Outdoor air controls for packaged HVAC systems

A heating ventilating and cooling (HVAC) system includes an outdoor air chase having a first end and a second end. The second end of the outdoor air chase is fluidly coupled to a condenser compartment at a location to receive outside air from the condenser compartment and the first end is fluidly coupled to the return air compartment. The outdoor air chase has a conduit through the outdoor air chase. The system includes a configurable flow regulating plate disposed in the outdoor air chase member across the conduit or otherwise across the outdoor airflow that has a plurality of discharge apertures. Initially, the plurality of discharge apertures is covered by a plurality of knockout panels. Each panel is removably secured to the plate. In installation, the installer removes as many of the knockout panels as required for a desired flow of outdoor air. Other systems and methods are presented.

FIELD

This application is directed, in general, to heating, ventilation, and cooling (HVAC) systems, and more specifically, to outdoor air controls for packaged HVAC systems.

BACKGROUND

Heating ventilating and cooling (HVAC) systems come in many sizes and shapes. Some HVAC systems may be installed in a generally vertical format. For example, vertical packaged HVAC systems or packaged terminal air conditioners are self-contained HVAC systems that are commonly used in apartment buildings, high rises, and hotels. The systems are designed to go through a wall, often using a wall sleeve. One example is the MAGIC-PAK® brand system from Allied Air Enterprises LLC. In other situations, a horizontal HVAC system may be used. In any event, while HVAC systems have been used for a long time, improvements are still desired.

SUMMARY

According to an illustrative embodiment, a packaged heating ventilating and cooling (HVAC) system includes a cabinet having a condenser compartment at a bottom portion, a return air compartment at a first portion, and a condenser discharge air compartment between the condenser compartment and the return air compartment. The system further includes a fan panel proximate a bottom of the condenser discharge air compartment and a top of the condenser compartment and an outdoor air chase. The outdoor air chase has a top end and a bottom end. The bottom end of the outdoor air chase is fluidly coupled to the condenser compartment at a location to receive outside air from the condenser compartment. The top end of the outdoor air chase is fluidly coupled to the return air compartment. The outdoor air chase has a conduit through the outdoor air chase.

The system further includes a configurable flow regulating plate disposed in the outdoor air chase member across the conduit. The configurable flow regulating plate includes a plate having a plurality of discharge apertures. In an initial position before installation, the plurality of discharge apertures is covered by a plurality of knockout panels that are removably secured to the plate.

According to an illustrative embodiment, a method of installing a vertical packaged heating ventilating and cooling (HVAC) system includes providing the vertical packaged heating ventilating and cooling (HVAC) system. The system includes a cabinet having a condenser compartment at a bottom portion, a return air compartment at a top portion, and a condenser discharge air compartment between the condenser compartment and the return air compartment.

The method further includes providing an outdoor air chase having a conduit through the outdoor air chase and fluidly coupling the outdoor air chase between the condenser compartment and the return air compartment. The method further includes providing a configurable flow regulating plate. The configurable flow regulating plate includes a plate having a plurality of discharge apertures, and wherein in an initial position before installation the plurality of discharge apertures is covered by a plurality of knockout panels that are removably secured to the plate. The method also includes removing one or more of the plurality of knockout panels and securing the configurable flow regulating plate in the conduit of the outdoor air chase.

According to still another illustrative embodiment, a heating ventilating and cooling (HVAC) system includes a cabinet having a condenser compartment, a return air compartment, and a condenser discharge air compartment between the condenser compartment and the return air compartment, and includes a fan panel proximate the condenser discharge air compartment and the condenser compartment. The HVAC system further includes an outdoor air chase member having a first end and a second end. The second end of the outdoor air chase is fluidly coupled to the condenser compartment at a location to receive outside air from the condenser compartment. The first end of the outdoor air chase is fluidly coupled to the return air compartment, and the outdoor air chase has a conduit through the outdoor air chase. The HVAC system also includes a configurable flow regulating plate disposed in the outdoor air chase member across the conduit. The configurable flow regulating plate includes a plate having a plurality of discharge apertures, and wherein, in an initial position before installation, the plurality of discharge apertures is covered by a plurality of knockout panels. Each knockout panel of the plurality of knockout panels is removably secured to the configurable flow regulating plate. Other systems, methods, and devices are disclosed herein.

