Patent Publication Number: US-10788226-B2

Title: System and method for operating a packaged terminal air conditioner unit

Description:
FIELD OF THE INVENTION 
     The present disclosure relates generally to air conditioner units, and more particularly to packaged terminal air conditioner units and related methods of operation. 
     BACKGROUND OF THE INVENTION 
     Air conditioner or conditioning units are conventionally utilized to adjust the temperature indoors—i.e. within structures such as dwellings and office buildings. Such units commonly include a closed refrigeration loop to heat or cool the indoor air. Typically, the indoor air is recirculated while being heated or cooled. A variety of sizes and configurations are available for such air conditioner units. For example, some units may have one portion installed within the indoors that is connected, by e.g., tubing carrying the refrigerant, to another portion located outdoors. These types of units are typically used for conditioning the air in larger spaces. 
     Another type of unit, sometimes referred to as a packaged terminal air conditioner unit (PTAC), may be used for somewhat smaller indoor spaces that are to be air conditioned. These units may include both an indoor portion and an outdoor portion separated by a bulkhead and may be installed in windows or positioned within an opening of an exterior wall of a building. PTACs often need to draw air from the outdoor portion into the indoor portion. Accordingly, certain PTACs allow for the introduction of make-up air into the indoor space, e.g., through a vent aperture defined in the bulkhead that separates the indoor and outdoor side of the unit. The vent aperture is usually equipped with an auxiliary fan and/or make-up air module to urge a flow of make-up air from the outdoor side of the PTAC into the conditioned room. 
     The amount of outdoor air, i.e., “make-up air,” needed varies depending on a variety of factors, such as the number of room occupants, the size of the room, etc. For example, a facility manager could program the PTAC to provide sufficient make-up air to meet government regulations or building codes based on the number of room occupants or the room size. In certain situations, the auxiliary fan may not be capable of providing a sufficient flow rate of make-up air to meet the room requirements. Alternatively, the auxiliary fan may generate too much noise or consume too much energy when trying to supply higher flow rates of make-up air. 
     Accordingly, improved air conditioner units and methods for providing make-up air would be useful. More specifically, a packaged terminal air conditioner unit that can supply the requested make-up air while reducing auxiliary fan noise and energy usage would be particularly beneficial. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present subject matter provides a packaged terminal air conditioner unit (PTAC) and methods for operating the same. The PTAC includes a vent aperture defined in a bulkhead of the PTAC through which make-up air may flow. An indoor fan urges a flow of primary make-up air at a primary flow rate and an auxiliary fan urges a flow of auxiliary make-up air at an auxiliary flow rate. A controller determines a target make-up air flow rate, e.g., based on a user setting which is determined from building code calculations factoring in expected room occupancy, room size, and other factors. The controller then operates the auxiliary fan to urge the flow of auxiliary make-up air at the auxiliary flow rate which is substantially equivalent to the target make-up air flow rate minus the primary flow rate. Additional aspects and advantages of the invention will be set forth in part in the following description, may be obvious from the description, or may be learned through practice of the invention. 
     In accordance with one embodiment, a packaged terminal air conditioner unit is provided including a bulkhead defining an indoor portion and an outdoor portion and a vent aperture defined in the bulkhead. An indoor fan is positioned within the indoor portion and being configured for urging a flow of primary make-up air from the outdoor portion through the vent aperture to the indoor portion. An auxiliary fan is positioned proximate the vent aperture and is configured for urging a flow of auxiliary make-up air from the outdoor portion through the vent aperture to the indoor portion. A controller is operably coupled to the indoor fan and the auxiliary fan. The controller is configured for determining a target make-up air flow rate and determining a primary flow rate of the flow of primary make-up air urged by the indoor fan. The controller is further configured for operating the auxiliary fan to urge the flow of auxiliary make-up air at an auxiliary flow rate, the auxiliary flow rate being substantially equivalent to the target make-up air flow rate minus the primary flow rate. 
