COMBINATION HEATING SYSTEM FOR RECREATIONAL VEHICLES AND BOATS

Abstract

A combination heating system and method, including a combustion chamber, a combustion heat exchanger receiving heat from the combustion chamber, and a thermal storage reservoir. The combustion heat exchanger includes first fins extending outward from the combustion heat exchanger, and at least some of the first fins may have a profile that is at least partially curved or S-shaped. The thermal storage reservoir has an outer wall and an inner wall, and may contain a fluid such as glycol between the outer wall and the inner wall. The inner wall forms a hollow passageway through which the combustion heat exchanger extends. The thermal storage reservoir also includes second fins extending inward from the inner wall toward the combustion heat exchanger. The first fins interdigitate with the second fins in a spaced-apart manner such that airgaps exist between adjacent interdigitated ones of the first fins and the second fins.

Claims

1. A combination heating system, the system comprising: a combustion chamber; a combustion heat exchanger receiving heat from the combustion chamber, wherein the combustion heat exchanger includes first fins extending outward from the combustion heat exchanger, wherein at least some of the first fins have a profile that is at least partially curved; and a thermal storage reservoir having: an outer wall, an inner wall, wherein the thermal storage reservoir is configured to contain a fluid between the outer wall and the inner wall, wherein the inner wall forms a hollow passageway through which the combustion heat exchanger extends, and second fins extending inward from the inner wall toward the combustion heat exchanger, wherein the first fins interdigitate with the second fins in a spaced-apart manner such that airgaps exist between adjacent interdigitated ones of the first fins and the second fins.

2. The combination heating system of claim 1, wherein the profile of at least some of the first fins are S-shaped or forms at least one sinusoidal wave form.

3. The combination heating system of claim 2, wherein at least a portion of surfaces of at least some of the first fins have a plurality of ridges or a rippled or corrugated texture.

4. The combination heating system of claim 1, wherein at least some of the first fins have an end piece that is wider than a width of the profile of at least some of the first fins and, in a heated state, the first fins are configured to expand such that the end piece contacts at least one of the inner wall of the thermal storage reservoir and one of the second fins.

5. The combination heating system of claim 1, further comprising at least one exhaust pipe, wherein at least one segment of the at least one exhaust pipe is routed into the thermal storage reservoir and then routed back out from the thermal storage reservoir such that exhaust from the combustion chamber provides additional heat to the fluid in the thermal storage reservoir before being expelled out of the at least one exhaust pipe.

6. The combination heating system of claim 1, further comprising a controller and a fuel delivery system having at least three solenoid valves activated by the controller and configured to provide four or more levels of heating power based on combinations of one or more of the at least three solenoid valves being opened.

7. The combination heating system of claim 1, further comprising a fluid pump and a plate-to-plate heat exchanger fluidly coupled with the thermal storage reservoir and configured to receive the liquid pumped from the thermal storage reservoir to the plate-to-plate heat exchanger via the fluid pump.

8. The combination heating system of claim 7, further comprising water pipes that are configured to be attached to a water source and are routed through and then back out of the plate-to-plate heat exchanger to heat water flowing through the water pipes to output hot water.

9. The combination heating system of claim 7, further comprising a loop of one or more hydronic tubes configured to circulate the liquid to and from floor radiant heating systems, convectors, or other heat exchanges during hydronic operation of the combination heating system.

10. The combination heating system of claim 1, further comprising a controller configured to determine periods of low heat demand and to shut off the combustion chamber during the periods of low heat demand, while energy stored in the thermal storage reservoir continues to provide heat to be used by the combination heating system.

11. A combination heating system that combines forced air heating, domestic water heating, and hydronic heating in one self-contained system, the combination heating system comprising: a combustion chamber; a combustion heat exchanger receiving heat from the combustion chamber, wherein the combustion heat exchanger includes first fins extending outward from the combustion heat exchanger, wherein at least some of the first fins have a profile that is at least partially curved; a glycol tank having: an outer wall, an inner wall, wherein glycol is contained between the outer wall and the inner wall, wherein the inner wall forms a hollow passageway through which the combustion heat exchanger extends, and second fins extending inward from the inner wall toward the combustion heat exchanger, wherein the first fins interdigitate with the second fins in a spaced-apart manner such that airgaps exist between adjacent interdigitated ones of the first fins and the second fins; and a blower that moves heated air across or through the combustion heat exchanger.

12. The combination heating system of claim 11, wherein the profile of at least some of the first fins is S-shaped or forms at least one sinusoidal wave form.

13. The combination heating system of claim 12, wherein at least a portion of surfaces of at least some of the first fins has a rippled or corrugated texture.

14. The combination heating system of claim 11, wherein at least some of the first fins have an end piece that is wider than a width of the profile of at least some of the first fins and, in a heated state, the first fins are configured to expand such that the end piece contacts at least one of the inner wall of the glycol tank and one of the second fins.

15. The combination heating system of claim 11, further comprising at least one exhaust pipe, wherein at least one segment of the at least one exhaust pipe is routed into the glycol tank and then routed back out from the glycol tank such that exhaust from the combustion chamber provides additional heat to the glycol in the glycol tank before being expelled out of the at least one exhaust pipe.

16. The combination heating system of claim 11, further comprising a fluid pump and a plate-to-plate heat exchanger fluidly coupled with the glycol tank and configured to receive glycol pumped from the glycol tank to the plate-to-plate heat exchanger via the fluid pump.

17. The combination heating system of claim 16, further comprising water pipes that are configured to be attached to a water source and are routed through and then back out of the plate-to-plate heat exchanger to heat water flowing therethrough to output hot water.

18. The combination heating system of claim 16, further comprising a loop of one or more hydronic tubes configured to circulate glycol to and from floor radiant heating systems, convectors, or other heat exchanges during hydronic operation of the combination heating system.

19. The combination heating system of claim 11, further comprising at least one of a controller and a solenoid configured to place the combination heating system in one or more of a forced air heating mode, a domestic water heating mode, and a hydronic heating mode individually or in parallel.

