CONTEMPORANEOUS HYBRID HEATING

Abstract

Contemporaneous hybrid heating may be provided by a heat pump, including: an indoor heat exchanger located in or in communication with the conditioned environment; an outdoor heat exchanger located in or in communication with the outdoor environment, wherein the outdoor heat exchanger is in fluid communication with the indoor heat exchanger via a refrigerant circuit; a fueled heater; and a controller, configured to, when the system is operating in a hybrid heating mode, activate both of the heat pump and the fueled heater at a given time based on an air rise temperature measured across the indoor heat exchanger.

Description

BACKGROUND

This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the presently described embodiments to help facilitate a better understanding of various aspects of the present embodiments. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

A heat pump is a heating, ventilating, and air conditioning (“HVAC”) system that is typically operable in both cooling and heating modes. While air conditioners are familiar examples of heat pumps, the term “heat pump” is more general and applies to many HVAC systems used for both space heating and space cooling using one system.

When a heat pump is used for heating, the heat pump employs the same refrigeration-type cycle used by an air conditioner, but in the opposite direction. That is, heat is released into the conditioned space rather than the outdoor environment. In this use, heat pumps generally draw heat from cooler external air or from the ground, and this heat is then transferred into the conditioned environment.

When operating in the heating mode, thermal energy is provided to the conditioned environment (e.g., internal occupant spaces within a structure), and thus the outdoor ambient temperatures are relatively cold when the outdoor heat exchanger is on the “cold” side of the refrigeration cycle. The combination of cold outdoor ambient temperatures and cold refrigerant within the outdoor heat exchanger can result in the decreased effectiveness of heat pumps as outdoor temperatures drop and more heating is needed in the conditioned environment. This decrease in efficiency is due, in part, to there being less heat available to extract from the outdoor environment to bring into the indoor conditioned environment, and thus the heat pump having to work harder to move that heat into the conditioned environment. Accordingly, although heat pumps can offer great energy efficiency over other heating and cooling devices, heat pumps may be deployed less often in environments that experience frequent low temperatures (e.g., at or below 20 degrees Fahrenheit) compared to environments that do not experience these low temperatures as frequently.

SUMMARY

The present disclosure provides contemporaneous hybrid heating, in which a heat pump is operated at the same time as a fueled or other auxiliary heat source to heat air in a conditioned environment. By monitoring the air rise temperature across of a heat exchanger outputting heated air into the conditioned environment, the heating unit can operate in a hybrid heating mode. The hybrid heating mode takes advantage of the energy efficiency of the heat pump at higher environmental temperatures and the reliability of the fueled or other auxiliary heat source at lower environmental temperatures. Accordingly, the heating unit can operate both at intermediate temperatures where the heat pump operates at reduced efficiency (albeit with competitive efficiency to the auxiliary heating systems), with a bias for the most appropriate heat source as temperatures change.

Additional features and advantages of the disclosed method and apparatus are described in, and will be apparent from, the following Detailed Description and the Figures. The features and advantages described herein are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the figures and description. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a schematic view of a hybrid Heating Ventilation and Air Conditioning (HVAC) system, according to embodiments of the present disclosure.

FIGS. 2A-2C illustrate schematic views of an example cabinet for including elements of a hybrid HVAC system for conditioning the air of a conditioned environment, according to embodiments of the present disclosure.

FIG. 3 illustrates a side elevation schematic view of a fueled heating unit, according to embodiments of the present disclosure.

FIG. 4 is a flowchart for an example method for contemporaneous hybrid heating, according to embodiments of the present disclosure.

FIG. 5 illustrates a computing device, as may be used as a controller for an HVAC system, according to embodiments of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure are described herein. In an effort to provide a concise description of these embodiments, not all features of an actual implementation may be described. It should be appreciated 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 appreciated 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.

When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

The present disclosure relates to heat pump heating, ventilating, and air conditioning (“heat pump HVAC”, or more simply referred to herein as “HVAC”) systems, and more particularly to systems and methods for contemporaneous hybrid heating, in which a heat pump is operated at the same time as a fueled or other auxiliary heat source to heat air in an indoor, conditioned environment. By monitoring the output of a heat exchanger into the conditioned environment, the heating unit can operate in a hybrid heating mode that takes advantage of the energy efficiency of the heat pump at higher temperatures and the reliability of the auxiliary heat source at lower temperatures to operate both at intermediate temperatures, with a bias for the most appropriate heat source as temperatures change depending on the efficiency of the system and the cost of operation.

Although various components are identified as “indoor” or “outdoor” in the present disclosure in relation to a structure, one of ordinary skill in the art will appreciate that these labels are provided for convenience in relation to the air being conditioned and do not necessary indicate a physical location of the devices so labeled. For example, an “indoor” heat exchanger may be located outside of a structure (the inside of which is a conditioned environment), and is ducted to receive air from and direct air back to the inside environment of the structure to heat or cool. Additionally, although referred to as “inside,” one of ordinary skill in the art will appreciate that various structures may have conditioned or “inside” environments that are open or semi-enclosed (e.g., a cooled environment separated from a non-cooled environment via curtains, a house with open windows, an outdoor seating area or pavilion with blown hot air for use in colder months or blow cold are for use in warmer months, etc.).

Similarly, although referred to as “outside,” one of ordinary skill in the art will appreciate that various structures may have non-conditioned or “outside” environments that are fully enclosed or semi-enclosed (e.g., a hangar, dock, or garage, holding a vehicle or trailer with a separate HVAC system; a protective structure around an otherwise “outdoor” heat exchanger). Additionally, the space immediately outside of the structure in question may not be the non-conditioned environment for that structure. For example, an air-conditioned factory structure may enclose an air-conditioned cleanroom structure, and both structures may use the “outside” of the factory structure as the non-conditioned environment (e.g., rather than the cleanroom structure using the inside of the factory structure as the “outside”).

FIG. 1 illustrates a schematic view of a hybrid Heating Ventilation and Air Conditioning (HVAC) system 100, according to embodiments of the present disclosure. The HVAC system 100 includes a heat pump system 110 that includes an indoor heat exchanger 112a (generally or collectively, heat exchanger 112) located in or in communication with (e.g., via ducting) a conditioned environment (e.g., an indoor environment) to heat or cool.

Although generally discussed in relation to one HVAC system 100 used for conditioning one structure, the present disclosure contemplates that several HVAC systems 100 may be used in different zones of one structure. When a structure is associated with multiple HVAC systems 100, each HVAC system 100 may be operated in tandem or separately from one another to heat or cool different environmental zones inside of one structure to different desired temperatures using the same or different operational modes according to embodiments of the present disclosure.

The heat pump system 110 also includes an outdoor heat exchanger 112b located in or in communication with (e.g., via ducting) a non-conditioned environment (e.g., the outdoors or outdoor environment) to extract heat from or expel heat to. The heat pump system 110 also includes a refrigeration circuit 114 linking the heat exchangers 112 and through which a thermal transfer medium also travels and passes through an expansion valve 116 and a compressor 118. As shown in FIG. 1 by arrows D1 and D2, the thermal transfer medium is routed in a first direction through the refrigeration circuit to draw heat from the non-conditioned environment and transfer the heat into the conditioned environment (e.g., an indoor environment), but the direction of flow of the thermal transfer medium may be reserved to operate the heat pump system 110 in a cooling mode (e.g., moving heat from the indoor environment to the outdoors).