DETAILED DESCRIPTION

The ability to vary the outdoor air introduced in many dwellings is important because many dwellings today are being substantially sealed to maximize efficiency. Outdoor air is introduced to promote healthy living as part of the operation of a packaged heating, ventilation, and air cooling (HVAC) when installed. The illustrative embodiments of the disclosure control the outdoor air delivered to provide the desired amount of outdoor air, balancing with system performance and electrical efficiency. In an illustrated embodiment, a configurable flow regulating plate allows the outdoor air flow to be adjusted inside the primary HVAC unit and may allow for control of the amount of air that infiltrates the space for a given sized HVAC system. This may facilitate introduction of the required outdoor air, e.g., amount required under ASHRAE 62.1/62.2. The configurable flow regulating plate may control the amount of outdoor air from 2% to 15% of rated system air in increments as low as 2%, or even lower in some embodiments. In one illustrative embodiment, a mechanical enclosure that is located inside the HVAC system has physical forms, or knockouts, on one portion that can be removed to provide the desired outdoor airflow into a conditioned space of the dwelling.

The configurable flow regulating plate that allows the outdoor air flow to be adjusted inside the primary HVAC unit may be used on a vertical HVAC system or a horizontal system or another orientation. For illustration purposes, a vertical packaged HVAC system is presented, but those skilled in the art should understand that a horizontal unit or one with another orientation may utilize the configurable flow regulating plate in an analogous manner. Moreover, in some embodiments, a the configurable flow regulating plate is part of an outdoor air chase that extends into numerous compartments, but in some illustrative embodiments, the configurable flow regulating plate may be otherwise mounted to be in the outdoor airflow path in any manner.

Referring now to the figures and initially and primarily toFIG.1, a packaged heating, ventilation, and air cooling (HVAC) unit or system100is presented according to one illustrative embodiment. The packaged HVAC unit100, however, includes an outdoor air chase assembly that allows for outdoor air to be introduced at varying flow rates as desired.

The packaged HVAC unit100is mounted against an exterior wall104through which the packaged HVAC unit100gains access to outside air. A supply duct opening108is visible from a top portion112. As used herein the terms “top,” “side,” and “bottom” are for the orientations shown in the figures and are not necessarily meant to be limited to gravitation orientation. A return duct opening116is also on the top portion112. The unit100rests on a floor or support120. The packaged HVAC unit100may be used in apartments, high rises, or other locations. An exterior cut (not explicitly shown) is made in the exterior wall104to allow access to the outdoor air by a wall sleeve (not shown).

The packaged HVAC unit100may be formed with a cabinet122having one or more front panels124. For the orientation shown, the packaged HVAC unit100has the top portion112, a bottom portion128, a first side132, and a second side136.

In some installations, depending on the applicable code or user desires or requirements, a certain amount of outdoor air is introduced through the packaged HVAC unit100into the conditioned space of the residential or commercial unit that the HVAC unit100serves. As building envelopes get tighter, bringing air inside from the outside in a controlled manner is increasingly important. The outdoor air introduced is mixed with the recirculating air from the conditioned space and returned again to the living space, or conditioned space. The embodiments herein may allow adjustment of the airflow from the outside in an efficient manner and provide for easy installation. The outside air is introduced through an outdoor air chase (see e.g.,200inFIG.2) into the blower compartment, or return air compartment (see228inFIG.2). In one embodiment, a configurable flow regulating plate (see, e.g.,300inFIG.5) covers the top of an outdoor air chase and can readily have different panels (knockouts panels or punches or forms) removed to expose openings and thereby adjust the airflow rate through the configurable flow regulating plate. For each packaged unit or system, a correlation may be done so that each knockout panel removed will give a certain airflow rate (see, e.g., Table A further below).

Referring now primarily toFIG.2, the packaged HVAC unit100with the plurality of front panels124removed is shown. The packaged HVAC unit100has, at the bottom portion128, a unit base140, which is a bottom of a condenser compartment144. The unit base140may be formed from a plastic base or metal or other material that is at least semi-rigid. The unit base140forms the bottom of the condenser compartment144. A condenser coil (not shown but well known) is, in the assembled position, in the condenser compartment144, but has been removed from the figure for clarity. The track148where the condenser coil would mount in this illustrative embodiment is shown.

