Patent Publication Number: US-2023152002-A1

Title: Bottom drain pan for packaged terminal air conditioner sleeve

Description:
CROSS REFERENCE 
     This application is a divisional of U.S. application Ser. No. 17/138,211, filed Dec. 30, 2020, which is a continuation in part of U.S. application Ser. No. 16/996,436, filed Aug. 18, 2020, titled “Packaged Terminal Air Conditioner System and Sleeve Therefore,” which is a continuation in part of, and claimed the benefit of U.S. application Ser. No. 16/665,205, filed Oct. 28, 2019, which claimed the benefit of U.S. Provisional Application No. 62/866,788, filed Jun. 26, 2019, the entireties of each of which are hereby incorporated by reference. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to air conditioning systems, and more particularly to drainage maintenance of packaged terminal air conditioning (PTAC) units. 
     BACKGROUND OF THE DISCLOSURE 
     Air conditioning systems are in widespread use and are provided in two general arrangements. There are “split” systems where the evaporator unit is located indoors, and the compressor unit is located outside, with refrigerant lines connecting the two units through a wall of the structure. There are also self-contained units that package the evaporator and compressor together in one unit. Some self-contained air conditioning (A/C) systems are designed to be mounted in a window, and other similar A/C units are designed to be mounted in a through-wall opening. A common self-contained A/C unit configuration is the packaged terminal air conditioner (PTAC), which are commonly used in hotel rooms, and similar multi-occupancy structures. As with all A/C systems, the evaporator unit chills air that is drawn or blown over the evaporator coil by a fan, resulting in moisture vapor in the warm air condensing and accumulating on the coil, where it collects and runs into a pan, and drains through a drain hole into a drainage line. In some arrangements, the water is simply routed to an outside port of the PTAC unit, allowing it to drip out. In some applications the cold water is used to cool the condenser coil by routing collected condensate to the condenser portion of the unit, and a fan can splash the water onto the condenser coil. 
     The high moisture environment inside of a PTAC unit is highly conducive to the growth of certain molds, algae, and other microbial growth. Over time, this growth can obstruct the drain, causing a blockage, resulting in an overflow of water into the interior of the structure, resulting in water damage and potentially giving rise to other forms of mold growth in the building structure. Accordingly, property owners want to avoid the cost of repairs due to water damage caused by overflowing A/C units. This is especially problematic in self-contained A/C units because the drain pan is typically designed to hold some water to cool the coil of the compressor unit. 
     The problem of microbial growth in PTAC units is treated as a maintenance issue, and to prevent drain blockage from occurring, chemicals are periodically introduced into the drain pan to kill or suppress microbial growth. Chemical treatment is typically accomplished by the use of slow dissolving tablets that are placed in the drain pan. These tablets slowly dissolve in the condensate water, which creates a solution that flows into the drain, killing and inhibiting growth. However, to put these tablets into the drain pan, the PTAC unit must be taken apart by removing the chassis from the wall sleeve in order to access the interior and place the tablets in the drain pan. Although the tablets only need to be added once every several weeks or so, because of the difficulty and inconvenience involved, PTAC units often go untreated for too long, or not at all. It isn&#39;t until leakage is noticed that the drain blockage is recognized. 
     Therefore, a need exists to overcome the problems with the prior art as discussed above. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with some embodiments of the inventive disclosure, there is provided a drain pan for a wall sleeve of a packaged terminal air conditioner that includes a floor having a perimeter, and a reservoir formed in the floor that extends downward from the floor and includes a drain opening. The floor is formed such that it slopes downward from the perimeter of the floor to the reservoir, and the drain pan is configured to be located under a chassis of the packaged terminal air conditioner in the wall sleeve. 
     In accordance with a further feature, the drain pan further includes a rim around the drain opening, wherein the rim is lower than a side height of the reservoir. 
     In accordance with a further feature, the drain pan further includes a vertical side wall formed around the perimeter of the floor. 
     In accordance with a further feature, a back side wall portion includes an overhang lip at top of the back side wall portion and on the outside of the back side wall portion. 
     In accordance with a further feature, the drain pan further includes a plurality of staking protrusions extending from the bottom surface of the floor that are configured to mate with corresponding holes in bottom portions of the wall sleeve. 
     In accordance with a further feature, the reservoir is positioned on the floor such that a back wall of the reservoir meets a lower wall portion of a wall having a wall opening through which the wall sleeve is mounted when the wall sleeve is sufficiently extended through the wall opening. 
     In accordance with a further feature, the back wall of the reservoir is flat and parallel to a back side of the floor. 
     In accordance with a further feature, a front of the reservoir is positioned such that a sub-base of the packaged terminal air conditioner, when installed under a front of the wall sleeve, meets the front of the reservoir. 
     In accordance with a further feature, the reservoir further includes a drain extension that extends downward from a bottom of the reservoir around the drain opening, and wherein the drain extension is adapted to mate with a drain plumbing line in either a push-on or a threaded connection. 
     In accordance with a further feature, the floor slopes downward from the perimeter to the reservoir at an angle of four to twenty degrees. 
     In accordance with some embodiments of the inventive disclosure, there is provided a wall sleeve for a packaged terminal air conditioner (PTAC) that includes first and second opposing vertical sides which extend from a front of the wall sleeve to a back of the wall sleeve. The wall sleeve further includes a top that extends horizontally between the first and second opposing vertical sides at a top of each of the first and second vertical sides, and which further extends from the front of the wall sleeve to the back of the wall sleeve. The wall sleeve further includes a bottom that extends between the first and second opposing vertical sides at a bottom of each of the first and second vertical sides, and which further extends from the front of the wall sleeve to the back of the wall sleeve, wherein the bottom is configured as a drain pan. Specifically, the bottom includes a floor and a reservoir formed in the floor that extends downward from the floor and includes a drain opening. The floor slopes downward from the opposing vertical sides and the front and back of the wall sleeve to the reservoir. 
     In accordance with a further feature, the drain pan further includes a rim around the drain opening, wherein the rim is lower than a side height of the reservoir. 
     In accordance with a further feature, the drain pan further includes a vertical side wall formed around a perimeter of the floor. 
     In accordance with a further feature, a back side wall portion includes an overhang lip at top of the back side wall portion and on the outside of the back side wall portion. 
     In accordance with a further feature, the drain pan further includes a plurality of staking protrusions extending from a bottom surface of the bottom that are configured to mate with corresponding holes in bottom portions of each of the opposing vertical sides. 
     In accordance with a further feature, the reservoir is positioned on the floor such that a back wall of the reservoir meets a lower wall portion of a wall having a wall opening through which the wall sleeve is mounted when the wall sleeve is sufficiently extended through the wall opening. 
     In accordance with a further feature, the back wall of the reservoir is flat and parallel to a back side of the floor. 
     18. The drain pan of claim  11 , wherein a front of the reservoir is positioned such that a sub-base of the packaged terminal air conditioner, when installed under a front of the wall sleeve, meets the front of the reservoir. 
     In accordance with a further feature, the drain pan further includes a drain extension that extends downward from a bottom of the reservoir around the drain opening, and wherein the drain extension is adapted to mate with a drain plumbing line in either a push-on or a threaded connection. 
     In accordance with some embodiments of the inventive disclosure, there is provided a drain pan for a wall sleeve of a packaged terminal air conditioner that includes a floor having a perimeter, a drain opening formed in the floor, and a rim formed around the drain opening on a top side of the floor. The floor slopes downward from the perimeter to the drain opening and forms a reservoirs around the rim, and the drain pan is configured to be located under a chassis of the packaged terminal air conditioner in the wall sleeve. 
     Although the disclosure is illustrated and described herein as embodied in a wall sleeve for a packaged terminal air conditioner unit and a packaged terminal air conditioner unit using the wall sleeve, it is, nevertheless, not intended to be limited to the details shown because various modifications and structural changes may be made therein without departing from the spirit of the disclosure and within the scope and range of equivalents of the claims. Additionally, well-known elements of exemplary embodiments of the disclosure will not be described in detail or will be omitted so as not to obscure the relevant details of the disclosure. 
     Other features that are considered as characteristic for the disclosure are set forth in the appended claims. As required, detailed embodiments of the present disclosure are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the disclosure, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to variously employ the present disclosure in virtually any appropriately detailed structure. Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the disclosure. While the specification concludes with claims defining the features of the disclosure that are regarded as novel, it is believed that the disclosure will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward. The figures of the drawings are not drawn to scale. 
     Before the present disclosure is disclosed and described, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. The terms “a” or “an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The term “coupled,” as used herein, is defined as connected, although not necessarily directly, and not necessarily mechanically. The term “providing” is defined herein in its broadest sense, e.g., bringing/coming into physical existence, making available, and/or supplying to someone or something, in whole or in multiple parts at once or over a period of time. 
