Method of Operating a Makeup Air Module of an Air Conditioner Unit

The present disclosure relates generally to air conditioner units, in particular air conditioner units having a fresh air make-up capability.

Air conditioners or air conditioner units are conventionally utilized to adjust the temperature in an indoor space. A typical type of air conditioner unit, commonly referred to as packaged terminal air conditioners (PTAC), may be utilized to adjust the temperature in, for example, a single room or group of rooms, or conditioned spaces, of a structure such as a dwelling or an office building. Such air conditioning units commonly include a reversible heat pump system with a closed refrigeration loop to heat or cool the indoor air. In some applications, the air conditioning unit introduces outdoor makeup air to provide fresh air ventilation to the conditioned space. Typically, the makeup air is introduced to a recirculating flow of indoor conditioned air prior to introduction of the combined flow to the conditioned space. The makeup air may be conditioned before it is introduced to the recirculating flow of indoor air, the combined flow of indoor air and outdoor makeup air may be conditioned before it is introduced to the conditioned space, or unconditioned outdoor makeup air may be introduced to a flow of conditioned indoor air before the combined flow is introduced to the conditioned space.

Under some circumstances, the cooling or heating capacity of the air conditioning unit is insufficient to condition the flow of outdoor makeup air to the desired indoor air characteristics, e.g., temperature. For example, outdoor air temperature may be too high, or too low, for the air conditioning unit to cool, or heat, to the desired temperature of the conditioned space. In another example, the air conditioning unit may be unable to properly condition the makeup air due to equipment malfunction or defect. In either case, continued introduction of outdoor makeup air to the conditioned space will negatively impact the temperature of the conditioned space. Accordingly, an air conditioning unit controlled to adjust or block the flow of makeup air when the conditioning capacity of the air conditioner is exceeded may be desirable.

Aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention.

In one exemplary aspect, an air conditioning system is provided including a refrigeration loop comprising an indoor heat exchanger and an outdoor heat exchanger, a compressor operably coupled to the refrigeration loop and being configured to urge refrigerant through the refrigeration loop, an indoor fan operable to urge an inlet flow of indoor air through the indoor heat exchanger, an auxiliary fan operable to urge an outdoor makeup air flow to combine with the inlet flow to produce a mixed discharge air flow, and a controller operably coupled to the compressor, the indoor fan, and the auxiliary fan. The controller is configured to operate the compressor at a first compressor speed, operate the indoor fan at a first indoor fan speed, operate the auxiliary fan at a first auxiliary fan speed, determine a temperature of the inlet flow of indoor air, determine a temperature of the mixed discharge air flow, determine that a temperature differential between the inlet flow temperature and the mixed discharge flow temperature deviates from a predetermined range, and implement a responsive action in response to determining the temperature differential deviates from the predetermined range.

In another exemplary aspect, a method of operating an air conditioning system is provided. The air conditioning system includes a refrigeration loop comprising an indoor heat exchanger, an outdoor heat exchanger, a compressor configured to urge refrigerant through the refrigeration loop, an indoor fan operable to urge an inlet flow of indoor air through the indoor heat exchanger, and an auxiliary fan operable to urge an outdoor makeup air flow to combine with the inlet flow to produce a mixed discharge air flow. The method includes operating the compressor at a first compressor speed, operating the indoor fan at a first indoor fan speed, operating the auxiliary fan at a first auxiliary fan speed, determining a temperature of the inlet flow of indoor air, determining a temperature of the mixed discharge air flow, determining that a temperature differential between the inlet flow temperature and the mixed discharge flow temperature deviates from a predetermined range, and implementing a responsive action in response to determining the temperature differential deviates from the predetermined range.

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.

Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present 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.

As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined and/or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,” “an,” and “the” include plural references unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,” “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and/or systems. For example, the approximating language may refer to being within a 10 percent margin, i.e., including values within ten percent greater or less than the stated value. In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V.

The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, 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 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, an air conditioner unitis provided. The air conditioner unitis a one-unit type air conditioner, also conventionally referred to as a room air conditioner or a packaged terminal air conditioner (PTAC). The unitincludes an indoor portionand an outdoor portion, 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. Although aspects of the present subject matter are described with reference to PTAC unit, it should be appreciated that aspects of the present disclosure may be equally applicable to other air conditioner unit types and configurations, such as single package vertical units (SPVUs) and split heat pump systems.

