Patent Publication Number: US-2023151997-A1

Title: Dampers placed on the half face of the inlet and the outlet of side-by-side airflow energy recovery sections used as recirculation path

Description:
FIELD 
     This disclosure relates generally to an air handler with recirculation dampers for a heating, venting, air conditioning, and refrigeration (HVACR) system, particularly the arrangement, construction, and/or configuration of the recirculation dampers in the air handler. 
     BACKGROUND 
     A heat exchange assembly, such as an air handler with a heat exchanger core, can help mechanical ventilation of a controlled space be more cost-effective by reclaiming a portion of energy from vented indoor air before exhausting the vented indoor air into the environment. The vented indoor air and the fresh air exchange energy in the core and recapture a portion of the energy from the vented indoor air that would otherwise be lost if the vented indoor air were exhausted directly to the environment. The air handler can further reduce energy consumption by recirculating the vented indoor air into the controlled space while bypassing the core. The recirculation function can be achieved by recirculation dampers installed for the air handler. 
     SUMMARY 
     This disclosure relates generally to an air handler with recirculation dampers for a heating, venting, air conditioning, and refrigeration (HVACR) system, particularly the arrangement, construction, and/or configuration of recirculation dampers in the air handler. 
     By including dampers on a faceplate of an air handler housing instead of on a middle of unit wall shared by an indoor air inlet tunnel and an indoor air return tunnel connected to the air handler, flow of recirculation path within the air handler can be improved while saving space. By placing the dampers on the face of the air handler housing instead of the middle of unit wall, the tunnels connected to the air handler do not need to account for the size requirements of the damper. Accordingly, more compact recirculation flow paths can be used while still achieving sufficient flow and good pressure drop properties across the air handler. 
     According to an embodiment, an air handler for an HVACR system includes a housing. The housing includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. A septum protrudes into the housing from a first side of the faceplate. A core is disposed within the housing and has a front edge connected to an edge of the septum, a top edge connected to the roof panel, a bottom edge connected to the base panel, a first side plate connected to the first side panel, and a second side plate connected to the second side panel. A first tunnel connects to a first area on the faceplate from a second side of the faceplate. The second side is opposite to the first side of the faceplate. A second tunnel connects to a second area of the faceplate from the second side. The second area is disjointed from the first area. A first recirculation path is defined by the faceplate, the roof panel, the septum, the first side panel, the second side panel, and the core. The first recirculation path is configured to channel a first portion of airflow from the first tunnel to the second tunnel. A second recirculation path is defined by the faceplate, the septum, the base panel, the first side panel, the second side panel, and the core. The second recirculation path is configured to channel a second portion of the airflow from the first tunnel to the second tunnel. A first damper is disposed in the first area of the faceplate and configured to obstruct the first recirculation path. A second damper is disposed in the second area of the faceplate and configured to obstruct the second recirculation path. A first opening is disposed in the first area of the faceplate and connecting the first tunnel to the second recirculation path. A second opening is disposed in the second area of the faceplate and connecting the second tunnel to the first recirculation path. 
     According to another embodiment, the second damper is disposed adjacent to the first side panel and the roof panel, and the first damper is disposed adjacent to the second side panel and the base panel. 
     According to yet another embodiment, the second opening is adjacent to the first side panel and the base panel, and the first opening is adjacent to the second side panel and the roof panel. 
     According to yet another embodiment, the first tunnel is an indoor air inlet from a controlled space, and the second tunnel is an indoor air return to the controlled space. 
     According to yet another embodiment, the core is a fixed plate heat exchanger or a rotary type wheel heat exchanger. 
     According to yet another embodiment, the core is in a horizontal configuration substantially parallel to the septum, and the fixed plate heat exchanger includes heat transfer plates that are in a vertical configuration when the core includes a fixed plate heat exchanger, and the rotary type wheel heat exchanger includes at least two side-by-side wheels when the core includes a rotary type wheel heat exchanger. 
     According to yet another embodiment, the first tunnel and the second tunnel are separated by a middle of unit wall that is substantially perpendicular to the faceplate on a first plane and substantially perpendicular to the septum on a second plane, wherein the second plane is substantially perpendicular to the first plane. 
     According to yet another embodiment, the first damper includes a plurality of sections that are configured to open or close independently among one another or in unison, and the second damper includes a plurality of sections that are configured to open or close independently among one another or in unison. 
     According to yet another embodiment, the first damper obstructs the first portion of the airflow from entering the first recirculation path when the first damper is in a closed position. 
     According to yet another embodiment, the second damper obstructs the second portion of the airflow from entering the second tunnel when the second damper is in a closed position. 
     According to yet another embodiment, the first portion of the airflow is recirculated to the second tunnel through the second opening when the first damper is in an open position, and the second portion of the airflow is recirculated to the second tunnel through the first opening and the second recirculation path when the second damper is in an open position. 
     According to yet another embodiment, the airflow entered the first tunnel from a controlled space is recirculated into the controlled space when the first and the second dampers are in their open positions. 
     According to yet another embodiment, the core further includes at least one of a bypass damper or a defrost damper. 
     According to one embodiment, a method of providing recirculation capabilities using an air handler with a core, includes opening a first damper and a second damper; receiving vented indoor air from a controlled space through a first tunnel; channeling a first portion of the vented indoor air from the first tunnel to a second tunnel through the first damper, a first recirculation path, and a second opening; channeling a second portion of the vented indoor air from the first tunnel to the second tunnel through a first opening, a second recirculation path, and the second damper; and returning the first portion of the vented indoor air and the second portion of the vented indoor air from the second tunnel into the controlled space. The air handler has a housing that includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel. The first recirculation path and the second recirculation path are separated by a septum protruding into the housing from a first side of the faceplate. The housing contains the core having a top edge connected to the roof panel, a bottom edge connected to the base panel, a front edge connected to the septum, a first side plate connected to the first side panel, and a second side plate connected to the second side panel. The first tunnel connects to the faceplate at a first area of a second side of the faceplate. The second side is opposite to the first side of the faceplate. The second tunnel connects to the faceplate at a second area of the first side of the faceplate. The second area is disjointed from the first area. The first damper and the first opening are disposed in the first area on the faceplate. The second damper and the second opening are disposed in the second area on the faceplate. The first recirculation path is defined by the roof panel, the faceplate, the first side panel, the second side panel, the septum, and the core. The second recirculation path is defined by the base panel, the faceplate, the first side panel, the second side panel, the septum, and the core. 
