Patent Publication Number: US-2020292205-A1

Title: Side-mounted electric heater

Description:
FIELD 
     An HVACR fan cabinet and heater assembly for use in commercial packaged HVACR products. 
     BACKGROUND 
     Commercial packaged HVACR systems such as rooftop units for servicing large buildings such as office buildings, multi-tenant dwellings, or warehouses, use centrifugal blowers such as plenum fans to drive airflow through the systems. Near a centrifugal blower such as a plenum fan, the airflow may be a horizontal tornado, with a rotation determined by the direction in which the fan is spinning. This can result in uneven pressurization of the fan cabinet and result in uneven flow through heating elements attached to the fan cabinets which are used to heat buildings. This uneven flow may require a larger cabinet to allow airflows to normalize before the airflow passes through heating elements used to heat the air then supplied to a building by the HVACR system, causing the HVACR system to be larger than necessary and limiting the building which can be serviced by the HVACR system. 
     SUMMARY 
     An HVACR fan and heating assembly including a fan cabinet with a heater mounted vertically and horizontally biased towards one of the side walls of the fan cabinet. The cabinet contains a centrifugal blower and has at least a blower-side wall, a solid blockoff opposite the blower-side wall, a first side wall that is to the left of the centrifugal blower from the perspective of the blockoff, a second side wall to the right of the centrifugal blower from the perspective of the blockoff, and a heater mount on the solid block-off that is biased towards the first side wall or the second side wall based on the direction of rotation of the centrifugal blower. 
     In an embodiment, the blockoff may be a smooth planar surface without flanges or protrusions into the cabinet. 
     In an embodiment, the centrifugal blower may be a plenum fan or a housed fan. 
     In an embodiment, the heater mount may be aligned vertically, such that the height of the mounted heater is greater than its width. 
     In an embodiment, the biasing based on the direction of rotation of the centrifugal blower may be towards the second side wall where the centrifugal blower rotates clockwise with respect to the blockoff, or may be on a towards the first side wall where the blower rotates counter-clockwise with respect to the blockoff. 
     In an embodiment, the HVACR cabinet may further include at least a second centrifugal blower, and one or more baffles disposed within the cabinet. 
     In an embodiment, the baffles may be disposed between a centrifugal blower and a second centrifugal blower. 
     By accounting for the cyclonic flow of air leaving a centrifugal blower, the airflow exiting a fan cabinet through a heater can be made more even. Improving the evenness of airflow through the heater improves the safety and efficiency of the heater by improving heat transfer from the heater to the airflow and preventing the formation of hot spots on the heater, which accelerate heater wear and present a fire risk. Additionally, ways to improve the evenness of airflow without requiring a lengthening of the fan cabinet facilitate integration of such fan cabinets and fan and heater assemblies into packaged HVACR solutions such as rooftop units. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram displaying an example embodiment of an HVACR cabinet with a heater mounting. 
         FIG. 2  is a diagram of the embodiment of  FIG. 1  providing a view from the perspective of a blockoff side of a fan cabinet. 
         FIG. 3  is a view of the embodiment of  FIG. 1  from the perspective of a side wall of a fan cabinet. 
         FIG. 4  is a diagram of an embodiment with a horizontally-mounted heater, from the perspective of a blockoff side of the fan cabinet. 
         FIG. 5  is a diagram of an embodiment integrated into an HVACR system and the airflow through the system 
         FIG. 6  is a top-down view of the embodiment of  FIG. 1 , showing airflows during operation. 
         FIG. 7  is a top-down view of a fan cabinet featuring two centrifugal blowers and including a heater mounting according to the heater mounting of  FIG. 4 , and showing airflows during operation. 
         FIG. 8  is a diagram of airflow through an embodiment of the prior art. 
     
    
    
     DETAILED DESCRIPTION 
     In an HVACR fan and heater assembly, the heater may be placed biased to one side of a fan cabinet and mounted vertically such that the height of the heater is greater than its width, receiving airflow more evenly across the entire heater, and improving the safety and efficiency of the unit. The fan and heater assembly may be incorporated into a larger HVACR unit, such as a rooftop system serving a structure, such as an office building, apartment complex, or warehouse. 
