Patent Application
20130276722
The present disclosure relates to apparatus and methods in which thermal insulation is used to provide a thermal break and/or thermally insulative barrier between the body and flange assembly of a gas water heater control.
This section provides background information related to the present disclosure which is not necessarily prior art.
Storage water heaters may be utilized domestically and industrially in various applications. Domestically, a storage water heater is used for generation of hot water that may be used for bathing, cleaning, cooking, space heating, and the like.
A conventional gas fired water heater includes a water storage tank and gas fired burner assembly for heating water within the tank. In operation, combustion gases generated by the firing of the burner assembly may be directed upwardly through a flue pipe via a hood. The combustion gases serve to transfer heat to the water contained within the storage tank. The top of the water heater may include suitable fittings for connection to a supply of water and a water distribution system with a water inlet provided with a dip tube, which serves to direct the inflow of cold water to the bottom of the tank.
Additionally, the water heater includes a control, controller, or control system for controlling the supply of gas to the burner assembly in response to the sensed temperature of the water within the tank. For example, if the water temperature reaches a preset temperature, the control will close the valve supplying the fuel (e.g., natural gas, propane, etc.) to the burner assembly. Closing the valve discontinues the supply of fuel to the burner assembly, which shuts down or turns off the burner assembly.
A typical gas valve used on conventional, storage-type gas water heaters includes an aluminum body, a brass flange, and a copper tube. The copper tube is attached (e.g., usually threaded, etc.) to the brass flange. The brass flange is attached (e.g., usually with screws, etc.) to the body of the gas valve. The brass flange is threaded to mate and provide a leak-tight seal with a threaded hole in the water heater tank. The copper tube extends several inches into the water tank and serves as the temperature sensing device for the system. The copper tube expands and contracts (in length) in response to changes in water temperature. When hot water is drawn from the tank, cold water enters the tank. When cold water hits the copper tube, it contracts. This movement is what actuates the gas valve by pushing on a rod. The rod pushes on a lever, which opens the valve via a series of springs. As the water heats up, this process is reversed and the valve shuts off. This type of system may be known as or referred to as “Rod & Tube” system.
By way of example,
The electronic control 200 shown in
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
According to various aspects, exemplary embodiments are disclosed in which thermal insulation is used to provide a thermal break and/or thermally insulative barrier generally between a body and flange assembly of a gas water heater control. An exemplary embodiment of a valve assembly for a water heater generally includes a flange, a body, and a thermal insulator. The thermal insulator is configured for placement generally between the body and the flange. The thermal insulator has a lower thermal conductivity than the flange and the body. The thermal insulator is operable for inhibiting heat loss from within the storage tank through the valve assembly.
Another exemplary embodiment includes a valve assembly for adjusting fuel flow in a fuel-fired water heater having a storage tank. In this example, the valve assembly generally includes a thermal insulator and a first component configured to be coupled to the storage tank. A second component is coupled to the first component with the thermal insulator generally between the first and second components. A third component is coupled to the first component. The third component is configured to extend at least partially into the storage tank for sensing temperature of water within the storage tank when the first component is coupled to the storage tank. The thermal insulator has a lower thermal conductivity than the first, second, and third components for inhibiting heat loss from within the water storage tank through the valve assembly.
Also disclosed are exemplary embodiments of methods for inhibiting heat loss from a storage tank of a water heater through a valve assembly of the water heater. In an exemplary embodiment, a method generally includes positioning a thermal insulator generally between a body and flange of the valve assembly. The thermal insulator has a thermal conductivity less than a thermal conductivity of the flange and the body.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Example embodiments will now be described more fully with reference to the accompanying drawings.
In a conventional, storage-type gas water heater, the water tank may be thermally insulated to reduce heat loss to the surrounding area. But the inventors hereof have recognized that the gas valve is a weakness in this thermal insulation scheme given that heat may be lost through the gas valve. This is because the typical gas valve has an aluminum body that is thermally linked (e.g., via a thermally efficient heat path defined by thermally conductive components, etc.) to the hot water in the storage tank directly through a brass flange and copper tube of a flange assembly. The flange assembly may be part of a mechanical or electronic control that is operable for controlling fuel flow in the water heater system.
The copper tube is attached (e.g., usually threaded, etc.) to the brass flange. The brass flange is attached (e.g., usually with screws, etc.) to the body of the gas valve. The brass flange is threaded to mate and provide a leak-tight seal with a threaded hole in the water heater tank. The copper tube extends into the water tank and serves as the temperature sensing device for the system.