20. The combination heating system of claim 19, wherein the controller is configured to determine periods of low heat demand and to shut off the combustion chamber during the periods of low heat demand, with energy stored in the glycol tank continuing to provide heat to be used by the combination heating system.

21. A method of combustion heating a recreational vehicle with a self-contained heating system that combines forced air heating, domestic water heating, and hydronic heating in one unit, wherein the method includes: activating heating of glycol in a glycol tank via a combustion chamber heating a combustion heat exchanger extending in a hollow passageway formed through the glycol tank, wherein the combustion heat exchanger includes first fins extending outward from the combustion heat exchanger toward inner walls of the hollow passageway, wherein at least some of the first fins have a profile that is S-shaped or forms at least one sinusoidal wave form; actuating a blower to move heated air across or through the combustion heat exchanger; sensing periods of low heat demand via one or more sensors or settings; and shutting off the combustion chamber during the periods of low heat demand, while energy stored in the glycol tank continues to provide heat to be used by the self-contained heating system.

22. The method of claim 21, wherein second fins extending inward from the inner wall toward the combustion heat exchanger interdigitate with the first fins in a spaced-apart manner such that airgaps exist between adjacent interdigitated ones of the first fins and the second fins.

23. The method of claim 21, wherein the first fins are aluminum and the second fins are steel.

24. The method of claim 21, further comprising selectively operating different modes of the self-contained heating system individually at different times or selectively operating two or more of the different modes in parallel simultaneously, wherein the modes include a forced air heating mode, a domestic water heating mode, and a hydronic heating mode.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0010] Embodiments of a combination heating system are described in detail below with reference to the attached drawing figures, wherein:

[0011] FIG. 1 is a front perspective view of a combination heating system in accordance with embodiments of the technology described herein;

[0012] FIG. 2 is the front perspective view of the combination heating system of FIG. 1 with a housing removed to show internal details;

[0013] FIG. 3 is a rear perspective view of the combination heating system of FIG. 2 in accordance with embodiments of the technology described herein;

[0014] FIG. 4 is the rear perspective view of the combination heating system of FIG. 3 with a thermal storage reservoir removed to show a combustion heat exchanger in accordance with embodiments of the technology described herein;

[0015] FIG. 5 is a top perspective view of the combination heating system of FIG. 4 depicting an exhaust redirect pipe in accordance with embodiments of the technology described herein;

[0016] FIG. 6 is a rear elevation view of first fins of the combustion heat exchanger of FIG. 4 in accordance with embodiments of the technology described herein;

[0017] FIG. 7 is an enlarged rear perspective view of the first fins of FIG. 6;

[0018] FIG. 8 is a cross-sectional schematic view of an optional mixing valve attachable to water output from the combination heating system of FIG. 1 in accordance with embodiments of the technology described herein;

[0019] FIG. 9 is a perspective view of a three-stage fuel delivery system for fluid connection between a fuel tank and a combustion chamber of the combination heating system of FIG. 1 in accordance with embodiments of the technology described herein;

[0020] FIG. 10 is a flow chart of a method for combustion heating a recreational vehicle with a self-contained heating system that combines forced air heating, domestic water heating, and hydronic heating in one unit in accordance with embodiments of the technology described herein;

[0021] FIG. 11A-E together form a first row of a controller flow chart depicting an example embodiment of steps and processes performed by a controller of the combination heating system based on various settings or user selections;

[0022] FIG. 12A-E together form a second row of the controller flow chart continued from FIGS. 11A-E above;

[0023] FIG. 13A-F together form a third row of the controller flow chart continued from FIGS. 12A-E above;

[0024] FIG. 14A-H together form a fourth row of the controller flow chart continued from FIGS. 13A-F above;

[0025] FIG. 15A-G together form a fifth row of the controller flow chart continued from FIGS. 14A-H above; and

[0026] FIG. 16 is a figure key depicting how to arrange each of the figures in each of the rows of the controller flow chart of FIGS. 11A-15G to display the controller flow chart in its entirety.

[0027] The drawing figures do not limit the current disclosure to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure.

DETAILED DESCRIPTION

[0028] The following detailed description of the technology references the accompanying drawings that illustrate specific embodiments in which the technology can be practiced. The embodiments are intended to describe aspects of the technology in sufficient detail to enable those skilled in the art to practice the technology. Other embodiments can be utilized and changes can be made without departing from the scope of the current disclosure. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the current disclosure is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0029] The present disclosure is directed toward a combination heating system that combines different heating modes, specifically forced air heating, hydronic heating, and domestic water heating, in one self-contained system or unit. In some embodiments, the combination heating system may include one or more controllers and a fuel delivery system configured to manage the operation of each of these heating modes (e.g., a forced air heating mode, a hydronic heating mode, and a domestic water heating mode) individually or two or more of these heating modes in parallel.

[0030] In one example embodiment, the heater is a 9 KW (31,000 btu/hour) combination domestic hot water, forced air heating and hydronic system, fueled by either propane, diesel, or gasoline, and may have a supplemental electric heating of 1.8 kW (6,142 Btu/hour). Regarding heating capacity, the combination heating system is versatile enough for multiple heating scenarios in air heating, hydronic heating, and domestic water performance (e.g., heating 1.2 gallons per minute at 49 C.). However, the combination heating system may have other specifications without departing from the scope of the disclosure herein.

[0031] The combination heating system 10, as depicted in FIGS. 1-9, comprises a housing 12, a recovery or expansion tank 14, a combustion chamber 16 coupled with an external fuel source, a combustion heat exchanger 18, and a thermal storage reservoir 20 (such as a glycol tank referenced herein) containing glycol or other such liquids (e.g., coolant) between outer walls 22 and at least one inner wall 24 forming a hollow passageway 26 through which the combustion heat exchanger 18 extends. The combination heating system 10, in one or more embodiments, further includes a coolant pump 28 to circulate the glycol or coolant, a plate-to-plate heat exchanger 30 into which the heated glycol or coolant is circulated through via the coolant pump 28, a hydronic loop of pipes 32, and a domestic hot water loop of pipes 34 extending through portions of the plate-to-plate heat exchanger 30. In some embodiments the combination heating system 10 additionally or alternatively includes combustion air/exhaust pipes 36, which may include an exhaust redirect pipe 38 routed through the thermal storage reservoir 20, as later described herein.