     According to another embodiment, the method further includes closing the first damper and the second damper; obstructing the vented indoor air in the first tunnel from entering into the first recirculation path; channeling the vented indoor air in the first tunnel into the second recirculation path through the first opening; channeling the vented indoor air in the second recirculation path into the core; channeling fresh air into the core; exchanging energy in the core between the vented indoor and the fresh air; channeling the fresh air in the core into the first recirculation path; obstructing the fresh air in the first recirculation path from entering into the first tunnel; channeling the fresh air in the first recirculation path into the second tunnel through the second opening; exhausting the vented indoor air from the core after exchanging energy; and channeling the fresh air from the second tunnel to the controlled space. 
     According to yet another embodiment, the second damper is disposed adjacent to the first side panel and the roof panel, and the first damper is disposed adjacent to the second side panel and the base panel, and the second opening is adjacent to the second side panel and the roof panel, and the first opening is adjacent to the first side panel and the base panel. 
     According to yet another embodiment, the first tunnel is an indoor air inlet from the controlled space, and the second tunnel is an indoor air return to the controlled space. 
     According to yet another embodiment, the core is a fixed plate heat exchanger or a rotary type wheel heat exchanger. 
     According to yet another embodiment, the core is in a horizontal configuration substantially parallel to the septum, and the fixed plate heat exchanger includes heat transfer plates that are in a vertical configuration when the core includes a fixed plate heat exchanger, and the rotary type wheel heat exchanger includes at least two side-by-side wheels. 
     According to yet another embodiment, the first tunnel and the second tunnel are separated by a middle of unit wall that is substantially perpendicular to the faceplate on a first plane and substantially perpendicular to the septum on a second plane, wherein the second plane is substantially perpendicular to the first plane. 
     According to yet another embodiment, the first damper includes a plurality of sections that are configured to open or close independently among one another or in unison, and the second damper includes a plurality of sections that are configured to open or close independently among one another or in unison. 
     According to yet another embodiment, the core is a counter flow air to air heat exchanger. 
     According to yet another embodiment, the core is a rotary type wheel heat exchanger. For example, the core can be at least two side-by-side energy wheels (“EW”), cool-dry-quiet (“CDQ”) desiccant wheels, or dehumidification wheels. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       References are made to the accompanying drawings that form a part of this disclosure, and which illustrate embodiments in which the systems and methods described herein can be practiced. 
         FIG.  1 A  is a perspective view of an air handler with recirculation capabilities according to one embodiment. 
         FIG.  1 B  is a side view of the air handler in a ventilating mode according to the embodiment of  FIG.  1 A . 
         FIG.  1 C  is a perspective view of the air handler in a recirculation mode according to the embodiment of  FIG.  1 A . 
         FIG.  1 D  is a top view of the air handler in a recirculation mode according to the embodiment of  FIG.  1 A . 
         FIG.  2 A  is a perspective view of an air handler with recirculation capabilities according to another embodiment. 
         FIG.  2 B  is a side view of the air handler in a ventilating mode according to the embodiment of  FIG.  2 A . 
         FIG.  2 C  is a perspective view of the air handler in a recirculation mode according to the embodiment of  FIG.  2 A . 
         FIG.  2 D  is a top view of the air handler in a recirculation mode according to the embodiment of  FIG.  2 A . 
         FIG.  3 A  is a side view of the air handler according to the embodiment of  FIG.  1 A , to illustrate space savings. 
         FIG.  3 B  is a side view of a known air handler to illustrate space savings of the air handler of  FIG.  1 A . 
         FIG.  4 A  a side view of the air handler according to the embodiment of  FIG.  2 A , to illustrate space savings. 
         FIG.  4 B  is a side view of a known air handler to illustrate space savings compared to the air handler of  FIG.  2 A . 
     
    
    
     Like reference numbers represent like parts throughout. 
     DETAILED DESCRIPTION 
     This disclosure relates generally to an air handler with recirculation dampers for a heating, venting, air conditioning, and refrigeration (HVACR) system, particularly the arrangement, construction, and/or configuration of the recirculation dampers in the air handler. 
       FIG.  1 A  is a perspective view of an air handler  100  with recirculation capabilities, according to one embodiment. As shown in  FIG.  1 A , air handler  100  includes a housing and a heat exchanger core  125 . 
     The housing includes the faceplate  114 , a rear faceplate  114 A, a roof panel  162  (shown in  FIG.  1 B ), a base panel  164  (shown in  FIG.  1 B ), a first side panel  166  (shown in  FIG.  1 D ), and a second side panel  168  (shown in  FIG.  1 D ). According to an embodiment, the he air handler  100  further includes a septum  170 , or alternatively referred to as a septum panel  170 , protruding from a first side of the faceplate  114 . The septum  170  extends from the first side panel  166  on one end of the septum  170 , to the second side panel  168  on the other end of the septum  170 . The septum  170  is joined to the faceplate  114  on one side of the septum  170 , and to the core  125  on the other side of the septum  170 . 
     The heat exchanger core  125  can alternatively be referred to as the core  125  or an energy recovery section  125 . The housing connects to a first tunnel  130  and a second tunnel  140  at a faceplate  114  of the air handler  100 . 
