Patent Publication Number: US-2023147346-A1

Title: Low height heat pump system and method

Description:
TECHNICAL FIELD 
     The instant disclosure relates generally to heat pumps and, more particularly but without limitation, to heat pump systems for commercial and multi-unit residential applications. 
     BACKGROUND 
     Typically, heating, ventilation, and air conditioning (HVAC) systems provide comfortable air temperatures and/or improved air quality for occupants within a building or structure. Multiple HVAC systems are typically required for use in connection with commercial and multi-unit residential buildings. For instance, a multi-level building, such as a high rise building, may include a separate HVAC system for each of a plurality of housing units within the building. Oftentimes, those HVAC systems consume a relatively large amount of physical space and are arranged in a manner that are difficult to service. 
     For instance, one type of HVAC system for residential high rise buildings incorporates a floor-mounted vertical heat pump that is housed within a dedicated closet of a respective residential unit. The closet may consume an undesirable amount of valuable floor space within the unit and/or make it difficult for a service provider to access the heat pump for servicing. 
     Another type of HVAC system for residential high rise buildings is a split system. Such a system may have a condensing unit that is installed along a floor or wall of a unit and a fan coil unit that is installed to hang from a ceiling of the unit to limit the amount of floor space consumed by the HVAC system. However, the condensing unit may still require an undesirable amount of floor space within the unit. The height of the fan coil unit may require the ceiling of the floor to be lowered or cause the height of each floor to be increased, thereby consuming valuable vertical space within the corresponding building and requiring additional building materials to enclose the heat pump system. Additionally, the arrangement of the fan coil unit suspended from the ceiling may make it difficult for a service provider to access and service internal components of the fan coil unit. 
     Customers of HVAC systems, and particularly heat pump systems for residential high rise buildings, hotel rooms, and the like, want the smallest HVAC system possible at the lowest cost while delivering equal or better performance than predecessor systems. A challenge exists, however, to reduce the height of known systems while also being capable of delivering equal or better heating and cooling performance than predecessor systems. Consequently, there exists a need for an apparatus that solves these and other problems. 
     SUMMARY 
     Disclosed are various embodiments of a low-height heat pump system and methods of assembling the same. 
     One embodiment of the instant disclosure includes a heat pump system that includes a low-height cabinet configured to be mounted to a ceiling. The low-height cabinet includes a frame and a plurality of panels that define a compressor compartment, a blower compartment, and a plenum compartment. The frame includes one or more dividers that separate the blower compartment, the plenum compartment, and the compressor compartment from each other. The heat pump system also includes a compressor installed horizontally in the compressor compartment, a heat exchanger installed vertically in the compressor compartment, a blower assembly installed in the blower compartment, and an air coil installed in the blower compartment. 
     The frame of the heat pump system may include side rails, end rails, cross rails, side panels, end panels, bottom panels, and a top panel. 
     The frame of the heat pump system may include a first divider that separates the blower compartment from the plenum compartment. 
     Further, the frame of the heat pump system may include a second divider that separates the compressor compartment from the blower compartment and the plenum compartment. 
     The frame of the heat pump system may include an end panel and a side panel that partially form the plenum compartment. Each of the end panel and the side panel includes one or more knockout panels that are removable to enable ductwork to fluidly connect to the plenum compartment. 
     The plurality of panels of the heat pump system may include a first bottom panel that partially forms the blower compartment and is detachable from the frame to facilitate a technician in accessing the blower compartment from below the low-height cabinet when the low-height cabinet is mounted to the ceiling. 
     Further, the heat pump system may include a drain pan that is installed below the air coil in the blower compartment. The drain pan is configured to be removable from the blower compartment when the low-height cabinet is mounted to the ceiling. 
     Further, the blower assembly may include a blower panel, one or more blowers, and a blower motor. The one or more blowers and the blower motor are mounted to the blower panel. 
     Also the blower assembly may include slider brackets to which the blower panel is slidably mounted. The blower panel is configured to be slidably lowered at least partially out of the blower compartment when the first bottom panel is detached from the frame to facilitate the technician in accessing the one or more blowers and the blower motor from below the low-height cabinet when the low-height cabinet is mounted to the ceiling. 
     Additionally, the blower assembly may include a latch coupled to the blower panel. The latch is configured to engage the frame to secure the blower assembly in a retracted position in the blower compartment. The latch is configured to disengage from the frame to enable the blower assembly to lower into an extended position. 
     Moreover, the latch may be a spring-loaded latch. 
     The plurality of panels of the heat pump system may include an end panel, a plurality of side panels, and a plurality of bottom panels that partially form the compressor compartment. Each of the end panel, the plurality of side panels, and the plurality of bottom panels is detachable from the frame to facilitate a technician in accessing the compressor compartment when the low-height cabinet is mounted to the ceiling. 
     The air coil may be sized to fit in a low height of the low-height cabinet and provide heat exchange capable of controlling a temperature of a space 
     The heat exchanger of the heat pump system may be a brazed-plate heat exchanger that lies upright within a low height of the low-height cabinet and provide heat exchange capable of controlling a temperature of a space. 
     Further, the compressor of the heat pump system may be a horizontal rotary compressor installed horizontally in the compressor compartment to enable the compressor to fit in a low height of the low-height cabinet. 
     The low-height cabinet of the heat pump system may include a control panel, an electronics housing, and a cover panel. The electronics housing and the cover panel partially define an electronics compartment of the low-height cabinet. The control panel is coupled to the cover panel. 
     Further, the cover panel may include a pin and the electronics housing may define a curved slot configured to receive the pin. The pin is configured to slide in the curved slot to enable the control panel to be rotated from a first position at which the control panel is oriented to be accessed horizontally and a second position at which the control panel is oriented to be accessed horizontally from below the low-height control panel. 
     Further, the heat pump system may include a disconnect switchbox that includes switch extending outward from a bottom side of the low-height cabinet to enable a technician to engage the switch before accessing an interior of the low-height cabinet. 
     The plurality of panels of the heat pump system may include a top panel extending along a top side of the low-height cabinet. The top includes opposing flanges. Each of the opposing flanges defines mount holes such that one of the mount holes is located at each corner of the top panel. 
     Further, the heat pump system may include a plurality of grommet assemblies configured to provide low-height hanger mounts for the low-height cabinet. Each of the plurality of grommet assemblies are configured to extend through a respective one of the mount holes and couple to a corresponding one of the opposing flanges to mount the low-height cabinet to respective hanger rods. 
     The low-height cabinet of the heat pump system may have a height of about  9  inches. 
     In another embodiment of the instant disclosure, a heat pump system includes a low-height cabinet configured to be mounted to a ceiling. The low-height cabinet includes a frame and a plurality of panels that define a compressor compartment, a blower compartment, and a plenum compartment. The frame includes one or more dividers that separate the blower compartment, the plenum compartment, and the compressor compartment from each other. The heat pump system also includes a horizontal rotary compressor positioned horizontally in the compressor compartment to enable the compressor to fit in a low height of the low-height cabinet. The heat pump system also includes a brazed-plate heat exchanger positioned in the compressor compartment of the low-height cabinet. The brazed-plate heat exchanger lies upright within the low height of the low-height cabinet and provides heat exchange capable of controlling a temperature of a space. The heat pump system also includes a blower assembly positioned in the blower compartment and an air coil positioned in the blower compartment. The air coil has a height and a length where the height is configured to lie within the low height of the low-height cabinet and the length is longer than the height. 
     In another embodiment, a method for assembling a heat pump system with a low-height cabinet includes assembling a base of a frame together in an upside-down orientation by attaching a plurality of rails together. The plurality of rails includes side rails, end rails, and cross rails. The method also includes attaching a plurality of bottom panels to the base of the frame when the base of the frame is in the upside-down orientation and repositioning the base of the frame and the plurality of bottom panels in a right-side up orientation to enable subsequent assembly of the heat pump system in the right-side up orientation. The method also includes attaching a plurality of dividers of the frame to the base of the frame to form and separate a plenum compartment a blower compartment, and a compressor compartment in the low-height cabinet. The method also includes installing a compressor horizontally in the compressor compartment of the low-height cabinet, installing a heat exchanger installed in the compressor compartment of the low-height cabinet, installing a blower assembly in the blower compartment of the low-height cabinet, and installing an air coil in the blower compartment of the low-height cabinet. 
     The method may also include attaching compressor cross rails to the base of the frame when the frame is in the right-side up orientation. 
     Further, the method may also include installing the compressor in the compressor compartment includes attaching the compressor to the compressor cross rails. 
     The compressor may be installed horizontally in the compressor compartment is a horizontal rotary compressor. 
     Installing the heat exchanger in the compressor compartment may include attaching the heat exchanger to the frame. 
     The heat exchanger installed vertically in the compressor compartment may be a brazed-plate heat exchanger. 
     The method may also include attaching an expansion valve and a filter drier to the heat exchanger. 
     Further, the method may also include connecting refrigerant piping and a reversing valve to the heat exchanger, the expansion valve, and the filter drier. 
     Also, the method may also include connecting additional refrigerant piping to and between the air coil and the expansion valve. 
     The method may also include, when the base of the frame is in the upside-down orientation, attaching a drain pan to the base of the frame in the blower compartment. 
     Further, the method may also include installing the air coil in the blower compartment includes positioning the air coil above the drain pan and attaching the air coil to the frame. 
     The method may also include comprising attaching an electronics housing to the base of the frame to form an electronics compartment of the low-height cabinet. 
     Further, the method may also include rotatably and slidably coupling a cover panel to the electronics housing by positioning a pin of the cover panel in a curved slot defined the electronics housing. A control panel is coupled to the cover panel. 
     The method may also include attaching a disconnect switchbox to an inner surface of a first bottom panel of the plurality of bottom panels. The first bottom panel defines an opening through which a switch of the disconnect switchbox is to extend. 
     Installing the blower assembly in the blower compartment may include vertically attaching a set of slider brackets of the blower assembly to the frame of the low-height cabinet in the blower compartment and slidably mounting a blower panel of the blower assembly to the set of slider brackets, wherein one or more blowers and a blower motor are attached to the blower panel. 
     The method may include attaching one or more corner posts to the base of the frame. 
     Further, the method may include connecting an inlet water leg to and between an inlet port of the heat exchanger and an inlet opening defined by a first corner post of the one or more corner posts and connecting an outlet water leg to and between an outlet port of the heat exchanger and an outlet opening defined by the first corner post. 
     Further, the method may include attaching one or more discharge panels to the frame adjacent the plenum compartment. Each of the one or more discharge panels includes one or more knockout panels that are removable to enable ductwork to be fluidly connected to the plenum compartment. 
     Further, the method may include attaching a top panel to at least one of the one or more posts or the plurality of dividers of the frame. The top panel includes flanges configured to provide low-height hanger mounts for the low-height cabinet. 
     Further, the method may include attaching a plurality of side and end panels to the frame to enclose the blower compartment and the compressor compartment. 
     In another embodiment, a freeze-protection system for a heat pump includes a refrigerant circuit including a first circuit portion, a second circuit portion, a third circuit portion, a fourth circuit portion, a fifth circuit portion, and a sixth portion. The freeze-protection system also includes a reversing valve that includes a first reversing port connected to the fifth circuit portion, a second reversing port connected to the second circuit portion, a third reversing port connected to the sixth circuit portion, and a fourth reversing port connected to the first circuit portion. The freeze-protection system also includes a source heat exchanger that includes an inlet port configured to receive water from a source, an outlet port configured to return the water to the source, a third source port connected to the second circuit portion, and a fourth source port connected to the third circuit portion. The freeze-protection system also includes a compressor connected to the sixth circuit portion and the first circuit portion between the third reversing port and the fourth reversing port, a load heat exchanger connected to the fourth circuit portion and the fifth circuit portion between the fourth source port and the first reversing port, a thermostat, and a controller. The controller is configured to receive a signal from the thermostat to run the compressor, monitor for a low flow rate event and a low temperature event in response to receiving the signal from the thermostat, and set the heat pump in a lockout mode to prevent the compressor from running in response to detecting at least one of the low flow rate event or the low temperature event. 
     The controller of the freeze-protection system may be configured to run the compressor in response to not detecting both the low flow rate event and the low temperature event. 
     The controller of the freeze-protection system may be configured to monitor for the low flow rate event and the low temperature event simultaneously. 
     The freeze-protection system may further include a flow switch positioned adjacent the outlet port of the source heat exchanger. The flow switch is configured to monitor a water flow rate of the water returning to the source. 
     To monitor for the low flow rate event, the controller may be configured to determine whether a monitored flow rate of the water returning to the source has been less than a predefined flow rate threshold continuously for at least a first predefined duration. 
     Further, in response to determining that the monitored flow rate has been less than the predefined flow rate threshold continuously for at least the first predefined duration, the controller may be configured to disable the compressor and determine whether the monitored flow rate has been less than the predefined flow rate threshold continuously for at least a second predefined duration. The second predefined duration is greater than the first predefined duration. 
     Also, the controller of the freeze-protection system may be configured to detect the low flow rate event in response to determining that the monitored flow rate has been less than the predefined flow rate threshold continuously for at least the second predefined duration. 
     Additionally, in response to detecting the low flow rate event, the controller of the freeze-protection system may be configured to disable a water pump or a motorized water valve fluidly connected to the inlet port of the source heat exchanger. 