     In accordance with another embodiment, a method of operating a packaged terminal air conditioner unit is provided. The packaged terminal conditioner unit includes an indoor fan positioned within an indoor portion and an auxiliary fan positioned adjacent a vent aperture defined in a bulkhead of the packaged terminal air conditioner unit. The method includes determining a target make-up air flow rate and operating the indoor fan to urge a flow of primary make-up air through the vent aperture to the indoor portion at a primary flow rate. The method further includes operating the auxiliary fan to urge a flow of auxiliary make-up air through the vent aperture to the indoor portion at an auxiliary flow rate, a sum of the primary flow rate and the auxiliary flow rate being substantially equivalent to the target make-up air flow rate. 
     In accordance with still another embodiment, a packaged terminal air conditioner unit is provided including a bulkhead defining an indoor portion and an outdoor portion and a vent aperture defined in the bulkhead. A first fan is configured for urging a first flow of make-up air through the vent aperture and a second fan is configured for urging a second flow of make-up air through the vent aperture. A controller is operably coupled to the first fan and the second fan. The controller is configured for determining a target make-up air flow rate and operating the first fan at a first flow rate. The controller is further configured for operating the second fan at a second flow rate, the second flow rate being substantially equivalent to the target make-up air flow rate minus the first flow rate. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a perspective view of an air conditioner unit, with part of an indoor portion exploded from a remainder of the air conditioner unit for illustrative purposes, in accordance with one exemplary embodiment of the present disclosure. 
         FIG. 2  is another perspective view of components of the indoor portion of the exemplary air conditioner unit of  FIG. 1 . 
         FIG. 3  is a schematic view of a refrigeration loop in accordance with one embodiment of the present disclosure. 
         FIG. 4  is a rear perspective view of an outdoor portion of the exemplary air conditioner unit of  FIG. 1 , illustrating a vent aperture in a bulkhead assembly in accordance with one embodiment of the present disclosure. 
         FIG. 5  is a front perspective view of the exemplary bulkhead assembly of  FIG. 4  with a vent door illustrated in the open position in accordance with one embodiment of the present disclosure. 
         FIG. 6  is a rear perspective view of the exemplary air conditioner unit and bulkhead assembly of  FIG. 4  including a sealed system for conditioning make-up air in accordance with one embodiment of the present disclosure. 
         FIG. 7  is a schematic view of a control system used to operate an indoor fan and an auxiliary fan of the exemplary air conditioner unit of  FIG. 1  according to an exemplary embodiment of the present subject matter. 
         FIG. 8  depicts certain components of a control system according to example embodiments of the present subject matter. 
         FIG. 9  illustrates a method for controlling a packaged terminal air conditioner unit in accordance with one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     Referring now to  FIG. 1 , an air conditioner unit  10  is provided. The air conditioner unit  10  is a one-unit type air conditioner, also conventionally referred to as a room air conditioner or a packaged terminal air conditioner (PTAC). The unit  10  includes an indoor portion  12  and an outdoor portion  14 , and generally defines a vertical direction V, a lateral direction L, and a transverse direction T. Each direction V, L, T is perpendicular to each other, such that an orthogonal coordinate system is generally defined. 
     A housing  20  of the unit  10  may contain various other components of the unit  10 . Housing  20  may include, for example, a rear grill  22  and a room front  24  which may be spaced apart along the transverse direction T by a wall sleeve  26 . The rear grill  22  may be part of the outdoor portion  14 , and the room front  24  may be part of the indoor portion  12 . Components of the outdoor portion  14 , such as an outdoor heat exchanger  30 , an outdoor fan  32  ( FIG. 2 ), and a compressor  34  ( FIG. 2 ) may be housed within the wall sleeve  26 . A casing  36  may additionally enclose outdoor fan  32 , as shown. 
     Referring now also to  FIG. 2 , indoor portion  12  may include, for example, an indoor heat exchanger  40  ( FIG. 1 ), a blower fan or indoor fan  42 , and a heating unit  44 . These components may, for example, be housed behind the room front  24 . Additionally, a bulkhead  46  may generally support and/or house various other components or portions thereof of the indoor portion  12 , such as indoor fan  42  and the heating unit  44 . Bulkhead  46  may generally separate and define the indoor portion  12  and outdoor portion  14 . 