In a hybrid heating system, a third, combustion heat exchanger 112c associated with the hot gas from a heater 130, such as a combustion chamber, may also be present, which vents the exhaust from the combustion of a fuel to an ambient environment after exchanging heat with the air to heat for the conditioned environment.

In various embodiments, fans 160a-c (generally or collectively, fans 160) are associated with the heat exchangers 112a-c to move air across the respective heat exchangers 112, as show in FIG. 1 by arrow A for air from the indoor environment to be conditioned (e.g., heated or cooled), by arrow B for air moved between the indoor heat exchanger 112a and the combustion heat exchanger 112c, and by arrow C for air that is directed back to the indoor environment after being conditioned by one or both of the indoor and combustion heat exchanges 112a/112c. The fans 160 may be of various types (e.g., fixed speed, two speed, variable speed, etc.) as suitable for the HVAC system 100, and may be omitted or provided as optional equipment from some of the heat exchangers 112. Although not illustrated, the heat pump system 110 may include additional components, such as accumulators, receivers, charge compensators, flow control devices, air movers, pumps, filters, guards, filter driers, air ducts, and the like.

A refrigerant or other thermal transfer medium circulates through the refrigerant circuit 114 to perform a vapor compression refrigeration cycle, whereby heat is exchanged with a non-conditioned environment at the outdoor heat exchanger 112b and with the conditioned environment at the indoor heat exchanger 112a to cool or heat the conditioned environment to a desired temperature. In a heating mode, as is shown in FIG. 1, the refrigerant is compressed by the compressor 118 and is sent to the indoor heat exchanger 112a. The refrigerant dissipates heat to air from the conditioned environment at the indoor heat exchanger 112a, lowering the temperature of the refrigerant. The refrigerant then travels through the expansion valve 116, where the refrigerant expands to reduce the pressure and temperature of the refrigerant. The refrigerant then flows to the outdoor heat exchanger 112b where the low temperature and low pressure refrigerant from the expansion valve 116 exchanges heat with the outdoor environment at the outdoor heat exchanger 112b. That is, the refrigerant absorbs heat from the ambient air in the non-conditioned environment. Thus, in a heating mode, the outdoor heat exchanger 112b operates as an evaporator. After the heat exchange at the outdoor heat exchanger 112b, the refrigerant is evaporated into a gaseous state and is sucked into the compressor 118 to repeat the cycle.

The HVAC system 100 also includes a fueled heater 130 that ignites a combustible fuel, supplied via a fuel source 135, to extract potential chemical energy from the fuel. The combustion of the fuel converts the potential chemical energy into thermal energy, which is transferred to the conditioned environment via the combustion heat exchanger 112c to heat the conditioned environment. For example, the fueled heater 130 may use natural gas, propane, hydrogen, fuel oil, wood pellets, or the like as a fuel that is burned to produce heat for the conditioned indoor environment.

In various embodiments, the fueled heater 130, the combustion heat exchanger 112c, and the indoor heat exchanger 112a are displaced in a shared cabinet 120 to share ducting into or in communication with the conditioned environment. In various embodiments, the shared cabinet 120 also includes exhaust ducting to remove combustion byproducts (e.g., carbon monoxide, carbon dioxide, smoke, ash, etc.) from the shared cabinet 120. The shared cabinet 120 prevents or reduces entry of these byproducts into the conditioned environment and instead releases these byproducts into the non-conditioned environment.

The cabinet 120 also includes a first temperature sensor 122a at an intake side of the indoor heat exchanger 112a (e.g., that receives air to be heated or cooled from the conditioned environment) and a second temperature sensor 122b at an output side of the indoor heat exchanger 112a (e.g., that passes the heated or cooled air back into the conditioned environment at the desired temperature). The temperature sensors 122a and 122b may be referred to generally or collectively as temperature sensor 122. By comparing the measured temperature on opposing sides of the indoor heat exchanger 112a, the temperature sensors 122 allow the system to calculate an air rise temperature across the indoor heat exchanger 112a, which indicates how much the air has been heated by the indoor heat exchanger 112a. As used herein, the term “air rise temperature” is a measure of a difference between two measured temperatures relative to another object or reference point (e.g., across a heat exchanger 112), and may identify an increase, a decrease, or no change in temperature.

Although shown within the shared cabinet 120, in various embodiments, the temperature sensors 122 may be included in the ducts leading into or out of the shared cabinet 120 and may include one or more first temperature sensors 122a and one or more second temperature sensors 122b that provide additional readings based on detected differences in air rise temperature. When multiple first temperature sensors 122a or multiple second temperature sensors 122b are included, the system may calculate multiple air rise temperatures (e.g., at different points of the indoor heat exchanger 112a), calculate one air rise temperature using aggregated readings from several temperature sensors 122, reserve some temperature sensors 122 as back-up or redundant sensors, use different temperature sensors 122 within different temperature ranges, or combinations thereof.

Temperature within the conditioned environment may be monitored by one or more thermostats 140 located in the conditioned environment or remote from the structure. The thermostats may include thermometers, bimetal resistors, or other temperature sensors that indicate the temperature of the conditioned environment to a controller 150, which processes information from the sensors to determine the temperature. In various embodiments, the controller 150 and a thermostat 140 may be included in a single device that is provided to a user to select what temperature that the HVAC system 100 attempts to maintain in the conditioned environment, and how the HVAC system 100 is permitted to reach the desired temperature.

For example, the controller 150 may provide a graphical user interface or a set of buttons, knobs, sliders, or the like to allow the user to set a desired temperature, a mode of operation for the HVAC system 100, schedule changes in the desired temperature and mode of operation, etc. In a cooling mode, the heat pump system 110 extracts heat from the conditioned environment for transfer to the non-conditioned environment. In an exclusive heat-pump heating mode, the heat pump system 110 alone extracts heat from the non-conditioned environment for transfer to the conditioned environment and other heat sources are not operated. In an exclusive alternative heat source heating mode, an alternative heat source from the heat pump system 110 generates heat for the environment, and the heat pump is not operated. In a hybrid heating mode, the heat pump system 110 extracts heat from the non-conditioned environment for transfer to the conditioned environment and at least one non-heat-pump heat source is operated at the same time as the heat pump, although the controller 150 may set the operational output for one or both of the heat pump system 110 and the non-heat-pump heat source to 0% of rated output temporarily.

As used herein, a system may be operated in a “standby” or “idle” mode to operate at a rated output for that system that is insufficient to heat the conditioned environment to the desired temperature, but is sufficient to avoid having to perform shutdown or startup operations. Accordingly, the standby mode keeps the system ready to rapidly respond to commands from the controller 150 to increase the output thereof. This standby mode may be characterized as operating the system at a low percentage of rated output (e.g., approximately 0%, 0-5%, etc.), which may be due to an imposed duty cycle (e.g., operating at 100% rated output for less than 1% of the time), a constantly reduced power/fuel consumption rate (e.g., receiving less than 1% of the inputs needed to operate at 100% of rated output), and combinations thereof.

The controller 150 may include one or more a computing devices (e.g., computing device 500 discussed with respect to FIG. 5) that controls the HVAC system 100. The controller 150 may be configured to communicate with a remote controller. A user can send, for example, a set values of temperatures of rooms in the conditioned environment to the controller 150 from the remote controller. In addition to controlling the mode of operation of the hybrid HVAC system 100, the controller 150 is able to adjust (automatically or with user input) various thresholds for when to trigger operation of the various heating sources within the various modes.