     Upon detecting the low flow rate event, the controller may be configured to remove the heat pump from the lockout mode in response to identifying that power for the heat pump has been cycled and a monitored flow rate of the water returning to the source has increased to be greater than a predefined flow rate threshold. 
     The freeze-protection system may also include an expansion valve connected to the third circuit portion and the fourth circuit portion between the fourth source port and the load heat exchanger. 
     Further, the freeze-protection system may also include a first temperature sensor positioned adjacent the inlet port of the source heat exchanger and configured to collect a water temperature measurement of the water flowing from the source and a second temperature sensor positioned along the third circuit portion and configured to collect a refrigerant temperature measurement of refrigerant flowing between the source heat exchanger and the expansion valve. 
     Also, the controller may be configured to detect the low temperature event in response to detecting that the water temperature measurement is less than a first predetermined temperature threshold and detecting that the refrigerant temperature measurement is less than a second predetermined temperature threshold. 
     Additionally, in response to detecting the low temperature event, the controller may be configured to disable a water pump or a motorized water valve fluidly connected to the inlet port of the source heat exchanger. 
     Upon detecting the low temperature event, the controller may be configured to remove the heat pump from the lockout mode in response to identifying that power for the heat pump has been cycled. 
     In another embodiment, a freeze-protection method for a heat pump includes receiving, via a controller, a signal from a thermostat to run a compressor and monitoring, via the controller, for a low flow rate event in response to receiving the signal from the thermostat. The freeze-protection method also includes monitoring, via the controller, for a low temperature event in response to receiving the signal from the thermostat and setting, via the controller, the heat pump in a lockout mode to prevent the compressor from running in response to detecting at least one of the low flow rate event or the low temperature event. 
     The freeze-protection method may include running the compressor in response to not detecting both the low flow rate event and the low temperature event. 
     The freeze-protection method may include monitoring for the low flow rate event and monitoring for the low temperature event occur simultaneously. 
     The freeze-protection method may include monitoring, via a flow switch, a water flow rate of water returning to a source from a source heat exchanger. The flow switch is positioned adjacent an outlet port of the source heat exchanger. 
     Monitoring for the low flow rate event may include determining, via the controller, whether a monitored flow rate of water returning to a source from a source heat exchanger has been less than a predefined flow rate threshold continuously for at least a first predefined duration. 
     Further, the freeze-protection method may include, in response to determining that the monitored flow rate has been less than the predefined flow rate threshold continuously for at least the first predefined duration, disabling a compressor and determining whether the monitored flow rate has been less than the predefined flow rate threshold continuously for at least a second predefined duration. The second predefined duration is greater than the first predefined duration. 
     Also, the low flow rate event may be detected in response to determining, via the controller, that the monitored flow rate has been less than the predefined flow rate threshold continuously for at least the second predefined duration. 
     Additionally, the freeze-protection method may include disabling a water pump or a motorized water valve fluidly connected to an inlet port of the source heat exchanger in response to detecting the low flow rate event. 
     The freeze-protection method may include, upon detecting the low flow rate event, removing the heat pump from the lockout mode in response to the controller identifying that power for the heat pump has been cycled and a monitored flow rate of water returning to a source from a source heat exchanger has increased to be greater than a predefined flow rate threshold. 
     The freeze-protection method may include collecting, via a first temperature sensor, a water temperature measurement of water flowing from a source to an inlet port of a source heat exchanger and collecting, via a second temperature sensor, a refrigerant temperature measurement of refrigerant flowing between a source heat exchanger and an expansion valve. 
     Further, the low temperature event may be detected in response to detecting that the water temperature measurement is less than a first predetermined temperature threshold and detecting that the refrigerant temperature measurement is less than a second predetermined temperature threshold. 
     Also, the freeze-protection method may include disabling a water pump or a motorized water valve fluidly connected to the inlet port of the source heat exchanger in response to detecting the low temperature event. 
     The freeze-protection method may include, upon detecting the low temperature event, removing, via the controller, the heat pump from the lockout mode in response to identifying that power for the heat pump has been cycled. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view an embodiment of a low-height heat pump system of the instant disclosure. 
         FIG.  2    is a first end view of the system of  FIG.  1   . 
         FIG.  3    is a second end view of the system of  FIG.  1   . 
         FIG.  4    is a first side view of the system of  FIG.  1   . 
         FIG.  5    is a second side view of the system of  FIG.  1   . 
         FIG.  6    is a top view of the system of  FIG.  1   . 
         FIG.  7    is a bottom view of the system of  FIG.  1   . 
         FIG.  8    is a bottom perspective view of the system of  FIG.  1   . 
         FIG.  9    is another perspective view of the system of  FIG.  1   . 
         FIG.  10 A  is a partial perspective view of a top corner of the system of  FIG.  1    that depicts a grommet assembly for mounting and/or hanging the system in a designated location. 
         FIG.  10 B  is another partial perspective view of the top corner of  FIG.  10 A  without the grommet assembly. 
         FIG.  100    is another partial perspective view of the top corner of  FIG.  10 A  with the grommet assembly of  FIG.  10 A  secured to a bolt for mounting and/or hanging the system of  FIG.  1   . 
         FIG.  10 D  is a side view of the top corner of  FIG.  10 A  with the grommet assembly of  FIG.  10 A  secured to the bolt of  FIG.  100   . 
         FIG.  11    depicts a step of an example method of the instant disclosure for assembling the system of  FIG.  1   . 
         FIG.  12    depicts another step of the method for assembling the system of  FIG.  1   . 
         FIG.  13    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  14 A  depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  14 B  is a closeup view of a cross rail of a frame of the system of  FIG.  1   . 
         FIG.  14 C  is a further closeup view of the cross rail of  FIG.  14 B . 
         FIG.  15    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  16    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  17    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  18    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  19    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  20    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  21    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  22    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  23    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  24    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  25    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  26    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  27    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIG.  28    depicts yet another step of the method for assembling the system of  FIG.  1   . 
         FIGS.  29 A- 29 C  depict an example flowchart of the instant disclosure for assembling the system of  FIG.  1   . 
         FIG.  30    is another perspective view of the system of  FIG.  1    with bottom panels of the cabinet removed. 
         FIG.  31    is another perspective view of the system of  FIG.  1    with panels removed to depict a control panel installed within an electronics compartment of the cabinet and rotated to be accessed horizontally. 
         FIG.  32    is a cutaway side view of a portion of the system of  FIG.  1    that depicts the control panel of  FIG.  31    installed within the cabinet and rotated to be accessed from below. 
         FIG.  33    is a side view of the electronics compartment of  FIG.  31    as the control panel of  FIG.  31    is being rotated to be accessed horizontally. 
         FIG.  34    is a perspective view of the electronics compartment of  FIG.  31    as the control panel of  FIG.  31    is being rotated to be accessed horizontally. 
         FIG.  35    depicts a portion of the control panel of  FIG.  31    and external water connections of the system of  FIG.  1   . 
         FIG.  36    is a perspective view of a portion of the system of  FIG.  1    with a bottom panel of the cabinet removed to access a blower-and-coil compartment of the cabinet. 
         FIG.  37    is another perspective view of the blower-and-coil compartment of  FIG.  36   . 
         FIG.  38 A  is an expanded view of a blower assembly of the system of  FIG.  1    having a blower panel secured within the blower-and-coil compartment of  FIG.  36    via a latch in a secured position. 
         FIG.  38 B  is another expanded view of the blower panel of  FIG.  38 A  with the latch in a sliding position. 
         FIG.  39    depicts the blower assembly of  FIG.  38 A  partially lowered from the blower-and-coil compartment of  FIG.  36    via the blower panel of  FIG.  38 A . 
         FIG.  40    depicts the blower assembly of  FIG.  38 A  further lowered from the blower-and-coil compartment of  FIG.  36    via the blower panel of  FIG.  38 A . 
         FIG.  41    depicts the blower assembly of  FIG.  38 A  fully lowered from the blower-and-coil compartment of  FIG.  36    via the blower panel of  FIG.  38 A . 
         FIG.  42    is a side cutaway view of the blower assembly of  FIG.  38 A . 
         FIG.  43    depicts a perspective view of a portion of the system of  FIG.  1    with a top panel of the cabinet removed. 
         FIG.  44    is a perspective view of a bottom panel of the system of  FIG.  1    through which a disconnect switch extends. 
         FIG.  45    is a cutaway side view of a switchbox housing the disconnect switch of  FIG.  44   . 
         FIG.  46    is a perspective view of another embodiment of a low-height heat pump system of the instant disclosure. 
         FIG.  47    is a perspective view of another embodiment of a low-height heat pump system of the instant disclosure. 
         FIG.  48    is another perspective view of the system of  FIG.  47   . 
         FIG.  49    is an end perspective view of the system of  FIG.  47    with a panel of the cabinet removed to show a control panel of the system. 
         FIG.  50    is another perspective view of the system of  FIG.  47    with a blower assembly in its fully lowered position and one or more bottom panels of the cabinet removed to show various system components inside in the cabinet. 
         FIG.  51    is a schematic diagram illustrating an embodiment of a heat pump system of the instant disclosure. 
         FIG.  52    is a block diagram depicting electrical components associated with one or more embodiments of the instant disclosure. 
         FIGS.  53 A- 53 C  depict an example flowchart for providing freeze protection for a heat exchanger associated with a heat pump system of the instant disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Although the figures and the instant disclosure describe one or more embodiments of a heat pump system, one of ordinary skill in the art would appreciate that the teachings of the instant disclosure would not be limited to these embodiments. It should be appreciated that any of the features of an embodiment discussed with reference to the figures herein may be combined with or substituted for features discussed in connection with other embodiments in this disclosure. 
     The instant disclosure provides an improved heat pump system comprising uniquely configured heat pump system components together with an improved enclosure that enable (i) easy and efficient assembly of the system at the factory, (ii) installation in locations that are extremely limited in height, such as the ceiling space in a housing unit, a hotel room, or a commercial office unit, for example, that separates vertically adjoining rooms or units, (iii) field configurable options for connecting to existing HVAC system components, and (iv) easy component serviceability while the system is installed. Embodiments of the improved enclosure (also interchangeably called a “cabinet,” a “cabinet system,” a “cabinet enclosure,” or a “cabinet assembly” for purposes of this disclosure) provide for a low-height heat pump system, such as a 9-inch-tall system measured from the bottom of the cabinet to the top of the cabinet. The reduced height of the cabinet and uniquely configured heat pump components housed therein enables the cabinet to be installed in shallow ceiling spaces, such as in a furred ceiling area at an entry of a hotel room, a condominium, or an apartment, etc. In turn, the reduced height of the cabinet suspended from or otherwise mounted to the ceiling reduces the total height of the corresponding floor, thereby reducing the height of each floor within a building. In some instances, the height savings for each floor that results from the cabinet of the instant disclosure may enable in an additional floor to be added for every predetermined (e.g., ten) floors in a high-rise building. Additionally, embodiments of the disclosed cabinet and the uniquely configured heat pump components housed therein increase the size of the available floor space for the corresponding unit by removing the need to dedicate a portion of the floor space, such as a dedicated closet, for the heat pump system. Embodiments of the disclosed cabinet and the uniquely configured heat pump components housed therein also are capable of being retrofitted into older buildings with reduced floor heights and minimal available floor space for a new HVAC system. 
     Embodiments of the low-height cabinet system disclosed herein include uniquely configured cabinet components and heat pump components therein that enable a technician to easily install the cabinet in a shallow ceiling space. Embodiments of the disclosed cabinet include integrated low-profile hanger features that facilitate the cabinet in being installed in shallow spaces. Embodiments of the disclosed cabinet are configured to house various components of a water source heat pump in a novel, compact arrangement to reduce the amount of height consumed by the HVAC system and its cabinet enclosure. For example, embodiments of the instant disclosure may be about 50 inches long, about 20 inches wide, and a maximum of about 9 inches in height. To achieve the reduced height of 9 inches, embodiments of the low-height cabinet system of the instant disclosure include a refrigerant-to-air load heat exchanger with horizontally-oriented heat exchange tubes with heat exchange passes stacked vertically above one another to a height that enables the heat exchanger to fit within the 9 inch cabinet enclosure. With the maximum height being fixed, the horizontal length of the heat exchange tubes and the number of horizontal passes are defined by the desired heat exchange between air passing over the tubes and the refrigerant conveyed within the tubes. In addition, embodiments of the instant disclosure include the use of a horizontally-oriented compressor and a relatively small brazed-plate source heat exchanger, both enabling the reduced height of  9  inches. One of ordinary skill would appreciate that the use of a brazed-pate heat exchanger introduces the risk of damage from freezing of water or other source liquid therein, and the use of a relatively small brazed-plate heat exchanger as disclosed herein only enhances that risk due to the relatively small voids or volumes of water therein that may more easily and/or more quickly freeze under the same conditions. Consequently, the use of a brazed-plate heat exchanger as disclosed herein provides unexpected advantages for helping solve the problem of achieving a low height of  9  inches. Embodiments of the disclosed cabinet also include an integrated air-discharge plenum that unexpectedly provides fan/motor sound attenuation while also allowing the integration of such components or features inside the cabinet as opposed to, for example, having a plenum entirely separate from and outside the cabinet. Additionally, embodiments of the disclosed cabinet are formed of lightweight components, such as rail frames formed of thin-gauge steel, to facilitate the cabinet in easily being installed in a ceiling space or suspended from a ceiling. Further, the components provide rigidity to the cabinet that reduces vibrations and/or lowers acoustic signatures without incorporating additional noise-insulating materials. 