[0032] In some embodiments, for domestic water heating purposes, the combination heating system 10 may further include an optional mixing valve 40 (e.g., see FIG. 8) placed outside the combination heating system 10 at an output of the domestic hot water loop of pipes 34 to protect the unit against scalding water temperatures. Furthermore, particularly for forced air heating, the combination heating system 10 may also comprise an air return entry 42, at least one air fan or blower 44, and at least one vent or plenum (not shown). In some embodiments, the combination heating system 10 further comprises a controller 46 having processing elements, a memory, and/or a user interface. The controller 46 may be configured to switch the combination heating system 10 between a plurality of modes later described herein (e.g., for forced air heating, domestic water heating, and/or hydronic heating in one self-contained system). The controller 46 may be configured to selectively run these various heating modes individually or to selectively run two or three of these various heating modes in parallel.

[0033] Turning to FIGS. 1-3, the recovery or expansion tank 14 may be fluidly coupled with the thermal storage reservoir 20, such that when the coolant or glycol in the thermal storage reservoir 20 expands during heating thereof, extra coolant or glycol can flow into the expansion tank 14. Likewise, when the coolant or glycol cools and contracts, the extra coolant or glycol can flow back into the expansion tank 14.

[0034] The fuel source or fuel tank (not shown) may be any external source of fuel, such as fuel from a vehicle associated with the recreational vehicle (e.g., the gas tank of the vehicle to which the mobile home or the like is attached) or an alternative auxiliary fuel tank. Though the fuel source may correspond with the same source of fuel used for the vehicle's engine, the combination heating system 10 herein may be operatable while the vehicle engine is on or off without departing from the scope of the technology herein. The fuel source may be fluidly coupled with the combustion chamber 16 for fueling operation thereof. The fuel source may contain therein a pressurized gas or liquid fuel such as propane, diesel, or gasoline. However, in some alternative embodiments the fuel source may include other external or internal fuel tanks or fuel sources without departing from the scope of the technology described herein.

[0035] In some embodiments, the combination heating system 10 also includes a three-stage fuel delivery system 48 (as depicted in FIG. 9) that provides, for example, four or five levels of heating power associated with the fuel source. The fuel delivery system 48 may have solenoid valves 50 (e.g., three solenoid valves) operatable by a user interface and/or the controller 46 and those solenoid valves 50 may be configured to provide four or more levels of heating power based on which one of the solenoid valves 50 or which combination of the solenoid valves 50 are open. The fuel is provided from the solenoid valves 50 to an input port in the combustion chamber 16. In other embodiments, the three-stage fuel delivery system 48 may be provided with additional solenoid valves for even greater flexibility in an amount of fuel delivered to the combustion chamber 16 without departing from the scope of the technology herein.

[0036] The combustion chamber 16 or combustion furnace may be any combustion chamber or combustion furnace known in the art. For example, the combustion chamber 16 can include a combustion motor or combustion engine, an intake fan 52 for introducing air that is mixed with the fuel for combustion, a burner, and a confined space therein where fuel and oxygen are mixed and ignited to create energy/heat. This combustion ignites the burner, which is used to heat air within the combustion heat exchanger 18 (e.g., via a flame provided from the burner). The combustion chamber 16 or combustion furnace may provide heat directly to the combustion heat exchanger 18 via the burner or the flame extending therefrom being located proximate to or in direct contact with the combustion heat exchanger 18.

[0037] The combustion heat exchanger 18 may be made of metal such as aluminum and may be configured to transfer heat generated from the combustion process (e.g., burning fuel) of the combustion chamber 16 to the surrounding air, allowing useful heat to be utilized while safely exhausting combustion byproducts outside the combination heating system 10. In some embodiments, the combustion heat exchanger 18 is configured to separate hot combustion gases from air being heated, preventing toxic fumes from entering living spaces, cabins, or rooms within a recreational vehicle, for example. Specifically, as depicted in FIG. 5, one or more embodiments of the combustion air/exhaust pipes 36 include at least one exhaust pipe receiving exhaust from the combustion chamber 16. Furthermore, in some embodiments, at least one segment of the exhaust pipe 36, referred to herein as the exhaust redirect pipe 38, is routed into the thermal storage reservoir 20 and then routed back out from the thermal storage reservoir 20 such that exhaust from the combustion chamber 16 provides additional heat to the coolant or fluid (e.g., the glycol) in the thermal storage reservoir 20 before the exhaust is then expelled out of the at least one exhaust pipe 36. In this configuration, exhaust from combustion routed through the thermal storage reservoir 20 improves heating efficiency and reduces exhaust temperatures output from the combustion air/exhaust pipes 36. In some alternative embodiments, the thermal storage reservoir 20 may use water instead of glycol and provide heated water directly for vehicle occupant use. However, this alternative system may not be capable of heating auxiliary hydronic equipment as disclosed in the glycol embodiments described herein.

[0038] In one or more of the embodiments as depicted in FIGS. 4-7, the combustion heat exchanger 18 is an elongated hollow metal cylinder, however other elongated hollow shapes can be used without departing from the scope of the technology described herein. Furthermore, in one or more of the embodiments, the combustion heat exchanger 18 includes a plurality of spaced-apart first fins 54 extending outward from a surface of the combustion heat exchanger 18, such as radially outward from the cylinder thereof. The first fins 54 may be made of aluminum or may alternatively be made of other metals or metal alloys.