A housingof the unitmay contain various other components of the unit. Housingmay include, for example, a rear grilland a room frontwhich may be spaced apart along the transverse direction T by a wall sleeve. The rear grillmay be part of the outdoor portionin or adjacent to outdoor environment, and the room frontmay be part of the indoor portionin or adjacent to the conditioned space. Components of the outdoor portion, such as an outdoor heat exchanger, an outdoor fan, and a compressormay be housed within the wall sleeve. A fan shroudmay additionally enclose outdoor fan, as shown to direct the flow of outside air over or through the outdoor heat exchanger.

Indoor portionmay include, for example, an indoor heat exchanger, a blower fan or indoor fan, and a supplemental heating unit. These components may, for example, be housed behind the room front. Additionally, a bulkheadmay generally support and/or house various other components or portions thereof of the indoor portion, such as indoor fanand the supplemental heating unit. Bulkheadmay generally separate and define the indoor portionand outdoor portion, and accordingly separate the outdoor environmentfrom the conditioned space. According to some embodiments, indoor fanis a variable speed fan, for example, a variable centrifugal blower or fan as illustrated, for example in.

Outdoor and indoor heat exchangers,may be components of a sealed system or refrigeration loop, which is shown schematically in. Refrigeration loopmay, for example, further include compressorand an expansion device, both operably coupled to the loop. As illustrated, compressorand expansion devicemay be in fluid communication with outdoor heat exchangerand indoor heat exchangerto flow refrigerant therethrough as is generally understood. The compressoris configured to urge refrigerant to flow through the refrigeration loopin a refrigeration cycle. More particularly, refrigeration loopmay include various lines for flowing refrigerant between the various components of refrigeration loop, thus providing fluid communication therebetween. Refrigerant may thus flow through such lines from indoor heat exchangerto compressor, from compressorto outdoor heat exchanger, from outdoor heat exchangerto expansion device, and from expansion deviceto indoor heat exchanger. 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 loopmay include pentafluoroethane, difluoromethane, or a mixture such as R410a, although it should be understood that the present disclosure is not limited to such examples and rather that any suitable refrigerant may be utilized.

As is understood in the art, refrigeration loopmay be alternately 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, when refrigeration loopis operating in a cooling mode and thus performing a refrigeration cycle, the indoor heat exchangeracts as an evaporator and the outdoor heat exchangeracts as a condenser. Alternatively, when the refrigeration loopis operating in a heating mode and thus performs a heat pump cycle, the indoor heat exchangeracts as a condenser and the outdoor heat exchangeracts as an evaporator. The outdoor and indoor heat exchangers,may each include coils through which a refrigerant may flow for heat exchange purposes, as is generally understood.

According to an exemplary embodiment, compressormay be a variable speed compressor. In this regard, compressormay be operated at various speeds depending on the current air conditioning needs of the conditioned space, the demand from refrigeration loop, or under other conditions as determined by controller. For example, according to an exemplary embodiment, compressormay be configured to operate at any speed between a minimum speed, e.g., about 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., about 6000 RPM. Notably, use of variable speed compressorenables efficient operation of refrigeration loop(and thus air conditioner unit), minimizes unnecessary noise when compressordoes not need to operate at full speed, and ensures a comfortable environment within the conditioned space. According to some embodiments, the compressor speed may be increased or decreased, sometimes referred to as ramped up or ramped down, from a first speed to a second higher or lower speed at a predetermined compressor ramp up or ramp down rate of, for example, about 100 RPM/minute. The second speed may be a maximum compressor speed, e.g., about 6000 RPM or a minimum compressor speed, e.g., about 1500 RPM.