For example, the controller 150 may determine the temperature of the conditioned environment via one or more thermostats 140 and activate the hybrid HVAC system to heat or cool the conditioned environment when the measured temperature is at least a set amount above or below a target temperature for the conditioned environment. When operating in the hybrid heating mode, the controller 150 may also adjust a triggering threshold for when the air rise temperature is sufficiently high or low to merit increasing or decreasing the output rate of one or both of the fueled heater 130 and the heat pump system 110. These adjustments may be based on one or more of a cost of fuel for the fueled heater 130, a user preference for operating the fueled heater 130 relative to the heat pump system 110, a temperature in the non-conditioned environment at the given time, a forecasted temperature for the non-conditioned environment at a future time, a current time of day (e.g., to avoid expending fuel to heat the conditioned environment when no persons are present), or a fuel availability for the fueled heater 130 (e.g., to avoid expending fuel when a fuel level of the fuel source 135 is below a threshold value).

The controller 150 also performs at least on/off control of the compressor 118, the fans, and the blowers used to move air across the heat exchangers 112 or in the environments. In addition, when motors within the system are variable speed motors (e.g., motor(s) for the compressor 118, fans, and blowers), the controller 150 may be configured to individually control the speed of each motor over a range of speeds rather than simply on or off. In this manner, the rate of heat exchange of the HVAC system 100 may be controlled by controlling the blower motor rotational speed, thereby controlling the flow rate of the blower airflow across the heat exchangers 112. Similarly, the rate of heat exchange of the HVAC system 100 may be controlled by controlling the motor of the compressor 118, thereby controlling the flowrate of refrigerant in the refrigerant circuit 114.

In some embodiments, the expansion valve 116 may be a thermal expansion valve (TXV), an electronic expansion valve (EEV), or a fixed-orifice expansion valve. When the expansion valve 116 is a TXV, the TXV is controlled using a temperature sensing bulb and an equalizer line (not shown) that may be connected to the refrigerant circuit 114 at a position downstream of the sensing bulb. The temperature sensing bulb may be placed on a compressor suction line upstream from the compressor 118 with respect to the refrigerant flow. When an accumulator is used, the bulb may be placed in the compressor suction line upstream or downstream of the accumulator, with respect to the refrigerant flow. In this manner, the output of the sensing bulb is adjusted to account for the amount of liquid refrigerant within the accumulator. The location of the sensing bulb may be selected to optimize vapor compression refrigeration cycle, depending on user preferences for the HVAC system 100.

Additionally, the HVAC system 100 may include an equalization line (not shown) in communication with the heat exchangers 112 to equalize or release pressure. In the cooling mode for example, the indoor heat exchanger 112a is the evaporator and the pressure of the refrigerant leaving the indoor heat exchanger 112a is communicated to the TXV through the equalizer line. Pressure communicated through the equalizer line may be used to balance the pressure communicated to the expansion valve 116 from the sensing bulb to operate the TXV. The TXV may be set to maintain a compressor superheat level while optimizing whichever of the indoor heat exchanger or outdoor heat exchanger is operating as the evaporator. Controlling the TXV with this method allows the evaporator superheat level to be maintained more efficiently. Further, the expansion valve 116 may include an internal bleed port to maintain a more accurate and stable control, as well as equalize the high side pressure and low side pressure during the off-cycle. Further, the TXV may also be a so-called balanced port design with the pressure of the refrigerant at the condenser balanced across the valve.

In embodiments that include an accumulator in the compressor suction line (e.g., a line upstream from the compressor 118), the accumulator allows for the collection of some liquid refrigerant, if any, before the liquid refrigerant flows to the compressor 118. This provides the benefit of separating some non-vaporized refrigerant before passing to the compressor 118. Further, the expansion valve 116 is also configurable to control the flow of refrigerant to store some refrigerant in an accumulator if there is a refrigerant charge imbalance in the refrigeration circuit. In doing so, the expansion valve 116 may be configured to lower a superheat level of the evaporator, which in the cooling mode is the indoor heat exchanger 112a, compared to not including the accumulator in the HVAC system 100. This allows an evaporator with a lesser peak heating/cooling capacity to be used for the load of the HVAC system 100. As an example, the expansion valve 116 is configurable to control flow of the refrigerant through the evaporator such that a superheat level of the evaporator is as close to zero as possible while maintaining a superheat level control at the compressor 118.

Alternatively, in some embodiments, the expansion valve 116 may be an electronic expansion valve (“EEV”), and a pair of temperature or temperature/pressure sensors (not shown) may be connected to a controller 150 to provide measurement data for the control of the EEV bi-flow expansion valve 116 operation. The temperature and/or pressure sensors are positioned to sense temperature and/or pressure in the compressor suction line and/or the accumulator upstream of the compressor 118. The main controller processes the measurement data and provides control commands to the EEV expansion valve 116 to operate the HVAC system 100 similarly to the TXV operation discussed above.

In addition to the components described above, the HVAC system 100 includes various bypass valves that operate to route the refrigerant to or around various components of the HVAC system 100. For example, a first bypass valve and a second bypass valve can route the refrigerant through or bypass the indoor heat exchanger 112a, to allow for maintenance of the indoor heat exchanger 112a with reduced loss of refrigerant.

FIGS. 2A-2C illustrate schematic views of an example cabinet 120 for including elements of a hybrid HVAC system for conditioning the air of a conditioned environment, according to embodiments of the present disclosure. FIG. 2A shows a front elevated view, FIG. 2B shows a side elevated view, and FIG. 2C shows a rear elevated view, which are intended to collectively describe a cabinet 120, according to embodiments of the present disclosure.

The cabinet 120 encloses a heat exchange space 210 into which air from the conditioned environment is pulled and then pushed back out into the conditioned environment after exchanging heat with the HVAC system 100; either being cooled or heated in the cabinet 120. Although not illustrated, the cabinet 120 may be connected to one or more sets of ducts that deliver air to the heat exchange space 210 from the conditioned environment or from the heat exchange space 210 to the conditioned environment. Such sets of ducts may include various filters, vents, airflow control elements, supplemental blowers, or the like.

The indoor heat exchanger 112a of the heat pump system 110 is located in the heat exchange space 210 in the flowpath 250 according to arrows A for air, and a fan 160c is provided to circulate air to establish the flowpath 250 further according to arrows B and C in the desired direction. In various embodiments, the fan 240/160c includes ducting or cowling 245 to direct the intake of air from the portion of the heat exchange space 210 where the indoor heat exchanger 112a is located the portion of the heat exchange space 210 where the fueled heat exchanger 112c is located, and back to the conditioned environment in the flowpath 250. Also located in the cabinet 120 are the fueled heater 130 and an (optional) electric heater 220, which are provided as alternative heat sources to the heat pump system 110. Each of the alternative heat sources may be operated per user commands, (e.g., in an auxiliary heat only mode of operation for the HVAC system 100) or in a hybrid mode with the heat pump system 110, with one another (e.g., a fueled heater 130 and an electrical heater 220), or with both one another and the heat pump system 110.

