Abstract:
A pre-packaged air conditioning system for providing heating, cooling, ventilation and energy recovery, the system comprising: an energy recovery ventilator, condenser, condenser fan, compressor, expansion device, flow reversing valve, evaporator and evaporator fan; an inlet for providing outside air to the evaporator, the inlet for extending beyond a wall of a host structure; and an exhaust duct for exhausting air outside of the host structure, the exhaust duct for extending beyond a wall to the host structure; wherein the energy recovery ventilator, condenser, condenser fan, compressor, evaporator and evaporator fan are housed within a single envelope configured for installation inside the host structure.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. provisional patent application Ser. No. 61/447361 filed Feb. 28, 2011, the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This application relates generally to heating, ventilation, and cooling (HVAC) systems and particularly to a packaged HVAC system configured for indoor installation. An HVAC system typically comprises several components installed in distributed locations both inside and outside a home. For example, HVAC systems often include an air handler positioned inside a structure, the air handler having one or more fans or blowers to move an airstream through various system components and to distribute the conditioned airstream via a system of ducts. In such systems, an evaporator may be positioned within the airstream in a first location inside the home and may be configured to remove heat from the airstream and transfer that heat to a working fluid (e.g., R-410A refrigerant). The working fluid may be carried through a fluid line (e.g., copper pipe) through an exterior wall of the home to a compressor and a condenser where heat can be effectively released directly to the atmosphere. Such compressor/condenser units are often positioned outside the structure on a concrete slab, and electric service to the compressor is provided through an electric line passing through the exterior wall of the structure. Finally, the cooled, compressed working fluid is returned to the evaporator via another fluid line passing through the exterior wall to the inside of the structure. 
         [0003]    To provide heating of the airstream, an electric heating element or a gas heat exchanger may also be positioned in the conditioned airstream, often near the evaporator. For gas-burning applications, combustion air is typically carried from outside the home to a burner, and, following a transfer of heat to the conditioned airstream, the products of combustion are exhausted outside the home. The gas heat exchanger is coupled to a set of ducts that carry the combustion air and the products of combustion through an exterior wall to and from a location outside the home. 
         [0004]    Thus, conventional HVAC systems often comprise a number of interconnected subsystem components positioned remotely from one another, both inside and outside the host structure. The subsystem components are coupled to one another via ducts and fluid lines and lines carrying electricity and gas. A common example of a conventional HVAC system is known as a split-system, which comprises an indoor unit that includes an air handler with an integrated heater and evaporator and an outdoor unit that integrates the compressor and condenser into a single packaged unit. 
         [0005]    Due to the variety of available components making up a conventional HVAC system and the wide degree of variation in the structures into which conventional HVAC systems are installed, HVAC systems tend to be unique and widely varied. This necessitates a relatively high degree of skill for HVAC technicians to be able to properly specify, adapt, install, evaluate, and repair HVAC systems in individual homes. Moreover, due to the distributed nature of conventional HVAC systems, and the requirements that fluid lines, electrical lines, gas lines, and system ducts (i.e., mechanical interconnections) connect with the subsystem components and properly integrate with the structural and mechanical elements of the home, cooperation between many construction trades (e.g., framers/carpenters, electricians, plumbers, drywall contractors, etc., is necessitated. It has also been recognized that each of the lines and ducts passing through the exterior walls of a structure introduce the potential for air leaks and energy inefficiencies. 
         [0006]    Thus, a need exists for a pre-packaged HVAC system that can reduce or eliminate the need for external (i.e., positioned completely or partially outside the HVAC packaging) mechanical interconnections that may be exposed to the host structure or that interact with and/or interfere with and/or penetrate the host structure. 