       FIG. 1  depicts an embodiment including a fan cabinet  10 , which has blower-side wall  12 , side walls  14  and  16 , and a blockoff  18 . The fan cabinet  10  has a bottom  20  and a top  22 . The fan cabinet contains a centrifugal blower  24 . A heater  26  is connected to the fan cabinet on the side of the blockoff  18 , with the blockoff  18  running at least from a side of the heater  26  to one of the side walls  14  or  16 . In some embodiments, the blockoff  18  may also run above or below the heater between the top or bottom of the heater and the top  22  or bottom  20  of the fan cabinet  10 . In some embodiments, the blockoff may be on either side of the heater, extending from the sides of the heater to both of the side walls  14  and  16 . 
     The fan cabinet  10  may be defined by the blower-side wall  12 , the side walls  14  and  16 , the bottom  20 , the top  22  and the blockoff  18 . The blower-side wall  12  may include an inlet through which air may enter the centrifugal blower  24 . The centrifugal blower  24  is located primarily within the fan cabinet  10 , though some of it may extend past the blower-side wall  12  in some embodiments. First side wall  14  is, from the perspective of the blockoff  18 , to the left of the centrifugal blower  24 . Second side wall  16  is, from the perspective of the blockoff  18 , to the right of the centrifugal blower  24 . Heater  26  is mounted on the fan cabinet, at an opening in the blockoff  18 . 
     The centrifugal blower  24  may be, for example, a plenum fan or a housed fan. Centrifugal blower  24  takes in air through an inlet in blower-side wall  12  and forces the air into the fan cabinet  10 . The centrifugal blower  24  may rotate in a clockwise or counter-clockwise direction, that direction defined by the rotation of the centrifugal blower with respect to the blockoff  18 . In the embodiment depicted in  FIG. 1 , the centrifugal blower  24  rotates in a clockwise direction. The centrifugal blower  24  brings air through an inlet in the blower-side wall  12  axially, and within the fan cabinet  10  distributes the air radially. In some embodiments, multiple centrifugal blowers may be used within a single fan cabinet. 
     In the fan cabinet  10 , opposite the blower-side wall  12 , there is a blockoff  18  and a heater  26 . The blockoff  18  prevents escape of the air within the fan cabinet  10 , forcing air to travel through the heater  26  in order to escape the fan cabinet  10 . A side of the blockoff  18  faces the inside of the fan cabinet  10 . The side of the blockoff  18  facing the inside of the fan cabinet may be a smooth planar surface free of flanges or protrusions which may affect airflow. In some embodiments, there may be a recess  32  in the side of the blockoff facing the outside of the fan cabinet, where, for example, a control panel for the HVACR unit which includes the fan cabinet may be located. 
     Heater  26  is a heater, such as an electric heater, warming the airflow that passes through as the airflow exits the fan cabinet  10 . The heater has a height  28  and a width  30 . In some embodiments, the heater may be oriented vertically. In the vertical orientation, the long side of the heater runs in a direction from the bottom  20  of fan cabinet  10  towards the top  22  of fan cabinet  10 . In the vertical orientation, the major axis of the heater is in the direction from the bottom  20  of the fan cabinet towards the top  22  of the fan cabinet. In the vertical orientation, the height  28  of the heater, running in the direction from the bottom of the fan cabinet  20  towards the top of the cabinet  22  is greater than the width of the cabinet running the direction from the first side wall  14  towards the second side wall  16 . In an embodiment, the height  28  of the heater  26  matches the distance between the top  22  and bottom  20  of the fan cabinet  10 . In an embodiment, the height  28  of the heater  26  may be less than a height of the fan cabinet  10 , with the height of the fan cabinet  10  measured as distance between the top  22  and bottom  20  of the fan cabinet  10 . In embodiments where the height  28  of the heater  26  is less than the distance between the top  22  and the bottom  20  of the fan cabinet  10 , portions of the blockoff  18  cover the areas above the heater, up to the top  22  of the cabinet and below the heater down to the bottom  20  of the cabinet. In embodiments where the height  28  of the heater  26  is less than the distance between the top  22  and the bottom  20  of the fan cabinet  10 , and wherein the top of the heater  26  is not flush with the top  22  of the fan cabinet  10 , a baffle may be placed at or near the top  22  of the fan cabinet  10  to deflect airflow into an intake of the heater  26 . 
     In some embodiments, the heater  26  may be oriented horizontally, with its major axis running between the first side wall  14  and the second side wall  16 . When oriented horizontally, the width of the heater  30  is greater than the height of the heater  28 . In these embodiments, the width of the heater  30  may be less than the distance from the first side wall  14  to the second side wall  16  and the height of the heater  28  may be less than the distance from the bottom  20  of the cabinet  10  to the top  22  of the cabinet  10 . 