The fueled heater 130 includes burner elements in which a supplied fuel is burned to produce heat. One or more coils of heat tubing act as a heat exchanger 112c for the fueled heater 130 by receiving the gases heated by the burner elements and circulating those heated gasses in the heat exchange space 210 before venting the gases to the outdoor environment. Air is passed through the coils of the heat tubing as part of the flowpath 250, as is shown in FIG. 2C via arrow B from the fan assembly 240/160c and arrow C through the tubing and back to the conditioned environment. The tubing caries heated gasses from fuel combusted by the fueled heater 130 to thereby exchange heat from the combusted fuel to the air that is carried to the conditioned environment.

In various embodiments, one or more burner elements of the fueled heater 130 may be located in a combustion space 230 that is sealed off from the heat exchange space 210 by a firewall 260. The combustion space 230 is vented separately from the heat exchange space 210 to the outdoor environment to reduce or avoid introducing combustion byproducts (e.g., carbon monoxide, carbon dioxide, etc., including any gasses carried out of the cabinet 120 as part of the heated gasses through the heat tubing) into the conditioned environment while still receiving fresh air to enable combustion of the fuel. In some embodiments, vents from the burner elements may be routed away from the air of the conditioned environment, and the combustion space 230 is not open to the heat exchange space 210.

By sharing the cabinet 120 and placing the heat exchanger of the fueled heater 130 and the heat pump system 110 in the same heat exchange space 210, one or both of the heat sources can be active at the same time to heat the air of the conditioned environment flowing through the cabinet. The temperature sensors 122 in the cabinet 120 measure an air rise temperature of the input air compared to the output air to detect when the output of the heat pump system 110 should be augmented by using an alternative heat source, and when the output level of the alternative heat source can be reduced for the heat pump system 110 to provide additional heat to the conditioned environment.

In some embodiments, the cabinet 120 optionally includes an electrical heater 220 that produces heat by running a current through resistive elements. Although generally less energy efficient than running the heat pump system 110 to heat the conditioned environment, the electrical heater 220 may be provided as a backup electrically-powered heating unit. Additionally or alternatively, the electrical heater 220 may be used instead of the fueled heater 130 to operate in a hybrid mode with the heat pump system 110. For example, when the fuel supply is cut off, runs below a threshold value, or the cost of fuel exceeds the cost of electricity, the hybrid heating mode may activate the electrical heater 220 instead of the fueled heater 130. For example, when a renewable electrical power source is available and producing excess power, that would otherwise be stored to a battery, delivered back to a power grid, or go to waste, the electrical heater 220 may be activated in the hybrid mode of heating instead of the fueled heater 130.

FIG. 3 illustrates a detailed example of a compact fueled heater 130, according to embodiments of the present disclosure. Because space in a heating cabinet may be specified according to standard sizes used in building construction, the size and shape of the fueled heater 130 should conform to the available sizes of heating cabinets. Accordingly, the burner elements are located on one side of a firewall 260 and the heat exchange tubing 330 is located on the other side of the firewall 260 to position the heat exchange tubing 330 horizontally relative to the burner elements. By using the horizontal layout, the fueled heater 130 increases the space available for use in exchanging heat with the air in the heat exchange space 210 and improves the ability for technicians or users to install, uninstall, repair, and generally access the fueled heater 130 in the cabinet 120.

The burner elements include a fuel supply line 310 that delivers fuel from the fuel source 135 of FIG. 1 to one or more combustion chambers 320. In the combustion chambers 320, fuel is burned with oxygen to produce heat, which is carried by the combustion gasses into the heat exchange tubing 330 (e.g., which acts as the combustion heat exchanger 112c discussed in relation to FIG. 1) to radiate to the air in the heat exchange space 210. In various embodiments, each combustion chamber 320 includes a pilot light, which carries a flame (fed by fuel) at all times to provide an ignition source for when fuel is provided into the combustion chamber 320, although additionally or alternatively, an electric sparker may be used as an ignition source that does not consume fuel and is instead powered by electricity. As described herein, providing fuel to a pilot light is not considered to be part of the operational level of a fueled heater 130 (e.g., a fueled heater 130 may be deactivated or operate at 0% of rated capacity while still providing fuel to maintain the pilot light).

The heat exchange tubing 330 (which are represented by the heat exchanger 112c in FIG. 1) are arranged on the opposite side of the firewall 260 to a combustion chamber 320, and have a first diameter where connected to the gas output of the combustion chamber 320 and a second diameter, less than the first diameter, connected to an intake of the vent fan 340. As shown in FIG. 2C, more than one set of heat exchange tubing 330 may be provided, each of which is associated with a combustion chamber 320. In various embodiments, the heat exchange tubing 330 may gradually reduce in diameter from the output of the combustion chamber 320 to the intake of the vent fan 340, or may have one or more distinct sections with different diameters. The heat exchanged tubing 330 is curled into one or more coils that are arranged in a flowpath of the air through the cabinet 120 so that heat from the combustion process has multiple opportunities and greater surface area to radiate heat from the surfaces of the heat exchange tubing 330 to the air flowing through the coils. In various embodiments, the heat exchange tubing may be made of steel, copper, aluminum, etc.

To aid in the flow of the combustion gases through the heat exchange tubing 330, and ejection of those gases away from the air of the conditioned environment, a vent fan 340 is positioned at the output end of the heat exchange tubing 330. The vent fan 340 pulls the combustion gases through the heat exchange tubing 330 and out a vent 350. In various embodiments, the vent 350 is connected to ducting (not illustrated) which places the vent 350 in fluid communication with the non-conditioned environment (e.g., outdoors) so that the combustion gases are exhausted away from the conditioned environment and the heated air being directed to the conditioned environment.

FIG. 4 is a flowchart for an example method 400 for contemporaneous hybrid heating, according to embodiments of the present disclosure. Method 400 begins at block 410, where a controller 150 determines whether the HVAC system 100 is in a heating mode or a cooling mode (e.g., in a state to heat or cool a conditioned environment, respectively). When the HVAC system 100 is in the cooling mode, method 400 proceeds to block 412, where the controller 150 operates the HVAC system 100 to cool the conditioned environment via a heat pump system 110 pulling heat from the conditioned environment and sinking that heat into a non-conditioned environment (e.g., outside).

When the HVAC system 100 is in the heating mode, method 400 proceeds to block 420, where the controller 150 determines which heating mode is specified for the HVAC system 100 to operate in, which may include modes to exclusively operate a heat pump system 110, exclusively operate an alternative heating system, or to operate a heat pump system and one or more alternative heating systems in a hybrid mode in which two or more heating systems operate contemporaneously to heat the conditioned environment. When the HVAC system 100 is in the heating mode and directed to exclusively use a heat pump system 110, method 400 proceeds to block 422, where the controller 150 operates the heat pump system 110 to heat the conditioned environment and leaves the alternative heating system inactive. When the HVAC system 100 is in the heating mode and directed to exclusively use an alternative heating system, such as a fueled heater 130 or electric heater 220, method 400 proceeds to block 424, where the controller 150 operates the alternative heating system to heat the conditioned environment and leaves the heat pump system 110 inactive.

When the HVAC system 100 is in the heating mode and directed to contemporaneously use an alternative heating system, such as the fueled heater 130 or electric heater 220, and a heat pump system 110 in a hybrid heating mode to heat a conditioned environment, method 400 proceeds to block 430.