     “In the description of the embodiments of the present disclosure, unless otherwise specified, azimuth or positional relationships indicated by terms such as “up”, “down”, “left”, “right”, “inside”, “outside”, “front”, “back”, “head”, “tail” and so on, are azimuth or positional relationships based on the drawings, which are only to facilitate description of the embodiments of the present disclosure and simplify the description, but not to indicate or imply that the devices or components must have a specific azimuth, or be constructed or operated in the specific azimuth, which thus cannot be understood as a limitation to the embodiments of the present disclosure. Furthermore, terms such as “first”, “second”, “third” and so on are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance. 
     In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise clearly defined and limited, terms such as “installed”, “coupled”, “connected” should be broadly interpreted, for example, it may be fixedly connected, or may be detachably connected, or integrally connected; it may be mechanically connected, or may be electrically connected; it may be directly connected, or may be indirectly connected via an intermediate medium. As used herein, the terms “about” or “approximately” apply to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure. Those skilled in the art can understand the specific meanings of the above-mentioned terms in the embodiments of the present disclosure according to the specific circumstances. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and explain various principles and advantages all in accordance with the present disclosure. 
         FIG.  1    is an exploded isometric view of a package terminal air conditioner (PTAC) system  100  include a wall sleeve designed in accordance with some embodiments; 
         FIG.  2    a side cutaway view of a portion of an assembled PTAC system including guide structure to allow placement of treatment pellets into the PTAC, in accordance with some embodiments; 
         FIG.  3    is side cutaway view of a sidewall of a wall sleeve and a guide structure for guiding a treatment pellet into a chassis drain pan of the PTAC, in accordance with some embodiments; 
         FIG.  4    is side cutaway view of a sidewall of a wall sleeve and a guide structure for guiding a treatment pellet into a portion of the PTAC, in accordance with some embodiments; 
         FIG.  5    is a perspective view of a wall sleeve include guide structure for treatment pellets and for a drain snake under a chassis installed that would be installed into the wall sleeve, in accordance with some embodiments; 
         FIG.  6    is a side cutaway view of a PTAC showing a drain snake guide structure, in accordance with some embodiments; 
         FIG.  7    shows a side elevational view of a sidewall of a wall sleeve, at the outside, on which a cover is mounted for covering an aperture formed through the sidewall, in accordance with some embodiments; 
         FIG.  8    shows a perspective view of a wall sleeve assembly showing an outside of the side of the wall sleeve where a rotating cover is mounted, in accordance with some embodiments; 
         FIG.  9    shows a perspective view of a wall sleeve assembly showing an inside of the side of the wall sleeve where a mounting plate is mounted, and including a detail showing the various guide structures mounted in the wall sleeve, in accordance with some embodiments; 
         FIG.  10    shows a perspective view of a rotating cover, in accordance with some embodiments; 
         FIG.  11    shows an elevational view of a rotating cover as mounted on the side of a wall sleeve, in accordance with some embodiments; 
         FIG.  12    shows a perspective view of a mounting plate for use in mounting guide structures in a wall sleeve for a PTAC, in accordance with some embodiments; 
         FIG.  13    shows a front perspective view of a guide structure, in accordance with some embodiments; 
         FIG.  14    shows a rear perspective view of a guide structure, in accordance with some embodiments; 
         FIG.  15    shows a perspective view of a mounting plate with guide structures assembled into the mounting plate prior to mounting the mounting plate on a side, in accordance with some embodiments; 
         FIG.  16    shows a perspective view of a wall sleeve assembly showing an inside of the side of the wall sleeve including a pellet delivery tube for a drain reservoir of the wall sleeve, in accordance with some embodiments; 
         FIG.  17    shows a side partial cut-away view of a drain pan for use with a wall sleeve, in accordance with some embodiments; 
         FIG.  18    shows a side view of an end of a pellet delivery tube in a drain reservoir of a drain pan for a wall sleeve, in accordance with some embodiments; 
         FIGS.  19 A- 19 B  show the side and front elevational views of guide structures for use with spherical or belted spheroid treatment pellets, in accordance with some embodiments; 
         FIGS.  20 A- 20 C  show views of a belted spheroid treatment pellet, in accordance with some embodiments; 
         FIG.  21    shows a side partial cut-away view of a drain pan for use with a wall sleeve, in accordance with some embodiments; 
         FIG.  22    is a perspective view of a drain pan for use with a wall sleeve, in accordance with some embodiments; 
         FIG.  23    is a partial side cut-away view of a drain pan such as that shown in  FIG.  22    showing a integrally formed drain structure to retain some water in a reservoir, in accordance with some embodiments; 
         FIG.  24    is a partial side cut-away view of the rear of a drain pan for use with a wall sleeve, showing a leak preventing overhang lip, in accordance with some embodiments; 
         FIG.  25    is a perspective view of the bottom of a drain pan such as that shown in  FIG.  22   , in accordance with some embodiments; 
         FIG.  26    is an exploded perspective assembly view of a drain pan and wall sleeve, where the drain pan is staked into the wall sleeve, in accordance with some embodiments; 
         FIGS.  27 A-D  show various stages of staking a drain pan into a wall sleeve, in accordance with some embodiments; 
         FIG.  28    shows a top plan view of a drain pan having a drain reservoir positioned to properly locate the drain pan/wall sleeve assembly in a wall, in accordance with some embodiments; 
         FIG.  29    shows a side cutaway view of a drain pan such as that shown in  FIG.  28   , in accordance with some embodiments; 
         FIG.  30    shows a drain pan/wall sleeve assembly installed in a wall, in accordance with some embodiments; 
         FIG.  31    shows an overhead view of an equivalent alternative arrangement for the drain pan/floor of the PTAC wall sleeve, in accordance with some embodiments; 
         FIG.  32    shows a side cutaway view of a drain pan such as that shown in  FIG.  31   , in accordance with some embodiments; and 
         FIG.  33    shows a perspective view of a drain pan for a PTAC wall sleeve having storm overflow prevention features, in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     While the specification concludes with claims defining the features of the disclosure that are regarded as novel, it is believed that the disclosure will be better understood from a consideration of the following description in conjunction with the drawing figures, in which like reference numerals are carried forward. It is to be understood that the disclosed embodiments are merely exemplary of the disclosure, which can be embodied in various forms. 
     The present disclosure provides a novel and efficient self-contained air conditioner unit that allows drainage maintenance to be performed without having to take the air conditioner unit apart or disassemble any portion of the air conditioner unit. Embodiments of the disclosure provide a self-contained air conditioner unit suitable for a through-wall or in window application where the air conditioner unit provides access-ways that allow a person to place anti-microbial treatment pellets into the internal drain pan(s) of the unit, as well providing directed access to the drain line in units that are more permanently installed. 
       FIG.  1    is an exploded isometric view of a package terminal air conditioner (PTAC) system  100  including a wall sleeve designed in accordance with some embodiments. A PTAC is a self-contained air conditioner system that includes the compressor unit and evaporator unit together in a chassis  104  that is mounted in a wall sleeve  102 . The wall sleeve  102  is mounted in a wall, allowing access to the outside air. A PTAC is therefore different than a “split” system where the evaporator unit is located inside a building with an air handler, and where the compressor unit is located outside the building, and tubing is arranged between the two sections to carry refrigerant between them. PTAC systems are commonly used in hotel rooms, dormitories, and similar housing unit structures, and typically a PTAC system is installed through a wall, near the floor. A wall sleeve  102  is mounted in a similarly sized opening through the wall, and the small gap between the wall sleeve  102  and the wall can be weather sealed. The wall sleeve  102  can be formed of sheet metal, fiberglass, plastic, or any other suitable material, and is typically deeper, from front to back, than the wall (in which it is mounted) is thick. The wall sleeve  102  is designed to receive the chassis  104  into the wall sleeve  102  such that the chassis  104  is mounted in the wall sleeve  102 . The chassis  104  includes all of the mechanical and electrical components of the air conditioner system, including the evaporator and compressor sections, as well as control circuitry to adjust the thermostat control, fan speed, and so on. 
     The chassis  104  has a front portion that sits inside the room and is covered by a housing  106 , while the section including the condenser coil  120  is located in the back of the chassis  104  so that air from outside can be blown over the condenser coil  120  to remove heat from the compressed refrigerant in the condenser coil  120 . Typically the back of the chassis  104  is covered with a louvre panel (not shown), as is known. When the PTAC is operating in a cooling mode, moisture that is in the air inside the room will condense on the evaporator coil. As the condensate collects it is routed to a drain to prevent water leaking out of the unit. It is common to use a chassis drain pan  118  to collect some of the condensate, and use the collected cold water to help cool the condenser coil  120 . For example, the chassis drain pan  118  is typically arranged to collect water to a selected depth that allows the blades of the fan blowing air over the condenser coil  120  to splash water into the condenser coil  120 . However, because the water then has to rise to selected drain level, some of the water stagnates in the chassis drain pan  118 , allowing microbial growth to occur, which can clog the drainage path. 