Specifically, according to an exemplary embodiment, compressormay be an inverter compressor. In this regard, compressormay include a power inverter, power electronic devices, rectifiers, or other control electronics suitable for converting an alternating current (AC) power input into a direct current (DC) power supply for the compressor. The inverter electronics may regulate the DC power output to any suitable DC voltage that corresponds to a specific operating speed of compressor. In this manner compressormay be regulated to any suitable operating speed, e.g., from 0% to 100% of the full rated power and/or speed of the compressor. This may facilitate precise compressor operation at the desired operating power and speed, thus meeting system needs while maximizing efficiency and minimizing unnecessary system cycling, energy usage, and noise.

In an exemplary embodiment illustrated in, expansion devicemay be disposed in the outdoor portionbetween the indoor heat exchangerand the outdoor heat exchanger. According to the exemplary embodiment, expansion devicemay be an electronic expansion valve (“EEV”) that enables controlled expansion of refrigerant, as is known in the art. According to alternative embodiments, expansion devicemay be a capillary tube or another suitable expansion device configured for use in a thermodynamic cycle.

More specifically, according to exemplary embodiments, the electronic expansion device EEVmay be configured to precisely control the expansion of refrigerant to maintain a desired temperature differential of the refrigerant across the evaporator (i.e., the outdoor heat exchangerin heat pump mode). In other words, electronic expansion devicethrottles the flow of refrigerant based on the temperature differential across the evaporator to ensure that the refrigerant is in the gaseous state entering compressor.

According to the illustrated exemplary embodiment, outdoor fanis an axial fan and indoor fanis a centrifugal fan. However, it should be appreciated that according to alternative embodiments, outdoor fanand indoor fanmay be any suitable fan type. In addition, according to an exemplary embodiment, outdoor fanand indoor fanare variable speed fans. For example, outdoor fanand indoor fanmay rotate at different rotational speeds, thereby generating different air flow rates. It may be desirable to operate fans,at less than their maximum rated speed to ensure safe and proper operation of refrigeration loopat less than its maximum rated speed, e.g., to reduce noise when full speed operation is not needed. Further, it may be desirable to separately control the operation of outdoor fanto adjust the flow of outdoor makeup airthrough the air conditioner unit.

According to the illustrated embodiment, indoor fanmay operate in refrigeration loopto encourage the flow of indoor air over or through indoor heat exchanger. Accordingly, indoor fanmay be positioned downstream of indoor heat exchangeralong the flow direction of indoor air and downstream of a heating unit, supplemental heating unit, to “pull” air over or through the indoor heat exchanger. Alternatively, indoor fanmay be positioned upstream of indoor heat exchangeralong the flow direction of indoor air and may operate to “push” air over or through indoor heat exchangerand supplemental heating unit.

In exemplary embodiments, heating unit or supplementary heating unitincludes one or more heater banks. Each heater bankmay be operated (i.e., energized) as desired to produce heat under the control of controller. The heater banksmay be electrically powered heat sources selectively energized to provide heat energy to the mixed air flow. In some embodiments as shown, three heater banksmay be utilized. Alternatively, however, any suitable number of heater banksmay be utilized. Each heater bankmay further include at least one heater coil or coil pass, such as in exemplary embodiments two heater coils or coil passes. Alternatively, other suitable heating elements may be utilized to provide supplemental heat using other energy sources.

The operation of air conditioner unitincluding compressor(and thus refrigeration loopgenerally), indoor fan, outdoor fan, heating unit, expansion device, auxiliary fan, and other components of refrigeration loopmay be controlled by a processing device such as a controller(e.g.,). In some embodiments, control panelmay include or be in operative communication with one or more user input devices, such as one or more of a variety of digital, analog, electrical, mechanical, or electro-mechanical input devices including rotary dials, control knobs, push buttons, toggle switches, selector switches, and touch pads. Additionally, air conditioner unitmay include a display, such as a digital or analog display device generally configured to provide visual feedback regarding the operation of unit. For example, displaymay be provided on control paneland may include one or more status lights, screens, or visible indicators, to communicate settings, operation status, or fault conditions with any system of the air conditioning unit. According to exemplary embodiments, user input devicesand displaymay be integrated into a single device, e.g., including one or more of a touchscreen interface, a capacitive touch panel, a liquid crystal display (LCD), a plasma display panel (PDP), a cathode ray tube (CRT) display, or other informational or interactive displays.