[0039] In some embodiments, the first fins 54 are designed to expand and contract and have a shape that protects against stress fracturing resulting from the expansion and contraction. Specifically, in some embodiments of the present disclosure, the expansion of the aluminum during heating may contact the thermal storage reservoir 20 or glycol tank, accelerating heat conduction. Furthermore, the first fins 54 may have a curved profile, such as an S-shaped profile or a profile that forms at least one sinusoidal wave form. This curved profile may provide stress relief during the first fins' expansion and contact with the thermal storage reservoir 20 or glycol tank, while also providing increased surface area for heat transfer during air flow heating. The first fins 54 are not required to be bonded to the thermal storage reservoir 20, in part due to the added strength provided by the curvature of the first fins 54. Because of this lack of bonding, the first fins 54 can also advantageously contract away from the thermal storage reservoir 20 during increased air flow. So in their heated and expanded form, the first fins 54 can contact the inner wall 24 and thus increase heat transfer from the thermal storage reservoir 20 to the air flow stream during low interior heating demands and likewise prevent the thermal storage reservoir 20 from overheating during forced air heating operation, wherein the forced air can cool the first fins 54 to contract away from the inner wall 24. Furthermore, in some embodiments, at least a portion of surfaces of at least some of the first fins 54 has a rippled or corrugated texture 56 or ridges. This assists in providing more efficient heat transfer. Furthermore, the rippled or corrugated texture 56 or ridges increase turbulent air flow that further improves the heat transfer from the first fins 54 to the forced air. The curve, e.g., S-shape, or sinusoidal wave, may be formed in a generally radial direction from the combustion heat exchanger 18, with the profile of the first fins 54 extending along a length of the combustion heat exchanger 18 in an axial or longitudinal direction relative thereto. In some embodiments, the first fins 54 may be designed to touch the inner wall 24 of the thermal storage reservoir 20 (e.g., the glycol tank) for improved heat transfer thereto, especially during demands for domestic water heating when the thermal storage reservoir 20 needs to be kept at a desired temperature, maximizing heat transfer.

[0040] At least some of the first fins 54 may have a first end piece 58 that is wider than a width of the profile (e.g., a first web 60) of the first fins 54 and, in a heated state, the first fins 54 may be configured to expand such that the first end piece 58 contacts the inner wall 24 of the thermal storage reservoir 20 (and/or fins extending from the inner wall 24, as later described herein). In one or more embodiments, the first fins 54 may have a much smaller air gap between the first end pieces 58 and the thermal storage reservoir 20 or glycol tank, than prior art fins used for water tank heating, which traditionally have a larger air gap in order to avoid boiling of the water in the water tank. This boiling can be avoided in the present system through the use of glycol instead of water in the glycol tank or thermal storage reservoir 20 described herein. Furthermore, air between the fins described herein acts as an insulator and reduces heat conduction and convection.

[0041] The thermal storage reservoir 20 or glycol tank, as depicted in FIGS. 2-3, may be shaped and configured to substantially surround at least a portion of the combustion heat exchanger 18 within the hollow passageway 26. The hollow passageway 26 is configured such that air flows therethrough while glycol or another such fluid is retained between the outer walls 22 and the inner wall 24. In this configuration, the combustion heat exchanger 18 does not come into contact with glycol or coolant in the glycol tank or the thermal storage reservoir 20, for example. The thermal storage reservoir 20 or glycol tank may further comprise second fins 62 that extend inward from the inner wall 24 toward the combustion heat exchanger 18 and interdigitate with the first fins 54 in a spaced-apart manner. Specifically, the second fins 62 may extend inward from the inner wall 24 on an air flow side thereof. The second fins 62 may be made of a metal such as steel, or a metal alloy.

[0042] In some embodiments, the second fins 62 do not have a curved profile. The second fins 62 may be substantially T-shaped in some example embodiments, extending from the inner wall 24 to a perpendicular end portion. For example, at least some of the second fins 62 may have a second end piece 64 that is wider than a width of the profile (e.g., a second web 66) of the second fins 62. In a non-heated state, the first fins 54 do not touch the inner wall 24 of the thermal storage reservoir 20. However, in the heated state, the first fins 54 may expand such that a portion of at least some of the first fins 54 makes contact with the inner wall 24 and/or a portion of the second fins 62. This is advantageous over prior art systems, which have not heated a glycol tank from an interior combustion heat exchanger extending therethrough. Additionally, the second fins extending from the inner wall 24 of the thermal storage reservoir 20 or glycol tank can transfer heat (e.g., from heated glycol in the glycol tank) to the air flow during low interior heating demands.

[0043] The second fins 62 and the first fins 54 do not generally touch each other, but rather are spaced apart to allow heated air to flow therebetween, as depicted in FIGS. 6 and 7. The linear thermal expansion of the first fins 54, along with the curved, e.g., sinusoidal or S-shape, of the first fins 54, allows the first end pieces 58 to expand toward the inner wall 24 of the thermal storage reservoir 20 and/or to make physical contact with the inner wall 24 of the thermal storage reservoir 20. In one specific example, one of the first fins 54 may have the following specifications during combustion with low or now air flow: first fin length (along its arcuate, curved profile from the combustion heat exchanger 18 to the first end piece 58) of 1.222 inches, a radial fin height of 0.986 inches, and a total distance from the combustion heat exchanger 18 to the inner wall 24 of 0.984 inches, leaving an air gap of approximately 0.023 inches between the first end piece 58 and the inner wall 24. The arcuate, curved profile or the first web 60 beneficially provides fatigue relief when expansion of the aluminum presses the first end piece 58 into contact with the inner wall 24. Additionally, the arcuate, curved shape provides an increased length of the web, providing a desired amount of growth or expansion such that when heated the first fins 54 grow enough to traverse the air gap and make contact with the inner wall 24, to facilitate heat transfer between the combustion heat exchanger 18 and the thermal storage reservoir 20.