The condenser coil is typically horseshoe-shaped and mounted on or at the track148. For clarity, the back area152is the portion that has a back opening (not explicitly shown) and is open to the outside. The back area152is completely open or may be a solid panel with a partial opening. The opening in the back area152is typically covered by a louver (not explicitly shown). A unit frame160is visible in this view and has a front portion164. A compressor (not shown) is typically mounted on a mount168. At a middle portion172(within 25% of being equidistant between the top portion112and the bottom portion128) is a shelf176, or fan panel, where the condenser fan (not explicitly shown but well known) is attached. The fan panel176has a fan aperture178and a chase opening182, or aperture.

The condenser fan draws air from under the fan panel176through the outdoor coil of the condenser and discharges the air above the fan panel176from where the air is directed to the outside. A portion of the air in the condenser compartment144may be pulled to supply outside air into the conditioned space as may be desired to meet regulatory requirements as previously mentioned. A fan discharge compartment or area, or middle section180, just above the fan panel176is where air coming off the condenser coil is received and is forced outside after having helped cool the condenser.

A support brace184forms part of the frame160and helps tie the unit100together. A drain pan188is positioned proximate the support brace184and, in a fully assembled position, is under the evaporator (not explicitly shown, but well known). In this view, a side panel192on second side136is visible. A tray196is coupled on a left portion (for the orientation shown) on or proximate a shelf220(or member or intermediate floor) and allows the manufacturer to assemble and mount an outdoor air chase200to a left panel204on the first side132(FIG.1) and back panel152.FIG.2is an exploded view with respect to the location of the tray196and the outdoor air chase200. The tray196also provides a place for an optional damper assembly (seeFIGS.7and8) to be attached and other possible accessories.

The packaged HVAC unit100is formed with the cabinet122. The cabinet122forms at least three compartments: the condenser compartment144, condenser discharge air compartment180, and the return air compartment228.

The outdoor air chase200may be formed with a first aperture202at a top and a second aperture203at a bottom of the outdoor air chase200. The outdoor air chase200may have a folded over flange208. The outdoor air chase200is positioned in an aperture212through the tray196. The flange208formed a top210of the chase200may facilitate placement of the air chase200and provide a location for securing other members. A portion of the outdoor air chase200extends through an aperture216through in the member or shelf220, which is coupled with or proximate the drain pan188. The first end, or top,210of the outdoor air chase200communicates with a return air compartment228where there is reduced pressure (less than ambient or prevailing static pressure). The second end, or bottom,232of the outdoor air chase200extends through the fan panel176and into the condenser compartment144or is otherwise fluidly coupled to the condenser compartment144. To be clear,FIG.2is an exploded view with respect to the outdoor air chase's200position.

Referring now primarily toFIG.3, which is a detail fromFIG.2, the tray196is fastened to the member220, or intermediate floor, when in the assembled position. The outdoor air chase200may be secured in the aperture212in the manufacturing process with tabs and fasteners, welds, adhesives, or other attachment techniques. The combined outdoor air chase200and the tray196form an assembly236. That assembly236is installed in the member or floor220. In the assembled position, a portion of the outdoor air chase200extends down to the aperture182of the fan panel176or is otherwise fluidly coupled to the condenser compartment144. A gasket304(FIG.9) is disposed proximate the bottom end, or second end232of the outdoor air chase200, and a bug mesh316(FIG.9) covers the bottom end, or second end232, of the outdoor air chase200. The outdoor air chase200has a conduit238through the outdoor air chase200that allows air to flow through the outdoor air chase200.

Referring now primarily toFIG.4, a top view of the HVAC packaged unit100is shown with the top panel(s) and certain components, e.g., evaporator, removed for clarity. The drain pain188under the evaporator is shown. In this view, a feature240that allows one to snap in an overflow drain switch is visible. If the field drain gets clogged, the overflow drain switch mounted to feature240turns off the unit100. If water overflows, the water will exit through water overflow channel244, which allows the water to spill over. Filter guides248, or rails, are visible. The filter guides248direct the indoor air filter as it slides into position. An L-shaped panel, or division panel,252, which has portions256and260, is shown towards the second side136. The bottom and back of the return air compartment228(FIG.2) are formed by the L-shaped panel252. The L-shaped panel252is shown more clearly inFIG.9.