         [0007]    There is also a need for increased energy efficiency in home HVAC systems, and home designers are increasingly seeking to incorporate mechanical ventilation systems, often incorporating energy recovery features, into new homes. Such systems carry ventilation air from outside the host structure to the inside. A corresponding volume of air is returned from inside the structure to the outside. Such ventilation systems typically require openings in one or more exterior walls of the structure, through which the ventilation and exhaust air is passed. The incorporation of these additional ventilation systems exacerbates the need for simplification and integration of HVAC system components and for reduction of external mechanical interconnections. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0008]    An embodiment is a pre-packaged air conditioning system for providing heating, cooling, ventilation and energy recovery, the system comprising: an energy recovery ventilator (ERV), condenser, condenser fan, compressor, expansion device, flow reversing valve, evaporator and evaporator fan; an inlet for providing outside air to the evaporator, the inlet for extending beyond a wall of a host structure; and an exhaust duct for exhausting air outside of the host structure, the exhaust duct for extending beyond a wall to the host structure; wherein the energy recovery ventilator, condenser, condenser fan, compressor, evaporator and evaporator fan are housed within a single envelope configured for installation inside the host structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which: 
           [0010]      FIG. 1  is a schematic drawing of an exemplary pre-packaged HVAC system in one embodiment; 
           [0011]      FIG. 2  is a front view of an exemplary pre-packaged HVAC system in another embodiment; and 
           [0012]      FIG. 3  is a front view of an exemplary pre-packaged HVAC system in another embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0013]    Embodiments provide a pre-packaged HVAC system that greatly reduces the need for external mechanical interconnections that may be exposed within the host structure and that otherwise interact with and/or interfere with or require separate penetrations to the host structure. Embodiments also provide for integration with a mechanical ventilation system and for incorporation of energy recovery features, all while reducing the need for openings in the exterior walls of the host structure. Embodiments may also provide for simplified installation and reduced floor space. 
         [0014]    In an exemplary embodiment, a fully integrated HVAC system includes an energy recovery ventilator, condenser, condenser fan, and compressor, together with an evaporator and evaporator fan, all integrated into a single, prepackaged unit that is configured for installation inside the host structure. In accordance with this embodiment, the airflow over the condenser and its fan is acquired through the same external wall opening that service the air for the energy recovery ventilator. Incoming outside air may be preheated or pre-cooled, and energy may also be recovered from the stream of return air. As one skilled in the art will appreciate, the energy recovery ventilator may be configured to transfer not only thermal energy (heat or cool), but also moisture. To transfer moisture, the system may incorporate a membrane to recapture water from return air and transfer that moisture to the incoming stream of outside air. 
         [0015]    Energy recovery may be accomplished through a variety of devices including a rotating wheel, and internal dampers may be included so as to effectuate control of indoor return air and outside ventilation air. The energy recovery system may recover energy from the return air. The volume of an exemplary pre-packaged HVAC system may be in the range of six to fifteen cubic feet. The capacity of an exemplary pre-packaged HVAC system may be in the range of five to twenty four thousand BTUs. Accordingly, as one skilled in the art will appreciate, a pre-packaged HVAC system tends to reduce the risk of exposure to foreign objects or other environmental contaminants inherent in split system refrigerant piping installation, particularly as the HVAC package is configured to provided a substantially sealed environment for the compressor. 
         [0016]    An exemplary HVAC system may also include devices for providing one or more economizer modes by manipulating or even disabling the rotational speed of the energy recovery wheel and/or by adjusting or closing bypass dampers. 
         [0017]    In operation, the system transfers the stream of air used by the condenser to and from the outside of the host structure, and heat is transferred between the air and the condenser in a location inside the host structure, i.e., within the pre-packaged, integrated HVAC system. Moreover, the system of the employs a single system of ducts to carry both ventilation air and condenser airflow. 
         [0018]    In accordance with an exemplary embodiment, and as shown in  FIG. 1 , an integrated, pre-packaged HVAC system  100  includes insulated inlet  110  (i.e., duct), through which outside air stream  112  is received from the atmosphere  130  outside the host structure. Insulated inlet  110  passes through exterior wall  120  of a host structure such as a home, accepts air from the atmosphere  130 , and provides outside air stream  112  to inlet filter  140 , which filters outside air stream  112  before it is separated by inlet splitter  150  into outside air stream  152  and condenser stream  154 . In accordance with this embodiment, inlet splitter  150  may be equipped with inlet core damper  156  and a bypass dampers  158  configured so as to control the flow rates of outside air stream  152  and condenser stream  154 . 