       FIG.  1 B  is a side view of the air handler  100  in a ventilating mode, according to the embodiment of  FIG.  1 A . As shown in  FIG.  1 B , the air handler  100  further includes at least one of a top block-off  170 A, a bottom block-off  170 B, or a rear septum  170 C, according to an embodiment. The core  125  is disposed inside the housing. The core  125  includes a top edge  126 , a bottom edge  128 , a front edge  127 , and a back edge  129 . The top block-off  170 A connects the top edge  126  to the roof panel  162 . The bottom block-off  170 B connects a bottom edge  128  to the base panel  164 . The septum  170  connects the front edge  127  to the faceplate  114 . The rear septum  170 C connects the back edge  129  to the rear faceplate  114 A. 
       FIG.  1 C  is a perspective view of the air handler  100  in a recirculation mode, according to the embodiment of  FIG.  1 A . As shown in  FIG.  1 C , the first tunnel  130  connects to a second side of the faceplate  114  at a first area. The second side of the faceplate  114  is opposite to the first side of the faceplate  114  where the septum  170  protrudes from. The first tunnel  130  introduces vented indoor air into the housing. The vented indoor air can be indoor air removed from a controlled space and before the indoor air is exhausted to the outside environment. The controlled space is served by an HVACR system, and the controlled space can be a room, an office, a building, or the like. According to an embodiment, the vented indoor air from the controlled space is heated or cooled to a desired temperature that is generally different from the temperature of untreated fresh air from the outside environment. Without a core in the air handler, the vented indoor is exhausted into the environment, and nearly all the energy consumed to heat or cool the vented air would have been lost. 
     The second tunnel  140  connects to the faceplate  114  on the second side of the faceplate  114 . The second side of the faceplate  114  is the same side of the faceplate  114  where the first tunnel  130  also connects to the faceplate  114 . The second tunnel  140  connects to the second side at a second area that is disjointed from the first area connected to the first tunnel  130 . According to an embodiment, the first area and the second area are adjacent to but separated from each other at where a middle of unit wall  150  connects to the faceplate  114   
     A first damper  116  is disposed on the faceplate  114  within the first area. The first damper  116  connects a portion of the first tunnel  130  to a first recirculation path  110 A. A first opening  118  is disposed on the faceplate  114  within the first area. The first opening  118  connects another portion of the first tunnel  130  to a second recirculation path  110 B. A second damper  120  is disposed on faceplate  114  within the second area. The second damper  120  connects a portion of the second tunnel  140  to the second recirculation path  110 B. A second opening  122  is disposed on the faceplate  114  within the second area. The second opening  122  connects another portion of the second tunnel  140  to the first recirculation path  110 A. 
     According to one embodiment, the first damper  116  is disposed on a lower portion of the faceplate  114  below the septum  170 . The second opening  122  is disposed on the lower portion of the faceplate  114  below the septum  170 . The second damper  120  is disposed on an upper portion of the faceplate  114  below the septum  170 . The first opening  118  is disposed on the upper portion of the faceplate  114  below the septum  170 . 
     According to another embodiment, the first damper  116  occupies approximately one half of the first area on the faceplate  114 . The first opening  118  occupies approximately the other half of the first area. The second damper  120  occupies approximately one half of the second area on the faceplate  114 . The second opening  122  occupied approximately the other half of the second area. Further, the first damper  116 , the first opening  118 , the second damper  120 , and the second opening  122  each occupies a portion of the faceplate  114  that are disjointed from one another. 
     The first tunnel  130  conducts the vented indoor air into the air handler  100  via the first damper  116  and the first opening  118 . Accordingly, the first tunnel  130  functions as an indoor air intake  132 . The second tunnel  140  conducts air from the air handler  100  to the controlled space via the second damper  120  and the second opening  122 . Accordingly, the second tunnel  140  functions as an indoor air return  142 . The first tunnel  130  and the second tunnel  140  are separated by a middle of unit wall  150 . In an embodiment, the middle of unit walls  150  is substantially perpendicular to the faceplate  114  on a first plane and substantially perpendicular to the septum  170  on a second plane. Further, the second plane is substantially perpendicular to the first plane. 
       FIG.  1 D  is a top view of the air handler  100  in a recirculation mode, according to the embodiment of  FIG.  1 A . As shown in  FIGS.  1 B and  1 D , the core  125  within the air handler  100  has a top edge  126 , a front edge  127 , a bottom edge  128 , and a back edge  129 . The core  125  connects to the septum  170  at the front edge  127 . A top surface  125 A of the core  125  is located between the top edge  126  and the front edge  127 , and a bottom surface  125 B of the core  125  is located between the bottom edge  128  and the front edge  127 . The core  125  further includes a first side plate  125 C connected to the first side panel  166  of the air handler  100  and a second side plate  125 D connected to the second side panel  168  of air handler  100 . According to one embodiment, the core  125  is disposed in a horizontal configuration with heat exchanger plates (not shown) of the core  125  in a vertical configuration. According to one embodiment, the core  125  is in a horizontal configuration when the top edge  126 , the front edge  127 , the bottom edge  128 , or the back edge  129  is perpendicular to the middle of unit wall  150  that separates the first tunnel  130  and the second tunnel  140 . 
     The second recirculation path  110 B of the air handler  100  is defined by the roof panel  162 , the faceplate  114 , the septum  170 , the first side panel  166 , the second side panel  168 , and the core  125 . The first recirculation path  110 A of the air handler  100  is defined by the base panel  165 , the faceplate  114 , the septum  170 , the first side panel  166 , the second side panel  168 , and the core  125 . The first recirculation path  110 A and the second recirculation path  110 B are inside the housing and are separated by the septum  170 . 
     According to one embodiment, the second recirculation path  110 B of the air handler  100  is defined by the roof panel  162 , the faceplate  114 , the septum  170 , the first side panel  166 , the second side panel  168 , and the top surface  125 A. The first recirculation path  110 A of the air handler  100  is defined by the base panel  164 , the faceplate  114 , the septum  170 , the first side panel  166 , the second side panel  168 , and the bottom surface  125 B. 