     The heater  26  is positioned with a horizontal bias towards one of the side walls  14  or  16 , placing the heater closer to one side wall than it is to the other and offset from a center-line of the fan cabinet. In the embodiment depicted in  FIG. 1 , the position of the heater is biased towards the second side wall  16  and is further from the first side wall  14 . The biasing of the heater towards the first side wall  14  or the second side wall  16  may be such that the width of the heater  30  does not at any point overlap with the width of the centrifugal blower  24  when viewed from the perspective of the blockoff  18 . The heater may, in some embodiments, be mounted such that a side of the heater is flush with the side wall it is biased towards, as depicted in  FIG. 1 , where the side of the heater  26  is flush with the second side wall  16 . The heater may be mounted to the fan cabinet  10  by a heater mounting  34 , which includes an opening in the fan cabinet  10  and connection points for mounting the heater  26  to the fan cabinet  10 , such as tabs, flanges, holes for fasteners such as screws and/or other such mechanical connections, with the opening  34  matching the size of the inlet to the heater. 
     In some embodiments, the position of the heater  26  may be biased vertically. The heater  26  may be biased towards the top  22  of the cabinet  10  relative to the centrifugal blower  24 . In some embodiments, the heater  26  may be biased such that a top of the heater  24  is flush with the top  22  of the cabinet  10 . In these embodiments, the blockoff  18  extends from the first side wall  14  to the second side wall  16  below the heater  26 , and in embodiments where the heater  26  is not flush with the top  22  of the cabinet  10 , extend from the first side wall  14  to the second side wall  16  above the heater  26 , and extend from a side of the heater  26  to the first side wall  14  and/or the second side wall  16 , and extend from the first side wall  14  to the second side wall  16  below the heater  26 . In some embodiments, the biasing of the heater towards the top  22  of fan cabinet  10  may be such that the height of the heater  28  does not at any point overlap with the height of the centrifugal blower  24  when viewed from the perspective of the blockoff  18 . 
       FIG. 2  is a view of the embodiment of  FIG. 1  from the perspective of the blockoff  18 . The centrifugal blower  24  is offset towards one side of the cabinet from the center line  52 . The centrifugal blower includes a fan, which has a direction of rotation  50 . In the embodiment depicted in  FIG. 2 , the direction of rotation  50  is clockwise with respect to the position of the blockoff  18 , but in other embodiments the direction of rotation  50  may be counter-clockwise. The side towards which the position of the heater is biased may be based on the direction of rotation  50  of the fan from the perspective of the blockoff  18  and the heater  26 . The biasing of the heater position may be such that the centrifugal blower  24  is completely viewable from the perspective of the inside of blockoff  18 , and not obstructed by any portion of the width  30  of heater  26 . In embodiments, such as that shown in  FIG. 2 , where the centrifugal blower  24  or each of multiple centrifugal blowers rotate clockwise with respect to the blockoff  18  and heater  26 , the heater may be biased towards the second side wall  16 , placed within a region  54  extending towards the second side wall  16  from the center line of the cabinet  52 . In some embodiments, for example where there is more than one centrifugal blower  24 , the position of the heater  26  may be such that the width  30  of heater  26  overlaps with at the width of at least one of the centrifugal blowers, and at least one of the centrifugal blowers is not completely viewable from the perspective of the inside of blockoff  18 . In embodiments where the centrifugal blower  24  or each of multiple centrifugal blowers rotate counter-clockwise, the position of the heater  26  may be biased towards first side wall  14 , within a region  56  extending towards the first side wall  14  from the center line of the cabinet  52 . Region  54  and region  56  may be defined with respect to the centrifugal blower  24 . From the perspective of the blockoff  18 , the rotation of the centrifugal blower  24  in embodiments where there is one centrifugal blower  24  within the fan cabinet  10  may define a twelve-to-six orientation proceeding from the top center of the centrifugal blower  24 , clockwise around to the bottom center of the centrifugal blower  24 , with everything to this side from the center of the centrifugal blower to the second side wall defined as region  54 . This may also define a six-to-twelve orientation proceeding from the bottom center of the centrifugal blower  24  and rotating clockwise towards the top center of the centrifugal blower  24 , with everything on this side from the center of the centrifugal blower  24  to the first side wall  14  defined as region  56 . 
