TOP FIRED OUTDOOR GAS HEAT EXCHANGER

A furnace for a heating, ventilation, and air conditioning (HVAC) unit includes a heat exchange tube configured to flow combustion products therethrough and place the combustion products in a heat exchange relationship with an air flow directed across the heat exchange tube. The furnace also includes a burner assembly fluidly coupled to a first port of the heat exchange tube and configured to generate the combustion products directed into the heat exchange tube via the first port, and a draft inducer blower fluidly coupled to a second port of the heat exchange tube and configured to draw the combustion products through the heat exchange tube. The burner assembly is higher in position than the draft inducer blower relative to a base of the HVAC unit.

BACKGROUND

Heating, ventilation, and air conditioning (HVAC) systems are utilized to control environmental properties, such as temperature and humidity, for occupants of residential, commercial, and industrial environments. The HVAC systems may control the environmental properties through control of an air flow delivered to the environment. For example, an HVAC system may include several heat exchangers, such as a heat exchanger configured to place an air flow in a heat exchange relationship with a refrigerant of a vapor compression circuit (e.g., evaporator, condenser), a heat exchanger configured to place an air flow in a heat exchange relationship with combustion products (e.g., a furnace), or both. In general, the heat exchange relationship(s) may cause a change in pressures and/or temperatures of the air, the refrigerant, the combustion products, or any combination thereof. As the temperatures and/or pressures of the above-described fluids change, liquid condensate may be formed in or on the associated heat exchangers.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. It should be noted that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, this disclosure may encompass a variety of aspects that may not be set forth below.

In an embodiment, a furnace for a heating, ventilation, and air conditioning (HVAC) unit includes a heat exchange tube configured to flow combustion products therethrough and place the combustion products in a heat exchange relationship with an air flow directed across the heat exchange tube. The furnace also includes a burner assembly fluidly coupled to a first port of the heat exchange tube and configured to generate the combustion products directed into the heat exchange tube via the first port, and a draft inducer blower fluidly coupled to a second port of the heat exchange tube and configured to draw the combustion products through the heat exchange tube. The burner assembly is higher in position than the draft inducer blower relative to a base of the HVAC unit.

In another embodiment, a furnace for a heating, ventilation, and air conditioning (HVAC) system includes a panel comprising an inlet and an outlet, and a heat exchange tube fluidly coupled to the inlet and to the outlet on a first side of the panel. The heat exchange tube is configured to direct combustion products from the inlet to the outlet and place the combustion products in a heat exchange relationship with an air flow directed across the heat exchange tube along an air flow path through the furnace. The furnace also includes a burner assembly coupled to a second side of the panel at a first position along a vertical axis, and a draft inducer blower coupled to the second side of the panel at a second position along the vertical axis. The first position is above the second position along the vertical axis. The burner assembly is configured to generate the combustion products and direct the combustion products into the heat exchange tube via the inlet, the draft inducer blower is configured to draw the combustion products through the heat exchange tube towards the outlet.

In another embodiment, a furnace for a heating, ventilation, and air conditioning (HVAC) system includes a heat exchange tube having a first port configured to receive combustion products and a second port configured to discharge the combustion products. The heat exchange tube is configured to direct the combustion products from the first port to the second port. The furnace also includes a burner assembly fluidly coupled to the first port, and a draft inducer blower fluidly coupled to the second port. The burner assembly is configured to generate the combustion products and direct the combustion products into the heat exchange tube via the first port, and the draft inducer blower is configured to draw the combustion products through the heat exchange tube and remove the combustion products from the heat exchange tube via the second port. The first port is above the second port relative to gravity, and the heat exchange tube is configured to discharge liquid condensate from the heat exchange tube via the second port.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the specification. It should be noted that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be noted that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

The present disclosure is directed to a heat exchanger for heating, ventilation, and air conditioning (HVAC) systems configured to increase the temperature of an air flow directed through the HVAC system. In some embodiments, the heat exchanger (e.g., furnace) may be disposed in a packaged outdoor unit or a rooftop unit configured to both heat and cool an air flow, such as a supply air flow that is conditioned and directed to a conditioned space (e.g., a building). For example, the furnace may include a heat exchanger having tubes that is configured to receive relatively hot combustion products (e.g., flue gas) generated via a burner assembly. The furnace may also include a draft inducer (e.g., draft inducer blower) configured to circulate the combustion products through the tubes of the heat exchanger. Further, the furnace may include a blower configured to direct the supply air flow across the tubes, thereby placing the supply air flow in a heat exchange relationship with the relatively hot combustion products to heat the supply air flow.

In some circumstances, liquid condensate may form in or on the above-described heat exchanger. For example, during a cooling mode of the HVAC system (e.g., when the furnace is in an inoperative mode or shut-off), relatively cool supply air flow may be directed across the tubes of the heat exchanger. The relatively cool supply air flow may cause air within the tubes of the heat exchanger (e.g., ambient air) to cool, thereby causing moisture contained within the air to condense. As the air within the tubes condenses, liquid condensate may form within the tubes. However, collection of condensate within the tubes may adversely affect the heat exchanger, and therefore it may be desirable to drain the condensate from the heat exchanger. Unfortunately, traditional heat exchangers (e.g., furnaces) may be configured in a manner that does not adequately allow the condensate to drain from the heat exchanger. For example, existing designs may cause condensate to flow via gravity to the burner assembly, which may lead to degradation, operating interruptions, and/or inefficiencies in the heat exchanger. That is, traditional heat exchanger configurations typically include a burner assembly connected to heat exchange tubes at a base (e.g., bottom side, near a drain outlet) of the heat exchanger and a draft inducer connected to the heat exchange tubes near a top side of the heat exchanger. In such a configuration, the burner assembly is susceptible to potential degradation from liquid or liquid condensate that may flow toward the burner assembly via gravity.