     Outdoor and indoor heat exchangers  30 ,  40  may be components of a refrigeration loop  48 , which is shown schematically in  FIG. 3 . Refrigeration loop  48  may, for example, further include compressor  34  and an expansion device  50 . As illustrated, compressor  34  and expansion device  50  may be in fluid communication with outdoor heat exchanger  30  and indoor heat exchanger  40  to flow refrigerant therethrough as is generally understood. More particularly, refrigeration loop  48  may include various lines for flowing refrigerant between the various components of refrigeration loop  48 , thus providing the fluid communication there between. Refrigerant may thus flow through such lines from indoor heat exchanger  40  to compressor  34 , from compressor  34  to outdoor heat exchanger  30 , from outdoor heat exchanger  30  to expansion device  50 , and from expansion device  50  to indoor heat exchanger  40 . The refrigerant may generally undergo phase changes associated with a refrigeration cycle as it flows to and through these various components, as is generally understood. Suitable refrigerants for use in refrigeration loop  48  may include pentafluoroethane, difluoromethane, or a mixture such as R410a, although it should be understood that the present disclosure is not limited to such example and rather that any suitable refrigerant may be utilized. 
     As is understood in the art, refrigeration loop  48  may be alternately be operated as a refrigeration assembly (and thus perform a refrigeration cycle) or a heat pump (and thus perform a heat pump cycle). As shown in  FIG. 3 , when refrigeration loop  48  is operating in a cooling mode and thus performs a refrigeration cycle, the indoor heat exchanger  40  acts as an evaporator and the outdoor heat exchanger  30  acts as a condenser. Alternatively, when the assembly is operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchanger  40  acts as a condenser and the outdoor heat exchanger  30  acts as an evaporator. The outdoor and indoor heat exchangers  30 ,  40  may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood. 
     According to an example embodiment, compressor  34  may be a variable speed compressor. In this regard, compressor  34  may be operated at various speeds depending on the current air conditioning needs of the room and the demand from refrigeration loop  48 . For example, according to an exemplary embodiment, compressor  34  may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 3500 RPM. Notably, use of variable speed compressor  34  enables efficient operation of refrigeration loop  48  (and thus air conditioner unit  10 ), minimizes unnecessary noise when compressor  34  does not need to operate at full speed, and ensures a comfortable environment within the room. 
     In exemplary embodiments as illustrated, expansion device  50  may be disposed in the outdoor portion  14  between the indoor heat exchanger  40  and the outdoor heat exchanger  30 . According to the exemplary embodiment, expansion device  50  may be an electronic expansion valve that enables controlled expansion of refrigerant, as is known in the art. More specifically, electronic expansion device  50  may be configured to precisely control the expansion of the refrigerant to maintain, for example, a desired temperature differential of the refrigerant across the indoor heat exchanger  40 . In other words, electronic expansion device  50  throttles the flow of refrigerant based on the reaction of the temperature differential across indoor heat exchanger  40  or the amount of superheat temperature differential, thereby ensuring that the refrigerant is in the gaseous state entering compressor  34 . According to alternative embodiments, expansion device  50  may be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle. 
     According to the illustrated exemplary embodiment, outdoor fan  32  is an axial fan and indoor fan  42  is a centrifugal fan. However, it should be appreciated that according to alternative embodiments, outdoor fan  32  and indoor fan  42  may be any suitable fan type. In addition, according to an exemplary embodiment, outdoor fan  32  and indoor fan  42  are variable speed fans. For example, outdoor fan  32  and indoor fan  42  may rotate at different rotational speeds, thereby generating different air flow rates. It may be desirable to operate fans  32 ,  42  at less than their maximum rated speed to ensure safe and proper operation of refrigeration loop  48  at less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. In addition, according to alternative embodiments, fans  32 ,  42  may be operated to urge make-up air into the room. 