     As shown in  FIGS.  1 B and  1 C , the air handler can  100  be in a circulation mode or a ventilation mode. In the ventilation mode, the first damper  116  is in a closed position, the first damper  116  obstructs the vented indoor air from the indoor air intake  132  entering the first recirculation path  110 A and further obstructs the vented indoor air from entering the second tunnel  140  downstream from the first damper  116 . When the second damper  120  is in a closed position, vented indoor air from the indoor air intake  132  is allowed into to pass through the first opening  118 , but the second damper  120  obstructs the vented indoor air in the second recirculation path  110 B from entering the second tunnel  140 . Accordingly, the indoor air from the indoor air intake  142  is obstructed from recirculating into the controlled space through the second tunnel  140  as the indoor air return  142 . Accordingly, when the first and the second dampers  116  and  120  are both in their closed positions, vented indoor air entered into the first tunnel  130  is primarily exhausted after exchanging heat in the core  125 . 
     In the recirculation mode, the first damper  116  is in an open position, a first portion of the vented indoor air from the indoor air intake  132  can flow through the first damper  116  into the first recirculation path  110 A. The first portion of the vented indoor air in the first recirculation path  110 A can further enter into the second tunnel  140  through the second opening  122  as a portion of the indoor air return  142 . Accordingly, when the first damper  116  is in the open position, the first portion of the vented indoor air from the indoor air intake  132  is recirculated through the first recirculation path  110 A into the second tunnel  140  as a portion of the indoor air return  142 . The vented indoor air from the indoor air intake  132  is recirculated back to the controlled space. 
     In the recirculation mode, the second damper  120  is in an open position. A second portion of the vented indoor air from the indoor air intake  132  can flow through the first opening  118  into the second recirculation path  110 B. The second portion of the vented indoor air in the second recirculation path  110 B can further flow through the opened second damper  120  into the second tunnel  140  as another portion of the indoor air return  142 . Accordingly, when the second damper  120  is in the open position, the second portion of the vented indoor air from the indoor air intake  132  is recirculated through the second recirculation path  110 B into the second tunnel  140  as another portion of the indoor air return  142 . The indoor air from the indoor air intake  132  is recirculated back to the controlled space. Further, when the first damper  116  and the second damper  120  are both in their open positions, a portion of the indoor air from the first tunnel  130  is recirculated through the second tunnel  140  and back into the controlled space. 
     It is appreciated that, although the first damper  116  and the second damper  120  are depicted to have horizontal blades with linkages operated with rotary actuators, the dampers  116  and  120  are no limited to his configuration. According to one embodiment, the dampers  116  and  120  can be vertical blade type dampers. The blades on each of the recirculation dampers parallel blade configuration or an opposed blade configuration, or a combination of both. According to another embodiment, the dampers  116  and  120  can be any type of damper that obstruct airflow. It is also appreciated that, when the first damper  116  includes a plurality of sections, each of the sections can be operated independently from one another or in unison. When the second damper  120  includes a plurality of sections, each of the sections can be operated independently from one another or in unison. It is appreciated that the first damper  116  and the second damper  120  can be operated independently or in unison. 
     In the ventilation mode, energy is recovered in the core  125 . The first damper  116  is in the closed position and obstructs the vented indoor air in the first tunnel  130  from entering into the first recirculation path  110 A. The vented indoor air flows into the second recirculation path  110 B through the first opening  118 . The second damper  118  is in the closed position and obstructs the vented indoor in the second recirculation oath  110 B from entering the second tunnel  140 . Accordingly, the vented indoor air enters into the core  125 . Fresh air from the environment enters the core  125  through the rear faceplate  114 A and exchanges energy with the vented indoor air in the core  125 . After passing the core  125 , the fresh air enters into the first recirculation path  110 A. The fresh air is obstructed by the first damper  116  and channeled into the second tunnel  140  through the second opening  122 . The fresh air in the second tunnel  140  becomes the indoor air return  142  and is further channeled into the controlled space. The vented indoor air is exhausted into the environment after passing the core  125 . 
       FIG.  2 A  is a perspective view of an air handler  200  with recirculation capabilities, according to another embodiment. As shown in  FIG.  2 A , air handler  200  includes a housing and a heat exchanger core  225 . 
     The housing includes the faceplate  114 , a rear faceplate  114 A, a roof panel  162  (shown in  FIG.  2 B ), a base panel  164  (shown in  FIG.  2 B ), a first side panel  166  (shown in  FIG.  2 D ), and a second side panel  168  (shown in  FIG.  2 D ). According to an embodiment, the air handler  200  further includes a septum  270 , or a septum panel  270 , protruding from a first side of the faceplate  114 . The septum  270  connects to the first side panel  166  on one end of the septum  270 , to the second side panel  168  on the other end of the septum  270 , to the faceplate  114  on one side of the septum  270 , and to the core  225  on the other side of the septum  270 . 
     The heat exchanger core  225  can be alternatively referred to as the core  225  or an energy recovery section  225 . The housing connects to a first tunnel  130  and a second tunnel  140  at a faceplate  114  of the air handler  200 . 
       FIG.  2 B  is a side view of the air handler  200  in a ventilating mode, according to the embodiment of  FIG.  2 A . As shown in  FIG.  2 B , the air handler  200  further includes at least one of a top block-off  270 A, a bottom block-off  270 B, or a rear septum  270 C, according to an embodiment. The core  225  is disposed inside the housing. The core  225  includes a top edge  226  or a top surface  226 , a bottom edge  228  or a bottom surface  228 , a front edge  227  or a front surface  227 , and a back edge  229  or a back surface  229 . The top block-off  270 A connects the top edge  226  to the roof panel  162 . The bottom block-off  270 B connects a bottom edge  228  to the base panel  164 . The septum  270  connects the front edge  227  to the faceplate  114 . The rear septum  270 C connects the back edge  229  to the rear faceplate  114 A. 