It is now recognized that improved heat exchanger configurations and related features are desired to limit an amount of liquid condensate that may reach the burner assembly, thereby limiting potential degradation and inefficiencies of a furnace. In accordance with the present techniques, the heat exchanger may be configured to enable a liquid (e.g., condensate) within the heat exchange tubes to flow towards a drain outlet at a base of the heat exchanger. For example, one or more segments of the tubes may be positioned at an angle relative to horizontal to enable drainage of liquid therein via gravity. A draft inducer may be fluidly connected to the heat exchange tubes at a base of the heat exchanger and proximate to the drain outlet of the heat exchanger. A burner assembly may also be fluidly connected to the heat exchange tubes at a position above (e.g., top-fired heat exchanger) the draft inducer relative to gravity (e.g., near the top of the heat exchanger), such that liquid condensate formed within the heat exchange tubes (e.g., via condensation) will be directed away from the burner assembly and towards the drain outlet via gravity. The term “top-fired heat exchanger” used herein may refer to a general configuration in which the burner assembly is connected to a first end or port of the heat exchange tubes at a first position, the draft inducer is connected to a second end or port of the heat exchange tubes at a second position, and the first position of the burner assembly is higher than the second position of the draft inducer, relative to gravity. Such a configuration may limit an amount of liquid condensate from reaching the burner assembly, thereby increasing efficiency and reducing a likelihood of degradation to certain aspects of the furnace.

As will be appreciated, the heat exchanger systems disclosed herein may be used in association with any of a variety of HVAC systems, including those in residential and commercial settings. For example, the heat exchanger systems may be utilized in a rooftop unit (RTU), a dedicated outdoor air system, or a split system. Non-limiting examples of systems that may use the heat exchanger system of the present disclosure are described herein with respect toFIGS.1-4.

Turning now to the drawings,FIG.1illustrates a heating, ventilation, and air conditioning (HVAC) system for building environmental management that may employ one or more HVAC units. As used herein, an HVAC system includes any number of components configured to enable regulation of parameters related to climate characteristics, such as temperature, humidity, air flow, pressure, air quality, and so forth. For example, an “HVAC system” as used herein is defined as conventionally understood and as further described herein. Components or parts of an “HVAC system” may include, but are not limited to, all, some of, or individual parts such as a heat exchanger, a heater, an air flow control device, such as a fan, a sensor configured to detect a climate characteristic or operating parameter, a filter, a control device configured to regulate operation of an HVAC system component, a component configured to enable regulation of climate characteristics, or a combination thereof. An “HVAC system” is a system configured to provide such functions as heating, cooling, ventilation, dehumidification, pressurization, refrigeration, filtration, or any combination thereof. The embodiments described herein may be utilized in a variety of applications to control climate characteristics, such as residential, commercial, industrial, transportation, or other applications where climate control is desired.

Further, any of the systems illustrated inFIGS.1-4may include or operate in conjunction with a furnace in accordance with the present disclosure, such as the furnace system70ofFIG.3. For example, the furnace system70ofFIG.3may generate combustion products, sometimes referred to as flue gas or exhaust gas, and then rout the combustion products through tubes (or coils) of the furnace system70. During an operative mode (e.g., heating mode), a supply air flow may be forced across the tubes of the furnace system70, for example by a fan or blower, such that the supply air flow is heated by the combustion products in the tubes of the furnace system70prior to delivery of the heated air flow to a conditioned space. Similarly, during a cooling mode (e.g., when the furnace is shut-off or inoperative), ambient or other air may remain in the tubes of the furnace, and a relatively cool supply air flow may be directed across the tubes. As the air within the tubes is cooled via heat exchange with the supply air flow, liquid condensate may form inside of the tubes of the furnace system70.

In accordance with the present disclosure, a heat exchanger (e.g., a furnace) may be coupled to a heat source, such as a burner assembly (e.g., burner) that generates combustion products, to provide heat to a supply air flow directed across the heat exchanger via a supply air source (e.g., blower, fan). The heat exchanger may also be coupled to a draft inducer that directs (e.g., draws) the combustion products through one or more heat exchange tubes of the heat exchanger. The burner assembly may be fluidly connected to a first port of the heat exchange tubes at a first position proximate a top portion of the heat exchanger, and the draft inducer may be fluidly connected to a second port of the heat exchange tubes at a second position near a base portion of the heat exchanger. A drain outlet may also be located near the second end of the heat exchange tubes and may be configured to drain liquid condensate that forms within the heat exchange tubes during certain operations of the HVAC system, as described above. The first position (e.g., position of the burner assembly) may be higher relative to gravity than the second position (e.g., position of the draft inducer), thereby resulting in a top-fired heat exchanger configuration. By positioning the burner assembly at or near the top of the heat exchanger, liquid condensate formed within the heat exchange tubes may be directed away from the burner assembly at the first position and may instead be directed toward the drain outlet at the second position via the draft inducer and via gravity. In this manner, heat exchangers having the configuration discussed herein may be less susceptible to degradation, operating interruptions, and/or inefficiencies that may otherwise occur in traditional heat exchangers.