At block 430, the controller 150 initially selects the heat pump system 110 to heat the conditioned environment. In some embodiments, the controller may initially operate the heat pump system 110 at 100% of rated output and the alternative heating system at 0% of rated output (e.g., operating in an idle or “standby” mode) to determine whether to activate the alternative heating system. In some embodiments, the controller may initially operate the heat pump system 110 at less than 100% of rated output and the alternative heating system at more than 0% of rated output to determine whether to adjust the operational rates for one or both of the heat pump system 110 and alternative heating system at a later time.

Accordingly, when directed to heat a conditioned environment, the controller 150 detects which heating mode to use and selects one of (i) exclusively a heat pump system 110 (per block 422), (ii) exclusively an alternative heater, such as a fueled heater 130 or electric heater 220, and (iii) a combination of the heat pump system 110 and the alternative heater (per block 430) to activate at a given time to heat a conditioned environment. When operating in the hybrid heating mode, one of the heat pump system 110 and the alternative heating system may be deactivated and held in at idle or standby (e.g., operating at 0% of rated capacity, 1% of rated capacity, or 5% of rated capacity) at any given time, but remains an available option to operate at above 0% of rated capacity as the controller 150 adjusts a balance between the systems to provide heat to the conditioned environment. In contrast, when operating in one of the exclusive heating modes (e.g., using only the heat pump or only the alternative heat system), the controller 150 leaves the other heating system at 0% of rated capacity (e.g., deactivated) until a user manually directs the controller to activate the other heating system. Accordingly, even when temporarily deactivated, the controller 150 is able to activate one or both of the heating systems at the same time when operating in the hybrid heating mode.

In various embodiments, the initial run of the HVAC system 100 in the hybrid heating mode per block 430 may last for a predefined startup time before the controller 150 adjusts a ratio at which the multiple heating systems operate with respect to one another (e.g., to allow a heating system to “warm up”, circulate a working fluid, or otherwise reach a desired operational state). Once the predefined startup time has elapsed, method 400 proceeds to block 440.

The controller 150 determines when to activate the various heating systems while operating in the hybrid heating mode, and at what operational level, based on an air rise temperature across a heat exchanger 112 for the heat pump system 110 that is located in or in communication with the conditioned environment. In various embodiments, the various heating systems are located in, or ducted through, a shared cabinet that is ducted into an airflow path of the conditioned environment. In response to detecting that the air rise temperature is below a heating threshold, the controller 150 increases the portion of the heating load to be handled by the alternative heat source relative to the heat pump system 110 (e.g., by increasing an operational level of an alternative heat source, decreasing an operational level of the heat pump system 110, or both). Similarly, in response to detecting that the air rise temperature is above a sufficiency threshold, the controller increases the portion of the heating load to be handled by the heat pump system 110 relative to the alternative heat source (e.g., by decreasing an operational level of an alternative heat source, increasing an operational level of the heat pump system 110, or both). Monitoring and adjusting the balance between the various heating system is a continuous process, and the controller 150 may proceed through several iterations of increasing and decreasing the output levels of the various heating systems to cooperatively heat the conditioned environment as described in relation to blocks 440-490.

In various embodiments, the user may set the activation thresholds for when to adjust the relative output levels of the hating systems when operating in the hybrid heating mode. In some embodiments, the controller 150 adjusts the activation thresholds of the air rise temperature to trigger operation or adjust relative output levels of the various heating systems based on: a cost of fuel for the fueled heater 130; user preference for operating a fueled heater 130 relative to the heat pump system 110; temperature in a non-conditioned environment at the given time; forecasted temperature for the non-conditioned environment at a future time; a time of day for when to heat the conditioned environment; fuel availability for the fueled heater 130; and combinations thereof, among other considerations. In some embodiments, when the alternative heat sources include a fueled heater 130 and an electric heater 220, the controller 150 can identify that the electric heater 220 should be activated instead of the fueled heater 130 to supplement or replace the heating capacity of the heat pump system 110 when a fuel supply is below a threshold reserve level or a renewable energy source associated with the electric heater 220 is available at a threshold generation level (e.g., solar cells, windmills, or watermills associated with the conditioned environment are currently producing at least X Watts of power).

At block 440, the controller 150 measures the air rise temperature across a heat exchanger 112 through which air from the conditioned environment is passed to heat that air before being circulated to the conditioned environment. The air rise temperature may be measured via a first temperature sensor 122a on one side of the heat exchanger 112 that measures the temperature of the incoming air from the conditioned environment and a second temperature sensor 122b on a second side of the heat exchanger 112 that measures outgoing air back to the conditioned environment, although in various embodiments, more than two temperature sensors 122 may be used.

At block 450, the controller 150 determines whether the air rise temperature is outside of or within a hybrid range of operation. The air rise temperature across the heat exchanger 112 identifies how much (or whether) the heat exchanger 112 affects the temperature of the air, and as temperatures fall in the non-conditioned environment, the heat pump system 110 may become less effective in transferring heat into the conditioned environment when operating at a constant operational level. Accordingly, the controller 150 can identify when the current operation level of the heat pump system 110 is insufficient to heat the air to a desired temperature to activate (or increase an operational rate of) an alternative heat source, and thereby reduce the operational rate of (or deactivate) the heat pump system 110. Similarly, the controller 150 can identify when the current operational level of the alternative heat source is overly sufficient to heat the conditioned environment, and may reduce the operational rate of (or deactivate) the alternative heat source, and increase an operational rate of (or activate) the heat pump system 110. Accordingly, the controller 150 monitors the air rise temperature against a heating threshold and a sufficiency threshold to determine the operational levels of the individual heating systems in the hybrid HVAC system 100.

When the air rise temperature is within the operational thresholds, method 400 returns to block 440 to measure the air rise temperature at a subsequent time. In various embodiments, to avoid unnecessary adjustment to the operational levels of the heating systems due to fluctuations in heating demand, changes in environmental conditions, variability in sensors, or the like, the controller 150 may observe at least N air rise temperatures in a period of time that are of the threshold before determining that the air rise temperature is outside of the operational threshold.

In various iterations, method 400 proceeds to block 460 or block 470 from block 450 in response to determining that the air rise temperature is below the operational thresholds (e.g., the air rise temperature is lower than expected). When the heat produced by the heating systems operating in hybrid mode is less than expected, the air rise temperature may indicate that the heat pump is operating less efficiently (e.g., due to greater availability of heat to extract from the non-conditioned environment), that the alternative heating system is operating at a lower level than needed to heat the conditioned environment to the desired temperature, or combinations thereof. Accordingly, the controller 150 performs one or both of block 460, to increase the output of the alternative heating source and block 470, to decrease the output of the heat pump system 110.

In various embodiments, the controller 150 may be biased to select one or both of block 460 and 470 based on the current operational levels of the heat sources (e.g., more likely to increase the output level of the alternative heat source when closer to 0% of rated output, more likely to decrease the output level of the heat pump system 110 when closer to 100% of rated output), a period of time since the last performance of block 460 or block 470 in an iteration (e.g., less likely to adjust an output level of the same heating source in two consecutive adjustments), a period of time since the last performance of block 480 or block 490 (e.g., less likely to adjust an output level of the same heating source in two consecutive adjustments), and combinations thereof.

Method 400 then returns to block 440 to measure the air rise temperature for a subsequent iteration of hybrid heating management, which may maintain the current operational ratio between multiple heat sources to operate contemporaneously to heat the conditioned environment, or alter the operational ratio of the heat sources.