     Typically the chassis drain pan  118  drains into a wall sleeve drain pan  108 , which is essentially the bottom of the wall sleeve  102 . A drain hole  110  can be formed through the bottom of the wall sleeve drain pan  108 , and it is either connected to a drainage, or configured to drain out the rear of the unit (e.g. outside). Further, the wall sleeve drain pan  108  can have raised features  122  stamped or formed therein on which the bottom of the chassis  104  sits, providing space between the bottom of the chassis  104  and the wall sleeve drain pan  108 . 
     In a conventional PTAC unit, the cover  106  and chassis  104  must be removed, at least partially, from the wall sleeve  102  in order to add treatment pellets to inhibit microbial growth in the drain pans  108 ,  118 . Treatment pellets are formed of a chemical compound that dissolves slowly in water, and which then dissipates throughout the collected water, and into the drain, and can be formed in a variety of shapes and sizes, including, for example, spheres, belted spheres, disks, cylinders, and so on. Treatment pellets need to be added periodically since they dissolve and the flow of water dilutes the. Accordingly, it is common to establish a schedule for adding treatment pellets to the PTAC units in a facility like a hotel. However, the personnel tasked with doing so often find it difficult to take the PTAC units apart, as the chassis can be quite heavy, and care has to be taken to not spill water that may be sitting in the chassis drain pan  118 . As a result, personnel sometimes neglect to perform the process of depositing treatment pellets into the PTAC units, or some PTAC units. 
     In order to simplify the task of putting treatment pellets into a PTAC unit, one or more openings such as apertures or openings  112 ,  114 ,  116  can be formed through a sidewall  124  of the wall sleeve  102  at a location that, when the wall sleeve  102  is installed in a wall, is exposed inside the room (e.g. a portion of the wall sleeve  102  that extends forward from the wall). However, the opening or openings are positioned such that they are not obscured by components in the chassis  104  or part of the chassis  104 . On the inside of the wall sleeve  104 , as will be shown in subsequent drawings, in correspondence with each opening  112 ,  114 ,  116  is a guide structure. Some of the guide structures are configured to guide a treatment pellet that is inserted into the corresponding opening to a desired location inside the PTAC unit  100 . For example, aperture  112  can correspond to a guide structure that is configured to guide a treatment pellet into the chassis drain pan  118 . Likewise, aperture  116  can correspond to the guide structure that is configured to guide a treatment pellet between the chassis drain pan  118  and the inside of the side wall  124  into the wall sleeve drain pan  108 . A third aperture  114  can correspond to a guide structure that is configured to guide a drain snake to the drain  110  of the wall sleeve drain pan to allow servicing of the drain with the drain snake. Thus, once the PTAC unit  100  is assembled, with the chassis  104  mounted in the wall sleeve  102 , maintenance personnel will no longer have to pull the chassis  104  out of the wall sleeve  102  in order to place treatment pellets into the unit. In some embodiments a cover structure can be provide on the outside of the side wall  124  that is moveable, and which covers the opening(s)  112 ,  114 ,  116  so as to prevent any undesired object or debris from getting into the unit  100 . 
       FIG.  2    a side cutaway view of a portion of an assembled PTAC system  200  including one or more guide structures to allow placement of treatment pellets into the PTAC, in accordance with some embodiments. A wall sleeve  202  includes a sidewall  208  having an inside or interior surface  212  that is opposite the exterior surface on the outside of the wall sleeve  202  (which faces the wall in which it is installed). Mounted inside the wall sleeve is a chassis, of which, shown here, is a chassis drain pan  204 , having a bottom  210 , in which water condensate is collected from an evaporator coil (not shown). The chassis drain pan  204  is mounted on structure of the wall sleeve  202  that elevates the bottom of the chassis drain pan above the bottom  205  of the wall sleeve  202 . Specifically, the chassis is designed to be slid into the wall sleeve  202 , where, once the chassis is in the proper position in the wall sleeve  202 , a portion of the chassis can be screwed or bolted to corresponding portions of the wall sleeve  202 . A side  203  of the chassis drain pan  204  provides a barrier to contain water collected in the chassis drain pan  204 . The chassis drain pan  204  is mounted in the wall sleeve  202  such that a gap  224  is provided between the interior  212  of the sidewall  208  of the wall sleeve  202  and the side  203  of the chassis drain pan  204 . In other words, there is a space between the chassis  203  and the side of the wall sleeve  202 . 
     Attached to, or mounted on the inside  212  of the sidewall  208  of the wall sleeve  202  are several guide structures  206 ,  220 . The guide structures  206 ,  220  are provided such that their upper portions  214  each correspond to a respective aperture or opening (e.g.  112 ,  114 ,  116 ) through the sidewall  208 . A first guide structure  206  can be in the form of a tube that is bent at an angle at the top portion  214 . A lower portion  216  extends outward and downward such that a lower opening  218  is positioned over the chassis drain pan  204 . Thus, when a treatment pellet is inserted into the corresponding opening through the sidewall  202 , the treatment pellet is guided by the first guide structure  206  such that gravity moves the treatment pellet downward through the guide structure  206  until the treatment pellet falls into the chassis drain pan  204 . Thus, the PTAC unit does not need to be taken apart in order to place treatment pellets (or tablets, liquids, etc.) into the chassis drain pan  204 . 
     A second guide structure  220 , having its top portion mounted in correspondence with a second opening through the sidewall  208 , is configured to guide a treatment pellet from the second opening, upon insertion of the treatment pellet through the second opening, into the wall sleeve drain pan, formed by the bottom  205  of the wall sleeve  202 , through gap  224 . The lower portion  222  of the second guide structure  220  is configured such that anything passing through the guide structure  220  will fall past the chassis drain pan  204  and to the bottom  205  of the wall sleeve  202 . In some embodiments both the first and second guide structures  206 ,  220  can be made of sections of copper tubing such as that commonly used in plumbing applications. In some embodiments the guide structures  206 ,  220  can be made of plastic tubing or piping, such as polyvinyl chloride (PVC) piping. 
       FIG.  3    is side cutaway view  300  of a sidewall  302  of a wall sleeve and a guide structure  304  for guiding a treatment pellet  314  into a drain pan of the PTAC, in accordance with some embodiments. The guide structure  304  can be a tube component having a flared opening  305  against which a bracket  306  bears to hold the guide structure  304  in place. The flared opening  305  is positioned in correspondence with an opening or aperture  308  through the side wall  302 . The bracket  306  can be held against the interior of the side wall  302  and the outside of the flared opening  305  of the guide structure  304  by rivets  310 ,  312  that pass through the side wall  302  and the bracket  306 , thereby holding the guide structure  304  in place. Upon inserting a treatment pellet  314  into the opening  308 , the treatment pellet  314  will begin rolling down the guide structure  304  in the direction of arrow  316  until it exits the guide structure  304 , and into the chassis or wall sleeve drain pan. The treatment pellet can be spherically shaped and sized to fit through the opening  308  and the guide structure  304 . Being spherical, the treatment pellet  314  will easily roll down the guide structure  304 . As shown there, there is a short horizontal section of the guide structure  304  from the opening  308  to the downward directed portion, however, the guide structure  304  can also be configured to slope downwards from the opening  308 , without any horizontal portion. 
       FIG.  4    is side cutaway view  400  of a sidewall  402  of a wall sleeve and a guide structure  406  for guiding a treatment pellet into a drain pan of the PTAC, in accordance with some embodiments. The guide structure  406  is positioned in correspondence with an aperture or opening  404  through the sidewall  402 , and is configured as a chute having a bottom  408  and sides  410  which extend upward from the bottom  408 . The guide structure  406  can be held in place by a rivets such as rivet  412  (two such rivets can be used) through a lower lip  414  which can be a portion of the bottom  408  that is bent at an angle to the bottom  408  such that the bottom  408  is at a desired downward angle. This configuration for a guide structure can be used for many shapes of treatment pellets, including disks or tablets, as well as liquids. The guide structure  406  can be made out of sheet metal that has portions bent to form the sides  410  and bottom  408 . 