With this in mind,FIG.5is a perspective view of an embodiment of a packaged HVAC unit100that may employ one or more of the heat exchangers disclosed herein. In the illustrated embodiment, the packaged HVAC unit100includes multiple components enclosed within an internal volume of a housing102of the packaged HVAC unit100. The packaged HVAC unit100may be configured to circulate air and therefore may include a return section104to receive an air flow, such as a return air flow from the building10, and a supply section106to output an air flow, such as a supply air flow. As an example, the packaged HVAC unit100may be located in an outside environment, such as on a rooftop, and may be coupled to ductwork that directs air to and/or from rooms or other areas within a building, such as the building10ofFIG.1. The ductwork may couple to the return section104and the supply section106. In this manner, the packaged HVAC unit100may circulate air in the building10.

In addition to circulating air, the packaged HVAC unit100may change the temperature of the supply air flow directed therethrough. For example, the packaged HVAC unit100may include a refrigerant circuit that circulates a refrigerant therethrough, where the refrigerant circuit is in thermal communication with the air flow. The refrigerant may flow through a condenser108, where the refrigerant may be cooled.FIG.5illustrates the condenser108as including a fan that may direct ambient air across the condenser108to remove heat from the refrigerant via convection, but in other embodiments, the condenser108may use another means of cooling the refrigerant, such as via a coolant. After being cooled, the refrigerant may then flow through an evaporator110, where the refrigerant may absorb heat from the air flow (e.g., supply air flow) directed across the evaporator110. Thus, the refrigerant may be heated, and the air flow may be cooled at the evaporator110. After being heated at the evaporator110, the refrigerant may return to the condenser108where it may once again be cooled. It should be appreciated that the refrigerant circuit may include other components, such as a compressor, expansion valve, and so forth, that enable conditioning of the supply air flow via the refrigerant.

The packaged HVAC unit100may also be configured to operate in a heating mode and a cooling mode. During operation of the heating mode, air may be received by the packaged HVAC unit100at the return section104to enter an air flow path. As mentioned, air (e.g., return air) may be received from ductwork that is connected to a building. However, in other embodiments, air received by the packaged HVAC unit100may be ambient air, such as from an outside environment. In certain embodiments, the supply air flow directed through the packaged HVAC unit100may include air from the return section104as well as ambient air. After the air flow enters the packaged HVAC unit100, the air flow may pass across a filter112. The filter112may remove particles from the air flow, such as dirt or other debris. The filter112may be a pleated filer, an electrostatic filter, a HEPA filter, or a fiber glass filter that traps the debris when the air flow passes through the filter112. After being filtered, the air flow may be directed to the evaporator110. As discussed above, at the evaporator110, the air flow may be cooled by transferring heat to the refrigerant within the evaporator110. In addition, cooling the air flow may also remove moisture from the air flow and thus, the packaged HVAC unit100may also dehumidify the air flow. Once cooled, the air flow may be directed through a blower114, which may increase the velocity of the air flow and discharge the air flow as supply air via the supply section106of the packaged HVAC unit100. Thereafter, the supply air flow may be circulated through the ductwork. In some embodiments, the blower114may also operate to draw air through the return section104and thereby function to both draw in and expel air.

In some modes of operation (e.g., a heating mode), prior to exiting the packaged HVAC unit100, the air may be heated by a heat exchanger116(e.g., a furnace). By way of example, the heat exchanger116may be coupled to a heat source. In some embodiments, the heat exchanger116may be a gas heat exchanger and may be coupled to a gas burner (e.g., a burner assembly) that combusts a fuel (e.g., air-fuel mixture), such as acetylene, natural gas, propane, another gas, or any combination thereof to produce combustion products having an elevated temperature that are directed into the heat exchanger116. When the air flow is directed across the heat exchanger116, the air flow may absorb heat from the combustion products, thereby increasing the temperature of the air flow. Thereafter, the air flow may then exit the packaged HVAC unit100at a higher temperature compared to the air flow entering the packaged HVAC unit100.

During a cooling mode of the packaged HVAC unit100, the heat exchanger116may be inoperative (e.g., turned off). However, some of the combustion products generated during a previous heating mode may linger or remain within heat exchange tubes of the heat exchanger116. Additionally or alternatively, when the heat exchanger116is not operating, another flow of air (e.g., ambient air) may nevertheless flow or reside in the heat exchange tubes of the heat exchanger116. As a relatively cool air flow (e.g., supply air cooled by the evaporator110) is directed across the heat exchange tubes, air within the heat exchange tubes may lose heat to the relatively cool air flow, thereby causing any moisture within the air to condense and form liquid condensate within the heat exchange tubes of the heat exchanger116. To mitigate collection of the condensate within the heat exchange tubes, the heat exchanger116of the present disclosure is configured to enable removal of the liquid condensate from the heat exchange tubes while also mitigating contact between the condensate and other components of the heat exchanger116(e.g., the burner assembly). In this way, degradation, inefficiency, and/or other adverse effects that may otherwise be caused by the condensate is avoided. The features and aspects of the heat exchanger116are discussed in further detail below.

To separate various components within the packaged HVAC unit100, the packaged HVAC unit100may include partitions120(e.g., panels, vestibule panels, dividers, separation plates, etc.). As an example, the partitions120may divide the internal volume defined by the housing102into a first volume122, which may contain the heat source (e.g., burner assembly) of the heat exchanger116, a second volume124(e.g., supply air section) from the supply air flow may exit the packaged HVAC unit100, a third volume126that contains the condenser108, and a fourth volume128(e.g., return air section104) configured to receive air flow directed into the packaged HVAC unit100. Various components of the packaged HVAC unit100may also be oriented along a number of axes including a lateral axis190, a longitudinal axis192, and a vertical axis194.