In various iterations, method 400 proceeds to block 480 or block 490 from block 450 in response to determining that the air rise temperature is above the operational thresholds (e.g., the air rise temperature is higher than expected). When the heat produced by the heating systems operating in hybrid mode is greater than expected, the air rise temperature may indicate that the heat pump is operating more efficiently, that the alternative heating system is operating at a higher level than needed to heat the conditioned environment to the desired temperature, or combinations thereof. Accordingly, the controller 150 performs one or both of block 480, to decrease the output of the alternative heating source and block 490, to increase the output of the heat pump system 110.

In various embodiments, the controller 150 may be biased to select one or both of block 480 and 490 based on the current operational levels of the heat sources (e.g., more likely to decrease the output level of the alternative heat source when closer to 100% of rated output, more likely to increase the output level of the heat pump system 110 when closer to 0% of rated output), a period of time since the last performance of block 480 or block 490 in an iteration (e.g., less likely to adjust an output level of the same heating source in two consecutive adjustments), a period of time since the last performance of block 460 or block 470 (e.g., less likely to adjust an output level of the same heating source in two consecutive adjustments), and combinations thereof.

Method 400 then returns to block 440 to measure the air rise temperature for a subsequent iteration of hybrid heating management, which may maintain the current operational ratio between multiple heat sources to operate contemporaneously to heat the conditioned environment, or alter the operational ratio of the heat sources.

FIG. 5 illustrates a computing device 500, as may be used as a controller 150 and/or a thermostat 140 for a hybrid HVAC system 100 according to embodiments of the present disclosure. For example, the computing device 500 can be used as a controller 150 to control the blower(s), compressor(s), and valve(s) of an HVAC system 100 to route a refrigerant along different paths for heating and cooling. For example, the computing device 500 can be used as a thermostat 140 to receive user input and provide output to a user for setting and measuring temperatures in a conditioned environment. The computing device 500 may include at least one processor 510, a memory 520, and a communication interface 530 and may be used as a controller for the HVAC system 100 described herein.

The processor 510 may be any processing unit capable of performing the operations and procedures described in the present disclosure. In various embodiments, the processor 510 can represent a single processor, multiple processors, a processor with multiple cores, and combinations thereof.

The memory 520 is an apparatus that may be either volatile or non-volatile memory and may include RAM, flash, cache, disk drives, and other computer readable memory storage devices. Although shown as a single entity, the memory 520 may be divided into different memory storage elements such as RAM and one or more hard disk drives. As used herein, the memory 520 is an example of a device that includes computer-readable storage media, and is not to be interpreted as transmission media or signals per se.

As shown, the memory 520 includes various instructions that are executable by the processor 510 to provide an operating system 522 to manage various features of the computing device 500 and one or more programs 524 to provide various functionalities to users of the computing device 500, which include one or more of the features and functionalities described in the present disclosure. One of ordinary skill in the relevant art will recognize that different approaches can be taken in selecting or designing a program 524 to perform the operations described herein, including choice of programming language, the operating system 522 used by the computing device 500, and the architecture of the processor 510 and memory 520. Accordingly, the person of ordinary skill in the relevant art will be able to select or design an appropriate program 524 based on the details provided in the present disclosure.

The communication interface 530 facilitates communications between the computing device 500 and other devices, which may also be computing devices as described in relation to FIG. 5. In various embodiments, the communication interface 530 includes antennas for wireless communications and various wired communication ports. The computing device 500 may also include or be in communication, via the communication interface 530, one or more input devices (e.g., a keyboard, mouse, pen, touch input device, etc.) and one or more output devices (e.g., a display, speakers, a printer, etc.).

Although not explicitly shown in FIG. 5, it should be recognized that the computing device 500 may be connected to one or more public and/or private networks via appropriate network connections via the communication interface 530. It will also be recognized that software instructions may also be loaded into the non-transitory computer readable medium, such as the memory 520, from an appropriate storage media or via wired or wireless means. The communication interface 530 may also be connected to one or more thermostats, thermometers, hydrometers, flowmeters, motor controls, or the like to monitor and send commands to various components of the HVAC system 100.

Accordingly, the computing device 500 is an example of a system that includes a processor 510 and a memory 520 that includes instructions that (when executed by the processor 510) perform various embodiments of the present disclosure. Similarly, the memory 520 is an apparatus that includes instructions that when executed by a processor 510 perform various embodiments of the present disclosure.

In addition to the embodiments described above, many examples of specific combinations are within the scope of the disclosure, some of which are detailed below:

Clause 1: A system for conditioning air in a conditioned environment inside a structure with an outdoor environment outside the structure being non-conditioned, comprising: a heat pump, including: an indoor heat exchanger located in or in communication with the conditioned environment; an outdoor heat exchanger located in or in communication with the outdoor environment, wherein the outdoor heat exchanger is in fluid communication with the indoor heat exchanger via a refrigerant circuit; a fueled heater; and a controller, configured to, when the system is operating in a hybrid heating mode, activate both of the heat pump and the fueled heater at a given time based on an air rise temperature measured across the indoor heat exchanger.

Clause 2: The system as described in any of clauses 1 and 3-9, wherein the indoor heat exchanger and the fueled heater are located in a shared cabinet that is ducted into an airflow path of the conditioned environment.

Clause 3: The system as described in any of clauses 1-2 and 4-9, wherein the fueled heater further comprises: a firewall; a combustion chamber located on a first side of the firewall; a vent fan located on the first side of the firewall; and heat exchange tubing located on a second side of the firewall, opposite to the first side, having a first diameter connected to a gas output of the combustion chamber and a second diameter, less than the first diameter, connected to an intake of the vent fan.

Clause 4: The system as described in any of clauses 1-3 and 5-9, wherein the fueled heater is connected to a fuel supply that supplies a fuel to the fueled heater for combustion, the fuel including natural gas, propane, hydrogen, fuel oil, or combinations thereof.

Clause 5: The system as described in any of clauses 1-4 and 6-9, further comprising an electric heater, wherein the controller is further configured to activate the electric heater in place of the fueled heater at the given time when a fuel supply for the fueled heater is below a threshold reserve level or a renewable energy source associated with the electric heater is available at a threshold generation level.

Clause 6: The system as described in any of clauses 1-5 and 7-9, wherein, when the controller activates both of the heat pump and the fueled heater at the given time, the fueled heater and the heat pump each operate at between 0% and 100% of respective rated outputs.

Clause 7: The system as described in any of clauses 1-6 and 8-9, wherein the controller is configured to increase an operational rate of the fueled heater when the air rise temperature is below a sufficiency threshold for the heat pump.

Clause 8: The system as described in any of clauses 1-7 and 9, wherein controller is configured to decrease an operational rate of the fueled heater when the air rise temperature is above a sufficiency threshold for the heat pump.

Clause 9: The system as described in any of clauses 1-8, wherein the controller is configured to adjust a triggering threshold of the air rise temperature to trigger operating both the fueled heater and the heat pump at the given time based on at least one of: a cost of fuel for the fueled heater; a user preference for operating the fueled heater relative to the heat pump; a temperature in the outdoor environment at the given time; a forecasted temperature for the outdoor environment at a future time; a time of day of the given time; or an amount of fuel available for the fueled heater at the given time.