Accordingly, even though the gas valve body is externally located or outside the storage tank, there is a thermally conductive pathway from the hot water inside the tank to the gas valve body via the copper tube and flange. This causes the gas valve body to act as a heat sink and conduct heat out of the tank, which reduces efficiency and wastes energy. Also, the gas valve body being cooler than the hot water and being connected to the flange reduces the temperature of the outboard portion of the tube, which, in turn, reduces the thermal sensitivity of the system resulting in increased differentials. Additionally, the connected thermal mass of the gas valve body causes the temperature of the outboard portion of the tube to lag that of the water in time additionally increasing differential.
After recognizing the above drawbacks, the inventors hereof have disclosed exemplary embodiments in which thermal insulation (e.g., one or more thermal insulating materials or insulators, etc.) provides, creates, and/or defines a thermal break or thermally insulative barrier in or along the thermally conductive heat path that is normally defined from the hot water in the storage tank to the gas valve body via the tube (which extends into the hot water) and the flange (which is connected to both the tube and gas valve body). This thermal break or barrier, in turn, reduces heat transfer from the water storage tank via the flange assembly (which includes the tube and flange) to the gas valve body, and ultimately to the atmosphere. This helps increase the rated efficiency of the water heater in standby mode and inhibits heat loss from the hot water within the water heater storage tank through the valve assembly and/or control.
In exemplary embodiments, thermal insulation (e.g., one or more thermal insulating materials or insulators, etc.) is provided generally between or at a connection of first and second components, members, or portions of a gas valve assembly (e.g., a rod and tube valve type system, etc.). In such exemplary embodiments, the thermal insulation, the connection, and the first and second components of the gas valve assembly are located external to the storage tank. But the first component (e.g., flange, etc.) is coupled (e.g., threaded, etc.) to a third component (e.g., thermistor tube or other temperature sensing device, etc.) that extends into the hot water in the tank for sensing the temperature of the water. Accordingly, the thermal insulation thus provides a thermal break or thermally insulative barrier/impediment in or along the thermally conductive heat path that would otherwise exist from the hot water to the second component (e.g., gas valve body, etc.).
Exemplary embodiments are also disclosed of methods for stopping or inhibiting heat from a hot water tank from being lost through a valve assembly/control by providing, creating, and/or defining a thermal break or thermally insulative barrier in or along the thermally conductive heat path from the hot water in the storage tank to a body or other external portion of the valve assembly/control. Examples are disclosed herein in which thermal insulation (e.g., one or more thermal insulating materials, insulators, thermal isolation gaskets, etc.) is provided generally between first and second components, members, or portions of a gas valve assembly. In an exemplary embodiment, a method generally includes positioning a thermal insulator generally between first and second components of a gas valve assembly that are located external to the storage tank. The second component (e.g., flange, etc.) is thermally coupled (e.g., threaded, etc.) to at least one other component (e.g., tube, etc.) that extends into the hot water in the tank. The method may also include coupling (e.g., mechanically fastening, etc.) the second component to the first component (e.g., a body of the gas valve assembly, etc.) such that the thermal insulator is between the portions of the first and second components coupled together. By way of example, coupling the first and second components may include using one or more mechanical fasteners that are inserted through aligned fastener holes in the first and second components and the thermal insulator. By way of further example, the second component may be coupled to a fourth component, which, in turn, is coupled to the first component.
In an exemplary embodiment, a valve assembly for a fuel fired water heater includes a flange, a body, and thermal insulation (e.g., one or more thermal insulating materials or insulators, etc.) generally between the flange and the body. The flange may have a first end portion coupled (e.g., mechanically fastened, etc.) directly or indirectly to the body. For example, the first end portion of the flange may be coupled to a bracket, which bracket is coupled to the body. In other embodiments, the flange may be coupled directly to the body without an intervening bracket. The flange may have a second end portion configured (e.g., threaded, etc.) to mate and provide a leak-tight seal with a hole (e.g., threaded, etc.) in a water heater tank (see, e.g.,
The particular configuration (e.g., shape, size, materials, etc.) of the thermal insulation may vary depending, for example, on the particular installation, such as the type of control (e.g., mechanical or electronic, etc.) and/or configuration of the storage tank (e.g., capacity, etc.). For example, thermal insulators used with mechanical water heater controls may need to have certain properties (e.g., rigidity, stiffness, minimum Young's modulus of 200000, etc.) different than that needed for thermal insulators used with electronic water heater controls.