[0044] An exemplary equation describing variation in object length in inches for the first fins 54 is provided below:

[00001]$L=LT$

with L being the variation in object length (inches); being the linear expansion coefficient (1/ F.); L being the object's original length (inches); and T being the temperature change ( F.). In accordance with this example embodiment, some example values for each of these are provided below:

[00002]$\begin{array}{c}=12.310^{-6}/F.\left(\mathrm{for}\mathrm{aluminum}6000\mathrm{series}\right)\\ L=1.25\mathrm{in}.\left(\mathrm{arc}\mathrm{of}\mathrm{the}\mathrm{first}\mathrm{web}60\mathrm{is}\mathrm{included}\mathrm{in}\mathrm{material}\mathrm{length}\right)\\ T=70-1700F.\left(\mathrm{ambient}\mathrm{to}\mathrm{combustion}\mathrm{chamber}\mathrm{exterior}\mathrm{temperature}\right)\\ L=0.025\mathrm{in}.\end{array}$

However, other values may be used without departing from the scope of the technology herein.

[0045] The coolant pump 28, as depicted in FIGS. 3-4, may be any fluid pump configured for pumping liquid such as water, glycol, or the like, throughout the combination heating system 10. For example, the coolant pump 28 may be a 12V water pump or may be powered by other amounts and by any electric power source (e.g., a battery). In some embodiments, the coolant pump 28 is fluidly coupled with an input and an output port of the plate-to-plate heat exchanger 30, pumping heat into and out of the plate-to-plate heat exchanger 30 to provide heat thereto from the heated glycol or coolant in the thermal storage reservoir 20, for example.

[0046] The plate-to-plate heat exchanger 30, as depicted in FIGS. 2, 3, and 5, is a device that transfers heat between two fluids by stacking thin metal plates in parallel to create channels for the fluids to flow through. The plate-to-plate heat exchanger 30 may consist of a series of parallel plates that are spaced so as to allow the formation of a series of channels for fluids to flow between them. The space between two adjacent plates forms a channel in which the fluid flows. In one example embodiment, gaskets between the plates control fluid flow, allowing one fluid to flow through one gap and another fluid to flow through the adjacent gap. The plate-to-plate heat exchanger 30 may have a water input port and a water output port as well as a coolant input port and a coolant output port, for example. The water input port and the water output port may be coupled to input and output pipes of the domestic hot water loop of pipes 34 described below. In some embodiments, a flow meter may be placed at the water input port to determine water flow rate (e.g., gallons per minute) to be communicated to the controller 46 as feedback for use thereby and/or for use in controlling the fuel delivery system 48. The coolant input port and the coolant output port may each be fluidly coupled to the thermal storage reservoir 20 or the glycol tank with various internal pipes, with the coolant pump 28 associated with one of the internal pipes and located between a fluid outlet of the thermal storage reservoir 20 and at least one of the coolant input port and the coolant output port for pumping coolant such as glycol therethrough.

[0047] The hydronic loop of pipes 32 may allow glycol to flow to and from various systems of the recreational vehicle. For example, the hydronic loop of pipes 32 may send heated glycol or coolant from the glycol tank or the thermal storage reservoir 20 to a radiant floor or an external heat exchanger (e.g., a 12V heat exchanger, a fin/tube heat exchanger where it is not possible to run heating air ducts, etc.), and then from the radiant floor or the external heat exchanger back, via an external pump, into the glycol tank or thermal storage reservoir 20 to again be heated. In some alternative embodiments, an internal or external pump may be used to circulate glycol or other coolants to and from external systems like the radiant floor without departing from the scope of the technology herein.

[0048] The domestic hot water loop of pipes 34 may provide a path for water to circulate to and from various systems of the recreational vehicle. For example, the domestic hot water loop of pipes 34 may allow heated water to flow from the plate-to-late heat exchanger 30 to a water output like a sink faucet or a shower head or alternatively may send the heated water out to the mixing valve 40 or a similar water temperature control safety device configured to protect against scalding water temperatures. In some embodiments, an internal or external pump may be used to circulate domestic water to and from external systems like the mixing valve 40 or faucets without departing from the scope of the technology herein.

[0049] The air return entry 42 can be any vent, grate, or other opening through which air may be pulled from outside the combination heating system 10 to inside the combination heating system 10. The air fan or blower 44 may comprise, for example, a rotary motor attached to fan blades and operable to rotate the fan blades to blow air from outside to inside various compartments of the combination heating system 10, such as in the hollow passageway 26 of the thermal storage reservoir 20. As used herein, the plenum may be ductwork fluidly connected for air to flow into or alternatively may be a space such as above a ceiling or below a floor that is used to facilitate the transfer of air.

[0050] The controller 46 of the combination heating system 10, as depicted in FIG. 1, comprises processing elements, a memory, and/or a user interface to switch the combination heating system 10 between the plurality of modes as described in more details below. The processing elements are also described in more detail herein below, but generally may include any processors, microprocessors, computers, control circuitry, or the like, and the memory may include any data storage circuitry known in the art. Furthermore, the user interface may include switches, levers, knobs, buttons, keypads, keyboards, display screens, touch screens, or any electronic means for providing operational data or settings adjustments to the controller 46. In some embodiments, the user interface may further comprise remotely located smart phone, tablet, computer, or the like controlled by a user to provide remote changes to settings and modes of the combination heating system 10 as described below, such as byway of apps or software steps executed thereon and information sent and received via the internet or other wireless communication means.

[0051] Additionally or alternatively, in some embodiments of the combination heating system 10 described herein, the three-stage fuel delivery system 48 described above is operated by the controller 46 and may be configured to provide four levels of heating power, such as the levels provided in the table below, based on which one of the solenoid valves 50 or combination of the solenoid valves 50 are open.