Clause 10: A method for conditioning air inside a structure, comprising: activating, by a controller, a heat pump to heat a conditioned environment inside the structure; detecting, using a sensor, an air rise temperature across an indoor heat exchanger of the heat pump located in or in communication with the conditioned environment; determining, using the controller, whether the air rise temperature is below a triggering threshold; and when the air rise temperature is below the triggering threshold, activating, by the controller, a fueled heater to heat the conditioned environment contemporaneously with the heat pump at a given time.

Clause 11: The method as described in any of clauses 10 and 12-17, further comprising, in response to detecting that the air rise temperature across the indoor heat exchanger is below the triggering threshold: decreasing an output of the heat pump.

Clause 12: The method as described in any of clauses 10-11 and 13-17, further comprising, in response to decreasing the output of the heat pump to 0% of rated output: operating only the fueled heater to heat the conditioned environment; detecting, using the sensor, the air rise temperature across the indoor heat exchanger at a subsequent time to the given time; determining, using the controller, whether the air rise temperature is above a sufficiency threshold; and when the air rise temperature is above the sufficiency threshold, activating, by the controller, the heat pump to heat the conditioned environment contemporaneously with the fueled heater.

Clause 13: The method as described in any of clauses 10-12 and 14-17, further comprising, in response to determining that the air rise temperature across the indoor heat exchanger is above a sufficiency threshold while heating the conditioned environment via both the heat pump and the fueled heater: decreasing an output of the fueled heater; and increasing an output of the heat pump.

Clause 14: The method as described in any of clauses 10-13 and 15-17, further comprising: adjusting the triggering threshold of the air rise temperature to trigger operating both the fueled heater and the heat pump contemporaneously based on at least one of: a cost of fuel for the fueled heater; a user preference for operating the fueled heater relative to the heat pump; a temperature in a non-conditioned, outdoor environment outside the structure at the given time; a forecasted temperature for the outdoor environment at a future time a time of day of the given time; or an amount of fuel available for the fueled heater at the given time.

Clause 15: The method as described in any of clauses 10-14 and 16-17, wherein, when the controller activates both the heat pump and the fueled heater at the given time to heat the conditioned environment, the fueled heater and the heat pump each operate between 0% and 100% of respective rated outputs.

Clause 16: The method as described in any of clauses 10-15 and 17, further comprising: activating an electric heater in place of the fueled heater at the given time when a fuel supply for the fueled heater is below a threshold reserve level or a renewable energy source associated with the electric heater is available at a threshold generation level.

Clause 17: The method as described in any of clauses 10-16, wherein the indoor heat exchanger and the fueled heater are located in a shared cabinet that is ducted into an airflow path of the conditioned environment.

Clause 18: A computer readable medium including instructions, that when executed by a processor, cause the processor to perform operations including: activating, by a controller, a heat pump to heat a conditioned environment; detecting, using a sensor, an air rise temperature across a heat exchanger of the heat pump located in or in communication with the conditioned environment; determining, using the controller, whether the air rise temperature is below a triggering threshold; and when the air rise temperature is below the triggering threshold, activating, by the controller, a fueled heater to heat the conditioned environment at the same time as the heat pump at a given time.

Clause 19: The computer readable medium as described in any of clauses 18 and 20, the operations further comprise, in response to detecting that the air rise temperature across the heat exchanger is below the triggering threshold: decreasing an output of the heat pump; and in response to decreasing the output of the heat pump to 0% of rated output: operating only the fueled heater to heat the conditioned environment; detecting, using the sensor, the air rise temperature across the heat exchanger at a subsequent time to the given time; determining, using the controller, whether the air rise temperature is above a sufficiency threshold; and when the air rise temperature is above the sufficiency threshold, activating, by the controller, the heat pump to heat the conditioned environment contemporaneously with the fueled heater.

Clause 20: The computer readable medium as described in any of clauses 18-19, wherein, when the controller activates both the heat pump and the fueled heater at the given time to heat the conditioned environment, the fueled heater and the heat pump each operate at less than 100% of respective rated outputs.

Certain terms are used throughout the description and claims to refer to particular features or components. As one skilled in the art will appreciate, different persons may refer to the same feature or component by different names. This document does not intend to distinguish between components or features that differ in name but not function.

For the embodiments and examples given herein, a non-transitory computer readable medium can comprise instructions stored thereon, which, when performed by a machine, cause the machine to perform operations, the operations comprising one or more features similar or identical to features of methods and techniques described herein. The physical structures of such instructions may be operated on by one or more processors. A system to implement the described algorithm may also include an electronic apparatus and a communications unit. The system may also include a bus, where the bus provides electrical conductivity among the components of the system. The bus can include an address bus, a data bus, and a control bus, each independently configured. The bus can also use common conductive lines for providing one or more of address, data, or control, the use of which can be regulated by the one or more processors. The bus can be configured such that the components of the system can be distributed. The bus may also be arranged as part of a communication network allowing communication with control sites situated remotely from system.

In various embodiments of the system, peripheral devices such as displays, additional storage memory, and/or other control devices that may operate in conjunction with the one or more processors and/or the memory modules. The peripheral devices can be arranged to operate in conjunction with display unit(s) with instructions stored in the memory module to implement the user interface to manage the display of the anomalies. Such a user interface can be operated in conjunction with the communications unit and the bus. Various components of the system can be integrated such that processing identical to or similar to the processing schemes discussed with respect to various embodiments herein can be performed.

Optionally, the rotating equipment (e.g., motors) and valves disclosed herein are envisaged as being operable at specified speeds or variable speeds through inverter circuitry, for example. Moreover, the internal and external communication of the furnace may be accomplished through wired and or wireless communications, including known communication protocols, Wi-Fi, 802.11 (x), Bluetooth, to name just a few.

While the aspects of the present disclosure may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. But it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims. For example, certain embodiments disclosed here envisage usage with a powered fan rather than an inducer fan, or no fan at all. Moreover, the rotating equipment (e.g., motors) and valves disclosed herein are envisaged as being operable at specified speeds or variable speeds through inverter circuitry, for example. Moreover, the internal and external communication of the furnace may be accomplished through wired and or wireless communications, including known communication protocols, Wi-Fi, 802.11 (x), Bluetooth, to name just a few.

As used herein, “about,” “approximately” and “substantially” are understood to refer to numbers in a range of the referenced number, for example the range of −10% to +10% of the referenced number, preferably −5% to +5% of the referenced number, more preferably −1% to +1% of the referenced number, most preferably −0.1% to +0.1% of the referenced number.

Furthermore, all numerical ranges herein should be understood to include all integers, whole numbers, or fractions, within the range. Moreover, these numerical ranges should be construed as providing support for a claim directed to any number or subset of numbers in that range. For example, a disclosure of from 1 to 10 should be construed as supporting a range of from 1 to 8, from 3 to 7, from 1 to 9, from 3.6 to 4.6, from 3.5 to 9.9, and so forth.

As used in the present disclosure, a phrase referring to “at least one of” a list of items refers to any set of those items, including sets with a single member, and every potential combination thereof. For example, when referencing “at least one of A, B, or C” or “at least one of A, B, and C”, the phrase is intended to cover the sets of: A, B, C, A-B, B-C, and A-B-C, where the sets may include one or multiple instances of a given member (e.g., A-A, A-A-A, A-A-B, A-A-B-B-C-C-C, etc.) and any ordering thereof. For avoidance of doubt, the phrase “at least one of A, B, and C” shall not be interpreted to mean “at least one of A, at least one of B, and at least one of C”.