     Embodiments of the cabinet disclosed herein include features that enable a technician to easily access and service components housed in the cabinet from underneath, for example, without having to dismount the cabinet from its installed position in or near the ceiling. In addition, embodiments of the disclosed cabinet include a plurality of side and/or bottom panel air duct connection ports that can be configured in the field at the time of installation of the unit to facilitate connection of HVAC system air ducts to the heat pump system at the time of installation. Embodiments of the disclosed cabinet include a plurality of removable side and/or bottom panels to provide the technician with multiple points of access to internal components of the cabinet, thereby facilitating the technician in servicing various internal components from below the cabinet that is installed to or suspended from the ceiling. Embodiments of the disclosed cabinet include other features, such as a removable drain pan for a load heat exchanger, such as a refrigerant-to-air heat exchanger (also called an “air coil”) and/or a retractable and removable slide deck to which one or more fans or air blowers and a corresponding drive motor are mounted, to enable servicing of the one or more fans and/or motor(s) and to further facilitate the technician in accessing various internal components of the cabinet when the cabinet remains in its installed condition. 
     Embodiments of the disclosed cabinet also include safety features, such as a bottom-mounted electrical disconnect switch, to increase the safety of the technician servicing the heat pump system. Other safety features are also disclosed herein. For example, embodiments of the disclosed heat pump system include a freeze-protection system and method that restricts operation of the compressor of the heat pump system to prevent damage to heat pump components when tasked with operating when, for example, the source water is near or below freezing temperatures. Additionally, embodiments of the freeze-protection system disclosed herein may be implemented in other heat pump systems to protect system components from freezing and damage. 
     Additionally, embodiments of the cabinet disclosed herein have a reduced part count and an easy fabrication and assembly process, thereby reducing manufacturing costs for the cabinet. For example, embodiments of assembly methods disclosed herein enable components of the cabinet to be assembled from the bottom up, where upon completion of the assembly enables components housed therein to be accessible and serviceable from underneath the cabinet when installed. Embodiments of the disclosed cabinet are configured to be modular to facilitate a streamlined process for assembling differently-oriented cabinets. For example, the modularity of the cabinet components enables the same parts to be used for a cabinet that is assembled in a right configuration, a left configuration, and a split configuration. In turn, required inventory is reduced, material utilization is optimized, and manufacturing efficiency is increased. The modularity of the cabinet components also enables the cabinet to be configured for a diverse set of environments. 
     Turning now to the drawings,  FIGS.  1 - 10    illustrate various external views of an exemplary low-height heat pump system  5  of the instant disclosure, and particularly low-height heat pump cabinet assembly  10  that is configured to house uniquely configured heat pump components therein. In the illustrated example, the cabinet  10  has a low height of 9 inches, a length of 53 inches, and a depth of 22.5 inches.  FIGS.  1  and  8 - 10    depict various perspective views of the cabinet  10 ,  FIGS.  2 - 5    illustrate various elevation views of the cabinet  10 , and  FIGS.  6 - 7    depict representative top and bottom plan views, respectively, of the cabinet  10 . The cabinet  10  includes a top side  20 , a bottom side  25  opposite the top side  20 , a first side  30 , a second side  35  opposite the first side  30 , a first end  40 , and a second end  45  opposite the first end  40 . In the illustrated example, the cabinet  10  includes a plurality of panels defining outer surfaces of the cabinet  10 . 
     As shown in  FIG.  2   , an end panel  240  (also referred to as a “front panel,” a “side panel,” and an “access panel”) and portions of corner posts  180 ,  190  form the second end  45  of the cabinet  10 . 
     As shown in  FIG.  3   , end panels  230 ,  235  and a portion of a corner post  170  form the first end  40  of the cabinet  10 . The end panel  230  (also referred to as a “back panel,” a “side panel,” and a “discharge panel”) includes a duct panel  232  (also referred to as a “knockout panel”) that is removable from the end panel  230 . The duct panel  232  is configured to be decoupled from the end panel  230  to enable ductwork of an HVAC system to fluidly connect to the cabinet  10  via a corresponding opening formed where the duct panel  232  was removed from the end panel  230 . For example, the duct panel  232  includes one or more flanges extending from its edges to facilitate the duct panel  232  in being coupled to and decoupled from the end panel  230 . Additionally, an outlet  712  of a drain pan  710  ( FIG.  11   ) extends outwardly from the corner post  170 . The end panel  235  (also referred to as a “side panel” and an “access panel”) is positioned next to the end panel  230  in a side-by-side manner. 
     As shown in  FIG.  4   , side panels  250 ,  255 , a portion of the end panel  230 , a portion of a corner post  180 , and a portion of a divider  150  form the first side  30  of the cabinet  10 . The side panel  250  (also referred to as a “discharge panel”) is positioned adjacent the first end  40 , and the side panel  255  is positioned adjacent the second end  45 . The side panel  250  includes a plurality of duct panels  251 ,  252 ,  253  (also referred to as a “knockout panels”) that are arranged in a side-by-side manner. The side panel  255  (also referred to as an “access panel”) is positioned next to the side panel  250  in a side-by-side manner. 
     Each of the duct panels  251 ,  252 ,  253  are removable from the side panel  250  to form an opening for ductwork connecting to the cabinet  10 . For example, each of the duct panels  251 ,  252 ,  253  includes one or more flanges extending from its edges to facilitate the coupling to and decoupling from the side panel  250 . Ductwork of the HVAC system may fluidly connect to the cabinet  10  via an opening formed by the removal of one or more of the duct panels  251 ,  252 ,  253  in addition to or as an alternative to ductwork connecting to the cabinet  10  via the end panel  230 . For example, ductwork of the HVAC system may connect to the cabinet  10  via only the end panel  230 , via only the side panel  250 , and/or simultaneously via both the end panel  230  and the side panel  250 . In the illustrated example, each of the duct panels  251 ,  252 ,  253  are equally sized. In other examples, the duct panels  251 ,  252 ,  253  are differently sized with respect to each other to facilitate differently-sized ducts in connecting to the cabinet  10 . For example, the duct panel  251  having a first surface area may be removed to enable a first-sized duct to connect to the cabinet  10 , or the duct panel  252  having a second surface area may be removed to enable a second-sized duct to connect to the cabinet  10 . Additionally, or alternatively, different combinations of the duct panels  251 ,  252 ,  253  may be removed to facilitate differently sized ducts in connecting to the cabinet  10 . For example, one of duct panels  251 ,  252 ,  253  may be removed to enable a relatively small duct to connect to the cabinet  10 . Two adjacent ones of the duct panels  251 ,  252 ,  253  may be removed together to enable a moderately-sized duct to connect to the cabinet  10 . All three of the duct panels  251 ,  252 ,  253  may be removed together to enable a relatively large duct to connect to the cabinet  10 , for example, to facilitate proper air velocity and static pressure. 
     As shown in  FIG.  5   , a side panel  260 , a portion of the corner posts  170 ,  190 , and a portion of the divider  150  form the second side  35  of the cabinet  10 . The side panel  260  (also referred to as an “access panel”) is positioned adjacent the second end  45  of the cabinet  10 . An opening is defined along the second side  35  adjacent the first end  40  of the cabinet  10  between the top side  20  and the bottom side  25 . The opening exposes a refrigerant-to-air load heat exchanger, such as an air coil  700  housed within the cabinet  10 , to air outside of the cabinet  10 . In the illustrated example, a filter rack  730  is installed upstream of the air coil  700  and is configured to house a replaceable 1″ or a 2″ filter, for example. 
     As shown in  FIG.  6   , a top panel  270  forms the top side  20  of the cabinet  10 . In the illustrated example, the top panel  270  extends the entire length and width of the top side  20 . As shown in  FIGS.  1 ,  6 , and  9   , the top panel  270  includes flanges  272  that extend from opposing ends. One of the flanges  272  extends between the first and second sides  30 ,  35  and outwardly from the first end  40  of the cabinet  10 . The other of the flanges  272  extends between the first and second sides  30 ,  35  and outwardly from the second end  45  of the cabinet  10 . Additionally, each of the flanges  272  defines two mount holes  274  at opposing ends of the flange  272  such that one of the mount holes  274  is located at each corner of the top panel  270 . The mount holes  274  are configured to facilitate the cabinet  10  in being suspended from or otherwise mounted to a ceiling by a technician without additional brackets. 
     As shown in  FIGS.  10 A and  10 C- 10 D , the cabinet  10  also includes a plurality of low-profile hanger mounts comprising grommet assemblies  280  that further facilitate the cabinet  10  in being secured to or suspended from the ceiling. The grommet assemblies  280  are located at the corners of the cabinet  10  and configured to prevent potential operational vibrations of the cabinet  10  from migrating to the building structure to which the cabinet  10  is installed. The grommet assemblies  280  are compact and do not extend beyond the top panel  270  to facilitate the cabinet  10  in being installed in shallow ceiling spaces, such as in a furred ceiling areas. Each of the grommet assemblies  280  extends through a respective one of the mount holes  274  and secured through a respective one of the flanges  272 . Each of the grommet assemblies  280  includes a grommet  281  (e.g., rubber grommets), a washer  283 , a nut  284 , a lock washer  285 , and a hanger rod  286 . The grommet  281  includes a top cap  282  that extends through the mount hole  274  and is positioned adjacent a top surface of the flange  272 . The remaining portion of the grommet  281  is positioned below a bottom surface of the flange  272 . In the illustrated example, the grommet  281  contacts the bottom surface of the flange  272 . The hanger rod  286  extends through the grommet  281  and the mount hole  274 . The washer  283  engages a bottom of the grommet  281 , the lock washer  285  engages the washer  283 , and the nut  284  threadably receives the hanger rod  286 . The nut  284  is threaded onto the hanger rod  286  until the nut  284  securely fastens the flange  272  of the cabinet  10  to the bolt  286 . 
     As shown in  FIGS.  7  and  8   , the bottom side  25  of the cabinet  10  is formed by a plurality of bottom panels  212 ,  214 ,  216 ,  218 ,  220  that are arranged next to each other. Each of the bottom panels  212 ,  214 ,  216 ,  218 ,  220  are configured to be removed from a frame  100  ( FIG.  11   ) of the cabinet  10  to enable a technician to easily access different components housed within the cabinet  10  from a position below the cabinet  10 . For example, the bottom panel  212  is configured to be decoupled from the frame  100  to enable a technician to access components that are housed adjacent the bottom panel  212 , the bottom panel  214  is configured to be decoupled from the frame  100  to enable a technician to access components that are housed adjacent the bottom panel  214 , etc. In the illustrated example, the bottom panel  212  is configured to be decoupled from the frame  100  to provide access to a plenum compartment  50  ( FIG.  25   ) of the cabinet  10 . The bottom panel  214  is configured to be decoupled from the frame  100  to provide access to a blower compartment  60  ( FIG.  25   ) of the cabinet  10 . The bottom panel  216  and/or the bottom panel  218  is configured to be decoupled from the frame  100  to provide access to a compressor compartment  70  ( FIG.  17   ) of the cabinet  10 . The bottom panel  220  is configured to be decoupled from the frame  100  to provide access to an electronics compartment  80  ( FIG.  27   ) of the cabinet  10 . 
       FIGS.  11 - 28    depict various steps of an example assembly process for the heat pump system  5  of the instant disclosure. Initially, as shown in  FIG.  11   , a base of the frame  100  of the cabinet  10  is assembled together in an upside-down configuration at a workstation. For example, side rails  112 ,  114  and end rails  122 ,  124  of the frame  100  are coupled together (e.g., via fasteners) to form a rectangular shape and an outer frame of the cabinet  10 . The frame  100  also includes cross rails  132 ,  134 ,  136  that are each coupled to one or more of the side rails  112 ,  114  and/or end rails  122 ,  124 . The cross rails  132 ,  134  extend perpendicularly between and couple (e.g., via fasteners) to the end rails  122 , 124 . The cross rail  136  extends perpendicularly between and couple (e.g., via fasteners) to the end rails  122  and the cross rails  134 . 
     Subsequently, a drain pan  710  and the bottom panels  212 ,  214 ,  216 ,  218 ,  220  are then coupled to the frame  100  in an upside-down configuration such that the bottom side  25  is facing upward. The drain pan  710  for the air coil  700  extends between and is coupled to the end rail  122  and the cross rail  134 . The drain pan  710  is configured to be easily decoupled from the frame  100  to facilitate a technician in cleaning, maintaining, and/or repairing the drain pan  710 . An outlet  712  of the drain pan  710  is positioned to extend through one of two holes  121  of the end rail  122 , and an opposing end of the drain pan  710  is fastened to the cross rail  134 . For example, an end of the drain pan  710  includes a flange that is coupled to the cross rail  134  (e.g., via a fastener). In some examples, the outlet  712  on the opposing end of the drain pan  710  is a flexible drain coupling that is decouplable from the drain pan  710  to facilitate in the disassembly, removal, and/or servicing of the drain pan  710  with hand tools. 