       FIG.  5    is a perspective view of a wall sleeve  500  including guide structures for treatment pellets and for a drain snake under a chassis installed that would be installed into the wall sleeve, in accordance with some embodiments. The wall sleeve  500  is shown outside of a wall, and is configured to be installed in a through-hole in a wall, as is well known. A chassis including the air conditioner components and circuitry is mounted in the wall sleeve  500  and typically secured to the wall sleeve  500  using screws or bolts at a front rim  503  of the wall sleeve  500  which is inside the room or structure in which the wall sleeve  500  is mounted. The front rim  503  surrounds the front opening through which the chassis is inserted to mount the chassis into the wall sleeve  500 . 
     The wall sleeve  500  has first sidewall  502  that has an inside or interior surface  504 . The wall sleeve  500  further includes a bottom  506 , a second sidewall  505  and a top  507 . The bottom  506  includes a drain opening  508 , and the bottom  506  can be shaped to slope slightly downward from the sides to the drain opening  508  from the perimeter of bottom  506  to facilitate drainage. In some embodiments the edge of the drain hole  508  can be about one half inch to one and one half inches below the edges of the bottom  506 , where the bottom  506  meets the sides. When the chassis is mounted into the wall sleeve  500 , overflow from the chassis drain pan can drain into the bottom  506  of the wall sleeve  500  and through the drain hole  508  into a drain pipe. In some embodiments, however, water can be drained directly through the back/outside of the wall sleeve  500  to the outside environment. 
     The first sidewall  502  has several openings or apertures formed through the first sidewall from an exterior to the interior. There are several guide structures  510 ,  512 ,  514  which each have an end positioned in correspondence with a respective one of the several openings through the first sidewall  502 . Guide structure  510  can be a tube that is configured to be against, or in sufficient proximity to the bottom  506  of the wall sleeve  500  to be under the chassis when the chassis is mounted in the wall sleeve, and traverses across the wall sleeve  500  from the interior  504  of the first sidewall  502  at an opening to the bottom  506 , and across the bottom  506  to the drain hole  508 . The end of the guide structure  510  at the drain hole  508  is turned downward to direct anything passing through guide structure  510  into the drain through drain hole  508 . For example, a drain snake can be passed from the outside of the PTAC unit through the opening corresponding to the guide structure  510 , and through the guide structure  510  into the drain pipe through the drain hole  508  in order to clean out the drain pipe and dislodge any material that may be blocking the drain. Further, drain maintenance liquids (e.g. “drain de-clogger”) can be poured through guide structure  510  directly into the drainage line. These maintenance operations can be performed without having to disassemble the PTAC unit. 
     Likewise another guide structure  512  can be configured to have a free end disposed over the chassis drain pan when the chassis is mounted in the wall sleeve  500 , and is mounted on the interior  504  of the first side wall  502  of the wall sleeve at an aperture through the sidewall  502 . Thus, guide structure  512  allows a person to deposit a treatment pellet into the chassis drain pan by inserting the treatment pellet into the aperture through the sidewall  502  corresponding to the guide structure  512 , whereupon gravity will draw the treatment pellet down and through the guide structure  512  where the treatment pellet will fall into the chassis drain pan. Another guide structure  514  is configured to direct treatment pellets from yet another aperture through the sidewall  502  into the wall sleeve bottom  506 , which acts as a wall sleeve drain pan. Guide structure  514  is similar to guide structure  220  of  FIG.  2   , and directs treatment pellets though a gap between the chassis drain pan and the interior  504  of the first sidewall  502 , or through a tube or passageway formed in the chassis drain pan. An alternative guide structure  516  can be formed over the interior  504  of the first sidewall  502  that creates a passage between the interior surface  504  and the guide structure  516  to guide treatment pellets into the bottom  506  of the wall sleeve  500 . In particular disk-shaped tablets can be inserted into the opening corresponding toe guide structure  516  and even stacked inside guide structure  516 , allowing the bottom tablet to dissolve slowly, so that if maintenance personnel see room to add another tablet they can, and won&#39;t need to do so before there is room to add another tablet. 
     Guide structures  510 ,  512 ,  514 ,  516  are mounted on the interior  504  of the first side wall in a position so that the chassis of the PTAC unit can be moved in and out of the wall sleeve  500  without the guide structures  510 ,  512 ,  514 ,  516  snagging or interfering with the movement of the chassis in or out of the wall sleeve  500 . In particular, guide structure  512 , which extends over the chassis drain pan when the chassis in mounted in the wall sleeve  500 , does not extend far enough into the interior space of the wall sleeve that it will be in the way of components on the chassis when the chassis is moved into or out of the wall sleeve  500 . Accordingly, components on the chassis have to be configured such that there is clearance for the guide structure  512 , and that the chassis drain pan will be under the lower end of guide structure  512 . 
       FIG.  6    is a side cutaway view of a PTAC unit  600  showing a drain snake guide structure, in accordance with some embodiments. A wall sleeve  602  holds a chassis that includes a chassis drain pan  604  having a bottom  606 . The chassis drain pan  604  holds a selected level of water that condenses on the evaporator coil and drains down into the chassis drain pan  604 . The collected water is used to cool the condenser coil by the condenser fan splashing the collected water and blowing it into the condenser coil, as is well known. Excess water drains into the bottom  608  of the wall sleeve  602 , under the chassis drain pan  604  through, for example, notch  626  in the side of the chassis drain pan  604 . The chassis is mounted in the wall sleeve  602  such that there is a gap or space between the bottom  606  of the chassis drain pan  604  and the bottom  608  of the wall sleeve  602 . For example, several upward bosses  620  can be formed into the bottom  608  of the wall sleeve  602  that bear against the bottom  608  of the chassis drain pan  604  or other parts of the chassis. The bottom  608  is shown flat here, but can be configured to slope from the sides to the drain hole  618  to facilitate drainage. A guide structure  622  is provided in this space, and has a first end  610  positioned in correspondence with an opening through the sidewall of the wall sleeve  602 . The guide structure  622  can be a tube or narrow pipe assembly and has a second end  624  positioned over a drain hole  618 . A drain snake  612  can be inserted into the guide structure  622  in the direction of arrow  614  through the opening, and along the guide structure  622  until it comes out the second end  624  in the direction of arrow  616  and into the drain line. Thus, the guide structure  622  allows maintenance of the drain line without having to remove the chassis from the wall sleeve  602 . 
       FIG.  7    shows a side elevational view of a sidewall  700  of a wall sleeve, at the outside, on which a cover  702  is mounted for covering an aperture  708  formed through the sidewall, in accordance with some embodiments. In this view the cover  702  is positioned over (covering) the aperture  708 . The aperture  708  is an opening through the sidewall  700  and a guide structure is positioned on the other side of the sidewall  700  in correspondence with the aperture  708 . The aperture  708  is sized such that a treatment pellet or tablet can pass through the aperture. In some embodiments the aperture  708  can be sized to exclude standard tablet/disc shaped treatment pellets commonly available on the market but sized large enough to accept a spherical treatment pellet that will roll down the corresponding guide structure. 
     The cover  702  can be a flat member that is attached to the sidewall  700  at a pivot point  704  that allows the cover  702  to move about the pivot point  704  as indicated by arrows  706 . The pivot point is located directly over the aperture  708  and the cover  702  hangs on the pivot point  704  such that it naturally covers the aperture  708  unless moved to the side (i.e. in the direction of arrow  706 ). The cover  702  prevents debris and other objects from entering the PTAC unit. When a treatment pellet is to be provided into the PTAC unit, the cover  702  can be moved by pivoting it around the pivot point  704  to reveal the aperture  708 , thereby allowing a treatment pellet to be inserted into the opening  708 . The pivot point  704  can be a rivet or similar feature that attaches to the sidewall  700 . Other forms of covers can be used equivalently, including, for example, a flap that hangs over the aperture  708  or several apertures, having a bottom that lifts up and away from the sidewall. 