Air conditioner unitmay further include or be in operative communication with a processing device or a controllerthat may be generally configured to facilitate appliance operation. In this regard, control panel, user inputs, and displaymay be in communication with controllersuch that controllermay receive control inputs from user inputs, may display information using display, and may otherwise regulate operation of unit. In addition, controllermay receive signals sent or communicated by various sensors (e.g., inlet air temperature sensoror discharge air temperature sensor) for storage in a memory location or processing in a processor. The controllermay communicate a response or instruction to the various systems within unit. For example, signals generated or communicated by controllermay operate unit, including any or all system components, subsystems, or interconnected devices, in response to the position of user input devicesand other control commands. Control paneland other components of unitmay be in communication with controllervia, for example, one or more signal lines or shared communication busses. In this manner, Input/Output (“I/O”) signals may be routed between controllerand various operational components of unit.

As used herein, the terms “processing device,” “computing device,” “controller,” or the like may generally refer to any suitable processing device, such as a general or special purpose microprocessor, a microcontroller, an integrated circuit, an application specific integrated circuit (ASIC), a digital signal processor (DSP), a field-programmable gate array (FPGA), a logic device, one or more central processing units (CPUs), a graphics processing units (GPUs), processing units performing other specialized calculations, semiconductor devices, etc. In addition, these “controllers” are not necessarily restricted to a single element but may include any suitable number, type, and configuration of processing devices integrated in any suitable manner to facilitate appliance operation. Alternatively, controllermay be constructed without using a microprocessor, e.g., using a combination of discrete analog and/or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND/OR gates, and the like) to perform control functionality instead of relying upon software.

Controllermay include, or be associated with, one or more memory elements or non-transitory computer-readable storage mediums, such as RAM, ROM, EEPROM, EPROM, flash memory devices, magnetic disks, or other suitable memory devices (including combinations thereof). These memory devices may be a separate component from the processor or may be included onboard within the processor. In addition, these memory devices can store information and/or data accessible by the one or more processors, including instructions that can be executed by the one or more processors. It should be appreciated that the instructions can be software written in any suitable programming language or can be implemented in hardware. Additionally, or alternatively, the instructions can be executed logically and/or virtually using separate threads on one or more processors.

For example, controllermay be operable to execute programming instructions or micro-control code associated with an operating cycle of unit. In this regard, the instructions may be software or any set of instructions that when executed by the processing device, cause the processing device to perform operations, such as running one or more software applications, displaying a user interface, receiving user input, processing user input, etc. Moreover, it should be noted that controlleras disclosed herein is capable of and may be operable to perform any methods, method steps, or portions of methods as disclosed herein. For example, in some embodiments, methods disclosed herein may be embodied in programming instructions stored in the memory and executed by controller.

The memory devices included or coupled to controllermay also store data that can be retrieved, manipulated, created, or stored by the one or more processors or portions of controller. The data can include, for instance, data to facilitate performance of methods described herein. The data can be stored locally (e.g., on controller) in one or more databases and/or may be split up so that the data is stored in multiple locations. In addition, or alternatively, the one or more database(s) can be connected to controllerthrough any suitable network(s), such as through a high bandwidth local area network (LAN) or wide area network (WAN). In this regard, for example, controllermay further include a communication module or interface that may be used to communicate with one or more other component(s) of unit, controller, an external appliance controller, or any other suitable device, e.g., via any suitable communication lines or network(s) and using any suitable communication protocol. The communication interface 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.

Referring to, a vent aperturemay be defined in bulkheadfor providing fluid communication between indoor portionand outdoor portion. In particular, vent aperturefluidly couples the outside portionwith plenumand indoor fanwhich is in fluid communication with both the plenumand the conditioned space. Vent aperturemay be utilized in an installed air conditioner unitto allow outdoor air to mix with indoor air (i.e., recirculating indoor air) in the plenumadjacent to indoor fan, forming a mixed discharge airflowfor discharge into the conditionedspace through the discharge vent. In this regard, in some cases it may be desirable to allow fresh outside or outdoor air (i.e., “makeup air”) to flow into the conditioned space in order, e.g., to meet government regulations, to compensate for negative pressure created within the conditioned space, etc. In this manner, according to an exemplary embodiment, makeup airmay be provided into the space through fan assembly(described below), vent aperture, plenum, and discharge ventas required or when desired.