FIG.6is side view of an embodiment of a furnace200(e.g., heat exchanger) that can be used with or in any of the systems ofFIGS.1-5or any other suitable HVAC system. For example, the furnace200ofFIG.6may correspond to the heat exchanger116inFIG.5. The furnace200may be disposed within a housing130(e.g., support structure), such as a section of the housing102ofFIG.5, a section of an air handler, a standalone housing, or any other suitable support structure. The housing130may include a first side132(e.g., top side, panel, etc.) and a base134(e.g., bottom side, panel, etc.). However, in some embodiments, the furnace200may not include the first side132and/or the base134of the housing130.

A blower140(e.g., fan) may be coupled or secured to the first side132of the housing130and may be configured to generate or direct an air flow500along an air flow path510of the furnace200. The blower140may correspond to the blower114inFIG.5. The housing130may also include a vestibule panel150(e.g., side panel, panel, etc.), which may correspond to one of the partitions120ofFIG.5. In the embodiment illustrated inFIG.6, the furnace200includes a heat exchange section202coupled to the vestibule panel150. The heat exchange section202may include one or more heat exchange tubes204, with each heat exchange tube204having a first port206(e.g., first end, top end, upper end, inlet, upstream end, etc.) and a second port208(e.g., second end, bottom end, lower end, outlet, downstream end, etc.) that are each coupled to the vestibule panel150. The heat exchange tube204may extend from the first port206to the second port208in any suitable configuration, geometry, or arrangement. In the illustrated embodiment, the heat exchange tube204also includes a first bend210(e.g., top bend, upstream bend), a second bend212(e.g., middle bend, midstream bend), and a third bend214(e.g., bottom bend, downstream bend). The heat exchange tube204extends between each of the first port206, second port208, first bend210, second bend212, and third bend214. In this manner, the heat exchange tube204defines multiple passes (e.g., tube passes, tube segments, conduit segments, etc.) of the heat exchange tube204through which combustion products are directed and across which the air flow500is directed. More specifically, the heat exchange tube204defines a first pass216extending between the first port206and the first bend210, a second pass218extending between the first bend210and the second bend212, a third pass220extending between the second bend212and the third bend214, and a fourth pass222extending between the third bend214and the second port208. In some embodiments, one or more of the passes216,218,220,222may extend in a direction along the lateral axis190(e.g., in a horizontal direction, along a horizontal axis272). In other embodiments, one or more of the passes216,218,220,22may extend at an angle relative to the horizontal axis272, as described in greater detail below.

The first port206may be coupled or secured to a first side152of the vestibule panel150proximate an inlet160(e.g., passage, hole, aperture, opening, channel) formed in the vestibule panel150, and the second port208may be coupled to the first side152of the vestibule panel150proximate an outlet170(e.g., passage, hole, aperture, opening, channel) formed in the vestibule panel150. The first and second ports206,208may be coupled to the inlet160, and outlet170, respectively, via a swedging process or technique (e.g., expanding the first port206of the heat exchange tube204with the first port206positioned within the inlet160of the vestibule panel150), welding, brazing, or any other mechanical fastening technique. Each of the passes216,218,220, and222may be configured to extend crosswise relative to a direction of the air flow500along the flow path510, as described in greater detail below. It should be understood that each of the features of the heat exchange tube204described above may be fluidly coupled to one another to enable flow of fluids (e.g., combustion products, liquid condensate) through the heat exchange tube204towards the outlet170, as described in greater detail below. Further, in some embodiments, the heat exchange section202may include one or more heat exchange tubes204having additional features, alternative features, fewer or more bends, fewer or more passes, and so forth, based on selected characteristics, implementations, and/or operating parameters of the furnace200. Further still, the heat exchange tubes204have different orientations (e.g., offset, aligned relative to one another) to facilitate various tube configurations that may reduce an overall size, height, and/or footprint of the furnace200.

As discussed herein, the furnace200may also include a burner assembly230(e.g., combustor, heating element, burner system) configured to ignite a mixture of fuel and oxidant (e.g., air-fuel mixture) to generate combustion products. For example, the burner assembly230may be fluidly connected to a fuel source232and may also be fluidly coupled to the inlet160on a second side154of the vestibule panel150. The burner assembly230may include one or more burners (e.g., premix burners) configured to ignite the mixture of fuel and oxidant to generate the combustion products, which are then directed through the inlet160and into the first port206of the heat exchange tube204via the first port206fluidly coupled to the inlet160. That is, the burner assembly230and the first port206may be in fluid communication, such that the combustion products may generally travel from the burner assembly230, through the inlet160, through the first port206, through the first, second, third, and fourth passes216,218,220, and222, and towards the second port208of the heat exchange tube204. The second port208of the heat exchange tube204may be fluidly coupled to the outlet170, thereby enabling the combustion products to pass through the second port208and into the outlet170.