       FIG.  8    shows a perspective view of a wall sleeve  800  for a PTAC unit that is designed in accordance with some embodiments. In particular, the wall sleeve  800  provides drainage and maintenance features not found on existing PTAC units. The front  802  of the wall sleeve  800  is open, which allows for a PTAC chassis to be inserted into the wall sleeve  800 . The wall sleeve  800  is itself mounted through a wall so that heat can be removed from an interior space to the exterior space by otherwise conventional air conditioning techniques. The wall sleeve  800  has a bottom  804  that is sloped toward a drain  808 . That is, where the bottom  804  meets the drain is the lowest point of the bottom  804 , with the highest part of the bottom  804  being where the bottom  804  meet the sides, such as side  816 . The drain hole  808  can be on the order of one half inch to one and one half inches lower than the edges of the bottom  804  where the bottom  804  meets the vertical sides of the wall sleeve  800 . The bottom  804  can include several standoffs  806  which are raised portions that support the chassis and create space between the bottom of the chassis and the rest of the bottom  804 . A drain access tube  810  is a guide structure that can be used to guide a drain cleaning tool into the drain  808 . The drain access tube  810  therefore has one end over the drain  808  and another end on the side  816 , which can be concealed by a rotating cover  812 . The rotating cover  812  is a circular member that is mounted on the side  816  so as to rotate about its center point. The rotating cover  812  has an opening  814  formed through the rotating cover  812 , and by rotating the rotating cover about its center mounting point allows a user to align the opening  814  with the opening of any of two or more different guide structures, the drain access tube  810  being one of the guide structures. The opening  814  has a center that is a distance away from the center of the rotating cover  812 , and as a result, when the rotating cover  812  is rotated, the opening follows a circular path. The openings of the various guide structures are positioned in correspondence with this circular path. In the present example there are three total guide structures. The other two guide structures allow a user to deposit treatment pellets into the chassis pan or to the bottom  804  of the wall sleeve  800  which acts as a wall sleeve drain pan. 
       FIG.  9    shows a perspective view of the wall sleeve  802 , showing the inside of side  816 , and the guide structures attached to the side of the wall sleeve, in accordance with some embodiments. A mounting plate  900  is used to capture the openings of guide structures  902 ,  904 , and drain access tube  810  in alignment with corresponding holes through the side  816  of the wall sleeve. Guide structure  902  can be configured to guide a treatment pellet into the chassis pan from an opening on the side  816 . Likewise, guide structure  904  can be configured to guide a treatment pellet into the bottom  804  of the wall sleeve  800 . The openings of guide structures  810 ,  902 ,  904  are arranged on circular path that is traversed by the opening  814  of the rotating cover  812  on the outside of side  816 . 
       FIG.  10    shows a rotating cover  812  for use on the outside side of a wall sleeve  800 , in accordance with some embodiments. The rotating cover  812  can be a circular disk having a mounting hole  1000  at the center of the disk about which the rotating cover  812  will rotate once mounted on the wall sleeve  800 . The rotating cover  812  has an opening  814  through the rotating cover  812  that allows access to the opening of any of the various guide structures by rotating the rotating cover  812  until the opening  814  aligns with the opening of the desired guide structure. As the rotating cover  812  rotates about the mounting hole  1000 , the opening  814  follows a circular path.  FIG.  11    shows the rotating cover  812  mounted on the side  816  of the PTAC wall sleeve. The rotating cover  812  is mounted on a fastener that passes through the mounting hole  1000  and the side  816  of the wall sleeve. Accordingly, the rotating cover  812  can rotate about the mounting hole  1000  as indicated by arc  1108 . Further, opening  814  follows a circular path  1106  as the rotting cover  812  is rotated. The rotation is in a plane that is parallel to the plane of the side  816  of the wall sleeve. Also located in the circular path  1106  are the openings of several guide structures  1100 ,  1102 ,  1104 . Each of the openings  1100 ,  1102 ,  1104  connects to a different, respective guide structure. For example, opening  1100  can connect to the drain access tube  810 , opening  1102  can connect to guide structure  904 , and opening  1104  can connect to guide structure  902 . The openings  1100 ,  1102 ,  1104  can be the open end of the guide structures, which necessarily have to pass through similar openings in the side  816  of the wall sleeve. Alternatively, the openings  1100 ,  1102 ,  1104  can be openings in the side  816  which lead to the open end of the guide structures. 
       FIG.  12    shows a mounting plate  900  for use in securing guide structures to the side a wall sleeve, in accordance with some embodiments. The mounting plate  900  aligns and captures the guide structures against the inside of the wall sleeve in correspondence with their respective openings through the side of the wall sleeve (e.g.  1100 ,  1102 ,  1104 ). The mounting plate  900  includes a through hole  1200 . A pin or similar retaining structure (not shown) can pass through the through hole  1200  and the mounting hole  1000  of the rotating cover  812  and a corresponding hole in the side of the wall sleeve. The mounting plate  900  also include several shouldered holes  1202 ,  1204 ,  1206 , which are arranged on a circle centered at the through hole  1200 , which corresponds to circular path  1106  on which the openings  1100 ,  1102 ,  1104  are arranged. Further, each of the shouldered holes  1202 ,  1204 ,  1206  has an opening through the mounting plate  900  that is surrounded by a shoulder, in which an alignment notch is cut that is contiguous with the opening. This is shown in the detail of shouldered hole  1206  in which the opening  1207  is shown, surrounded by a shoulder  1208 , in which an alignment notch  1210  is cut. The shoulder  1208  is a circular section of the mounting plate that is reduced in thickness to capture a portion of the guide structure between the shoulder  1208  and the inside of the wall sleeve. The mounting plate  900  can also include alignment features to align the mounting plate  900  to the inside of the wall sleeve. For example, the mounting plate  900  can include a corner  1212  formed by sides  1214 ,  1216 . The corner  1212  and sides  1214 ,  1216  can align to a corresponding corner and sides on the inside of the wall sleeve, eliminating the need to measure the wall sleeve when installing the mounting plate  900  and guide structures. 
       FIGS.  13  and  14    show front and rear perspective views, respectively, of a portion of a guide structure  902  to be mounted in a mounting plate such as mounting plate  900 . The guide structure  902  is configured to guide a treatment pellet into a portion of a PTAC unit, or allow access to the drain for cleaning. The guide structure  902  can include a generally tubular body  1302  or equivalent structure formed to guide a treatment pellet or cleaning brush to a desired location in the PTAC from outside of the PTAC. The guide structure  902  has an end that forms an opening  1100  surrounded by a flange  1304 . The flange  1304  is sized to correspond with the recess of the shoulder  1208  of the shouldered holes  1202 ,  1204 ,  1206  of the mounting plate  900 . That is, the flange  1304  has a thickness that is as thick as the depth of the shoulder recess of the shoulder  1208 . Further, the flange  1304  is generally flat across the face of the flange as it is captured between the shoulder  1208  and the inside surface of the side of the wall sleeve. An alignment tab  1306  can be provided to fit into the alignment notch  1210  to align the guide structure in a proper orientation.  FIG.  15    shows an assembly  1500  of a mounting plate  900  with several guide structures  810 ,  902 ,  904  placed into the mounting plate  900  and ready to be mounted on the side of the wall sleeve. Each guide structure  810 ,  902 ,  904  has a flange portion that fits within a shoulder recess of a corresponding opening through the mounting plate  900 . When the mounting plate  900  is mounted in place against the side (the inside) of the wall sleeve, the guide structures  810 ,  902 ,  904  will be captured in place. The rotating cover (e.g.  812 ) will be mounted on the outside of the side of the wall sleeve and will allow only one of the guide structures  810 ,  902 ,  904  to be accessible at a time, or to cover all of them so as to keep out debris or other matter. 
       FIG.  16    shows a perspective view of a wall sleeve assembly showing an inside of the side of the wall sleeve  800  including a pellet delivery tube for a drain reservoir of the wall sleeve, in accordance with some embodiments. The wall sleeve  800  is substantially similar to that shown in  FIG.  8   , but includes the addition of a pellet delivery tube  818  that extends from the side wall  816  to the drain  808 . However, unlike the drain access tube  810 , which ends over the hole through which water drains, the end of the pellet delivery tube  818  is positioned over a floor of the reservoir created by the drain  808 . The bottom  804  of the wall sleeve is sloped toward to the drain  808  from the walls or sides of the wall sleeve. As a result, condensate draining onto the bottom  804  flows into the drain  808 , rather than accumulating in the bottom of the wall sleeve, as is conventional. In conventional wall sleeve, there can be on the order of one to two gallons of water that accumulates in the bottom of the conventional wall sleeve, which, if a leak occurs in the material of the wall sleeve, could result in a substantial amount of water leaking out of the wall sleeve. By sloping the bottom  804  only a small amount of water will normally accumulate, in the reservoir created by the drain  808 . The pellet delivery tube  818  can deliver treatment pellets into the drain reservoir to inhibit the growth of organic matter. 