     Additionally, the bottom panel  212  is coupled to the side rail  112 , the end rail  122 , and/or the cross rails  134 ,  136  via one or more fasteners (e.g., threaded fasteners) in a manner such that the bottom panel  212  covers the drain pan  710  in the upside-down orientation. The bottom panel  214  is coupled to the side rail  114 , the end rail  122 , and/or the cross rails  134 ,  136  via one or more fasteners (e.g., threaded fasteners). The bottom panel  216  is coupled to the side rail  112  and/or the cross rails  132 ,  134  via one or more fasteners (e.g., threaded fasteners), and the bottom panel  218  is coupled to the side rail  114  and/or the cross rails  132 ,  134  via one or more fasteners (e.g., threaded fasteners). The bottom panel  220  is coupled to the side rails  112 ,  114 , the end rail  124 , and/or the cross rail  132  via one or more fasteners (e.g., threaded fasteners). 
     The base of the frame  100 , the drain pan  710 , and the bottom panels  212 ,  214 ,  216 ,  218 ,  220  are then rotated right-side up and transported to an assembly line for further assembly of the cabinet  10 .  FIG.  12    depicts the assembled components of the cabinet  10  after being rotated right-side up. The remaining components of the cabinet  10  are assembled to the frame  100  in a right-side up orientation to enable the cabinet  10  to be assembled in a configuration that subsequently enables a technician to easily access those components from below the cabinet  10  by quickly removing one or more of the bottom panels  212 ,  214 ,  216 ,  218 ,  220  from the frame  100 . 
       FIG.  13    depicts compressor cross rails  312 ,  314  of the cabinet  10  that are positioned to rest on the cross rails  132 ,  134 , respectively. As shown in  FIG.  14 A , the compressor cross rail  312  extends between and is coupled to the side rails  112 ,  114 . Each end of the compressor cross rail  312  is coupled to one of the side rails  112 ,  114  via a fastener, and a middle portion of the compressor cross rail  312  rests on a surface of the of the cross rail  132 . Similarly, the compressor cross rail  314  extends between and is coupled to the side rails  112 ,  114 . Each end of the compressor cross rail  314  is coupled to one of the side rails  112 ,  114  via a fastener, and a middle portion of the compressor cross rail  314  rests on a surface of the of the cross rail  134 . 
       FIGS.  14 B- 14 C  further depict features of the cross rail  136 . One or more lips  138  protrude upward from a bottom edge of the cross rail  136 . Each of the lips  138  extend longitudinally along a portion of the cross rail  136  and are arranged in a side-by-side manner along the cross rail  136 . Additionally, the lips  138  are longitudinally spaced apart from each other along the cross rail  136 . The gaps formed between the lips  138  define blade openings  137  (to receive a lock blade  844  of a latch  842  as shown in  FIG.  38 A ). 
     Returning to  FIG.  14 A , the frame  100  includes the divider  150  and a divider  160  (also referred to as a “blower mounting panel”), and the blower assembly includes a slider bracket  854 . As shown in  FIG.  15   , the divider  150  includes mullions  152 ,  154  located at opposing ends of the divider  150 . The divider  150  extends along the cross rail  134  between the side rails  112 ,  114 , with the mullion  152  adjacent the side rail  112  and the mullion  154  adjacent the side rail  114 . In the illustrated example, the divider  150  is coupled to the cross rail  134 , the side rail  112 , and/or the side rail  114  via fasteners. For example, the mullion  152  is coupled to and extends along a portion of the side rail  112 , and the mullion  154  is coupled to and extends along a portion of the side rail  114 . As disclosed below in greater detail, the divider  150  is configured to extend along the cross rail  134 , between the first and second sides  30 ,  35 , and between the top and bottom sides  20 ,  25  to separate the compressor compartment  70  from both the plenum compartment  50  and the blower compartment  60 . 
     The divider  160  extends along the cross rail  136  between the end rail  122  and the divider  150 . In the illustrated example, the divider  160  is coupled to the end rail  122 , the cross rail  134 , the cross rail  136 , and/or the divider  150  via fasteners. As disclosed below in greater detail, the divider  160  is configured to extend along the cross rail  136 , between the first end  40  and the divider  150 , and between the top and bottom sides  20 ,  25  to separate the plenum compartment  50  from the blower compartment  60 . The divider  160  also defines one or more openings  162  to fluidly connect the plenum compartment  50  to the blower compartment  60  such that the plenum receives heated or cooled air exiting the blower compartment  60 . The duct panels  232 ,  251 ,  252 ,  253  enable the plenum compartment  50  to be accessed in multiple discharge directions for various duct configurations. The plenum compartment  50  enables air pressure to build for distribution down the installed duct paths. Additionally, the plenum compartment  50  facilitates a rapid expansion of airflow from the blowers  810 ,  820 , which may have a relatively small area and a relatively high-velocity throat, thereby rapidly lowering the airflow velocity and corresponding noise due to a reduced turbulence. That is, the rapid decrease in velocity results in an integral acoustic attenuator of the cabinet  10 . 
     As most clearly shown in  FIG.  19   , the slider bracket  854  is configured to extend between the top side  20  and the bottom side  25  of the cabinet  10  along the vertical edge where the divider  160  intersects the divider  150 . The slider bracket  854  is coupled to the divider  150  via fasteners. 
     Returning to  FIG.  15   , heat pump system  5  includes a compressor  300  that is configured to be positioned within the compressor compartment  70  of cabinet  10  and coupled to the frame  100 . The compressor  300  is coupled to compressor support rails  316 ,  318  that are spaced apart from and extend parallel to each other. The compressor  300  may be configured as a horizontal rotary compressor to permit the compressor to lay horizontally across support rails  316 ,  318  so as to minimize height of the overall heat pump system  5  , and particularly cabinet  10 . As shown in  FIG.  16   , the compressor support rails  316 ,  318  are coupled to the compressor support rails  312 ,  314  via fasteners to couple the compressor  300  to the frame  100 . When fastened together, the compressor support rails  316 ,  318  extend perpendicular to the compressor cross rails  312 ,  314 . The compressor cross rails  312 ,  314  and the compressor support rails  316 ,  318  are arranged with respect to each other and the frame  100  in a manner that enables the compressor  300  to be securely fastened and supported by the frame  100  of the cabinet  10 . 
       FIG.  16    further depicts a refrigerant-to-liquid source heat exchanger  400  of the heat pump system  5  and a support bracket  410  of the cabinet  10 . In the illustrated example, the heat exchanger  400  is a brazed-plate heat exchanger, which not only possesses sufficient heat exchange capacity but is quite small so as to enable the low-height configuration of the cabinet  10 . As will be discussed below, the use of a brazed-plate heat exchanger with small volumes for heat exchange may increase the chance for freezing of water or brine internally to the heat exchanger  400 , which can result in significant damage to the unit. However, the risk of freezing can be minimized or eliminated using the freeze protection system and method disclosed herein. Turning again to  FIG.  16   , the heat exchanger  400  of this embodiment includes four ports  402 ,  404 ,  406 ,  408 . The port  402  is an outlet port that is configured to return a liquid, such as water or brine, to a source after exchanging heat in the heat exchanger  400  with a refrigerant configured to circulate in a refrigerant circuit  650  as part of heat pump system  5 . The port  404  is an inlet port that is configured to receive a liquid, such as water or brine, from a source. As disclosed in greater detail with respect to  FIG.  51   , the ports  406 ,  408  are fluidly connected to refrigerant conduit  600  of the refrigerant circuit  650  to convey refrigerant therethrough to and from various heat pump components to cool and/or heat air for a space. 
     As shown in  FIG.  17   , the support bracket  410  is coupled to other portions of the cabinet  10  to enable the heat exchanger  400  to be secured in place. For example, the support bracket  410  is coupled to the side rail  114 , the cross rail  134 , the compressor cross rail  314 , and/or the divider  150  (e.g., the mullion  154  of the divider  150 ) via fasteners. The heat exchanger  400 , in turn, is coupled to the support bracket  410  via fasteners. Additionally or alternatively, the heat exchanger  400  may be coupled directly to the side rail  114 , the cross rail  134 , the compressor cross rail  314 , and/or the divider  150  (e.g., the mullion  154  of the divider  150 ) via fasteners. 
     In the illustrated example, the heat exchanger  400  is installed vertically within the compressor compartment  70  of the cabinet  10 . The inlet port  404  is positioned to be the lowest port of the heat exchanger  400  to avoid build-up of condensation within the heat exchanger  400  when the heat exchanger  400  is operating in condensing applications. The heat exchanger  400  of the illustrated example is sized to both ( 1 ) provide enough heat exchange capabilities to comfortably control the temperature of the space and ( 2 ) fit within the low-height profile of the cabinet  10 . 
       FIG.  17    further depicts an expansion valve  500  and a filter drier  510  of the heat pump system  5 . The expansion valve  500  and the filter drier  510  are fluidly connected to each other via a portion of refrigerant conduit  600  of the heat pump system  5 . As shown in  FIG.  18   , the filter drier  510  is fluidly connected to the port  408  via another portion of the refrigerant conduit  600 . In other embodiments, the filter drier may be omitted or moved to a different location along refrigerant conduit  600 . 
       FIG.  18    also depicts other portions of the refrigerant conduit  600  of heat pump system  5 . A reversing valve  330 , pressure switches  342 ,  344 , a saddle seat  350 , and a pressure switch  360  of the heat pump system  5  are connected to those portions of the refrigerant conduit  600 . The reversing valve  330  includes a solenoid  332  that enables the reversing valve  330  to reverse the direction of fluid flow throughout portions of the heat pump system  5 . As shown in  FIG.  19   , the portions of the refrigerant conduit  600  shown in in  FIG.  19    are coupled to the compressor  300 , the heat exchanger  400 , the expansion valve  500 , and the filter drier  510 . In turn, the compressor  300 , the heat exchanger  400 , the expansion valve  500 , the filter drier  510 , the reversing valve  330 , the pressure switches  342 ,  344 , and the pressure switch  360  are fluidly connected to each other via the refrigerant conduit  600 . 
       FIG.  19    further depicts the corner post  170 , the air coil  700 , a support bracket  720 , and another portion of the refrigerant conduit  600  of the heat pump system  5 . As shown in  FIG.  20   , the corner post  170  of the cabinet  10  is coupled to the side rail  112  and/or the end rail  122  via one or more fasteners. A bottom edge of the corner post  170  defines a hemispherical groove through which the outlet  712  of the drain pan  710  extends. In other examples, the corner post  170  may define a hole through which the outlet  712  of the drain pan  710  extends. 
     The support bracket  720  of the cabinet  10  is coupled to and extends along the side rail  112 . The air coil  700  is positioned over the drain pan  710  such that condensation from the air coil  700  is safely collected within the drain pan  710  and removed from the cabinet  10  through the outlet  712 . The air coil  700  is coupled to the side rail  112 , the divider  150  (e.g., the mullion  152  of the divider  150 ), the corner post  170 , and/or the support bracket  720  via one or more fasteners to securely position the air coil  700  in place within the blower compartment  60 . The air coil  700  is fluidly connected to other components of the heat pump system  5  via the refrigerant conduit  600 .  FIG.  20    further depicts other portions of the refrigerant conduit  600  that is configured to fluidly connect the components of the heat pump system  5  together. 
       FIG.  21    depicts an electronics housing  930  of the cabinet  10  that is configured to at least partially define electronics compartment  80 . In the illustrated example, the electronics housing  930  includes an integrally-formed U-shaped structure with a base panel  932  and two opposing arm panels  934 . The arm panels  934  extend from and perpendicularly to the base panel  932 . One of the arm panels  934  defines a curved slot  936  that, as disclosed in greater detail below, facilitates a control panel  910  in being securely positioned within and/or removed from the electronics compartment  80 . As shown in  FIG.  22   , the base panel  932  of the electronics housing  930  is configured to extend along and coupled to (e.g., via fasteners) the cross rail  132 . The arm panels  934  of the electronics housing  930  extend from the cross rail  132  and to the end rail  124 . In some examples the arm panels  934  are coupled to the cross rail  132  and/or the end rail  124  via fasteners. 
       FIG.  22    also depicts the corner post  180  the cabinet  10 . In the illustrated example, the corner post  180  defines an outlet opening  182  and an inlet opening  184 . Additionally,  FIG.  22    depicts a flow switch  420 , a motorized valve  430  (also referred to as a “motorized water valve”), a strainer valve  440 , a flow regulator valve  450 , and plate fittings  462 ,  464  of the heat pump system  5 . The motorized valve  430  includes an actuator  432  that is configured to control operation of the motorized valve  430  in a motorized manner. The flow switch  420  and the plate fitting  462  are fluidly connected to each other in series. The flow regulator valve  450 , the motorized valve  430 , the strainer valve  440 , and the plate fitting  464  are fluidly connected to each other in series. In other examples, pump  470  may take the place the of the motorized valve  430  between the strainer valve  440  and the flow regulator valve  450 . 
     As shown in  FIG.  23   , the corner post  180  is coupled to the side rail  114  and/or the end rail  124  via one or more fasteners. The flow switch  420  is connected to the outlet port  402  of the heat exchanger  400 . Further, the plate fitting  462  of the cabinet  10  is mounted to the corner post  180  adjacent the outlet opening  182 . In turn, an outlet water leg is formed that fluidly connects the outlet port  402  to the outlet opening  182  of the cabinet  10  with the flow switch  420  positioned along the outlet water leg. The flow regulator valve  450  is connected to the inlet port  404  of the heat exchanger  400 . In turn, an inlet water leg is formed that fluidly connects the inlet port  404  to the inlet opening  184  of the cabinet  10  with the flow regulator valve  450 , the motorized valve  430 , the strainer valve  440 , and the plate fitting  464  positioned along the inlet water leg. The plate fitting  464  of the cabinet  10  is mounted to the corner post  180  adjacent the inlet opening  184  so that the inlet port  404  of the heat exchanger  400  is fluidly connected to the inlet opening  184  of the cabinet  10 . 