     According to the illustrated embodiment, indoor fan  42  may operate as an evaporator fan in refrigeration loop  48  to encourage the flow of air through indoor heat exchanger  40 . Accordingly, indoor fan  42  may be positioned downstream of indoor heat exchanger  40  along the flow direction of indoor air and downstream of heating unit  44 . Alternatively, indoor fan  42  may be positioned upstream of indoor heat exchanger  40  along the flow direction of indoor air, and may operate to push air through indoor heat exchanger  40 . 
     Heating unit  44  in exemplary embodiments includes one or more heater banks  60 . Each heater bank  60  may be operated as desired to produce heat. In some embodiments as shown, three heater banks  60  may be utilized. Alternatively, however, any suitable number of heater banks  60  may be utilized. Each heater bank  60  may further include at least one heater coil or coil pass  62 , such as in exemplary embodiments two heater coils or coil passes  62 . Alternatively, other suitable heating elements may be utilized. 
     The operation of air conditioner unit  10  including compressor  34  (and thus refrigeration loop  48  generally) indoor fan  42 , outdoor fan  32 , heating unit  44 , expansion device  50 , and other components of refrigeration loop  48  may be controlled by a processing device such as a controller  64 . Controller  64  may be in communication (via for example a suitable wired or wireless connection) to such components of the air conditioner unit  10 . As described in more detail below with respect to  FIG. 8 , the controller  64  may include a memory and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of unit  10 . The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. 
     Unit  10  may additionally include a control panel  66  and one or more user inputs  68 , which may be included in control panel  66 . The user inputs  68  may be in communication with the controller  64 . A user of the unit  10  may interact with the user inputs  68  to operate the unit  10 , and user commands may be transmitted between the user inputs  68  and controller  64  to facilitate operation of the unit  10  based on such user commands. A display  70  may additionally be provided in the control panel  66 , and may be in communication with the controller  64 . Display  70  may, for example be a touchscreen or other text-readable display screen, or alternatively may simply be a light that can be activated and deactivated as required to provide an indication of, for example, an event or setting for the unit  10 . 
     Referring briefly to  FIG. 4 , a vent aperture  80  may be defined in bulkhead  46  providing fluid communication between indoor portion  12  and outdoor portion  14 . Vent aperture  80  may be utilized in an installed air conditioner unit  10  to allow outdoor air to flow into the room through the indoor portion  12 . In this regard, in some cases it may be desirable to allow outside air (i.e., “make-up air”) to flow into the room in order, e.g., to meet government regulations, or to compensate for negative pressure created within the room. In this manner, according to an exemplary embodiment, make-up air may be provided into the room through vent aperture  80  when desired. 
     As shown in  FIG. 5 , a vent door  82  may be pivotally mounted to the bulkhead  46  proximate to vent aperture  80  to open and close vent aperture  80 . More specifically, as illustrated, vent door  82  is pivotally mounted to the indoor facing surface of indoor portion  12 . Vent door  82  may be configured to pivot between a first, closed position where vent door  82  prevents air from flowing between outdoor portion  14  and indoor portion  12 , and a second, open position where vent door  82  is in an open position (as shown in  FIG. 5 ) and allows make-up air to flow into the room. According to the illustrated embodiment vent door  82  may be pivoted between the open and closed position by an electric motor  84  controlled by controller  64 , or by any other suitable method. 
     In some cases, it may be desirable to treat or condition make-up air flowing through vent aperture  80  prior to blowing it into the room. For example, outdoor air which has a relatively high humidity level may require treating before passing into the room. In addition, if the outdoor air is cool, it may be desirable to heat the air before blowing it into the room. Therefore, as illustrated in  FIG. 6 , unit  10  may further include an auxiliary sealed system, or make-up air module  90 , for conditioning make-up air. As shown, make-up air module  90  and/or an auxiliary fan  92  are positioned within outdoor portion  14  adjacent vent aperture  80  and vent door  82  is positioned within indoor portion  12  over vent aperture  80 , though other configurations are possible. According to the illustrated embodiment auxiliary sealed system  90  may be controlled by controller  64 , by another dedicated controller, or by any other suitable method. 