       FIG.  17    shows a side partial cut-away view of a drain pan for use with a wall sleeve, in accordance with some embodiments. The view here is perpendicular to the line A-A of  FIG.  16   , and centered on the drain pan. The bottom  804  is the surface on which water drips from other parts of the PTAC, and can be a bottom portion of the wall sleeve  800  or it can be a pan that is inserted in the bottom of a PTAC wall sleeve. As can be seen the bottom  804  slopes downward to the drain  808 , which drops below the rest of the bottom  804  to create a drain reservoir, including a reservoir floor  1700 , and a rim or lip  1702  around a drain opening  1704 . The drain reservoir is formed by the reservoir floor  1700  and the sidewall that extends downward from the bottom  804  into the drain. The drain access tube  810  is positioned so that the end of the drain access tube is over the drain opening  1704 . The pellet delivery tube  818  is positioned so that its end is over the reservoir floor  1700 . The end of the pellet deliver tube  818  is spaced  1706  from the reservoir floor  1700  to allow accumulated water to flow under the end of the pellet delivery tube but not so high as to allow a pellet to escape from under the end of the pellet delivery tube  818 . The water retained by the rim  1702  will dissolve the treatment pellet at the end of the pellet deliver tube  818 , which can be loaded with pellets to ensure a constant, gravity-fed supply of treatment pellets. As each successive treatment pellet dissolves, which occurs slowly, over the course of several days, typically, the chemical released are distributed into the water and carried into the drain through the drain opening  1704 . That is, as water continues to flow into the reservoir, it fills up the space above the reservoir floor  1700  and between the sides of the reservoir and the rim  1702 , spilling over the rim  1702  and carrying treatment chemicals into the drain so as to inhibit growth of organic matter in the drain as well as in the reservoir. 
       FIG.  18    shows a side view of an end of a pellet delivery tube  818  in a drain reservoir of a drain pan for a wall sleeve, in accordance with some embodiments. The pellet delivery tube connects to the side of the wall sleeve, and provides access for a user to load treatment pellets (e.g.  1804 ) into the tube  818  at a proximal end (with respect to the side of the wall sleeve). The distal end  1800  of the pellet delivery tube is positioned over the floor of a drain reservoir so as to capture a treatment pellet  1804  within the end  1800  of the pellet delivery tube and against the floor  1700  of the reservoir. Water  1806  will then interact with the treatment pellet  1804 , causing it to dissolve and release chemicals that inhibit organic matter growth. The end  1800  of the pellet delivery tube  818  can have notches  1802  to ensure water is able to make contact with the treatment pellet  1804  but retain the treatment pellet  1804  while it is in an undissolved state. The allows the distal end  1800  to be in contact with the floor  1700 , which can happen due to tolerances or the pellet delivery tube being displaced during assembly, for example. The tube can be loaded with treatment pellets as indicated. The treatment pellets  1804  can be spheroid in shape and fed into the tube  818  at the side of the wall sleeve using an access opening as previously described above for the guide structure(s). The pellets can be spheroid or spherical, allowing them to roll along the inside of the tube, as urged by gravity, or by other pellets being urged by gravity. Thus, as treatment pellet  1804  is dissolved, the next treatment pellet moves into place at the end of the tube  818  to eventually make contact with the water  1806  and also start to dissolve, providing a continuous supply of growth-inhibiting chemicals in the water collected in the drain reservoir. A user can then check the proximal end of the pellet delivery tube, and if the supply of treatment pellets in the tube is low, more can be added. 
       FIGS.  19 A- 19 B  show the side and front elevational views of a guide structure arrangement  1900  for use with spherical or belted spheroid treatment pellets, in accordance with some embodiments. A mounting plate  1902  can be configured to attach the side  816  of the wall sleeve of a PTAC unit. The mounting plate can support one or more guide structures. In particular a first guide structure  1904  can be configured to guide a treatment pellet inserted from the outside into a chassis pan of the PTAC unit. A second guide structure  1906  can be configured to guide a treatment pellet into the fluid or drain reservoir of a sloped drain pan or bottom of the PTAC unit. In particular, the first guide structure  1904 , as shown, is configured to drop a treatment pellet directly, or near-directly, into the chassis pan. The second guide structure  1906  includes a ramp end  1908  that deviates upward from vertical, and from a down section  1910 . When spherical or spheroid treatment pellet is inserted into the opening  1912  through the side  816  into the top of the second guide structure  1906 , the pellet can roll to the down section  1910 , increasing in velocity. The ramp end  1908  then directs the moving pellet into a more horizontal direction across the surface of the drain pan or bottom of the PTAC wall sleeve. 
       FIGS.  20 A- 20 C  show views of a belted spheroid treatment pellet  2000 , in accordance with some embodiments. In addition to spherical treatment pellets, it has been found that a belted spheroid shape can also be used and provides an advantage in manufacturing. Referring generally to  FIGS.  20 A- 20 C , a belted spheroid treatment pellet  2000  is formed by a press that compresses material as a powdered under pressure sufficient to form the powder into solid mass.  FIG.  20 A  shows a side elevational view,  FIG.  20 B  shows a top plan view, and  FIG.  20 C  is a top perspective view. 
     In testing the process, however, it was found that creating a perfectly spherical treatment pellet is difficult and a significant number of mold positions fail to produce a sufficiently compacted unit to retain the spherical shape. The provision of a cylindrical section around the middle of the unit—a belt—greatly increases the yield in molding treatment pellets and produces a pellet that can still roll sufficiently to reach the reservoir in the drain pan. 
     As shown, each belted spheroid treatment pellet  2000  includes a hemispherical top portion  2002  and a hemispherical bottom portion  2004 . The two hemispherical portions  2002 ,  2004  are oriented in opposing directions and are joined to a central cylindrical section  2006  that forms a belt around the belted spheroid treatment pellet  2000 . The pellet  2000  is made of a water-soluble material that inhibits the growth of various microbes known to grow in air conditioner units. The radius  2014  of the hemispherical portions  2002 ,  2004  can be greater than half a diameter  2016  of the pellet  2000 . In some embodiments the radius  2014  of the hemispherical portions  2002 ,  2004  can be in the range of 0.15 to 0.25 inches, or more or less than that in some embodiments. The diameter  2016  can be on the order of 0.35 to 0.45 inches in some embodiments, and more or less than that in some embodiments. The belt height  2010  can be in the range of 0.08 to 0.12 inches in some embodiments, and more or less than that in some embodiments. The height of the hemispherical portions  2002 ,  2004  from the belt  2006  can be in the range of 0.09 to 0.13 inches in some embodiments, and more or less than that in some embodiments. In some embodiments the cylindrical belt section  2006  can extend outward from the hemispherical portions  2002 ,  2004  to create a land that has a width of 0.004 to 0.008 inches in some embodiments, and more or less than that in some embodiments. In some embodiments the pellet  2000  can have the following dimensions, with a toleration of +/−0.003 inches: diameter  2016  of 0.375 inches, belt height  2010  of 0.107 inches, hemispherical portion height  2008  of 0.119 inches, and land width  2018  of 0.006 inches. A height  2012  between the peaks of the hemispherical portions  2002 ,  2004  can be less than a diameter  2016  of the cylindrical section  2006 . 
     Although the belted spheroid pellet  2000  is not perfectly spherical, when dropped through a guide structure such as second guide structure  1906  of  FIG.  19 A-B , the momentum achieved, combined with a slope in the drain pan, will result in the pellet  2000  rolling to the water reservoir, which is shown in  FIG.  21   . In  FIG.  21    there is shown a side partial cut-away view of a drain pan  2100  for use in a wall sleeve, in accordance with some embodiments. The drain pan  2100  can be a separate part that is inserted into the wall sleeve (e.g.  800 ) or it can be integrally formed as the bottom of the wall sleeve. As shown here, the chassis is not shown for the sake of clarity. The drain pan  2100  has a sloped bottom surface  2101  that slopes from the outer sides or edges to a centrally located drain reservoir  2102 . The sloped bottom  2101  directs condensate (water) to flow into the drain reservoir  2102 , where it will then flow into a drain member  2106  once the water level rises above the top of a drain rim  2104 . The drain member is a tube-like member that is open at the top and bottom to allow water to drain through it. The drain member  2106  can have a threaded portion over which a threaded collar  2108  is adjusted to bear against the bottom of the drain pan in the reservoir, and causing the drain rim  2104  to bear against the top of the drain pan bottom, thereby creating a water tight seal. In some embodiments the diameter of the drain member  2106  can be smaller than a drain pipe in which the bottom of the drain member  2106  is disposed, leaving room between the drain member  2106  and the drain pipe so that, even if the seal between the rim  2104 , collar  2108  and the drain pan leaks the water will still flow down the outside of the drain member  2106  into the drain pipe. 