The outdoor air chase200is angled as seen from above (plan view) in order to accommodate the horseshoe-shape of the outdoor condenser coil (not explicitly shown, but see track148inFIG.2). The angled shape, or wedge shape, of the outdoor air chase200uses more space on one end to provide a bigger opening than would otherwise exist. The angle goes from a wider portion proximate the back panel to a narrow portion near the front portion, and the outside air chase200may reduce in size by between 40 and 60 percent. In some embodiments, the packaged unit100draws air into the outdoor air chase200without that air going through the condenser coil; in that way, the air going to the outdoor air chase200is not heated by the condenser coil.

The flange208on the top210of the outdoor air chase200provides support and a sealing surface to seal against the tray196. There can be a gasket (see364inFIG.9) over the flange208; the gasket is over the flange208and the surface of the shelf176or tray196. The L-shaped panel252may have insulation on it—fiberglass insulation that acts as a gasket. There may also be a cover (see, e.g.,328inFIGS.12and408inFIG.13) over the top210of the outdoor air chase200and a gasket to seal the outdoor air chase.

Referring now primarily toFIG.5, a perspective view of an illustrative embodiment of the packaged HVAC system100with the left side and on or more panels (124inFIG.1) removed and certain components, e.g., evaporator and condenser, removed for clarity is presented. The system100is shown with the outdoor air chase200in the assembled position with those components removed. The condenser coil compartment144is shown at the bottom. The fan discharge area or middle section180is shown. An insulated wire chase264is visible, and the return air compartment (or evaporator compartment)228at the top is visible. An indoor blower assembly268is shown in the return air compartment228. Evaporator coils (not shown) would be approximately where272is shown; the evaporator sits vertically on the drain pan188in some embodiments. Heating elements are not visible but are mounted near the discharge of the indoor blower assembly268.

The figure presents a number of airflow patterns of the HVAC unit100. Outdoor air276goes through an opening in the exterior wall and then is pulled upward (for orientation shown). A portion of the outdoor air276goes into outdoor air chase200and then goes as chase air280into the lower pressure air in the return air compartment228and mixes with re-circulated air or return air284from the conditioned space. The return air284is pulled through a return duct or aperture116. The mixed air288is then moved by the indoor air blower assembly268across the evaporator coil or heaters and then out through a supply duct or aperture108as conditioned air292.

A configurable flow regulating plate300is disposed over the outdoor air chase200proximate the top210and regulates the flow of air through the outdoor air chase200. The configurable flow regulating plate300will be explained in more detail further below.

At the bottom or second end232of the outdoor air chase200is a gasket304that seals between the bottom232of the outdoor air chase200around the second aperture203and the fan panel176, or shelf. In one embodiment, a handful of fasteners308, e.g., screws, tabs, or other fasteners, are used to attach the fan panel176. Optional flanges312(FIG.3) of the air chase200are over the gasket304in some embodiments and under the gasket304in other embodiments. The gasket304prevents air leakage that might occur from laser etching or any other slits. The gasket304also prevents air and water from leaking into the fan discharge area180, or compartment.

As shown inFIG.6, a screen, or bug mesh316may go under the gasket or under the flange312and cover aperture182(FIG.3) or the second aperture203to keep bugs and particulate out of the airflow that enters the outdoor air chase200. The gasket304seals unwanted outdoor air from leaking through. The bug mesh316helps to avoid insect infestation or other debris that might otherwise enter.

Continuing to refer primarily toFIG.6, the packaged HVAC unit100is shown with the front and top panels removed and with various internal components removed for clarity. The gasket304and screen, or bug mesh316are shown clearly in this view. In this embodiment, the tray196on the shelf220is shown as a rectangular tray but other shapes might be used. The outdoor air chase200goes through the shelf220and the tray196with the chase's flanges208against a top of the tray196. The gasket304goes over the bottom232of the outdoor air chase200and is coupled with an adhesive backing, fastener, or other technique. The gasket304helps form a seal between the outdoor air chase200and the fan panel176.