     As illustrated, make-up air module  90  includes auxiliary fan  92  that is configured as part of auxiliary sealed system  90  and may be configured for urging a flow of air through auxiliary sealed system  90 . Auxiliary sealed system  90  may further include one or more compressors, heat exchangers, and any other components suitable for operating auxiliary sealed system  90  similar to refrigeration loop  48  described above to condition make-up air. For example, auxiliary system  90  can be operated in a dehumidification mode, an air conditioning mode, a heating mode, a fan only mode where only auxiliary fan  92  is operated to supply outdoor air, an idle mode, etc. 
     Referring now to  FIG. 7 , a control system  100  used to control an indoor fan, an auxiliary fan, and/or a make-up air module of a packaged terminal air conditioner unit is described according to an exemplary embodiment. Using unit  10  as an example, control system  100  is generally used to selectively operate indoor fan  42  and/or auxiliary fan  92  to provide a flow of make-up air into a room  102  at a desired flow rate. Although control system  100  is described herein as one exemplary control system configuration for operating indoor fan  42  and/or auxiliary fan  92 , it should be appreciated that other configurations and control methodologies are possible while remaining within the scope of the present subject matter. 
     According to the illustrated embodiment, control system  100  includes a packaged terminal air conditioner unit, such as unit  10 , positioned on an exterior wall of a room  102 . Unit  10  is configured for conditioning air within room  102  and supplying a flow of make-up air into room  102 . In addition, control system  100  includes an occupancy system  104  generally configured for obtaining a room occupancy status. As used herein, “room occupancy status” may be used to refer to an indication that the room is occupied or unoccupied, to the number of room occupants, to the target make-up air flow rate, or any other information that may be used by the packaged terminal air conditioner unit  10  or make-up air module  90  to determine the proper make-up air flow rate. 
     Occupancy system  104  may include an identification reader such as a keycard reader  106  that is generally configured for reading an occupancy identification source, such as a keycard  108 . More specifically, according to the exemplary illustrated embodiment, keycard reader  106  is positioned within room  102  near the door and keycard  108  includes a magnetic strip  110  that is configured to be read by the keycard reader  106 . Upon entering the room, the guest puts keycard  108  into a slot of keycard reader  106 . Keycard  108  may be encoded with information regarding the reserved room information as well as the number of guests staying in the room  102 . The room occupancy status may be relayed to unit  10  and/or make-up air module  90  in any suitable manner. 
     The exemplary embodiment described above describes the room occupancy status and other information being relayed to make-up air module  90  using magnetic strip  110  on keycard  108 . However, it should be appreciated that this information may be relayed using any other suitable method. For example, the room occupancy status may be entered by the guest using a keypad when they enter room  102 , may be encoded in a barcode and read by a barcode scanner, may be communicated using a mobile phone application, may be transmitted using an RFID chip, or may be relayed in any other manner. 
     Occupancy system  104 , including keycard reader  106  may be coupled to unit  10  through any suitable wired or wireless connection, as described in more detail below. For example, as illustrated, occupancy system  104  includes an occupancy system controller  120 , e.g., housed within keycard reader  106 , that is in operative communication with controller  64  of unit  10 . More specifically, according to the illustrated embodiment, controller  64  and occupancy system controller  120  may be in communication with through a direct or indirect, wired or wireless connection, such as via a network  122 . 
     After the room occupancy status is received by unit  10 , controller  64  determines a target make-up air flow rate. For example, according to one exemplary embodiment, the target make-up air flow rate is based on a user setting which is determined from building code calculations factoring in expected room occupancy, room size, and any other combination of suitable factors. Notably, tying the target make-up air flow rate to occupancy system  104  and the number of room occupants, unit  10  may deliver the appropriate amount of air to meet government regulations and building codes, keep the noise created by auxiliary fan  92  to a minimum, and maintain guest comfort and satisfaction at a maximum. 
       FIG. 7  illustrates one exemplary configuration of control system  100  configured for controlling the operation of indoor fan  42  and/or auxiliary fan  92  for the purpose of explaining aspects of the present subject matter. However, it should be appreciated that although specific exemplary embodiments are described, modifications and variations may be made to the illustrated control system  100  while remaining within the scope of the present subject matter. For example, controller  64  of unit  10  is illustrated as part of control system  100  for controlling operation of indoor fan  42  and/or auxiliary fan  92 . However, according to alternative embodiments, make-up air module  90  could include a dedicated controller. In addition, keycard reader  106  may be in operative communication with unit  10  and make-up air module  90  in any other suitable manner, e.g., through an in-room thermostat, through a direct wired connection, etc. 