As used in the present disclosure, the term “determining” encompasses a variety of actions that may include calculating, computing, processing, deriving, investigating, looking up (e.g., via a table, database, or other data structure), ascertaining, receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), retrieving, resolving, selecting, choosing, establishing, and the like.

Without further elaboration, it is believed that one skilled in the art can use the preceding description to use the claimed inventions to their fullest extent. The examples and aspects disclosed herein are to be construed as merely illustrative and not a limitation of the scope of the present disclosure in any way. It will be apparent to those having skill in the art that changes may be made to the details of the above-described examples without departing from the underlying principles discussed. In other words, various modifications and improvements of the examples specifically disclosed in the description above are within the scope of the appended claims. For instance, any suitable combination of features of the various examples described is contemplated.

Within the claims, reference to an element in the singular is not intended to mean “one and only one” unless specifically stated as such, but rather as “one or more” or “at least one”. Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provision of 35 U.S.C. § 112 (f) unless the element is expressly recited using the phrase “means for” or “step for”. All structural and functional equivalents to the elements of the various embodiments described in the present disclosure that are known or come later to be known to those of ordinary skill in the relevant art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed in the present disclosure is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims

Claims

1. A system for conditioning air in a conditioned environment inside a structure with an outdoor environment outside the structure being non-conditioned, comprising:

a heat pump, including: an indoor heat exchanger located in or in communication with the conditioned environment; an outdoor heat exchanger located in or in communication with the outdoor environment, wherein the outdoor heat exchanger is in fluid communication with the indoor heat exchanger via a refrigerant circuit;

a fueled heater; and

a controller, configured to, when the system is operating in a hybrid heating mode, activate both of the heat pump and the fueled heater at a given time based on an air rise temperature measured across the indoor heat exchanger.

2. The system of claim 1, wherein the indoor heat exchanger and the fueled heater are located in a shared cabinet that is ducted into an airflow path of the conditioned environment.

3. The system of claim 1, wherein the fueled heater further comprises:

a firewall;

a combustion chamber located on a first side of the firewall;

a vent fan located on the first side of the firewall; and

heat exchange tubing located on a second side of the firewall, opposite to the first side, having a first diameter connected to a gas output of the combustion chamber and a second diameter, less than the first diameter, connected to an intake of the vent fan.

4. The system of claim 1, wherein the fueled heater is connected to a fuel supply that supplies a fuel to the fueled heater for combustion, the fuel including natural gas, propane, hydrogen, fuel oil, or combinations thereof.

5. The system of claim 1, further comprising an electric heater, wherein the controller is further configured to activate the electric heater in place of the fueled heater at the given time when a fuel supply for the fueled heater is below a threshold reserve level or a renewable energy source associated with the electric heater is available at a threshold generation level.

6. The system of claim 1, wherein, when the controller activates both of the heat pump and the fueled heater at the given time, the fueled heater and the heat pump each operate at between 0% and 100% of respective rated outputs.

7. The system of claim 5, wherein the controller is configured to increase an operational rate of the fueled heater when the air rise temperature is below a sufficiency threshold for the heat pump.

8. The system of claim 5, wherein controller is configured to decrease an operational rate of the fueled heater when the air rise temperature is above a sufficiency threshold for the heat pump.

9. The system of claim 1, wherein the controller is configured to adjust a triggering threshold of the air rise temperature to trigger operating both the fueled heater and the heat pump at the given time based on at least one of:

a cost of fuel for the fueled heater;

a user preference for operating the fueled heater relative to the heat pump;

a temperature in the outdoor environment at the given time;

a forecasted temperature for the outdoor environment at a future time;

a time of day of the given time; or

an amount of fuel available for the fueled heater at the given time.

10. A method for conditioning air inside a structure, comprising:

activating, by a controller, a heat pump to heat a conditioned environment inside the structure;

detecting, using a sensor, an air rise temperature across an indoor heat exchanger of the heat pump located in or in communication with the conditioned environment;

determining, using the controller, whether the air rise temperature is below a triggering threshold; and

when the air rise temperature is below the triggering threshold, activating, by the controller, a fueled heater to heat the conditioned environment contemporaneously with the heat pump at a given time.

11. The method of claim 10, further comprising, in response to detecting that the air rise temperature across the indoor heat exchanger is below the triggering threshold:

decreasing an output of the heat pump.

12. The method of claim 11, further comprising, in response to decreasing the output of the heat pump to 0% of rated output:

operating only the fueled heater to heat the conditioned environment;

detecting, using the sensor, the air rise temperature across the indoor heat exchanger at a subsequent time to the given time;

determining, using the controller, whether the air rise temperature is above a sufficiency threshold; and

when the air rise temperature is above the sufficiency threshold, activating, by the controller, the heat pump to heat the conditioned environment contemporaneously with the fueled heater.

13. The method of claim 10, further comprising, in response to determining that the air rise temperature across the indoor heat exchanger is above a sufficiency threshold while heating the conditioned environment via both the heat pump and the fueled heater:

decreasing an output of the fueled heater; and increasing an output of the heat pump.

14. The method of claim 10, further comprising:

adjusting the triggering threshold of the air rise temperature to trigger operating both the fueled heater and the heat pump contemporaneously based on at least one of:

a cost of fuel for the fueled heater;

a user preference for operating the fueled heater relative to the heat pump;

a temperature in a non-conditioned, outdoor environment outside the structure at the given time;

a forecasted temperature for the outdoor environment at a future time;

a time of day of the given time; or

an amount of fuel available for the fueled heater at the given time.

15. The method of claim 10, wherein, when the controller activates both the heat pump and the fueled heater at the given time to heat the conditioned environment, the fueled heater and the heat pump each operate between 0% and 100% of respective rated outputs.

16. The method of claim 10, further comprising:

activating an electric heater in place of the fueled heater at the given time when a fuel supply for the fueled heater is below a threshold reserve level or a renewable energy source associated with the electric heater is available at a threshold generation level.

17. The method of claim 10, wherein the indoor heat exchanger and the fueled heater are located in a shared cabinet that is ducted into an airflow path of the conditioned environment.

18. A computer readable medium including instructions, that when executed by a processor, cause the processor to perform operations including:

activating, by a controller, a heat pump to heat a conditioned environment;

detecting, using a sensor, an air rise temperature across a heat exchanger of the heat pump located in or in communication with the conditioned environment;

determining, using the controller, whether the air rise temperature is below a triggering threshold; and

when the air rise temperature is below the triggering threshold, activating, by the controller, a fueled heater to heat the conditioned environment at the same time as the heat pump at a given time.

19. The computer readable medium of claim 18, the operations further comprise, in response to detecting that the air rise temperature across the heat exchanger is below the triggering threshold:

decreasing an output of the heat pump; and

in response to decreasing the output of the heat pump to 0% of rated output: operating only the fueled heater to heat the conditioned environment; detecting, using the sensor, the air rise temperature across the heat exchanger at a subsequent time to the given time; determining, using the controller, whether the air rise temperature is above a sufficiency threshold; and when the air rise temperature is above the sufficiency threshold, activating, by the controller, the heat pump to heat the conditioned environment contemporaneously with the fueled heater.

20. The computer readable medium of claim 18, wherein, when the controller activates both the heat pump and the fueled heater at the given time to heat the conditioned environment, the fueled heater and the heat pump each operate at less than 100% of respective rated outputs.