         [0019]    As one skilled in the art will appreciate, the flow rate of outside air stream  152  should be adjusted to provide the amount of air needed for proper ventilation, and the flow rate of condenser stream  154  should be adjusted to provide the amount of air for appropriate heat transfer (with acceptable pressure loss) in condenser  160 . For example, inlet splitter  150  may be configured (and/or inlet core and bypass dampers  156  and  158  may be positioned) such that the flow rate of outside air stream  152  is approximately 100 cubic feet per minute (cfm) and the flow rate of condenser stream  154  is approximately 800 cfm. 
         [0020]    After being split from condenser stream  154 , outside air stream  152  flows through heat recovery wheel  170 , and is mixed with recirculation stream  180  in mixer  190  to form supply stream  177  before passing through evaporator  102 , intake blower  104 , and heater  106  and subsequently being provided to distribution system  108  for distribution to conditioned space  114  within the home or other host structure. It should be noted that the order and positioning of evaporator  102 , heater  106 , and inlet blower  104  may be adjusted to suit system design requirements in individual systems. As one skilled in the art will appreciate, heater  106  may be electric, gas or any other known form of heater. Energy recovery wheel  170  is one form of energy recovery ventilator that may be used in the packaged system, and it is understood that other types of energy recovery ventilators may be used. 
         [0021]    In accordance with this embodiment, a return stream  187  is extracted from conditioned space  114  and passes through return filter  122  before being separated by return splitter  124  into recirculation stream  180  and exhaust stream  128 . In accordance with this embodiment, return splitter  124  may be equipped with exhaust damper  127  and recirculation damper  125  configured so as to control the flow rates of recirculation stream  180  and exhaust stream  128 . For example, splitter  124  may be configured, or dampers  125  and  127  may be positioned, such that the flow rate of recirculation stream  180  is approximately 300 cfm and the flow rate of exhaust stream  128  is approximately 100 cfm. As described above, recirculation stream  180  is mixed with outside air stream  152  to form supply stream  177  prior to passage through evaporator  102  and heater  106 . 
         [0022]    After being split from recirculation stream  180 , exhaust stream  128  is passed through heat recovery wheel  170  and is mixed with condenser stream  154  to form combined exhaust stream  182 , which flows through exhaust blower  184  and condenser  160  before passing through insulated exhaust duct  192 , which passes through an exterior wall  120  of the host structure, and being released to the atmosphere  130 . 
         [0023]    As outside air stream  152  flows through heat recovery wheel  170 , thermal energy is transferred between wheel  170  and outside air stream  152 . Similarly, as return stream  128  passes through heat recovery wheel  170 , thermal energy is transferred between wheel  170  and exhaust stream  128 . In this way, thermal energy (heating or cooling) is effectively transferred between outside air stream  152  and exhaust stream  128 . As one skilled in the art will appreciate, a number of mechanisms (e.g., a cross-flow core heat exchanger) could be employed—with or without a bypass damper to facilitate an economizer mode—so as to transfer heat between outside air stream  152  and exhaust stream  128 . It should also be noted that the use of a rotating wheel or cross-flow core heat exchanger and internal dampers allows for control of internal recirculation air, outside ventilation air, and allows for an economizer mode wherein the rotating energy recovery wheel is disabled and bypass dampers are closed. 
         [0024]    As supply stream  177  passes through evaporator  102 , heat is transferred between supply stream  177  and a working fluid flowing inside fluid lines  194 . As one skilled in the art will appreciate, compressor  195  moves the working fluid (e.g., refrigerant) through fluid lines  194  from compressor  195 , to condenser  160 , expansion device  161  and evaporator  102 . As combined exhaust stream  182  passes through condenser  160 , heat is transferred between combined exhaust stream  182  and the working fluid. It is understood that the refrigerant system may be run in reverse (e.g., as a heat pump) such that evaporator  102  serves as a condenser and condenser  160  serves as an evaporator. A flow reversing valve  163  is included to enable operation as a heat pump. 