In an exemplary embodiment, a thermal insulator for a mechanical water heater control is made from stainless steel (e.g., plate made of type 301 stainless steel full hard having a thickness of about 0.01 inches or more, etc.) or other suitable thermally insulating materials that are sufficiently rigid and stiff to meet the rigidity and stiffness requirements of the actuator system in a mechanical control. In this example, the stainless steel insulator (e.g., plate, etc.) may be configured (e.g., shaped, sized, provided with fastener holes and other openings, etc.) for placement between (e.g., mechanically fastened between, etc.) a brass flange and aluminum body of a gas valve of a mechanical control. Stainless steel is a poor conductor of heat and has a lower thermal conductivity than many other metals, including aluminum, brass, and copper. Thus, the stainless steel insulator may serve as a thermal break or barrier between the more thermally conductive brass flange and aluminum body of a mechanical control, to thereby reduce the amount of heat being conducted into the body of the gas valve.
In another exemplary embodiment, a thermal insulator for an electronic water heater control is made of a circuit board material (e.g., flame retardant 4 (FR-4) circuit board material, etc.), G-10 phenolic sheet material, or other suitable thermally insulating materials. By way of example only, a thermal insulator may be formed from a FR-4, G-10 phenolic sheet, or similar material having a thickness of about 0.020 inches (e.g., about 0.021 inches, etc.).
For an electronic control, less rigid/more flexible thermal insulators may be used because the same level of rigidity is not needed for an electronic control as a mechanical control. In this example, the thermal insulator may be configured (e.g., shaped, sized, provided with fastener holes and other openings, etc.) for placement between (e.g., mechanically fastened between, etc.) a brass flange and aluminum body of a gas valve of an electronic control. FR-4 circuit board material is a poor conductor of heat and has a lower thermal conductivity than many metals, including aluminum, brass, and copper. Thus, the FR-4 insulator may serve as a thermal break or barrier between the more thermally conductive brass flange and aluminum body of an electronic control, to thereby reduce the amount of heat being conducted into the body of the gas valve.
Thermal insulation may be provided to a wide range of valve assemblies, controls, and controllers for water heaters in accordance with the present disclosure. For example, thermal insulation may be provided to a controller such as the mechanical water heater control 100 shown in
The thermal insulator 120 is shaped (e.g., six sided polygon, etc.), sized, and provided with fastener holes 124 (
The thermal insulator 120 also includes openings or open portions 128. One of the holes 128 in the insulator 120 allows the upper portion or top of the valve actuation or “pusher” disk 144 to contact the pivot operator on the other side of the insulator 120. In operation, the “pusher” disk 144 acts to open or close the valve by applying pressure to a snap spring, which “snaps” the valve open or closed to avoid a walk open valve actuation. The pusher disk 144 is acted upon by the pivot 145, which is operated by the rod 146 within the tube 112. The rod 146 may typically be formed from invar (which has a very low coefficient of thermal expansion), and the tube 112 may typically be formed from copper (which has a high coefficient of thermal expansion). The tube 112 may thus change length quite noticeably with temperature changes of the water while the rod 146 does not change length, thereby operating the mechanism.
In addition, wires in the tube 112 of the mechanical control 100 may be connected to a fuse within the tube 112. If the water temperature exceeds a certain high limit, the fuse opens. Since the fuse is in the millivolt circuit which powers the mechanical safety valve, the safety valve drops out (closes) which also shuts off the pilot, which is heating the millivolt generator. Thus, both the pilot and main burners are disabled, and the over-temperature situation is abated. The wiring for the fuse enters through an opening in the side of the base of the flange 108.
The holes 128 are configured to enable the three interactive points that exist for normal operation of the valve mechanism. The rod 146 in the tube 112 pushes on a point which is offset from a second point (the pivot). The first two points are referenced by a third point, which is an adjustment screw attached to a dial on the front of the control 100. These three points act in relation to one another to operate the valve (open or close) as a function of the temperature of the water. The three holes 128 enable the mechanism to operate normally. Advantageously, the openings 124, 128 of the thermal insulator 120 thus allow the insulator 120 to be retrofitted to the mechanical water heater control 100 without interfering with the normal operations of the control 100 and without requiring modifications to the control 100.