       FIG.  2 C  is a perspective view of the air handler  200  in a recirculation mode, according to the embodiment of  FIG.  2 A . As shown in  FIG.  2 C , the first tunnel  230  connects to a second side of the faceplate  114  at a first area. The second side of the faceplate  114  is opposite to the first side of the faceplate  114  where the septum  270  protrudes from. According to one embodiment, the first tunnel  130  introduces vented indoor air into the housing. The vented indoor air is indoor air removed from a controlled space and before the indoor air is exhausted to the outside environment. The controlled space is served by an HVACR system, and the controlled space can be a room, an office, a building, or the likes. According to an embodiment, the vented indoor air from the controlled space is heated or cooled to a desired temperature that is generally different from the temperature of untreated fresh air from the outside environment. Without a core in the air handler, the vented indoor is exhausted into the environment, and nearly all the energy consumed to heat or cool the vented air would have been lost. 
     The second tunnel  140  connects to the faceplate  114  on the second side of the faceplate  114 . The second side of the faceplate  114  is the same side of the faceplate  114  where the first tunnel  130  also connects to the faceplate  114 . The second tunnel  140  connects to the second side at a second area that is disjointed from the first area connected to the first tunnel  130 . According to an embodiment, the first area and the second area are adjacent to and disjointed from each other at where a middle of unit wall  150  connects to the faceplate  114 . 
     A first damper  116  is disposed on the faceplate  114  within the first area. The first damper  116  connects a portion of the first tunnel  130  to a first recirculation path  210 A. A first opening  118  is disposed on the faceplate  114  within the first area. The first opening  118  connects another portion of the first tunnel  130  to a second recirculation path  210 B. A second damper  120  is disposed on faceplate  114  within the second area. The second damper  120  connects a portion of the second tunnel  140  to the second recirculation path  210 B. A second opening  122  is disposed on the faceplate  114  within the second area. The second opening  122  connects another portion of the second tunnel  140  to the first recirculation path  210 A. 
     According to one embodiment, the first damper  116  is disposed on a lower portion of the faceplate  114  below the septum  270 . The second opening  122  is disposed on the lower portion of the faceplate  114  below the septum  270 . The second damper  120  is disposed on an upper portion of the faceplate  114  above the septum  270 . The first opening  118  is disposed on the upper portion of the faceplate  114  above the septum  270 . 
     According to another embodiment, the first damper  116  occupies approximately one half of the first area on the faceplate  114 . The first opening  118  occupies approximately the other half of the first area. The second damper  120  occupies approximately one half of the second area on the faceplate  114 . The second opening  122  occupied approximately the other half of the second area. Further, the first damper  116 , the first opening  118 , the second damper  120 , and the second opening  122  each occupies a portion of the faceplate  114  that are disjointed from one another. 
     The first tunnel  130  conducts the vented indoor air into the air handler  200  via the first damper  116  and the first opening  118 . Accordingly, the first tunnel  130  functions as an indoor air intake  132 . The second tunnel  140  conducts air from the air handler  100  to the controlled space via the second damper  120  and the second opening  122 . Accordingly, the second tunnel  140  functions as an indoor air return  142 . The first tunnel  130  and the second tunnel  140  are separated by the middle of unit wall  150 . According to an embodiment, the middle of unit wall  150  is substantially perpendicular to the faceplate  114  on a first plane and substantially perpendicular to the septum  270  on a second plane. Further, the second plane is substantially perpendicular to the first plane. 
       FIG.  1 D  is a top view of the air handler  200  in a recirculation mode, according to the embodiment of  FIG.  2 A . As shown in  FIGS.  2 B and  2 D , the core  225  within the air handler  200  has a top edge  226 , a front edge  227 , a bottom edge  228 , and a back edge  229 . The core  225  connects to the septum  270  at the front edge  227 . A top surface  225 A of the core  225  is located between the top edge  226  and the front edge  227 , and a bottom surface  225 B of the core  225  is located between the bottom edge  228  and the front edge  227 . The core  225  further includes a first side plate  225 C connected to the first side panel  166  of the air handler  200  and a second side plate  225 D connected to the second side panel  168  of the air handler  200 . According to one embodiment, the core  225  is disposed in a side-by-side dual wheel configuration with heat exchanger wheels of the core  225  configured to rotate in the same vertical plane substantially parallel to the faceplate  114 , and the centers of rotation of both heat exchanger wheels are in a line substantially overlaps the intersection of the vertical plane of the rotating dual-wheels and the septum  270 . According to one embodiment, the core  225  includes at least three side-by-side heat exchanger wheels. 
     The second recirculation path  210 B (shown in  FIG.  2 C ) of the air handler  200  is defined by the roof panel  162 , the faceplate  114 , the septum  270 , the first side panel  166 , the second side panel  168 , and the core  225 . The first recirculation path  210 A (shown in  FIG.  2 C ) of the air handler  200  is defined by the base panel  165 , the faceplate  114 , the septum  270 , the first side panel  166 , the second side panel  168 , and the core  225 . The first recirculation path  210 A and the second recirculation path  210 B are inside the housing and are separated by the septum  270 . 
     According to one embodiment, the second recirculation path  210 B of the air handler  200  is defined by the roof panel  162 , the faceplate  114 , the septum  270 , the first side panel  166 , the second side panel  168 , and the top surface  225 A. The first recirculation path  210 A of the air handler  100  is defined by the base panel  164 , the faceplate  114 , the septum  170 , the first side panel  166 , the second side panel  168 , and the bottom surface  225 B. According to another embodiment where at least one of the first side plate  225 C, the second side plate  225 D, the top block-off  170 A, or the bottom block-off  170 A is included in the air handler  200 . The second recirculation path  210 B is further defined the at least one of the first side plate  225 C, the second side plate  225 D, the top block-off  170 A included in the air handler  200 . The first recirculation path  210 A is further defined the at least one of the first side plate  225 C, the second side plate  225 D, the bottom block-off  170 B included in the air handler  200 . 