     By sloping the bottom if the drain pan  2000 , water will only stand in the bottom of the reservoir  2102 . As a result, a volume of water on the order of ounces may be retained, rather than closer to a gallon in some prior art PTAC units. As microbial growth can occur where there is sufficient water, it is desirable to treat the drain reservoir  2102  in order to inhibit, if not prevent microbial growth. A treatment pellet  2000  can be inserted through the side  816  of the wall sleeve into the second guide structure  1906  to follow a path indicated by dashed arrow. As the pellet  2000  follows the shape of the second guide structure  1906  in a mostly vertical direction it gains velocity, and is then guided to more of a horizontal direction by the ramp end  1908 . The pellet  2000  will then roll across the bottom  2101  into the reservoir  2102  where it will slowly dissolve in water, thereby distributing the microbial growth inhibiting material into the standing water in the drain reservoir  2102  and into the drain. The angle of the slope encourages the belted spheroid pellet to roll to the reservoir  2102 , and can be, in some embodiments, in the range of four to twenty degrees relative to a plane defined by the perimeter of the floor. 
       FIG.  22    is a perspective view of a drain pan  2200  for use with a wall sleeve, in accordance with some embodiments. The drain pan  2200  includes a floor  2202  that slopes downward from the side walls  2208 ,  2210 ,  2212 ,  2214  to a drain reservoir  2204  that forms the lowest point of the floor  2202 , and which extends downward from the main portion of the floor  2202 . The drain reservoir  2204  can have a depth of about one inch from the main portion of the floor  2202  where in meets the drain reservoir  2204 . The drain reservoir can further have a width from front to back (in the direction from front wall  2212  to back wall  2208 ) of two to four inches. Similarly, the drain reservoir  2204  can have a wide, in a direction from side wall  2210  to side wall  2214 , of two to four inches. In some embodiments the width of the drain reservoir  2204  can be larger or smaller. The drain reservoir  2204  is positioned at the lowest point of the floor  2202  so that water produced by the AC unit that drains in the drain pan will flow down the sloped floor  2202  to the drain reservoir  2204 . Likewise, treatment pellets introduced into the wall sleeve can roll down the sloped floor  2202  into the drain reservoir  2204  where they will be dissolved the standing water held therein. Thus, the drain reservoir  2204  uses a raised lip or ridge  2304  around the drain opening, such as rim  1702  of  FIG.  17   . The back wall  2208  can include an overhang lip  2206  that extends to the rear and then downward, to engage wall portion of the louver cover that is placed on the outside of the PTAC unit. 
       FIG.  23    is a partial side cut-away view of a drain pan  2200  such as that shown in  FIG.  22    showing an integrally formed drain reservoir  2204  to retain some water in a reservoir, in accordance with some embodiments. The floor  2202  of the drain pan slopes downward toward the drain reservoir  2204 . The drain reservoir is formed by a wall  2308  that surrounds a space bounded at a bottom by a reservoir floor  2302 . A rim  2304  forms a small barrier around a drain opening. As shown here the drain opening is in a middle region of the reservoir floor  2302 , but can be located at a side, equivalently. The rim  2304  creates a barrier so that some water is retained on the reservoir floor  2302  to dissolve treatment pellets. A drain extension  2306  extends downward from the bottom of the drain reservoir  2204 , and has a circular diameter sized to couple with a drain fitting. The features shown here in drain pan  2200  are intended to be portions of a one-piece molded drain pan to facilitate high volume manufacturing. However, an equivalently functioning drain pan can be formed using discrete parts that result in substantially similar shapes of the features shown here. 
       FIG.  24    is a partial side cut-away view of the rear of a drain pan  2200  for use with a wall sleeve, showing a leak preventing overhang lip, in accordance with some embodiments. In particular, the view here is along cut line A-A′ of  FIG.  22   . The back wall  2208  includes an overhang lip  2206  that extends to the rear, and downward, creating a groove or slot in which the top edge of a wall segment  2402  of the wall sleeve  2600  can be captured. The overhang lip  2206  runs substantially the length of the back wall  2208 , and prevents water, such as rain, going between the wall segment  2402  and the back wall  2208  of the drain pan  2200 . Thus, the overhang lip  2206  prevents such leakage and can obviate the need for caulking. 
       FIG.  25    is a bottom inverted perspective view of the bottom of a drain pan  2200  such as that shown in  FIG.  22   , in accordance with some embodiments. The drain pan  2200  is shown inverted here to show a bottom view. The floor  2202  of the drain pan  2200  has a bottom surface  2502 . Extending from the bottom surface  2502  are several integrally formed staking protrusions  2504 . The staking protrusions mate with corresponding holes in the wall sleeve and allow the drain pan  2200  to be staked into the wall sleeve. The staking protrusions  2504  can be located on the bottom surface  2502  along the sides bounded by side walls  2210 ,  2214 . 
       FIG.  26    is an exploded perspective assembly view of a drain pan  2200  and wall sleeve  2600 , where the drain pan  2200  is staked into the wall sleeve, in accordance with some embodiments. The wall sleeve  2600  has substantially similar dimensions as wall sleeve  800  and fits into a standard PTAC wall opening. However, unlike wall sleeve  800 , wall sleeve  2600  does not have a floor/drain pan. The wall sleeve  2600  can be made of sheet metal, while the drain pan  2200  can be molded of a polymeric material. The advantage is that wall sleeve  2600  can be made using simple folds as it has all flat surfaces. Thus, the bottom does not have to be stamped or formed to create the features necessary to provide the sloped floor, drain reservoir, and rim around the drain opening. Instead, the drain pan  2200  can be a separately formed member that is molded of polymeric material, eliminating the stamping necessary to form sheet metal. Further, by eliminating fold seams in the floor, the drain pain  2200  has no seams that can leak. 
     The wall sleeve  2600  has a top  2604 , and opposing vertical sides  2606 ,  2608 , and is open at the front. Further, the wall sleeve  2600  has an opening  2602  at the back. The bottoms  2610  of the sides  2606 ,  2608  can be folded inward, and have a series of holes/apertures  2612  corresponding to the staking protrusions  2504 , which pass through the holes  2612 . The opposing vertical sides  2606 ,  2608  are parallel to each other and extend from the front of the wall sleeve  2600  to the back of the wall sleeve  2600 . The top  2604  extends from the top of one vertical side  2606  to the top of the other vertical side  2608 , and from the front to the back of the wall sleeve  2600 . 
       FIGS.  27 A-D  show various stages of staking a drain pan into a wall sleeve, in accordance with some embodiments. As shown here, the wall sleeve  2600  and drain pan  2200  are inverted from their orientations of  FIG.  26   . This is because, in assembling the drain pain  2200  into the wall sleeve  2600  it is easier to perform the staking in the inverted orientation used here. In  FIG.  27 A , the drain pan  2200  is moved into the wall sleeve  2600  such that staking protrusions  250  are aligned with openings  2612 . The drain pain  2200  and/or the wall sleeve  2600  are then moved into the position of  FIG.  27 B  where the staking protrusions  2504  are through the openings  2612 , and the bottom surface  2502  is against the bottom  2610  of the wall sleeve. In  FIG.  27 C  a heat element  2702  is moved into contact with each of the staking protrusions  2504 . The heal element softens and deforms the staking protrusion  2504  to reduce its height and flatten/spread out the material of the staking protrusion beyond the diameter of the opening  2612 . When the deformed material of the staking protrusion cools, it hardens, proving a retaining function similar to that of a rivet, as shown in  FIG.  27 D . Once each of the staking protrusions  2504  is heat staked, the drain pan  2200  is assembled into the wall sleeve  2600  to provide an assembled PTAC wall sleeve. 
       FIG.  28    shows a top plan view of a drain pan  2800  having a drain reservoir  2810  positioned and shaped to properly locate the drain pan/wall sleeve assembly in a wall, in accordance with some embodiments.  FIG.  29    shows a side cutaway view of a drain pan  2800  viewed in the direction of line B-B′. The floor  2802  of the drain pan  2800  is sloped downward from the sides  2803 ,  2805 ,  2807 ,  2809  at the perimeter of the floor  2802  to the reservoir  2810  so that water condensing in the AC unit that is collected by the floor  2802  flows into the reservoir  2810 . Further, the angle of the slope is selected such that the belted spherical treatment pellets as shown in  FIGS.  20 A-C  will often, but not necessarily always, roll to the reservoir  2810  when introduced into the PTAC through guide structure such as that shown in  FIG.  21   . In some embodiments the angle is in the range of four to twenty degrees to encourage treatment pellets to roll to the reservoir  2810  after being introduced into the drain pan through a guide structure, which gives the treatment pellets some velocity. 
     The reservoir  2810  can be formed by a portion of the floor  2802  that extends downward from the floor  2802 , and surrounds a volume/space. The bottom  2804  of the reservoir  2810  is lower than any other portion of the floor  2802 , and the top  2906  of the sides of the reservoir  2810  that turn downward from the floor  2802  are generally the lowest point of the floor outside of the reservoir  2810 . The reservoir  2810  can have a drain opening  2806  for water to exit the drain pan. The drain opening  2806  can have a rim around it, as rim  2304  in  FIG.  23   , or a small rim can be formed by a drain connector that fits into and through the drain opening  2806 . Likewise, the drain opening can include a drain extension like drain extension  2306  of  FIG.  23    that in integrally formed on the bottom of the drain pan  2800  around, and extending downward from the drain opening  2806 . The floor  2802  of the drain pan  2800  can have several standoffs  2808  that function to support the PTAC chassis in the same manner as standoffs  806 . 