       FIG. 3  is a view of the embodiment of  FIG. 1  from the perspective of a first side wall  14 . In this embodiment, centrifugal blower  24  distributes air through fan cabinet  10 . The centrifugal blower  24  may be mounted to the bottom  20  of the fan cabinet  10  using blower mounts  150 . In some embodiments, there may be raised portions of the bottom  20  of fan cabinet  10 , on which blower mounts  150  may be located. Space  152  is the area between the end of the centrifugal blower closest to the blockoff  18  and the blockoff  18 . Space  152  may be shortened in fan cabinets and systems where the heater  26  is oriented with its major axis or long direction running vertically from the bottom  20  of the fan cabinet  10  towards the top  22  of the fan cabinet  10 , and where the heater  26  is biased towards a first side wall  14  or a second side wall  16  based on the direction of rotation  50  of a centrifugal blower  24 . Shortening space  152  provides a more compact design which is more space-efficient compared to other orientations and positions which may require space  152  to be longer to allow airflow to even out before entering a heater  26 . 
       FIG. 4  is an embodiment where the heater  26  is mounted horizontally, and biased vertically towards a top  22  of the fan cabinet  10  and biased horizontally towards a second side wall  16 , viewed from the perspective of the blockoff  18 . In this embodiment, the major axis of the heater runs between the first side wall  14  and the second side wall  16 . The height of the heater  28  is less than the width of the heater  30 . In this embodiment, a side of the heater  26  is flush with the second side wall  16 , and the top of the heater  26  is flush with the top  22  of the cabinet  10 . In some embodiments, the heater may be mounted below the top  22  of the cabinet and/or with some of the blockoff  18  between each side of the heater and the first side wall  14  and second side wall  16 . In embodiments where the top of the heater  26  is not flush with the top  22  of the fan cabinet  10 , a baffle may be positioned at or near the top  22  of the fan cabinet  10  to direct airflow downwards from the top  22  of the cabinet towards an inlet to the heater  26 . In some embodiments, the width  30  of the heater  26  may cross the center line  52  of the cabinet  10 . In this example embodiment, the horizontal biasing of the heater is such that a greater portion of the width  30  of the heater  26  is on one side of the center line  52  of the cabinet  10 . In some embodiments, the heater  26  may be entirely on one side of the center line, for example in region  56  towards the second side wall  16  from the center-line  52 . The horizontal biasing may be based on a direction of rotation  50  for the centrifugal blower  24 , with the heater biased towards the second side wall  16  a clockwise direction of rotation  50 , and biased towards a first side wall  14  when the direction of rotation  50  is counter-clockwise. The vertical biasing of the position of the heater  26  may be such that the heater  26  is above the centrifugal blower  24  when viewed from the perspective of the blockoff  18 . 
       FIG. 5  is an embodiment of a rooftop HVACR system. The system may be located on the roof of a building to provide HVACR to the building. The system includes return air return air inlet  170 , through which air from the building enters the system, and in some embodiments may include outside air intake  172 , one or more openings through which air from outside the building may enter the HVACR system. The air entering the system through the return air inlet  170  and outside air intake  172  may then enter a filter unit  174 . The filter unit  174  is a cabinet which directs air to and through one or more filters. Following the filter unit there may be a chamber  176  prior to the fan cabinet  10 . Air is drawn into the fan cabinet  10  by centrifugal blower  24 , which then expels the air into fan cabinet  10 . Air circulates through fan cabinet  10  and exits fan cabinet  10  through heater  26 . Heater  26  is oriented vertically, with a major axis running between the bottom  20  and the top  22  of the fan cabinet  10 . Air exits heater  26  and travels into and through supply outlet  178 . Supply outlet  178  is one or more ducts or vents connecting the HVACR system to the HVACR distribution ducts or vents of the building. The rooftop HVACR system may additionally include condensers  180 . 
       FIG. 6  is a top-down perspective of the embodiment of  FIG. 1  and shows the airflow through the embodiment during operation. The centrifugal blower  24  draws air into the fan cabinet and the air circulates within the blower-side wall  12 , the side walls  14  and  16  and the blockoff  18 , ultimately entering and passing through the heater  26  on leaving the fan cabinet. The airflow passing through the fan cabinet may continue through a rooftop HVACR unit and be directed to and distributed through a building such as a commercial office building or a warehouse. 