As shown in, a vent door or dampermay be pivotally mounted to the bulkheadproximate to vent apertureto open and close vent aperture. More specifically, as illustrated, damperis pivotally mounted to the indoor facing surface of bulkheadand pivotable towards indoor portion. Vent doormay open to a plenumformed at the indoor facing side of bulkhead. The auxiliary fanurges a flow of outdoor make-up airinto the plenumto combine with the recirculating flow of indoor air, i.e., inlet air flow, to produce a mixed discharge airflowthat is directed through the discharge ventand into the conditioned space. The recirculating flow of indoor airand the mixed discharge airfloware motivated to flow by the action of indoor fanand the outdoor fan.

Dampermay be configured to pivot, i.e., is movable, between a first, closed position () where damperprevents air from flowing between outdoor portionand plenum, and a second, open position where damperis in an open position (as shown in) and allows make-up air to flow into the plenum. According to the illustrated embodiment (), dampermay be pivoted between the open and closed position by an electric motorcontrolled by controller, or by any other suitable method. Intermediate positions, between the fully closed and the open positions are provided by the electric motorin some embodiments. Other configurations of the vent apertureand dampermay be used to selectively control the flow of make-up airinto the plenum.

Referring now to, an auxiliary fan assembly, fan assembly, will be described according to an exemplary embodiment of the present subject matter. According to the illustrated embodiment, fan assemblyis generally configured for urging the flow of makeup airthrough vent apertureand into the plenumfor combination with the flow of inlet airfor discharge as a mixed discharge airflowinto the conditioned spacewithout the assistance of an auxiliary sealed system. In some embodiments, fan assemblycould be used in conjunction with a make-up air module including an auxiliary sealed system (not shown; similar to refrigeration loop) for conditioning the flow of outdoor makeup air. As illustrated in, fan assemblyincludes one auxiliary fanfor urging a flow of outdoor makeup airthrough a fan duct, through vent aperture, to indoor fan. In other embodiments, more than one auxiliary fanmay be used, or other configurations of fan assemblyare provided.

According to the illustrated embodiment of, auxiliary fanis an axial fan positioned at an inlet of fan duct, e.g., upstream from vent aperture. In embodiments, the auxiliary fanmay be a variable speed fan, with the fan speed controlled by the controller. However, it should be appreciated that any other suitable number, type, and configuration of fan or blower could be used to urge a flow of make-up air according to alternative embodiments. In addition, auxiliary fanmay be positioned in any other suitable location within air conditioner unit, and auxiliary fanmay be positioned at any other suitable location within or in fluid communication with fan duct. The embodiments described herein are exemplary and are not intended to limit the scope of the present subject matter.

Referring now to, operation of unitwill be described according to an exemplary embodiment. More specifically, the operation of components will be described during a cooling operation and a heating operation of unit. Moreover, although operation of unitis described below for the exemplary packaged terminal air conditioner (PTAC) unit, it should be further appreciated that aspects of the present subject matter may be used in any other suitable air conditioner unit, for example single package vertical units (SPVUs).

As illustrated, room frontof unitgenerally defines an intake ventand a discharge ventfor use in circulating a flow of indoor air (indicated by arrows) throughout a conditioned space. In this regard, indoor fanis generally configured for drawing in inlet airthrough intake ventand urging the flow of air over or through indoor heat exchangerbefore discharging the inlet airout of discharge vent. According to the illustrated embodiment, intake ventis positioned proximate to the bottom of unitand discharge ventis positioned proximate to the top of unit. However, it should be appreciated that according to alternative embodiments, intake ventand discharge ventmay have any other suitable size, shape, position, or configuration.