       FIG. 8  depicts certain components of control system  100  according to example embodiments of the present disclosure. As shown and described above, unit  10  includes controller  64  and occupancy system  104  includes occupancy system controller  120 . Controllers  64  and  120  can be configured to communicate directly or via one or more network(s) (e.g., network(s)  122 ). Controllers  64  and  120  can include one or more computing device(s)  130 . Although similar reference numerals will be used herein for describing the computing device(s)  130  associated with controllers  64  and  120  respectively, it should be appreciated that each of controllers  64  and  120  may have a dedicated computing device  130  not shared with the other. According to still another embodiment, only a single computing device  130  may be used to implement method  200  as described below, and that computing device  130  may be included as part of controllers  64  and  120 . 
     Computing device(s)  130  can include one or more processor(s)  130 A and one or more memory device(s)  130 B. The one or more processor(s)  130 A can include any suitable processing device, such as a microprocessor, microcontroller, integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), logic device, one or more central processing units (CPUs), graphics processing units (GPUs) (e.g., dedicated to efficiently rendering images), processing units performing other specialized calculations, etc. The memory device(s)  130 B can include one or more non-transitory computer-readable storage medium(s), such as RAM, ROM, EEPROM, EPROM, flash memory devices, magnetic disks, etc., and/or combinations thereof. 
     The memory device(s)  130 B can include one or more computer-readable media and can store information accessible by the one or more processor(s)  130 A, including instructions  130 C that can be executed by the one or more processor(s)  130 A. For instance, the memory device(s)  130 B can store instructions  130 C for running one or more software applications, displaying a user interface, receiving user input, processing user input, etc. In some implementations, the instructions  130 C can be executed by the one or more processor(s)  130 A to cause the one or more processor(s)  130 A to perform operations, as described herein (e.g., one or more portions of method  200 ). More specifically, for example, the instructions  130 C may be executed to transmit and/or receive occupancy status information, determine a target make-up air flow rate, and adjust the speed of an indoor or auxiliary fan. The instructions  130 C can be software written in any suitable programming language or can be implemented in hardware. Additionally, and/or alternatively, the instructions  130 C can be executed in logically and/or virtually separate threads on processor(s)  130 A. 
     The one or more memory device(s)  130 B can also store data  130 D that can be retrieved, manipulated, created, or stored by the one or more processor(s)  130 A. The data  130 D can include, for instance, data indicative of target make-up air flow rates for a given number of room occupants. The data  130 D can be stored in one or more database(s). The one or more database(s) can be connected to controller  64  and/or controller  120  by a high bandwidth LAN or WAN, or can also be connected to controller through network(s)  122 . The one or more database(s) can be split up so that they are located in multiple locales. In some implementations, the data  130 D can be received from another device. 
     The computing device(s)  130  can also include a communication module or interface  130 E used to communicate with one or more other component(s) of control system (e.g., controllers  64  and  120 ) over the network(s)  122 . The communication interface  130 E can include any suitable components for interfacing with one or more network(s), including for example, transmitters, receivers, ports, controllers, antennas, or other suitable components. 
     The network(s)  122  can be any type of communications network, such as a local area network (e.g. intranet), wide area network (e.g. Internet), cellular network, or some combination thereof and can include any number of wired and/or wireless links. The network(s)  122  can also include a direct connection between one or more component(s) of control system  100 . In general, communication over the network(s)  122  can be carried via any type of wired and/or wireless connection, using a wide variety of communication protocols (e.g., TCP/IP, HTTP, SMTP, FTP), encodings or formats (e.g., HTML, XML), and/or protection schemes (e.g., VPN, secure HTTP, SSL). 