       FIG.  23    further depicts another corner post  190  and a disconnect switchbox  940 . The disconnect switchbox  940  includes a switch body  942 , a switch  943  extending from the switch body  942 , a front housing  944 , a cover  946 , and a rear housing  948 . As shown in  FIG.  24   , the corner post  190  of the cabinet  10  is coupled to the side rail  112  and/or the end rail  124  via one or more fasteners. The disconnect switchbox  940  is securely coupled to the bottom panel  216  adjacent the electronics compartment  80 . 
     As shown in  FIG.  12   , the front housing  944  is previously coupled to an inner surface of the bottom panel  216 . To complete the assembly and installation of the disconnect switchbox  940  as shown  FIG.  24   , the cover  946  is positioned within the front housing  944 . The switch body  942  is then positioned on the cover  946  such that the switch  943  extends through a switch opening  947  defined by the front housing  944  and the cover  946 . The rear housing  948  is positioned over the front housing  944  such that the cover  946  and the switch body  942  are enclosed by the front and rear housings  944 ,  948 . Additionally, the switch body  942 , the front housing  944 , the cover  946 , and the rear housing  948  are coupled together via one or more fasteners. Switchbox  940  enables the switch  943  to lie within a recessed portion defined by front housing  944  ( FIG.  45   ) so as to protect switch  943  from damage and/or unintended activation or deactivation. 
       FIG.  24    further depicts a blower assembly of the heat pump system  5 . The blower assembly includes blowers  810 ,  820 , a blower motor  830 , a blower panel  840 , a slider bracket  852 , and the slider bracket  854 . The blowers  810 ,  820  and the blower motor  830  are mounted to the blower panel  840 . As shown in  FIG.  25   , the blower assembly is housed within the blower compartment  60  adjacent the air coil  700 . The slider bracket  852  is coupled to one end of the divider  160  adjacent the end rail  122  via one or more fasteners, and the slider bracket  854  is coupled to an opposing end of the divider  160  adjacent the divider  150  via one or more fasteners. The slider brackets  852 ,  854  are positioned vertically such that the slider brackets  852 ,  854  extend in a direction toward the bottom side  25  of the cabinet  10 . The blower panel  840  is slidably mounted to the slider brackets  852 ,  854  such that the blower panel  840  is positioned vertically within the blower compartment  60  of the cabinet  10 . As disclosed below in greater detail, the sliding configuration of the blower assembly facilitates a technician in easily accessing the blowers  810 ,  820  and the blower motor  830  from below when the cabinet  10  is installed to a ceiling surface. 
       FIG.  25    further depicts the end panel  230  and the side panel  250  each of which is a discharge panel that includes one or more duct panels. The end panel  230  includes the duct panel  232 , and the side panel  250  includes the duct panels  251 ,  252 ,  253 . As shown in  FIG.  26   , the end panel  230  is coupled to the end rail  122 , the side rail  114 , and/or the divider  160  via one or more fasteners. The side panel  250  is coupled to the side rail  114 , and/or the divider  150  (e.g., the mullion  154  of the divider  150 ) via one or more fasteners. 
       FIG.  26    further depicts a control panel  910  and a cover panel  920  of the heat pump system  5 . The control panel  910  includes an electrical circuit with a plurality of electrical components that are configured to control operation of the heat pump system  5  . For example, the control panel  910  includes a controller  912  ( FIG.  30   ) that is communicatively coupled (e.g., via wires) to a plurality of components used to control operation of the heat pump system  5 . In some examples, the controller  912  is a control board. Further, in some examples, the controller  912  includes a processor  914  and memory  916  ( FIG.  52   ). Example components communicatively connected to the controller  912  include an inlet-side water temperature sensor  403 , an outlet-side water temperature sensor  405 , a first low temperature sensor  502 , a second low temperature sensor  504 , the pressure switch  342  (also referred to as a first low pressure switch), the pressure switch  344  (also referred to as a second low pressure switch), the pressure switch  360  (also referred to as a high pressure switch), and the flow switch  420 . 
     The control panel  910  is coupled to an underside of the cover panel  920  such that the cover panel  920  covers the control panel  910  when coupled to the electronics housing  930  within the electronics compartment  80  of the cabinet  10 . The cover panel  920  is configured to cover fasteners (e.g., screws) that mount the electrical components to the control panel  910 . The cover panel  920  includes a pin  922  that is configured to facilitate a technician in coupling the control panel  910  to the electronics housing  930  and/or decoupling the control panel  910  from the electronics housing  930 . The pin  922  is configured to be slidably received by the curved slot  936  of the electronics housing  930  to facilitate the technician in securely positioning the control panel  910  within the electronics housing  930  and/or removing the control panel  910  from the electronics housing  930 .  FIG.  27    depicts the control panel  910  and the cover panel  920  when the cover panel  920  is coupled to the electronics housing  930  via the pin  922  and the curved slot  936 . 
       FIG.  27    further depicts the top panel  270  that is to be secured along the top side  20  of the cabinet  10 . As illustrated in  FIG.  28   , the top panel  270  includes downwardly-extending side and end flanges that are configured to be coupled to the divider  150  (e.g., the mullions  152 ,  154  of the divider  150 ), the divider  160 , the corner post  170 , the corner post  180 , the corner post  190 , the end panel  230 , and/or the side panel  250  via one or more fasteners (e.g., threaded fasteners). 
       FIG.  28    depicts the end panels  235 ,  240  and the side panels  255 ,  260  that are coupled to the first and second ends  40 ,  45  and the first and second sides  30 ,  35 , respectively. The end panels  235 ,  240  and the side panels  255 ,  260  are access panels that are configured to facilitate a technician in easily accessing components of the heat pump system  5  housed within the cabinet  10 . For example, the end panel  235  is configured to be coupled to the end rail  122 , the divider  160 , the corner post  170 , and/or the top panel  270  via one or more fasteners (e.g., threaded fasteners). The end panel  240  is configured to be coupled to the end rail  124 , the corner post  180 , the corner post  190 , and/or the top panel  270  via one or more fasteners (e.g., threaded fasteners). The side panel  255  is configured to be coupled to the side rail  114 , the divider  150  (e.g., the mullion  154  of the divider  150 ), the corner post  180 , and/or the top panel  270  via one or more fasteners (e.g., threaded fasteners). The side panel  260  is configured to be coupled to the side rail  112 , the divider  150  (e.g., the mullion  152  of the divider  150 ), the corner post  190 , and/or the top panel  270  via one or more fasteners (e.g., threaded fasteners). In the illustrated example, each of the end panels  235 ,  240  and the side panels  255 ,  260  includes side and top guide flanges that facilitate a technician in positioning the end panels  235 ,  240  and the side panels  255 ,  260  in place. 
       FIGS.  29 A- 29 C  depict a flowchart of an example method  1000  to assembled the heat pump system  5  disclosed herein. While the example method  1000  is described with reference to the flowchart illustrated in  FIGS.  29 A- 29 C , many other methods of assembling the heat pump system  5  may alternatively be used. For example, the order of execution of the blocks may be rearranged, changed, eliminated, and/or combined to perform the method  1000 . Further, because the method  1000  is disclosed in connection with the components of  FIGS.  1 - 28   , some functions of those components will not be described in detail below. 
     Initially, at block  1005 , a base of the frame is assembled together at a workstation in an upside down configuration. For example, the side rails  112 ,  114 , the end rails  122 ,  124 , and the cross rails  132 ,  134 ,  136  are coupled together to form the base of the frame  100 . At block  1010 , the drain pan  710  and the bottom panels  212 ,  214 ,  216 ,  218 ,  220  are attached to the base of the frame  100  in an upside-down configuration. At block  1015 , the base of the frame  100 , the drain pan  710 , and the bottom panels  212 ,  214 ,  216 ,  218 ,  220  are rotated right-side up and positioned on an assembly line for further assembly. 
     At block  1020 , the compressor cross rails  312 ,  314  are attached to the side rails  112 ,  114  of the base of the frame  100 . The compressor cross rail  312  is positioned to extend along and rest on the cross rail  132 , and the compressor cross rail  314  is positioned to extend along and rest on the cross rail  134 . At block  1025 , the divider  150 , including the mullions  152 ,  154 , and the divider  160  are attached to the base of the frame  100 . For example, the divider  150  is positioned to extend between the side rails  112 ,  114  and along the cross rail  134 , and the divider  160  is positioned to extend along the cross rail  136  and between the end rail  122  and the divider  150 . The divider  150  is coupled to the cross rail  134 , the side rail  112 , and/or the side rail  114 . The divider  160  is coupled to the end rail  122 , the cross rail  134 , the cross rail  136 , and/or the divider  150 . 
     At block  1030 , the compressor support rails  316 ,  318  are attached to the compressor cross rails  312 ,  314 , for example, in a perpendicular manner. The compressor  300  is previously coupled to the compressor support rails  316 ,  318  such that coupling the compressor support rails  316 ,  318  to the compressor cross rails  312 ,  314  results in the compressor  300  being coupled to the base of the frame  100 . At block  1035 , the heat exchanger  400  is attached to the base of the frame  100  via the support bracket  410 . For example, the heat exchanger  400  is a brazed-plate heat exchanger that is coupled to the frame  100  in an upright or vertical manner. At block  1040 , the expansion valve  500  and the filter drier  510  are attached to the heat exchanger  400  via a portion of the refrigerant conduit  600 . At block  1045 , the reversing valve  330 , the pressure switches  342 ,  344 , the pressure switch  360 , the compressor  300 , the heat exchanger  400 , the expansion valve  500 , and the filter drier  510  are fluidly connected to each other via portions of the refrigerant conduit  600 . 
     At block  1050 , the support bracket  720  for the air coil  700  and the corner post  170  are attached to the base of the frame  100 . For example, the support bracket  720  is coupled to and extends along the side rail  112 , and the corner post  170  is coupled to the side rail  112  and/or the end rail  122 . Additionally, the air coil  700  is attached to the support bracket  720 , the side rail  112 , the divider  150  (e.g., the mullion  152  of the divider  150 ), and/or the corner post  170  so that the air coil  700  is positioned above the drain pan  710 . At block  1055 , the air coil  700  is fluidly connected to other components of the heat pump system  5 , such as the expansion valve  500 , via portions of the refrigerant conduit  600 . 
     At block  1060 , the electronics housing  930  is coupled to the base of the frame  100 . For example, the base panel  932  of the electronics housing  930  is coupled to and extends along the cross rail  132 , and the arm panels  934  of the electronics housing  930  extend between the cross rail  132  and the end rail  124  of the frame  100 . 
     At block  1065 , the corner post  180  is attached to the base of the frame  100  and water legs are connected to the heat exchanger  400 . For example, the is coupled to the side rail  114  and/or the end rail  124  of the frame  100 . The inlet water leg is assembled that extends between the inlet port  404  of the heat exchanger  400  and the inlet opening  184  defined by the corner post  180 . The flow regulator valve  450 , the motorized valve  430 , and the strainer valve  440  are positioned along the inlet water leg. The outlet water leg is assembled that extends between the outlet port  402  of the heat exchanger  400  and the outlet opening  182  defined by the corner post  180 . The flow switch  420  is positioned along the outlet water leg. 
     At block  1070 , the corner post  190  is attached to the base of the frame  100 , and the disconnect switchbox  940  is assembled on the bottom panel  216 . For example, the corner post  190  is coupled to the side rail  112  and/or the end rail  124  of the frame  100 . To assemble the disconnect switchbox  940 , (1) the cover  946  is positioned within the front housing  944 , (2) the switch body  942  is positioned on the cover  946  such that the switch  943  extends through the switch opening  947 , (3) the rear housing  948  is positioned over the front housing  944  to enclose the cover  946  and the switch body  942  within the front and rear housings  944 ,  948 , and (4) the switch body  942 , the front housing  944 , the cover  946 , and the rear housing  948  are fastened together. 
     At block  1075 , the blowers  810 ,  820  and the blower motor  830  are securely and slidably positioned within the blower compartment  60  of the cabinet  10 . For example, the blowers  810 ,  820  and the blower motor  830  are mounted to the blower panel  840 . The slider brackets  852 ,  854  are fastened in a vertical manner to opposing ends of the divider  160 . The blower panel  840  is then slidably mounted to the slider brackets  852 ,  854  such that the blower panel  840  is positioned vertically within the blower compartment  60 . 
     At block  1080 , the discharge panels, including the end panel  230  and the side panel  250 , are coupled to the frame  100  around the plenum compartment  50 . For example, the end panel  230  is coupled to the end rail  122 , the side rail  114 , and/or the divider  160 . The side panel  250  is coupled to the side rail  114  and/or the divider  150  (e.g., the mullion  154  of the divider  150 ). 
     At block  1085 , the control panel  910  is securely positioned within the electronics compartment  80  of the cabinet  10 . For example, the control panel  910  is mounted to the cover panel  920 . The cover panel  920  include the pin  922  that is slidably received by the curved slot  936  of the electronics housing  930  to securely position the control panel  910  within the electronics compartment  80 . 