     As shown in  FIGS.  2 B and  2 C , the air handler  200  can be in a circulation mode or a ventilation mode. In the ventilation mode, the first damper  116  is in a closed position, the first damper  116  obstructs the vented indoor air from the indoor air intake  132  entering the first recirculation path  210 A and further obstructs the vented indoor air from entering the second tunnel  140  downstream from the first damper  116  via the first recirculation path  210 A. When the second damper  120  is in a closed position, vented indoor air from the indoor air intake  132  is allowed into the second recirculation path  210 B through the first opening  118 , but the second damper  120  obstructs the vented indoor air in the second recirculation path  210 B from entering the second tunnel  140 . Accordingly, the indoor air from the indoor air intake  142  is obstructed from recirculating into the controlled space through the second tunnel  140  as the indoor air return  142 . Accordingly, when the first and the second dampers  116  and  120  are both in their closed positions, vented indoor air entered into the first tunnel  130  is primarily exhausted after exchanging heat in the core  225 . 
     In the recirculation mode, the first damper  116  is in an open position. A first portion of the vented indoor air from the indoor air intake  132  can flow through the first damper  116  into the first recirculation path  210 A. The first portion of the vented indoor air in the first recirculation path  210 A can further enter into the second tunnel  140  through the second opening  122  as a portion of the indoor air return  142 . Accordingly, when the first damper  116  is in the open position, the first portion of the vented indoor air from the indoor air intake  132  is recirculated through the first recirculation path  210 A into the second tunnel  140  as a portion of the indoor air return  142 . The vented indoor air from the indoor air intake  132  is recirculated back to the controlled space. 
     In the recirculation mode, the second damper  120  is in an open position. A second portion of the vented indoor air from the indoor air intake  132  can flow through the first opening  118  into the second recirculation path  210 B. The second portion of the vented indoor air in the second recirculation path  210 B can further flow through the opened second damper  120  into the second tunnel  140  as another portion of the indoor air return  142 . Accordingly, when the second damper  120  is in the open position, the second portion of the vented indoor air from the indoor air intake  132  is recirculated through the second recirculation path  210 B into the second tunnel  140  as another portion of the indoor air return  142 . The indoor air from the indoor air intake  132  is recirculated back to the controlled space. Accordingly, when the first damper  116  and the second damper  120  are both in their open positions, at least a portion of the indoor air from the first tunnel  130  is recirculated through the second tunnel  140  and back into the controlled space. 
     It is appreciated that, although the first damper  116  and the second damper  120  are depicted to have horizontal blades with linkages operated with rotary actuators, the dampers  116  and  120  are not limited this configuration. According to an embodiment, the dampers  116  and  120  can be vertical blade type dampers. The blades on each of the dampers can be a parallel blade configuration or an opposed blade configuration, or a combination of both. According to another embodiment, the dampers  116  and  120  can be any type of damper that obstruct airflow. 
     In the ventilation mode, energy is recovered in the core  225 . The first damper  116  is in the closed position and obstructs the vented indoor air in the first tunnel  130  from entering into the first recirculation path  210 A. The vented indoor air flows into the second recirculation path  210 B through the first opening  118 . The second damper  118  is in the closed position and obstructs the vented indoor in the second recirculation oath  210 B from entering the second tunnel  140 . Accordingly, the vented indoor air enters into the core  225 . Fresh air from the environment enters the core  225  through the rear faceplate  114 A and exchanges energy with the vented indoor air in the core  225 . After passing the core  225 , the fresh air enters into the first recirculation path  210 A. The fresh air is obstructed by the first damper  116  and channeled into the second tunnel  140  through the second opening  122 . The fresh air in the second tunnel  140  becomes the indoor air return  142  and is further channeled into the controlled space. The vented indoor air is exhausted into the environment after passing the core  225 . 
     According to another embodiment, the core  125  or  225  further includes at least one of a defrost damper or a bypass damper (not shown). The defrost damper, when opened, introduces heated air or indoor air to the heat exchanger in the core  125  or  225 , and removes frost on the heat exchanger by warming the heat exchanger with the heated air. The bypass damper, when opened, conducts vented indoor air to the exhaust without passing through the core  125  or  225 . 
       FIG.  3 A  is a side view of the air handler to illustrate space savings. As shown in  FIG.  3 A , the air handler  100  includes the core  125 , the first recirculation path  110 A, and the second recirculation path  110 B. The first tunnel  130  connects to the air handler  100  at the first area of the faceplate  114 . A septum  170  connects the core  125  to the faceplate  114 . The second tunnel  140  connects to the air handler  100  at the second area of the faceplate  114 . The first tunnel  130  and the second tunnel  140  are separated by the middle of unit wall  150 . During the recirculating mode of the air handler  100 , vented indoor air recirculates through the first tunnel  130 , the first damper  116 , the first opening  118 , the first and second recirculation paths  110 A and  110 B, the second damper  120 , and the second opening  122 , and into the second tunnel  140 . Accordingly, the recirculation function of the air handler  100  can be accomplished by a distance of L1. The space represented by L1 includes the space for the core  125 . 
       FIG.  3 B  is a side view of a known air handler to illustrate space savings of the air handler  100  of  FIG.  3 A  in comparison to said known air handler. As shown in  FIG.  3 B , an air handler  10  includes a core  25 . The size or capacity of the core  25  is comparable to the size or capacity of the core  125  (shown in  FIG.  3 A ). The first tunnel  30  connects to the air handler  10  at a first area of a faceplate  14 . The second tunnel  40  connects to the air handler  10  at a second area of the faceplate  14 . The first tunnel  30  and the second tunnel  40  are separated by a middle of unit wall  50 . A recirculation damper  52  is included adjacent to the faceplate  14  on the middle of unit wall  50 . During the recirculating mode of the air handler  10 , vented indoor air enters the first tunnel  30  and is blocked by a first damper and a first block off plate on the first area of the faceplate  14  where the first tunnel  30  connects to the faceplate  14 . Accordingly, the vented indoor air is forced through the opened recirculation damper  52  into the second tunnel  40 . The vented indoor air is further blocked by a second damper and a second block off plate on the second are of the faceplate  14  where the second tunnel  40  connects to the faceplate  14 . Accordingly, the vented indoor air flows through the second tunnel  40  back to the controlled space. The recirculation function of the air handler  10  is accomplished in a distance of L′ with the core  25  having a similar size and capacity of the core  125  (as shown in  FIG.  4 A ). 