     The technology discussed herein makes reference to servers, databases, software applications, and other computer-based systems, as well as actions taken and information sent to and from such systems. It should be appreciated that the inherent flexibility of computer-based systems allows for a great variety of possible configurations, combinations, and divisions of tasks and functionality between and among components. For instance, computer processes discussed herein can be implemented using a single computing device or multiple computing devices (e.g., servers) working in combination. Databases and applications can be implemented on a single system or distributed across multiple systems. Distributed components can operate sequentially or in parallel. Furthermore, computing tasks discussed herein as being performed at the computing system (e.g., a server system) can instead be performed at a user computing device. Likewise, computing tasks discussed herein as being performed at the user computing device can instead be performed at the computing system. 
     Now that the construction of air conditioner unit  10  and the configuration of control system  100  according to exemplary embodiments has been presented, an exemplary method  200  of operating a packaged terminal air conditioner unit will be described. Although the discussion below refers to the exemplary method  200  of operating air conditioner unit  10 , one skilled in the art will appreciate that the exemplary method  200  is applicable to the operation of a variety of other air conditioning appliances. In exemplary embodiments, the various method steps as disclosed herein may be performed by controller  64  or a separate, dedicated controller. 
     In general, unit  10  controls the delivery of make-up air into indoor portion  12  through vent aperture  80 . More specifically, when vent door  82  is open, indoor fan  42  and auxiliary fan  92  operate to urge make-up air into the room. More specifically, indoor fan  42  may be referred to herein as urging a flow of primary make-up air at a primary flow rate and auxiliary fan  92  may be referred to as urging a flow of auxiliary make-up air at an auxiliary flow rate. According to the exemplary embodiment, the total flow rate of make-up air is the sum of the primary flow rate and the auxiliary flow rate. It should be appreciated that the terms “primary” flow and flow rate and “auxiliary” flow and flow rate are only intended to refer to the relative proportions/amounts of make-up air passing through vent aperture  80 . Each of indoor fan  42  and auxiliary fan  92  may be operated independently of each other or collectively to urge a flow of make-up air through vent aperture  80 . 
     Referring now to  FIG. 9 , method  200  includes, at step  210 , determining a target make-up air flow rate. For example, the packaged terminal air conditioner unit may be in operative communication with an occupancy system or an occupancy reader, such as a key card reader, directly, through a thermostat, or through one or more wired or wireless networks. The number of occupants in the room could be obtained using an occupancy system and the target make-up air flow rate may be based at least in part on the number of occupants in the room. In addition, or alternatively, the make-up air flow rate may be based on the room size, a detected air pressure within the room, government regulations, or any other suitable factors. 
     Method  200  further includes, at step  220 , operating an indoor fan to urge a flow of primary make-up air through a vent aperture to an indoor portion at a primary flow rate. In this regard, for example, when the vent door is closed and indoor fan is operating according to an air conditioning mode, air from within the room is circulated through indoor fan. However, when the vent door of the packaged terminal air conditioner unit is open, operation of the indoor fan also has a tendency to draw in make-up air through the vent aperture at a flow rate (i.e., the primary flow rate) roughly proportional to the fan speed. According to alternative embodiments, other means can be used to assist in drawing the primary make-up air through the vent aperture, such as a bathroom exhaust fan, which generates a negative pressure within the room, resulting in additional make-up air entering through the vent aperture. 
     Method  200  further includes, at step  230 , operating an auxiliary fan to urge a flow of auxiliary make-up air through the vent aperture to the indoor portion at an auxiliary flow rate. Notably, a sum of the primary flow rate and the auxiliary flow rate is substantially equivalent to the target make-up air flow rate so that the room receives the necessary flow rate of make-up air. In other words, according to aspects of the present subject matter, the indoor fan and the auxiliary fan work together to supply make-up air at the target make-up air flow rate. 
       FIG. 9  depicts steps performed in a particular order for purposes of illustration and discussion. Those of ordinary skill in the art, using the disclosures provided herein, will understand that the steps of any of the methods discussed herein can be adapted, rearranged, expanded, omitted, or modified in various ways without deviating from the scope of the present disclosure. Moreover, although aspects of method  200  are explained using unit  10  as an example, it should be appreciated that this method may be applied to operate suitable air conditioner unit. 