The outdoor air chase200is held against the gasket304based on the sizing of the air chase200from the top; that is the outdoor air chase200is sized and configured to press down on the gasket304in the assembled positioned. If someone needs to service the outdoor air chase200, one can pull the air chase200out from the top. Again, item316is a debris screen, or mesh, or bug screen.

Referring primarily toFIGS.6and12, the configurable flow regulating plate300, or knockout lid, helps regulate the airflow through the outdoor air chase200. The configurable flow regulating plate300includes a plurality of punch-out members320, or knockout panels/members, that may be selectively removed to vary the air flow through the configurable flow regulating plate300. Thus, for minimal flow, one knockout panel320is removed, and for maximum flow all the knockout panels320are removed. In manufacturing, starting with a plate that is used to form the configurable flow regulating plate300, the knockout members320can be cut with a laser, punch, angle grinder, saw, or other cutting device except for one or more tabs on each holding the knockout panel in place but allowing the panel to be readily removed by an installer. For example, in one illustrative embodiment, 95% of a rectangle is cut, but 5% is left as a tab. The tabs hold the knockout member320over what would otherwise be an open airflow aperture in the configurable flow regulating plate300. The tabs can be released, or “popped” or knocked free, with a screwdriver or other hand tool to open up a selected number of airflow apertures through the configurable flow regulating plate300. Again, the number of opened apertures determines the flow rate (see, e.g., Table A below).

The configurable flow regulating plate300is formed with a plurality of fastener apertures324for fasteners, e.g., screws, to go through. In some embodiments, the configurable flow regulating plate300is mounted on top of a cover plate328, which is typically solid. The configurable flow regulating plate300may have flanges that are angled up from other portions of the flow regulating plate300. The cover plate328has flanges that are angled up from the other portions of the cover plate328. A plurality of end tabs332may be formed on one end of the configurable flow regulating plate300that mate with slots334(FIG.7) on the tray196, or back panel, to hold the configurable flow regulating plate300in place with respect to the cabinet122; the tabs332are used in the assembly process and later fasteners may be used at more locations to secure the configurable flow regulating plate300in place relative to the cabinet122. The fastener apertures324may be the same or different sizes for different sized fasteners. When repairing in the field and the flow regulating plate300needs to be removed, one does not have to remove all the fasteners with this illustrative embodiment. One can just take fasteners out of the four smaller apertures. The rest of the fasteners would hold the remaining portion of the assembly of the air chase200together. When repairing in the field and the outdoor air chase needs to be removed, one would have to remove all the fasteners.

Referring now primarily toFIGS.7and8, an alternative embodiment is presented of the flow regulation scheme. In this illustrative embodiment, the arrangement is the same as that presented inFIG.6, except the tray196inFIG.7is formed with a dampener aperture340through the tray196that is sized and configured to receive a controllable damper344(FIG.8). In some jurisdictions, the authorities want the outdoor air opening to only be open when the blower is on. The authorities require a mechanical damper to do that. The tray196covers the top of the outdoor air chase200and requires the airflow to go through the dampener aperture340. The dampener aperture340is then controlled as desired by the controllable damper344.FIG.8shows an embodiment as a round damper, but other shapes may be used as well as one skilled in the art would appreciate.

The controllable damper344may be associated with a controller that can open and close the damper344. For example, the controller may make the controllable damper344open only when the blower is active. The damper aperture340and the damper344could take other shapes and sizes as one skilled in the art would appreciate. One example of the controllable damper344is Honeywell ARD5TZ. In one embodiment, the controllable damper344is binary (open or closed) and relies on a configurable flow regulating plate300(FIG.6) to adjust the flow rate. In still another illustrative embodiment, the controllable dampener344can assume a plurality of positions that control the flow rate through it.

The controllable damper344has a first end348and a second end352. When assembled, the second end352is inserted into the dampener aperture340. The controllable dampener344has a gate or valve that controls the flow through it. Again, the controllable dampener344may be binary (on or off) or may have intermediate settings to control the flow rate.