     At block  1090 , the top panel  270  is attached along the top side  20  of the cabinet  10 . For example, the top panel  270  is coupled to the divider  150  (e.g., the mullions  152 ,  154  of the divider  150 ), the divider  160 , the corner post  170 , the corner post  180 , the corner post  190 , the end panel  235 , and/or the side panel  250 . At block  1095 , the access panels, including the end panels  235 ,  240  and the side panels  255 ,  260 , are attached to the frame  100  and/or the top panel  270  of the cabinet  10 . For example, the end panel  235  is coupled to the end rail  122 , the divider  160 , the corner post  180 , and/or the top panel  270 . The end panel  240  is coupled to the end rail  124 , the corner post  180 , the corner post  180 , and/or the top panel  270 . The side panel  255  is coupled to the side rail  114 , the divider  150  (e.g., the mullion  154  of the divider  150 ), the corner post  180 , and/or the top panel  270 . The side panel  260  is coupled to the side rail  114 , the divider  150  (e.g., the mullion  152  of the divider  150 ), the corner post  190 , and/or the top panel  270 . 
       FIG.  30    depicts the bottom side  25  of the heat pump system  5  with the bottom panels  212 ,  214 ,  216 ,  218 ,  220  removed from the frame  100  of the cabinet  10 . For example, the bottom panel  212  is decoupled from the frame  100  to enable a technician positioned below the heat pump system  5  to easily access and service components of the heat pump system  5  housed within the blower compartment  60 , such as the air coil  700 , the drain pan  710 , the blowers  810 ,  820 , and the blower motor  830 . Additionally or alternatively, the end panel  235  is configured to be decoupled from the frame  100  to facilitate the technician in accessing the components housed in the blower compartment  60 . The bottom panel  214  is decoupled from the frame  100  to enable the technician positioned below the heat pump system  5  to easily access the plenum compartment  50 . The bottom panels  216 ,  218  are decoupled from the frame  100  to enable the technician positioned below the heat pump system  5  to easily access and service components housed within the compressor compartment  70 , such as the compressor  300 , the heat exchanger  400 , and the filter drier  510 . Additionally or alternatively, the side panel  255  and the side panel  260  are configured to be decoupled from the frame  100  to facilitate the technician in accessing the components housed in the compressor compartment  70 . For example,  FIG.  31    depicts the heat pump system  5  when the side panel  260  is decoupled from the frame  100  of the cabinet  10  to provide access to the motorized valve  430 , the strainer valve  440 , the flow regulator valve  450 , and the filter drier  510  of the heat pump system  5 . The bottom panel  220  is decoupled from the frame  100  to enable the technician positioned below the heat pump system  5  to easily access and service components housed within the electronics compartment  80  of the cabinet  10 , such as the controller  912  and/or other components of to the control panel  910 . Additionally or alternatively, the end panel  240  is configured to be decoupled from the frame  100  to facilitate the technician in accessing the components of the heat pump system  5  housed in the electronics compartment  80 . For example,  FIG.  31    depicts the heat pump system  5  when the end panel  240  is decoupled from the frame  100  of the cabinet  10  to provide access to the control panel  910 . 
       FIGS.  31 - 34    further depict features of the cabinet  10  that enable the technician to access and, in turn, service and/or replace electrical components of the control panel  910  such as the controller  912 , when the heat pump system  5  is installed along a ceiling surface.  FIG.  31    depicts the control panel  910  housed securely within and rotated to be accessed horizontally via the first side  30 , the second side  35 , and/or the second end  45 . The electronics compartment  80  is defined by the bottom panel  220 , the cover panel  920 , and the electronics housing  930 .  FIG.  32    is a cutaway side view of the control panel  910  housed securely within the electronics compartment  80  and oriented to be accessed from below the heat pump system  5 .  FIGS.  33 - 34    depict the control panel  910  being rotated within the electronics housing  930  via the pin  922  and the curved slot  936 . 
     To secure the control panel  910  within the electronics compartment  80 , the end panel  240  is detached from the frame  100 . The control panel  910  and the cover panel  920  is then inserted into the electronics compartment  80  through an opening where the end panel  240  was previously located. The control panel  910  and the cover panel  920  are positioned and oriented such that the pin  922  of the cover panel  920  is inserted into the curved slot  936  of the electronics housing  930 . A cap is attached to the pin  922  to securely retain the pin  922  within the curved slot  936 . The pin  922  of the cover panel  920  is then slid to an upper end of the curved slot  936  at which the pin  922  rests such that the cover panel  920  and the control panel  910  is slid and rotated into a rest position within the electronics compartment  80 . In some examples, an edge of the cover panel  920  is secured to the corner posts  180 ,  190  via fasteners to further secure the control panel  910  in place. The end panel  240  is then reattached to the frame  100  to securely enclose the control panel within the electronics compartment  80 . 
     When the control panel  910  is installed within the electronics compartment  80 , the curved slot  936  and the pin  922  enable the control panel to be rotated by the technician (e.g., about  120  degrees) so that the control panel  910  faces slightly upward and toward the second end  45  of the cabinet  10 . To access the control panel  910  for service, the end panel  240 , the side panel  255 , and/or the side panel  260  is detached from the frame  100 . In some examples, the cover panel  920  is decoupled from the corner posts  180 ,  190  while the control panel  910  remains facing downward. The control panel  910  and the cover panel  920  are slid and rotated (e.g., about 120 degrees) via the pin  922  and the curved slot  936  so that the control panel  910  faces slightly upward and toward the second end  45  of the cabinet  10 . Once the control panel  910  is serviced, the control panel  910 , cover panel  920 , the end panel  240 , the side panel  255 , and/or the side panel  260  are securely retained to their rest positions. 
       FIG.  35    depicts a corner of the cabinet  10  that is formed where the first side  30  and the second end  45  meet. In the illustrated example, the corner post  180 , the end panel  240 , and the side panel  255  are decoupled from the end rail  124  and the side rail  114  of the frame  100 . Components housed within the electronics compartment, such as the controller  912 , are accessible to the technician when the end panel  240  is detached from the frame  100 . Components housed within the compressor compartment  70 , such as the motorized valve  430 , the strainer valve  440 , the flow regulator valve  450 , the expansion valve  500 , and the filter drier  510 , are accessible to the technician when the side panel  255  is detached from the frame  100 . The plate fittings  462 ,  464  are accessible when the corner post  180  is detached from the frame  100 . 
       FIGS.  36 - 41    features of the cabinet  10  that enable components housed within the blower compartment  60 , such as the air coil  700 , the drain pan  710 , the blowers  810 ,  820 , and the blower motor  830 , to be easily accessed by the technician from below the heat pump system  5 . As shown in  FIGS.  36 - 37    the blower compartment  60  is accessed by decoupling the bottom panel  212  from the frame  100 . For example, the bottom panel  212  is detached from the side rail  112 , the end rail  122 , the cross rail  134 , and/or the cross rail  136  of the frame  100 . 
     As further depicted in  FIGS.  38 A- 42   , the blower assembly includes a sliding mechanism that facilitates the technician in accessing the blowers  810 ,  820  and the blower motor  830  from the below the heat pump system  5  installed to a ceiling surface. The blower panel  840  is slidingly engaged to the slider brackets  852 ,  854  of the blower assembly. The blower panel  840  is configured to slide along the slider brackets  852 ,  854 , which that are fixed in place, to slide the blowers  810 ,  820  and the blower motor  830  into and/or out of the blower compartment  60  of the cabinet  10 . The blower assembly also includes a latch  842  that enables the sliding mechanism to rest in a retracted position at which the blowers  810 ,  820  and the blower motor  830  are completely within the blower compartment  60 . The blower assembly is configured to provide a rigidity to the cabinet  10  that reduces vibrations and/or lowers acoustic signatures without incorporating additional noise-insulating materials. 
       FIGS.  38 A and  38 B  depict the blower assembly in the retracted position. More specifically,  FIG.  38 A  depicts the sliding mechanism in the retracted position with the latch  842  in a locked position, and  FIG.  38 B  depicts the sliding mechanism in the retracted position with the latch  842  in an unlocked position. A first end of the latch  842  is fastened to the blower panel  840  via a first fastener  846 , and an opposing second end of the latch  842  is couplable to the blower panel  840  via a second fastener  848 . The latch  842  is spring loaded and also includes a lock blade  844  that extends from the second end. When the latch  842  is in the locked position as shown in  FIG.  38 A , the second fastener  848  is coupled to the blower panel  840  to secure the second end of the latch  842  to the blower panel  840 . In turn, the lock blade  844  extends into one of the blade openings  137  ( FIGS.  14 A- 140   ) defined by the lips  138  ( FIGS.  14 A- 14 C ) of the cross rail  136 . When lock blade  844  is extended into one of the blade openings  137 , the lock blade  844  of the latch  842  prevents the blower panel  840  from sliding downward via the slider brackets  852 ,  854 . To transition the latch  842  to the unlocked position as shown in  FIG.  38 B , the second fastener  848  is decoupled from the blower panel  840 . The second end of the latch  842  is biased to flex away from the surface of the blower panel  840 . In turn, when the second fastener  848  is removed, the second end of the latch  842  flexes away from the blower panel  840  and the lock blade  844  of the latch  842  is slide out of the blade opening  137 . When the lock blade  844  is removed from the blade opening  137 , the blower panel  840  is enabled to slide downward via the slider brackets  852 ,  854 . 
       FIGS.  39  and  40    depict respective intermediate positions at which the blowers  810 ,  820  and the blower motor  830  are extended partially out of the blower compartment  60 .  FIGS.  41    depicts the sliding mechanism in a fully extended position at which the blowers  810 ,  820  and the blower motor  830  are completely outside of the blower compartment  60 . As shown in  FIG.  42   , the blower assembly includes a hanger-stop assembly that deters the blower panel  840  from unintentionally sliding beyond and disconnecting from the slider brackets  852 ,  854 . The hanger-stop assembly includes one or more of the lips  138  of the cross rail  136  and a lip  849  at a top end of the blower panel  840 . When the blower panel  840  has been slid to the bottom of the slider brackets  852 ,  854  at the fully extended position, the lip  849  of the blower panel  840  engages and hangs from the lips  138  of the cross rail  136  in such a manner that the blower panel  840  is impeded from disconnecting from the slider brackets  852 ,  854 . The hanger-stop assembly also is configured to enable the technician to fully remove the blower panel  840 . For example, to remove the blower panel  840 , the technician is to lift the blower panel  840  slightly upward, tilt the blower panel  840  toward the side rail  112 , and pull the blower panel  840  away from the slider brackets  852 ,  854 . 
       FIG.  43    further depicts the bottom side  25  of a portion of the cabinet  10  with the bottom panels  212 ,  214 ,  216 ,  218  removed from the frame  100 . For example, the bottom panel  212  is decoupled from the frame  100  to provide access to components of the heat pump system  5  housed within the blower compartment  60 , such as the air coil  700 , the blowers  810 ,  820 , and the blower motor  830 . The bottom panel  214  is decoupled from the frame  100  to provide access to the plenum compartment  50 . The bottom panels  216 ,  218  are decoupled from the frame  100  to provide access to components housed within the compressor compartment  70 . 
     In the illustrated example, the plenum compartment  50  is formed by the divider  150 , the divider  160 , the bottom panel  212 , the end panel  230 , the side panel  250 , and the top panel  270 . The blower compartment  60  is formed by the divider  150 , the divider  160 , the corner post  170 , the bottom panel  214 , the end panel  235 , and the top panel  270 . Additionally, the compressor compartment  70  is formed by the divider  150 , the divider  160 , the corner posts  180 ,  190 , the bottom panels  216 ,  218 , the end panel  240 , the side panels  255 ,  260 , and the top panel  270 . The electronics compartment  80  is formed by the bottom panel  220 , the end panel  240 , the top panel  270 , and the electronics housing  930 . 
       FIGS.  44 - 45    further depict the disconnect switchbox  940  of the heat pump system  5  that is coupled to the bottom panel  216 . As shown in  FIG.  45   , the front housing  944  is coupled to an inner surface of the bottom panel  216 . The cover  946  is positioned within the front housing  944 . The switch body  942  is positioned on the cover  946  such that the switch  943  extends through the switch opening  947 . The rear housing  948  is positioned over the front housing  944  such that the cover  946  and the switch body  942  are enclosed by the front and rear housings  944 ,  948 . The switch  943  extends through the switch opening  947  and out of the bottom side  25  of the cabinet  10  to enable the technician to easily change the position of the switch  943  thereby safely shutting off electrical power to the heat pump system  5  from below the heat pump system  5  before accessing components of the heat pump system  5  housed within the interior of the cabinet  10 . 
       FIG.  46    depicts another embodiment of a low-height heat pump system  2050  having a low-height heat pump cabinet  2100  as disclosed herein. The components of the heat pump system  2050  housed within the cabinet  2100  may be identical to those housed in the cabinet  10 . Additionally, the cabinet  2100  is substantially similar to the cabinet  10 . For example, the bottom panels  212 ,  216 ,  218 ,  220 ; the end panel  240 ; the side panels  250 ,  255 ; the top panel  270  and other components not shown are identical to those of the cabinet  10 . As such, those components and their functionality are not disclosed in further detail below with respect to the heat pump system  2050  and the cabinet  2100 . 