TABLE-US-00001 TABLE 1 Heating Input Propane Diesel/Gasoline Capacity Solenoid Fuel Delivery kW~Btu/hr. Application 1 17% Delivery 1.85~6,313 Low Air Heating - Rate Hydronic Mode - Domestic Water Demand < 0.4 gpm* (*gallons per minute) 1 + 2 27% Delivery 2.9~9,895 Medium Air Heating Rate Mode - Hydronic Mode - Domestic Water Demand 0.4 gpm 1 + 3 73% Delivery 7.85~26,787 Medium High Air Heating - Rate Hydronic Mode - Domestic Water Demand 0.65 gpm to 1 gpm 1 + 2 + 100% Delivery 10.75~36,680 High Air Heating Mode. 3 Rate Domestic Water Heating Mode - Domestic Water Demand > 1 gpm

[0052] The three-stage fuel delivery system may be relevant for various situations that require switching between lower and higher heat outputs and/or switching between different modes as described herein or simultaneously running in a plurality of the modes (which may require a different amount of heat or fuel). In one example embodiment, when a recreational vehicle is cold and needs to be heated, additional heat (e.g., more fuel) is needed. When the recreational vehicle is already warm, the combination heater system may need to cycle on to maintain interior heat, and the demand for fuel or heat output will be less. These scenarios will typically use 1-2 stages of the solenoid or solenoid valves 50. The 3rd stage may be used when there is a demand for domestic water heating and greater power is needed to maintain the thermal storage reservoir 20 or glycol tank's coolant temperature (remembering the glycol from the glycol tank may be sent to a plate-to-plate heat exchanger 30 to transfer heat to domestic water). In some embodiments, different quantities of solenoid valves 50 may be used (e.g., a four-stage fuel delivery system) for the fuel delivery system without departing from the scope of the technology described herein.

[0053] Furthermore, the three-stage fuel delivery system 48 (e.g., the solenoid valves 50) is described above as having 4 levels of heating power. However, in other embodiments, the three-stage fuel delivery system 48 (or a fuel delivery system having other quantities of stages) may provide a different quantity of levels without departing from the scope of the technology herein. For example, the three-stage fuel delivery system 48 may alternatively provide 5 levels of performance or heating power depending which valves are opened. For example, the following heating input capacity in kWBtu/hr may be as follows: [0054] 6800 (low). [0055] 13600 (medium-low). [0056] 20400 (medium). [0057] 27300 (medium-high). [0058] 34200 (high).

[0059] The three-stage fuel delivery system 48 may be configured for use on propane-fueled versions of the combination heating system 10 described herein, since such fuel is gaseouspressurized fuelcontrolled by opening/closing solenoids or solenoid valves at specified orifice sizes. The diesel-fueled and/or gasoline-fueled versions may have a different fuel delivery system for liquid fuel, such as by means of a metering pump. The metering pump pulse cycle may be changed depending on the heating needs in such alternative embodiments.

[0060] In operation in a forced air heating mode, air entering via the air return entry 42 is blown via the air fan or blower 44 into the hollow passageway 26 and over the first fins 54 of the combustion heat exchanger 18 (e.g., between the combustion heat exchanger 18 and the inner wall 24 of the thermal storage reservoir 20 (e.g., the glycol tank) through the air gap between the first fins 54 and the second fins 62). Air then exits the combustion heat exchanger 18 and exits the plenum at the opposing end of the hollow passageway 26, then entering a room or interior cabin of a recreational vehicle and/or duct work thereof for providing forced air heating to the room or interior cabin.

[0061] In a domestic water operation mode, the fluid or glycol in the glycol tank or thermal storage reservoir 20 is heated via the combustion chamber 16 and the combustion heat exchanger 18 in the hollow passageway 26, and this heated fluid or glycol is pumped through the plate-to-plate heat exchanger 30. Meanwhile, the domestic water is also made to flow through the plate-to-plate heat exchanger 30 (e.g., flowing through a second circuit in the plate-to-plate heat exchanger 30) to be heated therein. Furthermore, as described above, the mixing valve 40 may be installed outside of the combination heating system 10 and may mix water of differing temperatures in a manner so as to protect against scalding water temperatures. However, the mixing valve 40 may be omitted without departing from the scope of the technology described herein.

[0062] In a hydronic operation mode, the fluid or glycol in the glycol tank or thermal storage reservoir 20 is heated via the combustion chamber 16 and the combustion heat exchanger 18 in the hollow passageway 26, and this heated fluid or glycol is pumped via coolant pump 28 through the plate-to-plate heat exchanger 30. In the hydronic operation mode, the hydronic loop of pipes 32 may circulate glycol or other such coolants to and from the radiant floor or external heat exchanger and then from the radiant floor or the external heat exchanger back into the thermal storage reservoir 20 or glycol tank to again be heated. The hydronic loop of pipes 32 may also be attached to provide remote heating for a fin tube/air heat exchanger. This fin tube/air heat exchanger may be used to heat exterior recreational vehicle compartments such as water base or water storage tanks in some embodiments.

[0063] One or more of the modes described above may operate simultaneously or be operated separately based on user commands or settings. Advantageously, the heater burner (e.g., the combustion chamber 16) does not need to operate during low heating demands to maintain interior temperature. The energy stored in the thermal storage reservoir 20 or glycol tank may be used in those situations, with the controller 46 automatically turning off or turning down the combustion chamber 16 during such instances. Yet another advantage of the system and method described herein is that the exhaust from combustion being routed through the thermal storage reservoir 20 improves heating efficiency (e.g., the heated exhaust assists in heating the glycol or coolant in the thermal storage reservoir 20) and reduces exhaust temperatures output from the combustion air/exhaust pipes 36. Furthermore, due to the heating of glycol or coolant in the thermal storage reservoir 20 being accelerated with the aluminum fins in contact with the thermal storage reservoir 20, the combustion heat exchanger 18 may operate at lower temperatures and may output lower exhaust temperatures, thereby increasing the efficiency of the combination heating system 10 herein. Specifically, some embodiments of the combination heating system 10 described with the fin configuration herein can allow extracting heat from the thermal storage reservoir 20 (e.g., the glycol tank and/or the coolant or glycol heated therein) for lower interior air heating requirements, below lowest burner output (e.g., less than 6,300 btu/hour).