From the outlet170, the combustion products may be removed from the system (e.g., via an exhaust conduit). To this end, the furnace200may also include a draft inducer240(e.g., draft inducer blower, draft blower, draft fan, inducer fan) fluidly coupled to the outlet170on the second side154of the vestibule panel150. The draft inducer240is configured to facilitate flow of the combustion products through the heat exchange tube204. That is, the draft inducer240may be fluidly coupled to the second port208via the outlet170and may be configured to draw the combustion products through the heat exchange tube204. When operation of the furnace200is initiated to heat the air flow500(e.g., upon receipt of a call for heating), the draft inducer240may be operated prior to operation of the burner assembly230(e.g., 30 seconds before, a predetermined time period before, etc.), thereby removing any air or other gaseous compounds that may be present within the heat exchange tube204(e.g., via a suction air flow generated by the draft inducer240). The draft inducer240may also be coupled to an exhaust conduit (not shown) which may be configured to direct combustion gases, air, and/or other gaseous compound out of the furnace200(e.g., the HVAC system having the furnace200), as described in greater detail below.

As discussed above, the burner assembly230may be coupled or secured to the vestibule panel150at the inlet160of the vestibule panel150, and the draft inducer240may be coupled or secured to the vestibule panel150at the outlet170of the vestibule panel150. The burner assembly230and the draft inducer240may be secured via fasteners, brackets, pins, screws, or any other suitable mechanical fastening technique. As illustrated, the inlet160is located above (e.g., vertically above) the outlet170relative to the base134of the furnace200(e.g., relative to gravity, relative to the vertical axis194, etc.). Thus, when installed and coupled to the vestibule panel150, the burner assembly230is located at a top portion260of the furnace200, and the draft inducer is located at a bottom portion270of the furnace200. That is, the burner assembly230is higher in position than the draft inducer240relative to the base134of the furnace200(e.g., relative to gravity, relative to the vertical axis194). This configuration (e.g., top-fired configuration, top-burner configuration) limits, reduces, and/or prevents the potential of liquid and/or liquid condensate that may form within the heat exchanger tube204from flowing toward the burner assembly230, as described in greater detail below.

As previously described, operation of the furnace200may cause condensate to form within the heat exchange tube204as the air flow500travels across the heat exchange tube204along the flow path510, such as during a cooling mode of operation when the furnace200is not operating to heat the air flow500. As the liquid condensate forms within the heat exchange tube204, the liquid condensate may be directed away from the burner assembly230and towards the outlet170, such as via force of gravity. In some embodiments, each of the passes216,218,220, and220may generally extend along the lateral axis190and may be disposed at an angle relative to a horizontal axis272(e.g., a horizontal direction), such that condensate formed within the heat exchange tube204may directed away from the top portion260of the furnace200and towards the bottom portion270of the furnace200via gravity. The liquid condensate may flow through one or more of the passes216,218,220, and222and along one or more of the bends210,212,214towards the second port208of the heat exchange tube204that is in fluid communication with the outlet170. Liquid condensate that reaches the outlet170may then be discharged from the furnace200via a drain (e.g., drain outlet), a conduit, or any suitable discharge flow path fluidly coupled to the outlet170. In some embodiments, a gasket180(e.g., paper gasket) may be positioned between the outlet170of the vestibule panel150and the draft inducer240. The gasket180may surround the second port208of the heat exchange tube204, may have an opening formed therein that is aligned with the second port208, and may extend from the outlet170(e.g., in a horizontal direction along the horizontal axis272) away from the vestibule panel150. The gasket180may be configured to facilitate drainage of the liquid condensate by providing clearance for the liquid condensate to drain out of the heat exchange tube204before reaching the draft inducer240. That is, the gasket180may be composed of a porous material, thereby enabling liquid condensate to drain through the gasket180and out of the furnace200before reaching the draft inducer240. It should be noted that various aspects of the furnace200may be manufactured, configured, and/or arranged to block or reduce an undesirable impact of the liquid condensate on the furnace200that may otherwise be caused by contact with the liquid condensate. By way of example, components of the heat exchange section202, such as the heat exchange tube204, the inlet160, the outlet170, the gasket180, and the vestibule panel150may be made of stainless steel, chromium, and/or other suitable (e.g., corrosion resistant) material to reduce undesirable effects of the liquid condensate on the structural integrity and/or performance of the components.

The furnace200may also include a controller250configured to control operation of the burner assembly230and the draft inducer240, such as based on an operating mode of the furnace200. The controller250may be coupled to the vestibule panel150via welding, fasteners, screws, or other suitable technique. During operation, the controller250may receive a signal indicative of a call for operation in the cooling mode, and in response, the controller250may operate to shut-off or power down the burner assembly230and the draft inducer240such that combustion products are no longer generated and circulated through the heat exchange tubes204. At a different time, the controller may receive a signal indicative of a call for operation in the heating mode, and in response, the controller250may operate to activate or power on the draft inducer240and the burner assembly230(e.g., sequentially, power on the draft inducer240prior to powering on the burner assembly230, etc.) such that combustion products may be generated and circulated through the heat exchange tube204to enable heating of the air flow500directed across the heat exchange tube204along the air flow path510.

In some circumstances, the controller250may be operate to activate the draft inducer240without activating the burner assembly230. For example, a presence of liquid condensate within the heat exchange tube204may be detected via one or more sensors274(e.g., a liquid sensor, humidity sensor, condensate sensor, etc. fluidly coupled to and/or disposed within the heat exchanger tube204and communicatively coupled to the controller250). Based on detection of the presence of liquid condensate, the draft inducer240may be activated to draw an air flow through the heat exchange tube204to motivate the liquid condensate towards the second port208and away from the burner assembly230. To facilitate control of the components of the furnace200, the controller250may include a memory252with instructions stored thereon for controlling operation the furnace200and components of the furnace200, and processing circuitry254configured to execute such instructions. For example, the processing circuitry254may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof. Additionally, the memory252may include a non-transitory computer-readable medium that may include volatile memory, such as random-access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, optical drives, solid-state drives or any other suitable non-transitory computer-readable medium storing instructions that, when executed by the processing circuitry254, may control operation of the furnace200. AlthoughFIG.6illustrates the controller250as being coupled to the vestibule panel150, in some embodiments, the controller250may be disposed elsewhere, such as remotely relative to the furnace200.