Referring now primarily toFIG.9, a schematic, exploded, perspective view of a portion of the packaged HVAC unit100is presented according to one illustrative embodiment. The outdoor air chase200is shown in two parts,356,360. In this view, one may see a top gasket, or first gasket364, that goes between the top210of the outdoor air chase200and the configurable flow regulating plate300. The flange208receives the top gasket364, and the configurable flow regulating plate300is fastened to the flange208. The bottom gasket, or second gasket304, which is shown inFIG.10, is supported by the fan panel176, or shelf. The second gasket304is formed with aperture or opening368(FIG.10) to allow for airflow into the outdoor air chase200. The gaskets364and304may be water proof and may be formed from rubber, plastic, or any suitable gasket material. The gasket304is on top of the fan panel176and the fasteners hold the second gasket304in place while the outdoor air chase200is applied. The gasket304and bug mesh316are ultimately held secure in one illustrative embodiment by being sandwiched between the bottom232of the outdoor air chase200and the fan panel176.

The screen, or bug mesh316, which is shown inFIG.11, may cover aperture182(FIG.3) formed through the fan panel176or aperture203in the outdoor air chase200. The bug screen316is typically a metal mesh or plastic grid. Unlike the second gasket304, the bug mesh316is not formed with a central aperture, but an integral unit to cover the entire opening203to the outdoor air chase200. The bug mesh316is attached with fasteners, e.g., screws, or by adhesive, spot-welding, or other attachment techniques, to the panel.

Once installed, the outdoor air chase200applies pressure on the gasket304and the mesh screen316, and holds it all in place. The gasket304has an adhesive to keep the gasket304in place during assembly. The gasket304goes onto the bug mesh316.

In one alternative embodiment of an outdoor air chase for use with a packaged HVAC system, which is analogous to system100in many respects, an outdoor chase is formed from a styrofoam or plastic. The chase may be shaped like a rectangular member with an open bottom and lid that allows for variable flow. The lid may take various positions that each lead to different airflows through the outdoor air chase.

The systems herein allow outdoor air to be introduced and provide an easy way to regulate the amount coming into the re-circulated air.

Referring again primarily toFIG.12, the illustrative embodiment of the configurable flow regulating plate300is shown in more detail in plan view. The configurable flow regulating plate300has the plurality of knock-out members320, or punch-panels, or knockout panels. The plurality of punch-out members320includes knockout panels372-404that allow the desired airflow in segments or incrementally. The number of knockout panels removed will vary because the square footage of the conditioned spaces or areas varies from application to application. See the Table A further below for an example correlating knockout panels or punches and the resultant outdoor airflow. Some illustrative systems may be between ¾ to 3 ton units and may use this or other sizes too. Each model may have a chart. Those skilled in the art will appreciate that other sizes may be used.

Still referring primarily toFIG.12, for each knockout panel, or punch-out members320, an aperture is cut in the hosting plate. The aperture is cut along the border of the knockout panel320except a small tab that holds the particular knockout panel320in place until the tab is removed by hand or by a hand tool. The tab is strong enough to keep the knockout panel320in place with airflow across at the designed flow rates, but is also weak enough to allow removal by a hand tool.

In one illustrative embodiment, the plurality of discharge apertures (formed by removal of the plurality of knockout panels320) and plurality of knockout panels320are sized such that removal of each knockout panel320increases airflow of outdoor air through the outdoor air chase200during normal operation by between 1% and 5% of rated system air for the packaged HVAC unit100.

In an alternative design of an illustrative packaged HVAC unit, the outdoor air chase has the area varied by covers being inserted on a base. In another alternative, the outdoor air chase has a sliding cover on a base to vary the airflow. In still another alternative, the outdoor air chase includes a flow regulating plate that regulates the airflow by using an adjustable iris.

Referring now primarily toFIG.13, an in-field sizing approach may be described for a packaged HVAC system100.FIG.13on the right shows an HVAC system100with the air chase initially (unassembled position) with a factory panel408on the outdoor air chase. With reference toFIG.13on the left, one may see that the configurable flow regulating plate300has nine knockout panels (covering apertures and that are ready to be knocked out with screw driver or another hand tool),372,376,380,384,388,392,396400, and404. The packaged HVAC unit100comes with a factory panel408in position and that is replaced with the adjusted configurable flow regulating plate300after setting the desired flow rate.

The following table presents empirical-based information for one illustrative embodiment in order for a user to determine how many of the knockout panels to remove.