[0064] Method steps for an exemplary method of combustion heating a recreational vehicle with a self-contained heating system that combines forced air heating, domestic water heating, and hydronic heating in one unit will now be described in more detail, in accordance with various embodiments of the present disclosure. The steps of method 1000 may be performed in the order as shown in FIG. 10, or they may be performed in a different order. Furthermore, some steps may be performed concurrently as opposed to sequentially. In addition, some steps may not be performed.

[0065] In some example embodiments, a method of combustion heating a recreational vehicle with a self-contained heating system that combines forced air heating, domestic water heating, and hydronic heating in one unit may include activating heating of glycol in the thermal storage reservoir 20 (e.g., the glycol tank) via the combustion chamber 16 heating the combustion heat exchanger 18, as depicted in block 1002. This step may include activating the opening of any combination of the solenoid valves to provide four or more levels of heating power based on combinations of one or more of the at least three solenoid valves being opened. As described above, the combustion heat exchanger 18 extends in the hollow passageway 26 formed through the thermal storage reservoir 20 and includes the first fins 54 extending outward from the combustion heat exchanger 18 toward inner walls 24 of the hollow passageway 26. At least some of the first fins 54 have a profile that is curved, such as S-shaped or forms at least one sinusoidal wave form, in order to provide stress relief during the first fins' expansion and contacting of the thermal storage reservoir 20 or glycol tank while providing additional heat exchange surface area during air flow heating.

[0066] The method may also include actuating a blower for moving heated air across the combustion heat exchanger 18, as depicted in block 1004, and sensing periods of low heat demand via one or more sensors or settings, as depicted in block 1006. The method may also include a step of shutting off the combustion chamber 16 during the periods of low heat demand, as depicted in block 1008, while energy stored in the thermal storage reservoir 20 (e.g., the glycol tank) continues to provide heat to be used by the self-contained combination heating system 10.

[0067] The method may also comprise selectively operating different modes of the self-contained heating system individually at different times or selectively operating two or more of the different modes in parallel simultaneously, as depicted in block 1010. As described in more detail above, the modes may include a forced air heating mode, a domestic water heating mode, and a hydronic heating mode. The method may also include receiving other optional user selections as depicted in block 1012. These optional user selections may include, for example, desired temperatures of water (e.g., high or low), priority selections (e.g., indicating which of the modes should be given priority when multiple ones of the modes are in use), whether the burner or electric sources are operated on low or high, whether operation of certain functions is automatic or manual, and whether a boost is desired to more quickly warm up the recreational vehicle.

[0068] An example controller flow chart is shown in FIGS. 11A-15G and depicts processes for monitoring and controlling the multiple heating modes described above. A figure key depicting how to arrange each of the figures in each of the rows of the controller flow chart of FIGS. 11A-15G, in order to display the controller flow chart in its entirety, is depicted in FIG. 16. The example controller flow chart provides various decision branches for the modes described herein, such as the forced air heating mode (referred to as interior in the flow chart), the hydronic heating mode (referred to as hydronic in the flow chart), and the domestic water heating mode (referred to as water in the flow chart), and also depicts some or all of those modes being operated simultaneously and/or in parallel. Beginning at START in the middle of FIG. 13F, the controller 46 may receive a selection from a user to switch to any one or more of the modes described herein and depicted in FIGS. 11A-15G. Additionally or alternatively, which of the modes is selected may be based on user settings, sensor readings, or the like. In some example control flows depicted herein, automatic or manual modes may be used, such that air volume is adjusted manually or automatically, depending upon which option is selected. Furthermore, in some embodiments, a boost is selected, which runs one or more of the fans or blowers described herein at maximum speed (e.g., MAX) for a first internal heat cycle, for example. This allows a desired heat to be reached more quickly and then maintained thereafter. In some embodiments, an internal heating priority mode may be turned on, which may automatically impact which modes are operated simultaneously and which modes are turned off while other modes are used (e.g., when using hot water, turning off the forced air heating and/or the hydronic heating). As can be seen, different control paths may be taken by the controller 46 depending upon whether water is set on high or low heat, in addition to whether or not internal heating priority is on (e.g., if internal heating priority is off, water heating may take priority for example), and whether auto or manual control is selected. Note that the temperatures provided are merely exemplary and other temperature ranges and limits may be used without departing from the scope of the technology herein.

[0069] Some example issues encountered by the combination heating system 10 are now described in detail herein, including ways in which the controller 46 can be configured or programmed to respond. For example, if the following situation exists:

TABLE-US-00002 User Setting = Water High On AND Interior Heat Tank has reached High temperature mode at 75 - 90C (167-194F) User Setting Changed = Water Low On at 60 - 75C (140-167F)
then a problem faced in the combination heating system 10 herein may be that the burner of the combustion chamber 16 may stop or not turn on due to the glycol tank temperature being reached. Furthermore, air heating may not be available with the burner or combustion chamber 16 in the off state. However, a resolution may be achieved via the controller 46 described herein, which may be configured to allow air heat and ignore the glycol tank temperature. Furthermore, the controller 46 may also be configured to adjust air flow and burner rate to avoid further rise in the glycol tank temperature in this situation.

[0070] In another example issue encountered by the combination heating system 10 described above, if the following situation exists:

TABLE-US-00003 User Setting = Interior Heat On AND Hydronic Heat On Control of two zones - two modes of the heater operation to maintain air flow temperatures and glycol tank temperature.
then a problem faced in the combination heating system 10 herein may be that when the interior temperature is close to a set point, the burner or combustion chamber's power will be reduced, reducing the glycol tank temperatures and the glycol for the hydronic loop of pipes 32. When the hydronic loop temperature is reached, even though interior temperature was not reached), there may be a probability of the glycol tank overheating. However, a resolution may be achieved via the controller 46 described herein, which may be configured to adjust the air flow and the burner rate to avoid further rise in the glycol tank temperature in this situation. Furthermore, the controller 46 may monitor the glycol tank temperature to reduce the burner rate or switch off the burner as needed to prevent overheating. For example, if the burner goes to a lower state when the glycol in the glycol tank equals 80 C. If the temperature continues to rise, the burner may be placed into a lower rate via the controller 46, and at 85 C., for example, the burner may be switched off by the controller 46.