FIG.7is a schematic side view of an embodiment of the furnace200, illustrating various flow directions (e.g., flow paths) of liquid (e.g., liquid condensate) that may form within the heat exchange tube204, such as in the manners described above. As illustrated, each of the passes216,218,220,222extends at least partially in a direction of the lateral axis190and generally crosswise to the air flow path510(e.g., crosswise to the vertical axis194) through which the air flow500is directed across the heat exchange tube204. For example, one or more of the passes216,218,220, and222(e.g., passes216,222) of the heat exchange tube204may extend a length620(e.g., width, distance) from the vestibule panel150. However, some of the passes216,218,220, and222(e.g., passes218,220) may extend a length less than the length620. In some embodiments, the length620may be greater than a width630of the air flow path510, such that the air flow500directed along the air flow path510may contact each of the passes216,218,220,222as the air flow500flows through the air flow path510. When air (e.g., ambient air) within the heat exchange tube204is cooled via a relatively cool supply air flow (e.g., air flow500) directed along the air flow path510across the heat exchange tube204, such as during non-operation of the furnace200, moisture within the air inside the heat exchange tube204may condense, thereby forming liquid condensate within the heat exchange tube204. As mentioned above, one or more of the passes216,218,220, and222may be disposed at an angle relative to a horizontal axis272such that liquid condensate formed within the passes216,218,220, and222may be directed via gravity, through the heat exchange tube204towards the outlet170and the gasket180. Additionally, in some embodiments, one or more of the passes216,218,220, and222may extend in a direction along the lateral axis190(e.g., a horizontal direction, along the horizontal axis272).

For example, the first port206may be secured to the inlet160(e.g., passage, hole, aperture, opening, channel) at a first position300(e.g., first location along the vertical axis194). The first pass216may extend from the first port206to the first bend210at a first angle400(e.g., downward angle) relative to the horizontal axis272, such that liquid condensate formed within the first port206and/or the first pass216may be directed along a first flow path600of the heat exchange tube204towards the first bend210via gravity. That is, the first bend210may be disposed at a second position302(e.g., second location along the vertical axis194), which is lower relative to gravity than the first position300of the first port206. Thus, condensate formed within the first port206and/or the first pass216may travel from the first position300to the second position302along the first flow path600via gravity. Upon reaching the first bend210, liquid condensate may fall (e.g., via gravity) along a second flow path602of the heat exchange tube204towards the second pass218. The second pass218may be fluidly coupled to the first bend210at a third position304(e.g., third location along the vertical axis194). As shown in the illustrated embodiment, the third position304is lower than the second position302relative to gravity such that condensate traveling through the first bend210falls along the second flow path602and into the second pass218.

The second pass218may extend from the first bend210to the second bend212at a second angle402(e.g., downward angle) relative to the horizontal axis272, such that liquid condensate within the second pass218may be directed along a third flow path604of the heat exchange tube204towards the second bend212via gravity. That is, the second bend212may be disposed at a fourth position306(e.g., fourth location along the vertical axis194), which is lower relative to gravity than the third position304. Thus, condensate reaching the second pass218may travel from the third position304to the fourth position306along the third flow path604via gravity. Upon reaching the second bend212, liquid condensate may fall via gravity along a fourth flow path606of the heat exchange tube204towards the third pass220. The third pass220may be fluidly coupled to the second bend212at a fifth position308(e.g., fifth location along the vertical axis194). As shown in the illustrated embodiment, the fifth position308is lower than the fourth position306relative to gravity such that condensate traveling through the second bend212falls along the fourth flow path606and into the third pass220.

The third pass220may extend from the second bend212to the third bend214at a third angle404(e.g., downward angle) relative to the horizontal axis272, such that liquid condensate within the third pass220may be directed along a fifth flow path608of the heat exchange tube204towards the third bend214via gravity. That is, the third bend214may be disposed at a sixth position310(e.g., sixth location along the vertical axis194) which is lower relative to gravity than the fifth position308. Thus, condensate reaching the third pass220may travel from the fifth position308to the sixth position310along the fifth flow path608via gravity. Upon reaching the third bend214, liquid condensate may fall via gravity along a sixth flow path610of the heat exchange tube204towards the fourth pass222. The fourth pass222may be fluidly coupled to the third bend214at a seventh position312(e.g., seventh location along the vertical axis194). As shown in the illustrated embodiment, the seventh position312is lower than the sixth position310relative to gravity such that condensate traveling through the third bend214falls along the sixth flow path610and into the fourth pass222.