In some embodiments, auxiliary fandraws makeup airfrom an outdoor or outside environmentto provide fresh air (i.e., outdoor air) to the conditioned space. As illustrated in, auxiliary fandraws makeup airfrom the outdoor environmentand directs the flow to fan assemblyand fan duct. Fan ductdirects the flow of makeup airto the bulkheadand through the vent aperturewhen vent dooris in the open position (). The flow of makeup air continues to the plenumwhere it mixes with recirculating indoor air, inlet air, to form a mixed air flowfor discharge into the conditioned space. In some embodiments, makeup airis introduced to the flow of inlet airbefore the inlet airflows over or through the indoor heat exchanger. In other embodiments, for example the illustrative embodiment shown, the makeup airis introduced to the flow of inlet airafter the inlet airhas flowed over or through the indoor heat exchanger. In either case, the mixed flowis discharged to the conditioned space.

During a cooling cycle, refrigeration loopis generally configured for urging relatively cold refrigerant through indoor heat exchangerin order to lower the temperature of the flow of indoor air, inlet air, before discharging it back into the conditioned space. In this configuration, the indoor heat exchangeris operating as an evaporator and the refrigerant absorbs heat energy from the air flow over or through the indoor heat exchanger. Heat is rejected at the outdoor heat exchanger, which is operating as a condenser.

In embodiments, the flow of inlet airpasses over or through the indoor heat exchangerprior to being combined with outdoor make-up airto form a mixed airflowthat is discharged into the conditioned space. Specifically, during a cooling operation, controllermay be provided with a cooling target temperature, e.g., as set by a user for the desired room temperature (i.e., temperature in the conditioned space). In general, components of refrigeration loop, outdoor fan, indoor fan, auxiliary fan, and other components of unitoperate to continuously cool the flow of indoor air, and mix the outdoor make-up air with the cooled flow of indoor air (i.e., conditioned air), until the target temperature is reached and the cooling cycle ceases. If the room temperature reaches an upper limit temperature, for example a predetermined offset from the cooling target temperature, the cooling cycle may begin again. In embodiments providing a flow of make-up airto the conditioned space, for example using auxiliary fan, the auxiliary fanmay continuously operate independently of the cooling cycle.

During a heating cycle, the flow of refrigerant in the refrigeration loopis reversed from that of the cooling cycle as known in the art. To achieve this, a reversing valve is fluidly coupled to the refrigeration loopand selectively movable between a first position corresponding to the cooling mode and a second position corresponding to the heating mode. For example, relatively warm refrigerant flows from the compressorinto the indoor heat exchanger, which is operating as a condenser, to reject heat into the conditioned space. In some embodiments including a make-up air module having an auxiliary sealed system as described above, the auxiliary sealed system may be reversible to act as a heat pump to produce a heating cycle for the makeup air. In this case, the makeup air is heated prior to introduction to the inlet airin the plenum.

In some embodiments, a supplemental heat source is provided to augment the heating capacity of the air conditioning unit. For unitsused in anticipated cold environments, a supplemental heat source may be included to facilitate adequate heating for the conditioned space. For example, heater bankmay include one or more heater coilsconfigured to provide supplemental heat energy to the flow of recirculating inlet air. In an exemplary embodiment, heater coilsmay be electric resistance heat sources controlled by controller. In other embodiments, other supplemental heat sources may be used.

In order to facilitate operation of refrigeration loopand other components of unitin a method in accordance with this disclosure, unitmay include sensors for detecting conditions of the inlet air flowand the discharge flow of mixed airsupplied to the conditioned spaceby the unit. These conditions can be fed to controllerwhich may make decisions regarding operation of unitto rectify undesirable conditions or to otherwise condition the flow of mixed airinto the conditioned space. For example, as best illustrated in, unitincludes an inlet temperature sensorwhich is positioned upstream (i.e., in a direction against the indoor air flow) from the indoor heat exchangerto detect the temperature of the inlet air flowas it enters the room front, i.e., before conditioning at the indoor heat exchanger. In addition, unitincludes a discharge air temperature sensorwhich is positioned in the discharge flow of mixed air. The inlet and discharge air temperature sensors,are operatively connected to the controllerto communicate temperature signals proportional to the sensed temperatures of the inlet airand the discharge air, respectively.