     As shown in  FIG.  46   , the cabinet  2100  includes a bottom panel  2214  that is adjacent the plenum compartment  50 . The bottom panel  2214  is coupled to the side rail  114 , the end rail  122 , and/or the cross rails  134 ,  136  via one or more fasteners (e.g., threaded fasteners). The bottom panel  2214  includes a plurality of duct panels  2221 ,  2222 ,  2223  (also referred to as a “knockout panels”) that are arranged in a side-by-side manner. Each of the duct panels  2221 ,  2222 ,  2223  are removable from the bottom panel  2214  to form an opening for ductwork connecting to the plenum compartment  50  of the cabinet  2100 . Ductwork of the HVAC system may fluidly connect to the cabinet  2100  via an opening formed by the removal of one or more of the duct panels  2221 ,  2222 ,  2223  in addition to or as an alternative to ductwork connecting to the cabinet  2100  via the end panel  230  and/or the side panel  250 . For example, ductwork of the HVAC system may connect to the cabinet  2100  via only the end panel  230 , via only the side panel  250 , via only the bottom panel  2214  and/or simultaneously via any combination of the end panel  230 , the side panel  250 , and the bottom panel  2214 . In the illustrated example, each of the duct panels  2221 ,  2222 ,  2223  are equally sized. In other examples, the duct panels  2221 ,  2222 ,  2223  are sized differently with respect to each other to facilitate differently-sized ducts in connecting to the cabinet  2100 . Additionally or alternatively, different combinations of the duct panels  2221 ,  2222 ,  2223  may be removed to facilitate differently-sized ducts in connecting to the cabinet  2100 . 
       FIGS.  47 - 50    depicts another embodiment of a low-height heat pump system  3050  having a low-height heat pump cabinet assembly  3100  as disclosed herein. The components of the heat pump system  3050  housed within the cabinet assembly  3100  may be similar to those housed in the cabinet  10 . For example, the compressor  300 , the reversing valve  330 , the expansion valve  500 , the filter drier  510 , the heat exchanger  400 , the air coil  700 , the control panel  910 , the blower assembly, the sensors, the switches, etc. are identical to those housed in the cabinet  10 . Additionally, the cabinet assembly  3100  is substantially similar to the cabinet  10 . For example, the corner posts  170 ,  180 ,  190 ; the bottom panel  220 ; the end panels  230 ,  240 ; the side panels  250 ,  255 ,  260 ; and other components not shown are identical to those of the cabinet  10 . As such, those components and their functionality are not disclosed in further detail below with respect to the heat pump system  3050  and the cabinet assembly  3100 . 
     As shown in  FIGS.  47 - 50   , the heat pump system  3050  is a split system with the cabinet assembly  3100  including a first cabinet  3110  and a second cabinet  3120  that are split apart from each other. The first cabinet  3110  includes the plenum compartment  50  and the blower compartment  60 , and the second cabinet  3120  includes the compressor compartment  70  and the electronics compartment  80 . The first cabinet  3110  is connected to the second cabinet  3120  via refrigeration lines, electrical/power lines, and/or computer control lines. The first cabinet  3110  and/or the second cabinet  3120  may be wired or wirelessly (Wi-Fi/cellular/Bluetooth, etc.) connected to one another and/or to other local or remote equipment, including a thermostat, a controller, a display, and/or a user interface operating in a web browser, for example. In this way, a user may locally or remotely monitor a sensor, component, or function of heat pump system  3050  or locally or remotely interact with and/or control a function of heat pump system  3050 . The split configuration of heat pump system  3050  allows the first cabinet  3110  to be mounted in a different location than the second cabinet  3120  to accommodate architectural/physical constraints, such as beams, purlins, structural members, plumbing, and other building systems, and to provide maximum flexibility for installation in a particular building. For example, the second cabinet  3120  can be positioned in a closet adjacent to, for example, an apartment&#39;s water heating system while the first cabinet  3110  can be positioned in the ceiling. Example embodiments of the first cabinet  3110  may be about 35 inches long, about 25 inches wide, and a maximum of about 9 inches in height. In the illustrated example, the first cabinet  3110  has a low height of 9 inches, a length of 33.71 inches, and a depth of 22.5 inches. Example embodiments of the second cabinet  3120  may be about 27.5 inches long, about 25 inches wide, and a maximum of about 9 inches in height. The second cabinet  3120  of the illustrated example has a low height of 9 inches, a length of 26.097 inches, and a depth of 22.5 inches. 
     In the illustrated example, the second cabinet  3120  includes the corner posts  180 ,  190 ; end panels  240 ,  3230 ; side panels  255 ,  260 ; bottom panels  220 ,  3218 ; and a top panel  3275 . The end panels  240 ,  3230 , the side panels  255 ,  260 , and the bottom panels  220 ,  3128  are configured to be removed from the second cabinet  3120  to provide access to components of the heat pump system  3050  housed within the first cabinet  3120 . For example, in  FIG.  49   , the end panel  240  is removed to provide access to the control panel  910  housed within the electronics compartment  80  of the second cabinet  3120 . 
     The first cabinet  3110  of the illustrated example includes the corner post  170 ; end panels  230 ,  3240 ,  3244 ; knockout panels  3242 ,  3246 ; a mullion  3248 ; the side panel  250 ; a bottom panel  3212 , and a top panel  3270 . The end panel  230  is located on a first end of the first cabinet  3110  The end panels  3240 ,  3244 ; the knockout panels  3242 ,  3246 ; and the mullion  3248  are located on an opposing second side. The knockout panels  3242 ,  3246  are configured to be removed from first cabinet  3110  to provide access to the plenum compartment  50  and/or the blower compartment  60 . For example, one or more of the knockout panel  3242 ,  3246  is removed from the first cabinet  3110  to enable a portion of the refrigerant conduit  600  and/or electrical wiring to extend between (1) the plenum compartment  50  and/or the blower compartment  60  of the first cabinet  3110  and (2) the compressor compartment  70  and/or the electronics compartment  80  of the second cabinet  3120 . The side panel  250  includes the duct panels  251 ,  252 ,  253  that are removable to form an opening for ductwork connecting to the plenum compartment  50 . The bottom panel  3212  also includes duct panels  3214 ,  3215 ,  3216  that are removable to form an opening for ductwork connecting to the plenum compartment  50 . As shown in  FIG.  49   , another bottom panel  3213  is coupled to the bottom panel  3212  that extends a length and width of the first cabinet  3110 . As shown in  FIG.  50   , the bottom panel  3213  is configured to be decoupled from the bottom panel  3212  to provide access to the blowers  810 ,  820 ; the blower motor  830 ; and the blower panel  840  of the blower assembly housed within the blower compartment  60 . 
       FIG.  51    is a schematic illustrating the modes of operation of heat pump systems  5 ,  2050 ,  3050 . The components of heat pump systems  5 ,  2050 ,  3050  are fluidly coupled together via refrigerant conduit  600 . Control components, including control input devices and control output devices, of heat pump systems  5 ,  2050 ,  3050  are communicatively coupled to the controller  912 . For example, control input devices of heat pump systems  5 ,  2050 ,  3050  include the temperature sensors  403 ,  405 ,  502 ,  504 , the flow switch  420 , and the pressure switches  342 ,  344 ,  360 . The control input devices of heat pump systems  5 ,  2050 ,  3050  that are communicatively coupled to the controller  912  to control the conditioning of the space include, for example, the compressor  300 , the reversing valve  330 , and the blowers  810 ,  820 . 
     In the illustrated example, refrigerant circuit  650  of heat pump systems  5 ,  2050 ,  3050  includes various portions of refrigerant conduit  600  to convey refrigerant therethrough, including first portion  1120  extending from the compressor  300  to the fourth port  337  of reversing valve  330 , second portion  1130  extending from the second port  335  of reversing valve  330  to the port  406  of the refrigerant-to-liquid source heat exchanger  400 , third portion  1140  extending from the port  408  of the source heat exchanger  400  to the filter drier  510  and to the expansion valve  500 , fourth portion  1150  extending from the expansion valve  500  to the refrigerant-to-air load heat exchanger identified in these example embodiments as air coil  700 , fifth portion  1160  extending from the air coil  700  to the first port  334  of reversing valve  330 , and sixth portion  1170  extending from the third port  336  of reversing valve  330  to a suction accumulator  320  ( FIG.  15   ) and to the compressor  300 . 
     Heat pump systems  5 ,  2050 ,  3050  also include source loop  1110  to convey a liquid, such as water or brine, for example, to and from a source and to and from source heat exchanger  400  to enable heat exchange between the refrigerant and the liquid from the source. 
     The source loop  1110  of the illustrated example includes the inlet water leg and the outlet water leg. The inlet water leg is connected to the inlet port  404  of the heat exchanger  400  and the outlet water leg is connected to the outlet port  402  of the heat exchanger  400 . 
     In the illustrated example, the inlet water leg is configured to receive water, or brine, or other liquid from a source. The inlet side of the strainer valve  440  is configured to receive the water, for example, from the source. The outlet side of the strainer valve  440  is connected to the inlet side of the optional motorized valve  430 , the outlet side of the motorized valve  430  is connected to the inlet side of the optional pump  470 , the outlet side of the pump  470  is connected to the inlet side of the optional flow regulator valve  450 , and the outlet side of the flow regulator valve  450  is connected to the inlet port  404  of the heat exchanger  400 . In some examples, the motorized valve  430 , the pump  470 , and/or the flow regulator valve  450  are optional components that may not be included in the source loop  1110 . Additionally, the temperature sensor  403  is positioned along the inlet water leg adjacent the inlet port  404  to measure the temperature of water entering the heat exchanger  400 . 
     The outlet water leg of the illustrated example is configured to return the water to the source. The outlet port  402  of the heat exchanger  400  side is connected to the inlet side of the flow switch  420 , and the outlet side of the flow switch  420  is fluidly connected to the source. As disclosed below in greater detail, the flow switch  420  is configured to detect when the flow rate of the water leaving the heat exchanger  400  is less than a predefined temperature threshold. In other examples, a flow sensor and/or other flow monitoring device is used to detect when the flow rate is less than the predefined temperature threshold. Additionally, the temperature sensor  405  is positioned along the outlet water leg adjacent the outlet port  402  to measure the temperature of water leaving the heat exchanger  400 . 
     As illustrated in  FIG.  51   , the temperature sensor  502  is positioned along the third portion  1140  of the refrigerant conduit  600  of refrigerant circuit  650  between the filter drier  510  (if present) and adjacent to the expansion valve  500  to measure a temperature of the refrigerant along the third portion  1140 . The temperature sensor  504  is positioned along the fourth portion  1150  of the refrigerant conduit  600  of refrigerant circuit  650  adjacent to the expansion valve  500  to measure a temperature of the refrigerant along the fourth portion  1150 . A condensate sensor  715  is positioned on or near drain pan  710  to detect the presence of condensate collected by the drain pan  710  from air coil  700 . 
     The pressure switches  342 ,  344  are positioned along the sixth portion  1170  of the refrigerant conduit  600  of refrigerant circuit  650  between the reversing valve  330  and the suction accumulator  320  to monitor for a low pressure of the refrigerant during a cooling mode. As disclosed below in greater detail, the pressure switches  342 ,  344  are configured to detect when the pressure along the sixth portion  1170  is less than respective predefined pressure thresholds. In other examples, pressure sensors and/or other pressure monitoring devices are used to detect when the pressure is less than the predefined pressure thresholds. Additionally, in the illustrated example, a connection point  345  to controller  912  is positioned along the sixth portion  1170  between the reversing valve  330  and the suction accumulator  320  for monitoring a temperature and a pressure of the expansion valve  500 . 
     The pressure switch  360  is positioned along the first portion  1120  of the refrigerant conduit  600  of refrigerant circuit  650  to monitor for a high pressure of the refrigerant during a cooling mode. As disclosed below in greater detail, the pressure switch  360  is configured to detect when the pressure along the first portion  1120  is greater than a predefined pressure threshold. In other examples, a pressure sensor and/or other pressure monitoring device is used to detect when the pressure is greater than the predefined pressure threshold. 
     The heat pump systems  5 ,  2050 ,  3050  of the illustrated example are reversible flow heat pumps and can be configured to operate in a cooling mode and a heating mode by configuring reversing valve  330  to change the direction of flow of the refrigerant (see arrows in  FIG.  51   ) through refrigerant conduit  600 . In one operating mode, the heat pump systems  5 ,  2050 ,  3050  can be configured to operate in a cooling mode to provide air conditioning and, thus, cool a space. For example, when heat pump systems  5 ,  2050 ,  3050  are configured to operate in a cooling mode, the blowers  810 ,  820  may draw air through and/or across the air coil  700  acting as an evaporator to cool air for the space. In another operating mode, the heat pump systems  5 ,  2050 ,  3050  can be configured to operate in a heating mode to heat the space. For example, when heat pump systems  5 ,  2050 ,  3050  are configured to operate in a heating mode, the blowers  810 ,  820  may draw air through and/or across the air coil  700  configured as a condenser to heat air for the space. The controller  912  is configured to control a configuration of the reversing valve  330  to transition between the cooling mode and the heating mode of the heat pump systems  5 ,  2050 ,  3050 . 
     To place heat pump systems  5 ,  2050 ,  3050  in a cooling mode, the controller  912  sends a signal to the reversing valve  330  that causes the reversing valve  330  to fluidly connect (1) the first port  334  to the third port  336  and (2) the second port  335  to the fourth port  337 . In the illustrated example, the refrigerant flows in a counterclockwise direction through the refrigerant conduit  600 . Superheated refrigerant gas leaving the compressor is directed to (1) the fourth port  337  of the reversing valve  330 , (2) which conveys the refrigerant from the second port  335  of the reversing valve  330  to port  408  and through the heat exchanger  400  acting as a condenser, (3) through the filter drier  510 , (4) through the expansion valve  500 , (5) through the air coil  700  acting as an evaporator, (6) through the first port  334  of the reversing valve  330 , (7) through the third port  336  of the reversing valve  330 , ( 8 ) through the suction accumulator  320 , and (9) back to the compressor  300 . 