     According to alternative embodiments, method  200  may further be used to operate a packaged terminal air conditioner unit to achieve various alternative goals. For example, according to an alternative embodiment, the auxiliary fan may have a maximum flow rate or it may be desirable to select and arbitrary maximum flow rate which the auxiliary fan should not exceed. The maximum flow rate could be a flow rate where the auxiliary fan operates at its most energy efficient operating point or at a specific energy consumption level. 
     According to such an embodiment, the PTAC controller may be configured for determining that the target make-up air flow rate is greater than the maximum flow rate of the auxiliary fan. The controller may operate the auxiliary fan to urge the flow of auxiliary make-up air at the maximum flow rate. Finally, in order to meet the target make-up air flow rate, the controller may be configured for operating the indoor fan such that the primary flow rate is substantially equivalent to the target make-up air flow rate minus the maximum flow rate. In this manner, a predetermined operating threshold such as the maximum flow rate of the auxiliary fan may be maintained while the indoor fan is controlled as necessary to achieve the target make-up air flow rate. 
     It should be appreciated that such a control method may also be used to place limits on the operation of the indoor fan. More specifically, controller may set a maximum primary flow rate and auxiliary fan may be selectively operated to supply auxiliary make-up air at an auxiliary flow rate sufficient to meet the target make-up air flow rate. In addition, the predetermined operating threshold, whether it is selected for the indoor fan or the auxiliary fan, may be set for any particular purpose. For example, the auxiliary fan may be operated at a noise-limiting flow rate where the noise generated by the auxiliary fan reaches, but does not exceed a predetermined noise threshold. In this manner, when auxiliary fan begins to generate too much noise, the indoor fan can begin to supply the extra make-up air without the operation of the unit exceeding an undesirable noise level. 
     For example, according to one exemplary embodiment, the occupancy system may determine that there are three room occupants and that the target make-up air flow rate is about fifty cubic feet per minute (CFM) in order to satisfy guest comfort and government regulations. The controller may determine that the indoor fan is currently operating, and based on the indoor fan speed, may determine that the primary flow rate is about fifteen CFM. The controller will then calculate that the auxiliary flow rate which must be supplied by the auxiliary fan to achieve the target make-up air flow rate is about thirty-five CFM, and will adjust the speed of the auxiliary fan accordingly. By contrast, if the occupancy system determines that the room is unoccupied, e.g., such that the target make-up air flow rate is zero, the controller may pivot the vent door to the closed position and turn the auxiliary fan off to conserve energy. It should be appreciated that these are only exemplary manners of operating the packaged terminal air conditioner unit and are not intended to limit the scope of the present subject matter. 
     The construction of packaged terminal air conditioner unit  10 , control system  100 , and methods  200  described above provide a means for ensuring that indoor fan  42  and auxiliary fan  92  work together to ensure that the necessary amount of make-up air is provided while minimizing noise and energy usage. Thus, for example, if the target make-up air flow rate is higher than a maximum flow rate of the auxiliary fan or the auxiliary fan is operating at a noise level that is above a predetermined threshold, the indoor fan may operate to boost the make-up air flow rate, thereby reducing the load placed on the auxiliary fan. In addition, decreasing the auxiliary fan speed when the indoor fan is operating in a cooling mode can save energy while maintaining the target make-up air flow rate. Thus, coordinated operation of the indoor fan and the auxiliary fan may result in improved guest comfort, minimized energy usage, and the elimination of unnecessary noise from an auxiliary fan operating at higher than necessary speeds. 
     In this manner, unit  10  and auxiliary fan  92  provide the appropriate amount of air to meet government regulations and building codes, keeps the noise created by make-up air module  90  to a minimum, and maintains guest comfort and satisfaction at a maximum. In addition, by operatively connecting unit  10  with control system  100  and its associated occupancy system  104 , the target make-up air flow rate may be automatically adjusted to provide the required amount of make-up air without requiring a facility operator to make a manual change to the setting in each unit  10  when each guest or guests check into their room. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope 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 they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.