     As can be seen in  FIG.  28   , the front and back of the reservoir  2810  are flat. The back side  2814  the reservoir  2801  is flat an parallel to the back and front sides  2803 ,  2807 , as is the front side  2812  of the reservoir  2810 . More importantly, the reservoir  2810  is positioned such that the back side  2814  will make contact with the wall through which the PTAC unit is mounted and act as a guide. Thus, when the wall sleeve in which the drain pan  2800  is mounted is installed in a wall opening, the wall sleeve is inserted into the wall opening from the inside (e.g. interior space) towards the outside (e.g. outdoors) until the back side  2814  of the reservoir  2810  meets the wall below the wall opening. As indicated in  FIG.  29   , a distance  2902 , which is the distance from that back side  2803  of the drain pan  2800 , which will be substantially co-terminal with the back of the wall sleeve, is selected such that the wall sleeve will be properly positioned in the wall opening, laterally, and extend to the outside a correct distance. In other words, when installing the wall sleeve with drain pan  2800 , when the back side  2814  of the reservoir  2810  makes contact with the interior wall, the wall sleeve will be in the optimum position to mount the wall sleeve and PTAC unit. Furthermore, the front  2812  of the reservoir  2810  is positioned a distance  2904  from the front side  2807  of the drain pan  2800  such that a sub-base installed under the front of the wall sleeve/PTAC unit will contact the front side  2812  of the reservoir and will be properly aligned under the wall sleeve. 
       FIG.  30    shows a drain pan  2800  in a wall sleeve  2816  installed in a wall  3000 , in accordance with some embodiments. The wall sleeve  2816  is installed through a wall opening in the wall  3000  that has a top  3002  and a bottom  3004 . The wall  3000  meets a floor  3012 , and has an outside  3008  and inside  3006 . For clarity, the chassis, which contains the various AC system components, is not shown here. As can be seen the back of the wall sleeve  2816  extend to the outside of the wall  3000 . As installed, the back side  2814  of the reservoir  2810  is against the inside  3006  of the wall  3000  below the wall opening. A drain tube  3010  is coupled to the drain opening of the reservoir  2810 . A sub-base  2820  is installed under the front of the wall sleeve  2816  and can be against the front side  2812  of the reservoir  2810 . Area  2822  indicates an access area that allows a user to insert treatment pellets into the PTAC unit. It should be understood, although stated hereinabove, that the drawing here is not necessarily correctly proportioned or to scale, rather the drawing is configured to explain the structures involved and their relationships. 
       FIGS.  31  and  32    show an equivalent alternative arrangement for the drain pan/floor  3100  of the PTAC wall sleeve, in accordance with some embodiments.  FIG.  32    shows a side cut-away view along line C-C′. Briefly, the drain pan  3100  has a back wall  3103 , a first side wall  3015 , a front wall  3107 , and a second side wall  3109 . One or more standoffs  3108  can be formed in the floor  3102 . The walls  3103 ,  3105 ,  3107 ,  3109  are located at the perimeter of the floor  3102  and are extend vertically above the perimeter of the floor  3102 . The floor  3102  is sloped downward from the perimeter of the floor to a drain opening  3106 . The drain opening  3106  is surrounded by a rim that extends above the floor  3102  where the floor  3102  meets the drain opening  3106 . This results in a reservoir  3110  being formed around the rim  3104 . The rim  3104  acts as a dam, causing water to collect around the rim  3104  until the level of the water exceeds the height of the rim  3104 . The rim  3104  also stops treatment pellets from rolling through the drain opening  3106 . A drain extension can be provided around the drain opening that extends downward before the floor  3102  and rim  3104 , as described previously. 
       FIG.  33    shows a perspective view of a drain pan  3300  for a PTAC wall sleeve having storm overflow prevention features, in accordance with some embodiments. It has been found that, in some regions, heavy rains and winds can occur, and depending on the direction of the wind, and possibly the PTAC having been installed in a non-level state, the wind can blow rain water into the PTAC, and it can blow water already in the drain pan even when there is no rain. As a result, water can, in prior art drain pans, be blown over the front of the drain pan, leaking into the inside of the structure. 
     To prevent such wind/rain-induced overflow, the drain pan  3300  includes a sloped floor  3302  as shown, for example, in  FIG.  32   , which slopes down to a drain reservoir  3306  from the sides of the drain pan  3300 , which are bordered by the front wall  3304 , back wall  3310 , and side walls  3312 ,  3314 . The drain reservoir includes a riser or rim  3308  to ensure a small amount of water, under normal operation, is collected in the drain reservoir  3306 . Water from outside the PTAC that is blown into the PTAC unit can collect in the drain pan and be blown around the drain pan without flowing into the reservoir  3306 , even with a sloped floor  3302 . To catch and direct such wind-blown water into the drain reservoir  3306 , the floor  3302  of the drain pan  3300  includes a pair of lateral canals  3316  that extend lengthwise across the floor  3302 , from opposite sides of the reservoir  3306  to the respective sides  3312 ,  3314 . The canals  3316  can be on the order of three quarters of an inch across and about three eighths of an inch deep, and they otherwise follow the slope of the floor  3302  along the floor  3302  from the sides  3312 ,  3314  to the drain reservoir  3306 . The canals  3316  collect wind-blown water that might otherwise be forced out of the pan and leak into the structure. The geometry of the canals  3316  removes force of the wind on the water, allowing the water to flow into the reservoir  3306  and through the drain. Although the canals  3316  are shown parallel to the front  3304  and back  3310 , they can extend in other directions as well. In some embodiments the canals  3316  can be formed along the facet lines on the sloped floor  3302 , which extend from each of the corners to the drain reservoir  3306 . 
     A wall sleeve for a PTAC unit and a PTAC unit using the wall sleeve has been described that provides an external access port coupled with internally mounted guide structures that allow the provision of treatment pellets into the internal drain pan(s) of the PTAC unit without having to disassemble the PTAC unit. The embodiments of the inventive disclosure greatly simplifies routine maintenance to prevent growth and build-up of microbial matter than can foul internal components of the PTAC unit, which can reduce efficiency, and which can further block or obstruct drainage, resulting in leakage outside of the air conditioner unit that can damage interior structure, facilitate mold growth, and other issues associated with water leakage. By providing a simple and easy way to place treatment pellets into the PTAC unit, the PTAC unit does not have to be partially disassembled to place treatment pellets into the PTAC unit drain structures. This helps ensure that regular maintenance of PTAC units will be followed, and it greatly reduces the time needed to perform such maintenance. 
     Further, the wall sleeve is disclosed as having a bottom that acts as a drain pan. The bottom of the wall sleeve can be formed integrally with the other walls/side of the wall sleeve, or it can be made as a separate element that is assembled together into the wall sleeve. The drain pan provides a surface that acts to catch and direct water to a reservoir formed in the floor of the drain pan. The reservoir holds a small amount of water in order to allow treatment pellets to dissolve without falling into the drain, so as to produce a small volume of treated water that is eventually flushed into the drain system connected to the drain pan. The floor of the drain pan slopes downward from the sides of the drain pan to the reservoir, so that water falling anywhere on the floor of the drain pan will flow to the reservoir. The reservoir can have a rim around the drain opening to ensure that there will be a small amount of standing water in the bottom of the reservoir, and to prevent treatment pellets from rolling into the drain. When a treatment pellet sits in the standing water that is collected in the bottom of the reservoir, it dissolves, creating a treatment solution in the standing water of a specific concentration based on the rate of dissolution of the treatment pellet and the volume of water in the bottom of the reservoir. As water continues to collect in the bottom of the reservoir, the level of the standing water in the bottom of the reservoir will exceed the level or the rim around the drain opening, allowing the treatment solution to flow into the drain. Further, the reservoir can be shaped and positioned on the floor of the drain pan to aid in properly locating the wall sleeve in the wall opening when the wall sleeve is inserted into the wall opening. A substantial benefit of the sloped drain pan is that the amount of water collected in the reservoir is much less than the amount of water collected in a flat-bottomed drain pan, which reduces the volume of water collected in the drain pan by the reservoir compared to conventional flat-bottomed drain pans. As a result, if there is a leak or spill, the initial amount of water that could exit the drain pain into the structure is much less than can occur with a conventional flat-bottomed drain pan.