Controllerprocesses the signals from inlet and discharge temperature sensors,and operates the components of unitto maintain conditions of a flow of mixed airwithin a prescribed range. For example, in an embodiment, the controller receives signals from inlet and discharge temperature sensors,, and subtracts one from the other. In an embodiment, the controllerconverts signals from inlet and discharge temperature sensors,to corresponding temperatures, and subtracts one temperature from the other.

In the embodiment illustrated, the controllerdetermines a temperature differential formed by subtracting the mixed discharge air flow temperature from the inlet air flow temperature. In embodiments, air conditioning unitis reversible, that is the refrigeration loopmay be operated in a cooling mode to cool the conditioned space or may be operated in a heating mode to heat the conditioned space. The controllerwill use different predetermined temperature differentials in determining the operating condition of the air conditioning unit.

For example, in a cooling mode, the inlet airis drawn in through inlet ventwith the inlet air temperature sensorsensing the inlet air temperature. The inlet airflows through the air conditioning unitcomponents as described above. Discharge air, comprising inlet airand makeup air, is discharged through discharge vent. Discharge air temperature is sensed by discharge air temperature sensor. Controllerprocesses the received signals from the inlet and discharge temperature sensors,and determines a temperature differential equivalent to the discharge air temperature subtracted from the inlet air temperature. Under proper operating conditions in the cooling mode, the temperature of the discharge airis lower than the temperature of the inlet air. Accordingly, in a properly operating cooling mode, the differential is equal to or greater than zero. For example, the cooling mode differential may be between zero and 10 degrees Fahrenheit (° F.), or for example 5 OF. If the temperature differential is less than 0° F., i.e., the mixed discharge air temperature is greater than the inlet air temperature, the controllerdetermines that the temperature differential deviates from the prescribed range for the cooling mode differential and the controllerimplements a responsive action.

Alternately, in a heating mode, the inlet air temperature sensorand the discharge temperature sensorsense the respective air temperatures and communicate signals corresponding to the temperatures to the controller. Controllerprocesses the received signals and determines a temperature differential equivalent to the discharge air temperature subtracted from the inlet air temperature. Under proper operating conditions in the heating mode, the temperature of the discharge airis higher than the temperature of the inlet air. Accordingly, in a properly operating heating mode, the differential is less than or equal to zero. For example, the heating mode differential may be between zero and −10 degrees Fahrenheit (° F.), or for example −5° F. If the heating mode temperature differential is greater than 0° F., i.e., the inlet air temperature is greater than the mixed discharge air temperature, the controllerdetermines that the temperature differential deviates from the prescribed range for the heating mode differential and the controllerimplements a responsive action.

In cases where the temperature differential deviates from the prescribed range, for either the cooling mode or the heating mode, the responsive action implemented by the controllerincludes one or more of increasing the speed of the compressor, decreasing the flow rate of outdoor makeup air by decreasing the speed of the auxiliary fan, or turning off (i.e., de-energizing) the auxiliary fanand closing the vent door. In addition to the above responsive actions common to both modes, an additional responsive action in the heating mode includes energizing the supplemental heat source(i.e., energizing one or more heater coilsin the heater bank).

Each of the responsive actions will lessen the effect that the temperature of the outside make up airwill have on the conditioned spaceif the air conditioning unit is unable to adequately condition the makeup air. In some cases, temperature extremes in the outdoor environmentexceed the capacity of the properly functioning air conditioning unit. In other cases, a fault or defect in the operation of the air conditioning unit may negatively impact the ability of the unitto properly condition the makeup air. Regardless of the reason for inadequate conditioning of the makeup air, continued introduction of the makeup air would lead to occupant discomfort and dissatisfaction, and possibly damage to the structure of the conditioned space.

Now that the construction of air conditioner unitand the configuration of controlleraccording to exemplary embodiments have been presented, an exemplary methodof operating a packaged terminal air conditioner unit will be described. Referring to, methodincludes, at step, operating a compressor in an air conditioner unitat a first compressor speed. In this regard, continuing from the above example, the controlleris in operative communication with the compressorand may operate the compressorat a default speed measured in revolutions per minute (RPM). The default speed may have been determined or calculated to produce sufficient cooling capacity under a particular set of conditions. As above, the compressor urges the flow of working fluid, or refrigerant, through the refrigeration loopshown schematically in.