Table A has the number of knockout panels372-404(FIG.13) removed in the left column and airflow rates in cubic feet per minute (CFM) in the main cells of the table. The top row is for the different sized units. A is product MCE4-11-09. B is product MCE4-11-12. C is product MCE4-11-18. D is product MCE4-11-24. E is product MCE4-11-30. F is product MCE4-11-36. The configurable flow regulating plate300seals the return air compartment at the outdoor duct or air chase200unless one or more knockout panels372-404are removed. Yet, the installer/technician may choose to remove as many knockout panels as desired for a desired flow rate of outdoor air. This is only one illustrative example. In some embodiments, the outdoor air can be varied from 2% to 15% of rated system air in increments as low as 2%. Other sizing options are contemplated.

The relationship of air enthalpy and temperature may be used in setting the desired air flow rate. By using calculations from the thermodynamic laws, one may determine the size and quantity of the knockout panels for precise air control: Incoming outdoor airflow=[(incoming air enthalpy−indoor air enthalpy)/(outdoor air enthalpy−indoor air enthalpy)]*incoming airflow.

In some embodiments, the packaged HVAC unit100may come with the solid plate408, or factory panel, and with an optional configurable flow regulating plate300. In that way, the installer can exercise various options. In one illustrative embodiment, if too many knockouts are removed, one or more knockout apertures can be covered with duct tape or the like to reduce the number of open knockout apertures.

In some illustrative embodiments, an outdoor air mechanism that has a plurality of knockouts is provided. The knockouts cover apertures that allow for outdoor air entry into a conditioned space. With the selective removal of knockouts, the outdoor airflow may be adjusted to allow for precise adjustment of the outdoor airflow into the conditioned space. In another illustrative embodiment, instead of knockouts, the outdoor air mechanism has an automated dampener that may be controlled by a controller to further open or close the dampener and thereby control the airflow through the automated dampener. In another embodiment, a packaged HVAC system is sent from the factory with a solid plate for a set outdoor airflow or no outdoor airflow, and has a separate configurable flow regulating plate that may be easily applied to the outdoor air chase in the field during installment as desired.

In one illustrative embodiment, the a configurable flow regulating plate300is applied to the outdoor air chase200, but in addition, an automated dampener344is also applied to the outdoor air chase200. In this way, the airflow may be set using the knockout panels, but can also be controlled in a binary fashion (on/off, open/closed) so that airflow only occurs when desired. In this way, for example, the airflow may only be allowed when the blower is running.

In one illustrative embodiment the cabinet is 44, 48, 56, or 68 inches tall. In one illustrative embodiment, the outdoor air chase is six inches and in another 10 inches, but those skilled in the art will appreciate that other dimensions may be used.

Again, in some embodiments, the configurable flow regulating plate may be used with a horizontal or other orientation HVAC system. In some illustrative embodiments, the configurable flow regulating plate may be mounted in the outdoor airflow path in any fashion. For example, in one illustrative embodiment, the HVAC system is analogous to the packaged vertical HVAC system shown above, but is configured to be substantially horizontal, i.e., the long dimension is orthogonal to the gravitational field and the outdoor chase be mounted with fasteners and may be shorter than shown above.

Unless otherwise specified, any use of any form of the terms “connect,” “engage,” “couple,” “attach,” or any other term describing an interaction between elements is not meant to limit the interaction to direct interaction between the elements and may also include indirect interaction between the elements described. “Coupled” in some instances may refer to fluid coupling. In the discussion herein and in the claims, the terms “including” and “comprising” are used in an open-ended fashion, and thus should be interpreted to mean “including, but not limited to . . . ”

It will be understood that the benefits and advantages described above may relate to one embodiment or may relate to several embodiments. It will further be understood that reference to “an” item refers to one or more of those items.

The steps of the methods described herein may be carried out in any suitable order, or simultaneously where appropriate.

Although the present invention and its advantages have been disclosed in the context of certain illustrative, non-limiting embodiments, it should be understood that various changes, substitutions, permutations, and alterations can be made without departing from the scope of the invention as defined by the claims. It will be appreciated that any feature that is described in a connection to any one embodiment may also be applicable to any other embodiment.