         [0025]    Condenser  160 , compressor  195 , and fluid lines  194  are all contained within HVAC package  196 , which may be hermetically sealed. In effect, insulated inlet  110  and insulated exhaust  192  carry not only air for ventilation of the host structure, but also air for exchanging heat with condenser  160  and evaporator  102 . 
         [0026]    In accordance with an exemplary embodiment, pre-packaged HVAC system  100  may be located indoors (i.e., within the host structure such as a home or office), and such a placement is facilitated by incorporation of insulated inlet  110 , which passes through exterior wall  120  of the host structure and accepts air from atmosphere  130 , and insulated exhaust  192 , which also passes through an exterior wall of the host structure and releases combined exhaust stream  182  to atmosphere  130 . 
         [0027]    In an alternative embodiment, inlet splitter  150  of integrated, pre-packaged HVAC system  100  also splits from outside air  152  stream a combustion air stream  159 . As one skilled in the art will appreciate, combustion air stream  159  is adjusted to facilitate combustion in heater  106 , which would incorporate a gas heat exchanger, burner, and combustion blower. In accordance with this embodiment, combustible fuel is added to combustion air stream  159  and heat is extracted from the products of combustion. That heat is then transferred to supply airstream  177  in the gas heat exchanger contained within that embodiment of heater  106 . Products of combustion may be mixed with flow  154  prior to, or downstream of, the exhaust fan, preferably downstream of the ERV to avoid migration of combustion gas to indoor air. 
         [0028]      FIG. 2  is a front view of an exemplary pre-packaged HVAC system in another embodiment. In this embodiment, the ERV  170  is in a housing  202  mounted on the side of a cabinet  200  containing the evaporator  102  and condenser  160 . ERV  170  may be any type of ERV, including wheel or plate type, and include internal fans for moving air through the ERV core as known in the art. Housing  202  and cabinet  200  include openings to allow return air and outside to enter the ERV  170 . Similarly, openings in the housing  202  and cabinet  200  allow for supply air and exhaust air to exit the ERV  170  and pass over the evaporator  102  and condenser  160 , respectively. The housing  202  of ERV  170  is sealed to cabinet  200  to provide a packaged unit in a sealed envelope. The packaged HVAC system of  FIG. 2  interfaces with inlet  110  and exhaust duct  192  as described above. 
         [0029]      FIG. 3  is a front view of an exemplary pre-packaged HVAC system in another embodiment. In this embodiment, the ERV  170  is in a housing  202  mounted on top of a cabinet  200  housing the evaporator  102  and condenser  160 . ERV  170  may be any type of ERV, including wheel or plate type, and include internal fans for moving air through the ERV core as known in the art. Housing  202  and cabinet  200  include openings to allow return air to enter the ERV  170  and supply air to exit the ERV  170 . A first duct  210  couples the outside air from cabinet  200  to housing  202 , to provide outside air to the ERV  170 . A second duct  212  couples the exhaust air from housing  202  to cabinet  200 . Ducts  210  and  212  may be located within cabinet  200 , rather than outside cabinet  200  as shown in  FIG. 3 . The housing  202  of ERV  170  is sealed to cabinet  200  to provide a packaged unit in a sealed envelope. The packaged HVAC system of  FIG. 2  interfaces with an inlet  110  and exhaust duct  192  as described above. 
         [0030]    As a result, embodiments provide a fully-integrated HVAC system that combines the functionality of a high-efficiency heat pump with that of an energy-recovery ventilator, together with the condenser and condenser fan also integrated into a single packaged unit suitable for installation inside a host structure such as a home or apartment. Accordingly, embodiments provide a relatively high-efficiency, integrated, heat-pump system that can meet emerging needs for relatively low capacity installations. Embodiments overcome the need for split heat-pump systems and the issues inherent with distribution throughout the inside and outside of a host structure. Embodiments eliminate the need to place a condenser, condenser fan, and compressor outside the host structure. Embodiments include the compressor, condenser, and condenser fan in an integrated indoor unit and utilizes an integrated ventilation system to provide necessary condenser airflow. 
         [0031]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.