     As shown by comparing  FIGS.  3 A and  3 B , the damper configurations according to the air handler  100  save a distance of a difference between L1 and L1′, for example. This difference is similar to the width of the recirculation damper  52 , as shown in  FIG.  3 B . According to one embodiment, the recirculation damper  52  can be 24 to 48 inches wide. Accordingly, the space savings of the air handler  100  can be 24 to 48 inches. 
       FIG.  4 A  is a side view of the air handler  200  to illustrate space savings. As shown in  FIG.  4 A , the air handler  200  includes the core  225 , the first recirculation path  210 A, and the second recirculation path  210 B. The first tunnel  130  connects to the air handler  200  at the first area of the faceplate  114 . A septum  270  connects the core  225  to the faceplate  114 . The second tunnel  140  connects to the air handler  200  at the second area of the faceplate  114 . The first tunnel  130  and the second tunnel  140  are separated by the middle of unit wall  150 . During the recirculating mode of the air handler  200 , vented indoor air recirculates through the first tunnel  130 , the first damper  116 , the first opening  118 , the first and second recirculation paths  210 A and  210 B, the second damper  120 , and the second opening  122 , and into the second tunnel  140 . Accordingly, the recirculation function of the air handler  200  can be accomplished by a distance of L2. The space represented by L2 includes the space for the core  225 . 
       FIG.  4 B  is a side view of a known air handler  20  to illustrate space savings of the air handler  200  of  FIG.  4 A . As shown in  FIG.  4 B , an air handler  20  includes a core  25 A. The size or capacity of the core  25 A is comparable to the size or capacity of the core  225  (shown in  FIG.  4 A ). The first tunnel  30  connects to the air handler  10  at a first area of a faceplate  14 . The second tunnel  40  connects to the air handler  10  at a second area of the faceplate  14 . The first tunnel  30  and the second tunnel  40  are separated by a middle of unit wall  50 . A recirculation damper  52  is included adjacent to the faceplate  14  on the middle of unit wall  50 . During the recirculating mode of the air handler  10 , vented indoor air enters the first tunnel  30  and is forced through the opened recirculation damper  52  into the second tunnel  40 . Accordingly, the vented indoor air flows through the second tunnel  40  back to the controlled space. The recirculation function of the air handler  20  is accomplished in a distance of L2′ with the core  25 A having a similar size and capacity of the core  225  (as shown in  FIG.  4 A ). 
     As shown by comparing  FIG.  4 A  and  FIG.  4 B , the damper configurations according to the air handler  200  save a distance of a difference between L2 and L2′. This difference is similar to the width of the recirculation damper  52 , as shown in  FIG.  4 B . According to one embodiment, the recirculation damper  52  can be 24 to 48 inches wide. Accordingly, the space savings of the air handler  100  can be 24 to 48 inches. 
     It is appreciated that pressure drop is inversely proportional to the cross-sectional area of the flow path. Accordingly, when the two air handlers occupying the same amount of space, the air handler with damper configuration according to this disclosure will experience a smaller pressure drop. Additionally, a smaller pressure drop generally correlates to more uniformed downstream airflow. Accordingly, when the two air handlers occupying the same amount of space, the air handler with damper configuration according to this disclosure will have a more uniformed airflow downstream of air handler. 
     Aspects. It is noted that any of aspects 1-12 can be combined with any one of aspects 13-20.
 
Aspect 1. An air handler for an HVACR system, comprising:
 
     a housing having a faceplate, a roof panel, a base panel, a first side panel, and a second side panel; 
     a septum protruding into the housing from a first side of the faceplate; 
     a core disposed within the housing and having a front edge connected to an edge of the septum, a top edge connected to the roof panel, a bottom edge connected to the base panel, a first side plate connected to the first side panel, and a second side plate connected to the second side panel; 
     a first tunnel connected to a first area on the faceplate from a second side of the faceplate, wherein the second side is opposite to the first side of the faceplate; 
     a second tunnel connected to a second area of the faceplate from the second side, wherein the second area is disjointed from the first area; 
     a first recirculation path defined by the faceplate, the roof panel, the septum, the first side panel, the second side panel, and the core and configured to channel a first portion of airflow from the first tunnel to the second tunnel; 
     a second recirculation path defined by the faceplate, the septum, the base panel, the first side panel, the second side panel, and the core and configured to channel a second portion of the airflow from the first tunnel to the second tunnel; 
     a first damper disposed in the first area of the faceplate and configured to obstruct the first recirculation path; 
     a second damper disposed in the second area of the faceplate and configured to obstruct the second recirculation path; 
     a first opening disposed in the first area of the faceplate and connecting the first tunnel to the second recirculation path; and 
     a second opening disposed in the second area of the faceplate and connecting the second tunnel to the first recirculation path. 
     Aspect 2. The air handler of aspect 1, wherein 
     the second damper is disposed adjacent to the first side panel and the roof panel, and 
     the first damper is disposed adjacent to the second side panel and the base panel. 
     Aspect 3. The air handler of any one of aspects 1-2, wherein 
     the second opening is adjacent to the first side panel and the base panel, and 
     the first opening is adjacent to the second side panel and the roof panel. 
     Aspect 4. The air handler of any one of aspects 1-3, wherein 
     the first tunnel is an indoor air inlet from a controlled space, and 
     the second tunnel is an indoor air return to the controlled space. 
     Aspect 5. The air handler of any one of aspects 1-4, wherein 
     the core includes a fixed plate heat exchanger or a rotary type wheel heat exchanger. 
     Aspect 6. The air handler of any one of aspects 1-5, wherein 
     the core is in a horizontal configuration substantially parallel to the septum, and 
     when the core includes a fixed plate heat exchanger, the fixed plate heat exchanger includes heat transfer plates that are in a vertical configuration, and. 
     when the core includes a rotary type wheel heat exchanger the rotary type wheel heat exchanger includes at least two side-by-side wheels. 