     The airflow  70  exiting the centrifugal blower  24  in region  54  between the center line  52  of the fan cabinet  10  and the second side wall  16  flows towards the second side wall  16  and the blower-side wall  12 . The airflow  70  traveling along the blower-side wall  12  is deflected towards the second side wall  16 . The airflow  70  travels along and may be deflected by the second side wall  16  towards heater  26 , through which it leaves fan cabinet  10 . 
     The airflow  72  exiting the centrifugal blower  24  in region  56  between the center line  52  of the fan cabinet  10  and the first side wall  14  flows towards the blower-side wall  12  and is deflected by the blower-side wall  12  towards the first side wall  14 . The airflow  72  continues along and may be deflected by the first side wall  14  towards the blockoff  18 . 
     Air from airflow  72  may pass over or under the centrifugal blower  24  following airflow  74  or may pass between the end of the centrifugal blower  24  and the blockoff  18  following airflow  76 . Airflows  74  and  76  may converge with airflow  70  in region  54  of the fan cabinet  10  and follow the path of airflow  70  towards the blower-side wall  12 , then towards the second side wall  16 , and to and through the heater  26 . 
       FIG. 7  shows airflow through an embodiment where two centrifugal blowers  24 a and  24 b are located within the cabinet and where the heater mounting is oriented horizontally and biased horizontally and vertically according to the heater mounting of  FIG. 4 . In embodiments where there are two centrifugal blowers  24 a and  24 b, a baffle  90  may be disposed between the two blowers, in the form of a vertical plate. Air leaving centrifugal blower  24 a on the side of the first side wall  14  forms airflow  150 , which deflects off of first side wall  14 , with most of the airflow  150  traveling towards blower-side wall  12 . Some of airflow  150  is deflected towards the blockoff  18 , forming airflow  152  towards heater  26 . Airflow  154  leaving blower  24 b on the side of the second side wall  16  deflects off of the second side wall  16  and continues parallel to the second side wall  16  towards the blockoff  18 . Airflow  154  is deflected by the blockoff  18  towards first side wall  14 , forming a horizontal airflow  162 . Airflow  160  leaving the blower  24 a on the second side wall  16  side of the blower travels towards and through the heater  26 , with some horizontal deflection occurring where the airflow contacts horizontal airflow  162 . Airflow  156  leaves the blower  24 a on the first side wall  14  side of the blower, and travels towards the blower-side wall  12 , then along the blower-side wall  12  towards the second side wall  16 , where it may join airflow  154 . Airflows  152 ,  158 ,  160 , and portions of airflow  154  move to and through the heater  26 , where heat is transferred to the air. These airflows may leave a low-airflow region  118  entering the heater, resulting in a hot spot  120  forming where there is reduced heat transfer from the heater  26  to the airflows. Where such a hot spot  120  is located at a specific end of the heater  26 , the hot spot  120  may then be mitigated by reducing the width  30  of the heater  26  or adjusting the horizontal or vertical biasing of the position of the heater  26 . 
       FIG. 8  shows the airflow in a prior art configuration of fan cabinet and heater. In the prior art embodiment, the heater  26  is mounted such that the major axis of the heater  26  is horizontal, in a direction running from the first side wall  14  towards the second side wall  16 . In this horizontal orientation, the width of the mounted heater  26  is greater than its height. The heater  26  may cross the centerline of the fan cabinet and/or the center line of the centrifugal blower  24 . In the prior art, airflow  130  of air leaving the centrifugal blower  24  on the side of the first side wall  14  circulates between the centrifugal blower  24  and the first side wall  14 . A portion of airflow  130  moves to and through the horizontally-mounted heater  26  as airflow  132 , while other air from airflow  130  along with air exiting the top of centrifugal blower  24  travels as airflow  134 . Airflow  134  may join airflow  136 , which may also include air exiting the centrifugal blower  24  on the side of second side wall  16 , and airflow  136  circulates along second side wall  16  and towards and through heater  26 . The airflows  132  and  136  to and through the heater  26  result in a significant number of low-airflow regions  118 , reducing heater efficiency and resulting in the formation of dangerous hot spots  120 . Note that the prior art embodiment of  FIG. 8 , with a centrally positioned, horizontally-oriented heater produces significantly more low-flow regions  118  and corresponding hot spots  120  compared to the example embodiments. 
     Aspects: 
     It is to be appreciated that any one of aspects 1-8 may be combined with any of aspects 9-16 or 17-20, and that any of aspects  9 - 16  may be combined with any of aspects 17-20. 