The fourth pass222may extend from the third bend214to the second port208at a fourth angle406(e.g., downward angle) relative to the horizontal axis272, such that liquid condensate within the fourth pass222may be directed along a seventh flow path612of the heat exchange tube204towards the second port208via gravity. That is, the second port208may be disposed at an eighth position314(e.g., eight location along the vertical axis194) which is lower relative to gravity than the seventh position312. Thus, condensate reaching the fourth pass222may travel from the seventh position312to the eighth position314along the seventh flow path612via gravity. As discussed above, the embodiments included herein should not be considered limiting and other embodiments of the furnace200may include fewer or more passes, bends and heat exchange tubes as desired based on various design considerations of the furnace200. In the manner described above, the furnace200including the features described herein enables drainage and removal of liquid condensate from the furnace while also directing the liquid condensate away from the burner assembly230, thereby avoiding undesirable contact between liquid condensate and the burner assembly230and increasing efficiency and longevity of the burner assembly230.

It should be noted that in some embodiments, one or more of the passes216,218,220, and222may not extend at an angle relative to the horizontal axis272and instead may generally extend in a direction along the lateral axis190(e.g., in a horizontal direction along the horizontal axis272as illustrated inFIG.6). That is, each heat exchange tube204may include one or more passes216,218,220,222that extend at an angle relative to the horizontal axis272across the flow path510, one or more passes216,218,220,222that extend along the horizontal axis272(e.g., in a horizontal direction) across the flow path510, or any combination thereof.

FIG.8is a schematic side view of an embodiment of a portion of the furnace200, illustrating the draft inducer240and the gasket180configured to facilitate removal of liquid condensate from the furnace200. The gasket180may be disposed on the second side154of the vestibule panel150between the draft inducer240and the outlet170(e.g., passage, channel, hole, aperture, opening). As described above, liquid condensate that reaches the fourth pass222may travel along the seventh flow path612of the heat exchange tube204towards the second port208, the outlet170, and the gasket180. The gasket180may be disposed around (e.g., circumferentially around) the outlet170and around the port208and may extend to a drain outlet282. The gasket180may provide a channel, flow path, or other guide extending from the port208, through the outlet170, and to the drain outlet282such that liquid condensate directed along the seventh flow path612may flow from the outlet170and pass through or along the gasket180to be discharged from the furnace200. In some embodiments, the gasket180may be composed of a porous material, thereby enabling liquid condensate to pass through the gasket180and towards the drain outlet282to be discharged from the furnace200.

During an operative mode (e.g., heating mode), the draft inducer240may be configured to discharge combustion products circulated through the heat exchange tube204via an exhaust outlet280(e.g., outlet port, discharge port), which may be fluidly coupled to the draft inducer240, such as via a panel (e.g., side panel) of the packaged HVAC unit100ofFIG.5. In some embodiments, the exhaust outlet280may be fluidly coupled to a conduit290(e.g., vertical exhaust, exhaust conduit) configured to receive combustion products from the draft inducer240and direct flow of the combustion products in a direction700(e.g., vertical direction), as described in greater detail below, to discharge the combustion products from the furnace200and/or the packaged HVAC unit100.

FIG.9is a front perspective view of an embodiment of the furnace200, illustrating multiple heat exchange tubes204arranged along the longitudinal axis192. As illustrated, each of the heat exchange tubes204includes the first port206, which is fluidly coupled to the burner assembly230via respective inlets160(e.g., passage, channel, opening, aperture, hole) of the vestibule panel150, and may also include the second port208, which is fluidly coupled to the draft inducer240via respective outlets170(e.g., passage, channel, opening, aperture, hole) of the vestibule panel150. As noted above, the burner assembly230may be coupled to the vestibule panel150above the draft inducer240relative to gravity (e.g., along the vertical axis194). That is, the burner assembly230may be positioned above the draft inducer240such that the inlets160of the vestibule panel150are positioned above the outlets170of the vestibule panel150along the vertical axis194. Further, in some embodiments, a respective inlet160and the corresponding outlet170(e.g., inlet and outlet fluidly coupled together via a heat exchange tube204) are also aligned along the vertical axis194such that the first port206and the second port208of each respective heat exchange tube204are aligned with one another along the vertical axis194. For example, the burner assembly230may be coupled to the vestibule panel150such that a respective inlet160(e.g., a first inlet) is positioned a distance800from the base134of the housing130and a distance808from a side136of the housing130, and the draft inducer240may be coupled to the vestibule panel150such that a respective outlet170(e.g., a first outlet fluidly coupled to the first inlet160via a heat exchange tube204) is positioned a distance802from the base134of the housing130and a distance810from the side136of the housing130. The distance800may be greater than the distance802, and the distance808may be approximately equal to the distance810. Thus, each inlet160may be positioned within the vestibule panel150at a position above the corresponding outlet170relative to gravity such that the first port206of a respective heat exchange tube204is aligned with the corresponding second port208of the respective heat exchange tube204along the vertical axis.

As discussed above, the furnace200may be part of an outdoor or rooftop HVAC unit. In some embodiments, the burner assembly230may also be positioned within a threshold distance806from the first side132(e.g., top side) of the housing130, thereby providing a desired clearance between the burner assembly230and the first side132. For example, during a heating mode, the burner assembly230may be operated to generate combustion gases to heat an air flow. By positioning the burner assembly230near the first side132(e.g., within a threshold distance806from the first side132), heat generated from the operation of the burner assembly230may melt snow accumulated on the first side132of the housing such that the snow may be directed away from the burner assembly230via gravity, thereby reducing undesirable effects on the structural integrity and/or performance of the components of the burner assembly230that may otherwise be caused by contact with water or other liquid.