     Aspect 7. The air handler of any one of aspects 1-6, wherein 
     the first tunnel and the second tunnel are separated by a middle of unit wall that is substantially perpendicular to the faceplate on a first plane and substantially perpendicular to the septum on a second plane, wherein the second plane is substantially perpendicular to the first plane. 
     Aspect 8. The air handler of any one of aspects 1-7, wherein 
     the first damper includes a plurality of sections that are configured to open or close independently among one another or in unison, and 
     the second damper includes a plurality of sections that are configured to open or close independently among one another or in unison. 
     Aspect 9. The air handler of any one of aspects 1-8, wherein 
     the first damper obstructs the first portion of the airflow from entering the first recirculation path when the first damper is in a closed position. 
     Aspect 10. The air handler of any one of aspects 1-9, wherein 
     the second damper obstructs the second portion of the airflow from entering the second tunnel when the second damper is in a closed position. 
     Aspect 11. The air handler of any one of aspects 1-10, wherein 
     the first portion of the airflow is recirculated to the second tunnel through the second opening when the first damper is in an open position, and 
     the second portion of the airflow is recirculated to the second tunnel through the first opening and the second recirculation path when the second damper is in an open position. 
     Aspect 12. The air handler of any one of aspects 1-11, wherein 
     the airflow enters the first tunnel from a controlled space is recirculated into the controlled space when the first and the second dampers are in their open positions. 
     Aspect 13. The air handler of any one of aspect 1-12, wherein 
     the core further includes at least one of a bypass damper or a defrost damper. 
     Aspect 14. A method of providing recirculation capabilities using an air handler with a core, comprising: 
     opening a first damper and a second damper; 
     receiving vented indoor air from a controlled space through a first tunnel; 
     channeling a first portion of the vented indoor air from the first tunnel to a second tunnel through the first damper, a first recirculation path, and a second opening; 
     channeling a second portion of the vented indoor air from the first tunnel to the second tunnel through a first opening, a second recirculation path, and the second damper; and 
     returning the first portion of the vented indoor air and the second portion of the vented indoor air from the second tunnel into the controlled space, wherein 
     the air handler has a housing that includes a faceplate, a roof panel, a base panel, a first side panel, and a second side panel, 
     the first recirculation path and the second recirculation path are separated by a septum protruding into the housing from a first side of the faceplate, 
     the housing contains the core having a top edge connected to the roof panel, a bottom edge connected to the base panel, a front edge connected to the septum, a first side plate connected to the first side panel, and a second side plate connected to the second side panel, 
     the first tunnel connects to the faceplate at a first area of a second side of the faceplate, wherein the second side is opposite to the first side of the faceplate, 
     the second tunnel connects to the faceplate at a second area of the first side of the faceplate, wherein the second area is disjointed from the first area, 
     the first damper and the first opening are disposed in the first area on the faceplate, 
     the second damper and the second opening are disposed in the second area on the faceplate, 
     the first recirculation path is defined by the roof panel, the faceplate, the first side panel, the second side panel, the septum, and the core, and 
     the second recirculation path is defined by the base panel, the faceplate, the first side panel, the second side panel, the septum, and the core. 
     Aspect 15. The method of aspect 14 further comprising: 
     closing the first damper and the second damper; 
     obstructing the vented indoor air in the first tunnel from entering into the first recirculation path; 
     channeling the vented indoor air in the first tunnel into the second recirculation path through the first opening; 
     channeling the vented indoor air in the second recirculation path into the core; 
     channeling fresh air into the core; 
     exchanging energy in the core between the vented indoor and the fresh air; 
     channeling the fresh air in the core into the first recirculation path; 
     obstructing the fresh air in the first recirculation path from entering into the first tunnel; 
     channeling the fresh air in the first recirculation path into the second tunnel through the second opening; 
     exhausting the vented indoor air from the core after exchanging energy; and 
     channeling the fresh air from the second tunnel to the controlled space. 
     Aspect 16. The method of any one of aspects 14-15, wherein 
     the second damper is disposed adjacent to the first side panel and the roof panel, and the first damper is disposed adjacent to the second side panel and the base panel, and 
     the first opening is adjacent to the second side panel and the roof panel, and the second opening is adjacent to the first side panel and the base panel. 
     Aspect 17. The method of any one of aspects 14-16, wherein 
     the first tunnel is an indoor air inlet from the controlled space, and 
     the second tunnel is an indoor air return to the controlled space. 
     Aspect 18. The method of any one of aspects 14-17, wherein 
     the core includes a fixed plate heat exchanger or a rotary type wheel heat exchanger. 
     Aspect 19. The method of any one of aspects 14-18, wherein 
     the core is in a horizontal configuration substantially parallel to the septum, and 
     when the core includes a fixed plate heat exchanger, the fixed plate heat exchanger includes heat transfer plates of the core are in a vertical configuration, and 
     when the core includes a rotary type wheel heat exchanger the rotary type wheel heat exchanger includes at least two side-by-side wheels. 
     Aspect 20. The method of any one of aspects 14-19, wherein 
     the first tunnel and the second tunnel are separated by a middle of unit wall that is substantially perpendicular to the faceplate on a first plane and substantially perpendicular to the septum on a second plane, wherein the second plane is substantially perpendicular to the first plane. 
     Aspect 21. The method of any one of aspects 14-20, wherein 
     the first damper includes a plurality of sections that are configured to open or close independently among one another or in unison, and 
     the second damper includes a plurality of sections that are configured to open or close independently among one another or in unison. 
     The terminology used in this Specification is intended to describe particular embodiments and is not intended to be limiting. The terms “a,” “an,” and “the” include the plural forms as well, unless clearly indicated otherwise. The terms “comprises” and/or “comprising,” when used in this Specification, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, and/or components. 
     With regard to the preceding description, it is to be understood that changes may be made in detail, especially in matters of the construction materials employed and the shape, size, and arrangement of parts without departing from the scope of the present disclosure. This Specification and the embodiments described are exemplary only, with the true scope and spirit of the disclosure being indicated by the claims that follow.