[0071] Note that these example problems and resolutions handled by the controller 46 and/or other elements of the combination heating system 10 as described above are merely exemplary and may be adjusted, omitted, or the like without departing from the scope of the disclosure. For example, the precise temperatures described above may be adjusted or replaced with other values without departing from the technology described herein, and/or the temperatures instead may be within a range of plus or minus 5 or 10 C. from the temperatures described above.

[0072] Throughout this specification, references to one embodiment, an embodiment, or embodiments mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to one embodiment, an embodiment, or embodiments in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc. described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the heater currently disclosed can include a variety of combinations and/or integrations of the embodiments described herein.

[0073] Although the present application sets forth a detailed description of numerous different embodiments, it should be understood that the legal scope of the description is defined by the words of the claims set forth at the end of this patent and equivalents. The detailed description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical. Numerous alternative embodiments may be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims.

[0074] Throughout this specification, plural instances may implement components, operations, or structures described as a single instance. Although individual operations of one or more methods are illustrated and described as separate operations, one or more of the individual operations may be performed concurrently, and nothing requires that the operations be performed in the order illustrated. Structures and functionality presented as separate components in example configurations may be implemented as a combined structure or component. Similarly, structures and functionality presented as a single component may be implemented as separate components. These and other variations, modifications, additions, and improvements fall within the scope of the subject matter herein.

[0075] Certain embodiments are described herein as including logic or a number of routines, subroutines, applications, or instructions. These may constitute either software (e.g., code embodied on a machine-readable medium or in a transmission signal) or hardware. In hardware, the routines, etc., are tangible units capable of performing certain operations and may be configured or arranged in a certain manner. In example embodiments, one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware modules of a computer system (e.g., a processor or a group of processors) may be configured by software (e.g., an application or application portion) as computer hardware that operates to perform certain operations as described herein.

[0076] In various embodiments, computer hardware, such as the controller 46 or a processing element thereof, may be implemented as special purpose or as general purpose. For example, the processing element may comprise dedicated circuitry or logic that is permanently configured, such as an application-specific integrated circuit (ASIC), or indefinitely configured, such as an FPGA, to perform certain operations. The processing element may also comprise programmable logic or circuitry (e.g., as encompassed within a general-purpose processor or other programmable processor) that is temporarily configured by software to perform certain operations. It will be appreciated that the decision to implement the processing element as special purpose, in dedicated and permanently configured circuitry, or as general purpose (e.g., configured by software) may be driven by cost and time considerations.

[0077] Accordingly, the term processing element or equivalents should be understood to encompass a tangible entity, be that an entity that is physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein. Considering embodiments in which the processing element is temporarily configured (e.g., programmed), each of the processing elements need not be configured or instantiated at any one instance in time. For example, where the processing element comprises a general-purpose processor configured using software, the general-purpose processor may be configured as respective different processing elements at different times. Software may accordingly configure the processing element to constitute a particular hardware configuration at one instance of time and to constitute a different hardware configuration at a different instance of time.

[0078] Computer hardware components, such as communication elements, memory elements, processing elements, and the like, may provide information to, and receive information from, other computer hardware components. Accordingly, the described computer hardware components may be regarded as being communicatively coupled. Where multiple of such computer hardware components exist contemporaneously, communications may be achieved through signal transmission (e.g., over appropriate circuits and buses) that connect the computer hardware components. In embodiments in which multiple computer hardware components are configured or instantiated at different times, communications between such computer hardware components may be achieved, for example, through the storage and retrieval of information in memory structures to which the multiple computer hardware components have access. For example, one computer hardware component may perform an operation and store the output of that operation in a memory device to which it is communicatively coupled. A further computer hardware component may then, at a later time, access the memory device to retrieve and process the stored output. Computer hardware components may also initiate communications with input or output devices, and may operate on a resource (e.g., a collection of information).

[0079] The various operations of example methods described herein may be performed, at least partially, by one or more processing elements that are temporarily configured (e.g., by software) or permanently configured to perform the relevant operations. Whether temporarily or permanently configured, such processing elements may constitute processing element-implemented modules that operate to perform one or more operations or functions. The modules referred to herein may, in some example embodiments, comprise processing element-implemented modules.

[0080] Similarly, the methods or routines described herein may be at least partially processing element-implemented. For example, at least some of the operations of a method may be performed by one or more processing elements or processing element-implemented hardware modules. The performance of certain of the operations may be distributed among the one or more processing elements, not only residing within a single machine, but deployed across a number of machines. In some example embodiments, the processing elements may be located in a single location (e.g., within a home environment, an office environment or as a server farm), while in other embodiments the processing elements may be distributed across a number of locations.

[0081] Unless specifically stated otherwise, discussions herein using words such as processing, computing, calculating, determining, presenting, displaying, or the like may refer to actions or processes of a machine (e.g., a computer with a processing element and other computer hardware components) that manipulates or transforms data represented as physical (e.g., electronic, magnetic, or optical) quantities within one or more memories (e.g., volatile memory, non-volatile memory, or a combination thereof), registers, or other machine components that receive, store, transmit, or display information.

[0082] As used herein, the terms comprises, comprising, includes, including, has, having or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0083] The patent claims at the end of this patent application are not intended to be construed under 35 U.S.C. 112(f) unless traditional means-plus-function language is expressly recited, such as means for or step for language being explicitly recited in the claim(s).

[0084] Although the technology has been described with reference to the embodiments illustrated in the attached drawing figures, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the technology as recited in the claims.