In some embodiments, the exhaust outlet280of the draft inducer240may be fluidly coupled to the conduit290, which may extend in the direction700, such as along the vertical axis194. As shown in the illustrated embodiment, the conduit280may extend in the direction700to a position above the first side132of the housing130(e.g., along the vertical axis194). Directing the combustion products along the exhaust conduit280in the direction700may also facilitate reducing undesirable effects on the structural integrity and/or performance of the components of the furnace200. For example, heat from the combustion products discharged via the conduit290may also be used to melt snow or other environmental conditions which may accumulate on the first side132of the housing130and may have an undesirable impact on the performance of the furnace200and/or may cause the furnace200to bear an undesired weight.

FIG.10is front perspective view of an embodiment of the furnace200, illustrating multiple heat exchange tubes204arranged along the longitudinal axis192. As described above with respect toFIG.9, the respective inlets160may be positioned above the respective outlets170relative to gravity, and thus the first port206of each heat exchange tube204may also be positioned above the respective second port208relative to gravity. In some embodiments, the heat exchange tubes204may also be arranged such that the first port206is offset (e.g., horizontally offset) from the corresponding second port208of the heat exchange tube204along the longitudinal axis192. For example, the burner assembly230may be coupled to the vestibule panel150such that a respective inlet160is positioned a distance820from the side136of the housing130, and the draft inducer240may be coupled to the vestibule panel150such that the corresponding outlet170(e.g., outlet fluidly coupled to the respective inlet via the heat exchange tube204) is positioned a distance822from the side136of the housing130. The distance820is greater than the distance822, such that the respective inlet160and the corresponding outlet170are offset (e.g., horizontally offset) from one another along the longitudinal axis192by a distance824. Accordingly, when installed, a respective heat exchange tube204may include a first port206that couples to the inlet160at the distance820from the side136of the housing130, and a second port208that couples to the outlet170at the distance822from the side136of the housing130, and thus, the first port206and the corresponding second port208of the respective heat exchange tube204may also be offset from one another along the longitudinal axis192by the distance824. In some embodiments, the distance820may be less than the distance822.

In some embodiments, the respective inlets160and the corresponding outlets170may be offset from one another by the distance824, and the burner assembly230and the draft inducer240may nevertheless be aligned with one another along the vertical axis194. For example, the first port206of each heat exchange tube204may be fluidly coupled to a respective inlet160, the second port208may be fluidly coupled to a respective outlet170, and the heat exchange tubes204may each have a geometry or configuration that enables the first ports206and the corresponding second ports208to be offset from one another by the distance824. By arranging the inlets160, the outlets170, and the heat exchange tubes204in different orientations (e.g., inlet160and outlet170aligned with one another along the vertical axis194, inlet160and outlet170offset from one another relative to the longitudinal axis194, first and second ports206,208aligned with one another along the vertical axis194, first and second ports206,208offset from one another relative to the longitudinal axis192), an overall size, height, and/or footprint of the furnace200may be reduced, thereby reducing costs associated with manufacture, operation, and/or maintenance of the furnace200. For example, in the illustrated embodiment, the inlets160and corresponding outlets170are offset with one another relative to the longitudinal axis192(e.g., not aligned with one another along the vertical axis194), which reduces an overall height occupied by the furnace200.

As described above with respect toFIG.7, each of the heat exchange tubes204may include two or more passes (e.g., passes216,218,220,222ofFIG.7) and two or more bends (e.g., bends210,212,214). In some embodiments, one or more of the bends210,212,214may generally extend from one pass to another pass along the longitudinal axis192and may be disposed at an angle relative to the horizontal axis272(e.g., a horizontal direction) such that liquid condensate formed within the heat exchange tube204may be directed away from the burner assembly230via gravity. For example, the bend212may generally extend along the longitudinal axis192from the second pass218to the third pass220and may be disposed at an angle408relative to the horizontal axis272such that the bend212extends cross-wise to a direction of the airflow500(e.g., downward direction). In other embodiments, one or more of the bends210,212,214may extend in a direction along the vertical axis194. It should be noted that the heat exchange tubes204may each have a geometry or configuration that includes one or more bends that extend from one pass to another pass in a direction along the vertical axis194, one or more bends that extend from one pass to another pass in a direction along the longitudinal axis192at an angle relative to the horizontal axis272, one or more passes that extend in a direction along the lateral axis190(e.g., horizontal direction), one or more passes that extend in a direction along the lateral axis190at an angle relative to the horizontal axis272, or any combination thereof.

As set forth above, the furnace of the present disclosure may provide one or more technical effects useful in the operation of HVAC systems, such as packaged HVAC units, configured to operate in a cooling mode and in a heating mode. For example, the furnace may be disposed within an air flow path of the HVAC system to enable the furnace to heat an air flow during operation of the furnace in the heating mode. During operation of the HVAC system in the cooling mode, relatively cool air may be directed across heat exchange tubes of the furnace, and air (e.g., ambient air) residing within the heat exchange tubes thereby be cooled. As a result, moisture within the air may condense and form liquid condensate within the heat exchange tubes. The top-fired burner assembly configuration disclosed herein enables discharge of the liquid condensate from the furnace while also mitigating contact between the liquid condensate and the burner assembly, thereby reducing adverse impacts on components of the HVAC system that may otherwise be caused by the liquid condensate. That is, the presently disclosed techniques may reduce a likelihood of wear and degradation to the HVAC system and its components that may be caused by water contact during operation of the HVAC system. The technical effects and technical problems in the specification are examples and are not limiting. It should be noted that the embodiments described in the specification may have other technical effects and can solve other technical problems.