     Aspect 1. An HVACR fan and heater assembly, comprising: 
     a centrifugal blower, 
     a fan cabinet, comprising a blower-side wall, a blockoff opposite the blower-side wall a first side wall located to the left of the centrifugal blower from the perspective of the blockoff and a second side wall located to the right of the centrifugal blower from the perspective of the blockoff, 
     a heater, and 
     wherein the blockoff extends from the outside of the heater to at least one of the first side wall or the second side wall, 
     wherein a position of the heater is horizontally biased towards either the first side wall or the second side wall. 
     Aspect 2. The HVACR fan and heater assembly according to aspect 1, wherein the centrifugal blower is a plenum fan. 
     Aspect 3. The HVACR fan and heater assembly according to aspect 1-2, wherein the heater is mounted such that it has a width that is greater than its height and the position of the heater is vertically biased towards a top of the fan cabinet. 
     Aspect 4. The HVACR fan and heater assembly according to any of aspects 1-3, wherein the position of the heater is such that a side of the heater is flush with the first side wall or the second side wall. 
     Aspect 5. The HVACR fan and heater assembly according to any of aspects 1-4, wherein the centrifugal blower rotates clockwise with respect to the blockoff and the position of the heater is biased towards the second side wall. 
     Aspect 6. The HVACR fan and heater assembly according to any of aspects 1-4, wherein the centrifugal blower rotates counter-clockwise with respect to the blockoff and the position of the heater is biased towards the first side wall. 
     Aspect 7. The HVACR fan and heater assembly of any of aspects 1-6, further comprising a second centrifugal blower. 
     Aspect 8. The HVACR fan and heater assembly according to aspect 7 further comprising a baffle disposed between the centrifugal blower and the second centrifugal blower. 
     Aspect 9. An HVACR fan cabinet comprising: 
     a blower-side wall, 
     a blockoff, opposite the blower-side wall, 
     a first side wall joined to a left edge of the blower-side wall from the perspective of the blockoff 
     a second side wall joined to a right edge of the blower-side wall from the perspective of the blockoff, and 
     a heater mounting, wherein the position of the heater mounting is biased towards one of the first side wall or the second side wall, 
     wherein the blockoff extends from the heater mounting to at least one of the first side wall or the second side wall. 
     Aspect 10. The HVACR fan cabinet according to aspect 9, wherein the heater mounting is oriented such that the width of the heater mounting is greater than the height of the heater mounting and a vertical position of the heater mounting is biased towards a top of the fan cabinet. 
     Aspect 11. The HVACR fan cabinet according to any of aspects 9-10, wherein the position of the heater mounting is biased such that one side of the heater mounting is flush with one of the first side wall or the second side wall. 
     Aspect 12. The HVACR fan cabinet according to any of aspects 9-11, further comprising a heater connected to the heater mounting. 
     Aspect 13. The HVACR fan cabinet according to any of aspects 9-12, wherein the blower-side wall comprises an inlet. 
     Aspect 14. The HVACR fan cabinet according to aspect 13, further comprising a centrifugal blower mounted within the cabinet and wherein the centrifugal blower interfaces with the inlet of the blower-side wall. 
     Aspect 15. The HVACR fan cabinet according aspect 14, wherein the centrifugal blower rotates clockwise with respect to the blockoff and the position of the heater mounting is biased towards the second side wall. 
     Aspect 16. The HVACR fan cabinet according to aspect 14, wherein the centrifugal blower rotates counter-clockwise with respect to the blockoff and the position of the heater mounting is biased towards the first side wall. 
     Aspect 17. An HVACR system, comprising: 
     a return air inlet, 
     a filter, 
     a centrifugal blower, 
     a fan cabinet comprising a first side wall, a second side wall, a blower-side wall, a top, a bottom, and a blockoff, 
     a heater, mounted on the blockoff, with a horizontal position biased towards one of the first side wall or the second side wall, and 
     a supply outlet. 
     Aspect 18. The HVACR system of aspect 17, wherein the heater is mounted on the blockoff with a vertical position biased towards the top of the fan cabinet and oriented such that a width of the heater is greater than a height of the heater. 
     Aspect 19. The HVACR system according to any of aspects 17-18, wherein the return air inlet receives air from a building and the supply outlet provides air to the building. 
     Aspect 20. The HVACR system of any of aspects 17-19, the heater is flush with the first side wall or the second side wall of the fan cabinet. 
     The examples disclosed in this application are to be considered in all respects as illustrative and not limitative. The scope of the invention is indicated by the appended claims rather than by the foregoing description; and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.