multitude of combinations. For example, the steps  42  on the evaporation side tube described for the valve assembly  20  can be used on the valve assembly  300 . Other combinations of features not specifically mentioned are contemplated and possible. 
         [0076]    The invention may be embodied in other forms without departing from the spirit or novel characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.