     To place heat pump systems  5 ,  2050 ,  3050  in a heating mode, the controller  912  sends a signal to the reversing valve  330  that causes the reversing valve  330  to fluidly connect (1) the first port  334  to the second port  335  and (2) the third port  336  to the fourth port  337 . In the illustrated example, the refrigerant flows in a clockwise direction through the refrigerant conduit  600 . Superheated refrigerant gas leaving the compressor is directed to (1) the fourth port  337  of the reversing valve  330 , (2) which conveys the refrigerant from the first port  334  of the reversing valve  330  to port  408  and through the air coil  700  acting as a condenser, (3) through the expansion valve  500 , (4) through the filter drier  510 , (5) through the heat exchanger  400  acting as an evaporator, (6) through the second port  335  of the reversing valve  330 , (7) through the third port  336  of the reversing valve  330 , (8) through the suction accumulator  320 , and (9) back to the compressor  300 . 
     As described above for heat pump system  3050 , heat pump systems  5 ,  2050  may be wired or wirelessly (Wi-Fi/cellular/Bluetooth, etc.) connected to other local or remote equipment, including a thermostat, a controller, a display, and/or a user interface operating in a web browser, for example. In this way, a user may locally or remotely monitor a sensor, component, or function of heat pump systems  5 ,  3050  or locally or remotely interact with and/or control a function of heat pump systems  5 ,  3050 . 
       FIG.  52    depicts electronic components of the heat pump system  5 , the heat pump system  2050 , and/or the heat pump system  3050 . In the illustrated example, the electronic components include the controller  912 , a thermostat  918 , one or more input devices, and one or more output devices. 
     The controller  912  includes a processor  914  and memory  916 . The processor  914  may include any suitable processing device or set of processing devices such as, but not limited to, a microprocessor, a microcontroller-based platform, an integrated circuit. The memory  916  may include volatile memory (e.g., RAM, etc.), non-volatile memory (e.g., disk memory, FLASH memory, etc.), unalterable memory (e.g., EPROMs), read-only memory, and/or combinations thereof. The memory  916  is computer readable media on which one or more sets of instructions, such as the software for operating the methods of the present disclosure, can be embedded. For example, the instructions may embody one or more of the methods or logic as described herein. 
     The terms “non-transitory computer-readable medium” and “computer-readable medium” include a single medium or multiple media, such as a centralized or distributed database, and/or associated caches and servers that store one or more sets of instructions. Further, the terms “non-transitory computer-readable medium” and “computer-readable medium” include any tangible medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor or that cause a system to perform any one or more of the methods or operations disclosed herein. As used herein, the term “computer readable medium” is expressly defined to include any type of computer readable storage device and/or storage disk and to exclude propagating signals. 
     The input devices include the pressure switch  342 , the pressure switch  344 , the pressure switch  360 , the temperature sensor  403 , the temperature sensor  405 , flow switch  420 , the temperature sensor  502 , the temperature sensor  504 , and/or any other input device of the heat pump system  5 . The output devices include the compressor  300 , the reversing valve  330 , and the blower motor  830 . In the illustrated example, the controller  912  is communicatively coupled (e.g., via wires) to the thermostat  918 . The controller  912  also is communicatively coupled (e.g., via wires) to the compressor  300 , the reversing valve  330 , and the blower motor  830 . Further, in other examples, the controller  912  is communicatively coupled (e.g., via wires) to other devices, such as the motorized valve  430 , the pump  470 , the expansion valve  500 , the air coil  700 , etc. 
       FIGS.  53 A- 53 C  depict a flowchart of an example method  1200  for operating a freeze-protection system for the heat exchanger  400  of the heat pump system  5 , the heat pump system  2050 , and/or the heat pump system  3050 . One of ordinary skill would appreciate that the freeze protection system and related methods disclosed herein may be applied to any liquid source heat pump or similar system to minimize risk of damage to components that may arise due to ambient freezing conditions. The freeze-protection system of the instant disclosure is configured to prevent the water, brine, brine mixture, or other source liquid in the heat pump system  5 , the heat pump system  2050 , and/or the heat pump system  3050  from freezing conditions and, in turn, protect the heat exchanger  400  from being damaged, particularly but not exclusively when the heat exchanger  400  is a brazed-plate heat exchanger that is sized to be installed vertically within the low-height cabinet  10 , the cabinet  2100 , and/or the cabinet  3100  and/or in systems with small liquid source volume. For example, the freeze-protection system is configured to prevent the water, brine, brine mixture, or other source liquid from freezing that may otherwise occur due to (1) a startup at low ambient temperatures that corresponds with a low evaporating temperature and pressure, (2) no and/or otherwise disrupted flow rate of the water through the source loop  1110 , and/or (3) a simultaneous stopping of the compressor  300  and the pump  470  (also referred to as a “water pump”) at low suction temperatures. Additionally, the strainer valve  440  (e.g., a 20-mesh y strainer) deters the refrigerant from freezing that may otherwise occur due to fouling. 
     The flowchart of  FIGS.  53 A- 53 C  is configured to be executed by the controller  912 . For example, the flowchart is representative of machine readable instructions that are stored in memory and include one or more programs which, when executed by the controller  912 , cause the heat pump system  5 , the heat pump system  2050 , and/or the heat pump system  3050  to perform the blocks of  FIGS.  53 A- 53 C . While the example program is described with reference to the flowchart illustrated in  FIGS.  53 A- 53 C , many other methods of performing a freeze-protection sequence may alternatively be used. For example, the order of execution of the blocks may be rearranged, changed, eliminated, and/or combined to perform the method  1200 . Further, because the method  1200  is disclosed in connection with the components of  FIGS.  1 - 28  and  30 - 52   , some functions of those components will not be described in detail below. 
     Initially, at block  1205  of Fig,  53 A, the controller  912  determines whether a signal has been received from a thermostat to turn the compressor  130  on. In response to the controller  912  determining that such a signal has not been received, the method  1200  returns to block  1205 . Otherwise, in response to the controller  912  determining that such a signal has been received, the method  1200  proceeds to block  1210  at which the water flowing through the source loop  1110  is monitored for low flow rates. 
       FIG.  53 B  depicts a flowchart of an example method  1210  to perform the block  1210  of  FIG.  53 B  for monitoring the flow rate of water flowing through the source loop  1110 . Initially, at block  1212 , the controller  912  determines whether the pump  470  or the motorized valve  430  is on. In response to the controller  912  determining that the pump  470  or the motorized valve  430  is not on, the method  1210  returns to block  1212 . Otherwise, in response to the controller  912  determining that the pump  470  or the motorized valve  430  is on, the method  1210  proceeds to block  1216 . At block  1216 , the controller  912  determines whether the water flowing of the source loop  1110  is less than a predefined flowrate threshold and has been less than the predefined flowrate threshold continuously for at least a first predefined duration (e.g., 10 seconds). For example, the flow switch  420  is configured to monitor the water flow rate. In some examples, the flow switch  420  has an open contact when the flow rate is less than the predefined flowrate threshold and sends a corresponding signal to the controller  912 . In turn, the controller  912  determines that the water flow rate has been less than the predefined flowrate threshold for at least the first predefined duration when it continuously receives a corresponding signal from the flow switch  420  for the first predefined duration. 
     In response to the controller  912  determining that the water flowrate (1) is not currently less than the predefined flowrate threshold or (2) has not been less than the predefined flowrate threshold continuously for at least the first predefined duration, the method  1210  proceeds to block  1218  at which the controller  912  enables the compressor  300  to be run. Otherwise, in response to the controller  912  determining that the water flowrate is currently less than the predefined flowrate threshold and has been less than the predefined flowrate threshold continuously for at least the first predefined duration, the method  1210  proceeds to block  1220  at which the controller  912  disables the compressor  300 . 
     At block  1222 , the controller  912  determines whether the water flowing of the source loop  1110  is less than the predefined flowrate threshold and has been less than the predefined flowrate threshold continuously for at least a second predefined duration (e.g., 50 seconds). The second predefined duration is greater than the first predefined duration. In response to the controller  912  determining that the water flowrate (1) is not currently less than the predefined flowrate threshold or (2) has not been less than the predefined flowrate threshold continuously for at least the second predefined duration, the method  1210  returns to block  1212 . Otherwise, in response to the controller  912  determining that the water flowrate is currently less than the predefined flowrate threshold and has been less than the predefined flowrate threshold continuously for at least the second predefined duration, the method  1210  proceeds to block  1224  at which the controller  912  disables the pump  470  or the motorized valve  430 . At block  1226 , the controller  912  sets the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  into a lockout mode. 
     Returning to  FIG.  53 A , the controller  912  determines, at block  1230 , whether the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been set in the lockout mode due to a low flow rate of the water of the source loop  1110 . 
     In response to the controller  912  determining that the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  is set in the lockout mode, the method  1200  proceeds to block  1235  at which the controller  912  determines whether power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been cycled since being set to the lockout mode. In response to the controller  912  determining that power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has not been cycled, the method  1200  remains at block  1235 . Otherwise, in response to the controller  912  determining that power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been cycled, the method  1200  proceeds to block  1240 . 
     At block  1240 , the controller  912  determines whether the water flowrate of the source loop  1110  has increased to be greater than the predefined flowrate threshold. In response to the controller  912  determining the water flowrate is not greater than the predefined threshold, the method  1200  remains at block  1240 . Otherwise, in response to the controller  912  determining the water flowrate is greater than the predefined predefined threshold, the method  1200  returns to block  1205 . 
     Returning back to block  1230 , in response to the controller  912  determining that the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  is not set in the lockout mode, the method  1200  proceeds to block  1250  at which the controller  912  monitors the water of the source loop  1110  and the refrigerant of the refrigerant circuit  650  for low temperatures. 
       FIG.  53 C  depicts a flowchart of an example method  1250  to perform the block  1250  of  FIG.  53 A  for monitoring the temperature of fluids flowing through the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050 . Initially, at block  1252 , the controller  912  determines whether a temperature of the refrigerant is less than a first predefined temperature threshold. For example, the temperature sensor  502  is configured to measure the temperature of the refrigerant flowing through the refrigerant conduit  600  of refrigerant circuit  650  near the expansion valve  500 . The controller  912  receives a signal from the temperature sensor  502  indicative of the measured temperature and compares the measured temperature to the first predefined threshold. 
     In response to the controller  912  determining that the temperature of the refrigerant is not less than the first predefined temperature threshold, the method  1250  proceeds to block  1254  at which the controller  912  enables the compressor  300  to be run. Otherwise, in response to the controller  912  determining that the temperature of the refrigerant is less than the first predefined temperature threshold, the method  1250  proceeds to block  1256 . It should be understood that block  1252  may be performed at the same time as block  1256 . Alternatively, block  1256  may be performed before block  1252 . 
     At block  1256 , the controller  912  determines whether a temperature of the water flowing through the source loop  1110  is less than a second predefined temperature threshold. For example, the temperature sensor  405  is configured to measure the temperature of the water flowing from the heat exchanger  400  within the source loop  1110 . The controller  912  receives a signal from the temperature sensor  405  indicative of the measured temperature and compares the measured temperature to the second predefined threshold. 
     In response to the controller  912  determining that the temperature of the water is not less than the second predefined temperature threshold, the method  1250  proceeds to block  1254  at which the controller  912  enables the compressor  300  to be run. Otherwise, in response to the controller  912  determining that the temperature of the water is less than the second predefined temperature threshold, the method  1250  proceeds to block  1258  at which the controller  912  disables the compressor  300 . At block  1260 , the controller  912  sets the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  into the lockout mode. 
     While blocks  1252 ,  1256  are shown in a sequential manner in  FIG.  53 C , the controller  912  is configured to perform blocks  1252 ,  1256  simultaneously. For example, the controller  912  simultaneously checks whether (1) the temperature of the water flowing through the source loop  1110  is less than the second predefined temperature threshold and (2) the temperature of the refrigerant is less than the first predefined temperature threshold. If the controller  912  determines that both are simultaneously true, the controller  912  disables the compressor  300  at block  1258  and sets the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  in the lockout mode at block  1260 . Otherwise, the controller  912  enables the compressor  300  to be run at block  1254 . 
     Returning to  FIG.  53 A , the controller  912  determines, at block  1270 , whether the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been set in the lockout mode due to low fluid temperatures. 
     In response to the controller  912  determining that the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  is set in the lockout mode, the method  1200  proceeds to block  1280  at which the controller  912  determines whether power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been cycled since being set to the lockout mode. In response to the controller  912  determining that power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has not been cycled, the method  1200  remains at block  1280 . Otherwise, in response to the controller  912  determining that power for the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  has been cycled, the method  1200  returns to block  1205 . 
     In response to the controller  912  determining that the heat pump system  5 , the heat pump system  2050 , or the heat pump system  3050  is set in the lockout mode, the method  1200  proceeds to block  1275  at which the controller  912  causes the compressor  300  to run to heat the space based on the signal received from the thermostat. 
     While specific embodiments have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the disclosure herein is meant to be illustrative only and not limiting as to its scope and should be given the full breadth of the appended claims and any equivalents thereof.