A wide range of thermally insulating materials may be used for the thermal insulator 120, which preferably have a thermal conductivity of less than 16 Watts per meter Kelvin (W/mK) and/or a Young's module of at least 200000. The thermal insulator 120 is preferably made of a material(s) having a thermal conductivity significantly lower than the thermal conductivity of the material(s) of the flange 108 (e.g., brass, etc.) and body 104 (e.g., aluminum, etc.). In which case, the thermal insulator 120 may then define or serve as a thermal break, thermal isolation gasket, or thermally insulative barrier between the thermally conductive flange 108 and body 104, thereby reducing the amount of heat conducted into the body 104. The thermal insulator 120 thus disrupts and inhibits the transfer of heat along what is traditionally an efficient heat path from the hot water in the storage tank through the flange 108 to the body 104 of the control 100.
In an exemplary embodiment, the thermal insulator 120 is made from stainless steel (e.g., plate made of type 301 stainless steel full hard having a thickness of about .01 inches, etc.). Stainless steel is a poor conductor of heat and has a lower thermal conductivity than many other metals, including aluminum, brass, and copper. Alternative embodiments may include a thermal insulator made from other suitable thermally insulating materials besides stainless steel, which materials are sufficiently rigid and stiff to meet the rigidity and stiffness requirements of an actuator system in a mechanical control.
In some exemplary embodiments, the bolts or fasteners 132 are used to connect the flange 108 directly to the body 104. In other exemplary embodiments (e.g.,
The thermal insulator 220 is shaped (e.g., shaped similar to the letter H of the English alphabet, etc.), sized, and provided with fastener holes 224 such that the thermal insulator 220 may be mechanically fastened with bolts 232 or other suitable fasteners between the flange 208 and the bracket 204 coupled to the body of the electronic gas water heater control 200. The fastener holes 224 of the thermal insulator 220 are configured in a pattern such that the holes 224 match or align with the corresponding fastener holes 236 and 240 in the bracket 204 and flange 208, respectively.
The thermal insulator 220 also includes upper and lower open portions or openings 228, 230 (
A wide range of thermally insulating materials may be used for the thermal insulator 220, which preferably have a thermal conductivity of less than 16 Watts per meter Kelvin (W/mK) and/or a Young's module of at least 200000. The thermal insulator 220 is preferably made of a material(s) having a thermal conductivity significantly lower than the thermal conductivity of the material(s) of the flange 208 (e.g., brass, etc.), bracket 204, and body (e.g., aluminum, etc.). In which case, the thermal insulator 220 may then define or serve as a thermal break or thermally insulative barrier between the thermally conductive flange 208 and bracket 204, thereby reducing the amount of heat conducted into the body. The thermal insulator 220 thus disrupts and inhibits the transfer of heat along what is traditionally an efficient heat path from the hot water in the storage tank through the flange 208 and bracket 204 to the body of the control 200.
In an exemplary embodiment, the thermal insulator 220 is made from Flame Retardant 4 or FR-4 circuit board material. In another example embodiment, the thermal insulator 220 is made of stainless steel. In a further example embodiment, the thermal insulator 220 is made of glass fiber reinforced nylon 6,6. In yet a further embodiment, the thermal insulator 220 is made of composite G-10/FR-4 glass epoxy laminate and/or a material having a thickness of about 0.020 inches, less than 2 percent water absorption, a thermal conductivity of about 0.27 Watts per meter Kelvin, and a compression strength of greater than or equal to 30 kips per square inch (ksi). Alternative embodiments may include a thermal insulator made from other suitable thermally insulating materials besides FR-4, G-10, glass epoxy laminates, stainless steel, or glass fiber reinforced nylon.
In some exemplary embodiments, the bolts or fasteners 232 are used to connect the flange 208 to the body via a bracket 204. The bolts or fasteners 232 may be made of a material having a relatively low thermal conductivity, such as less than 16 Watts per meter Kelvin (W/mK). In addition, some exemplary embodiments may also include washers on the fasteners 232, which washers may be made of a material having a relatively low thermal conductivity (e.g., 16 Watts per meter Kelvin, etc.) to help further reduce heat transfer from the flange 208 through the bracket 204 and to the body. The washers may be made from the same material as the thermal insulator 220, such as stainless steel, a circuit board material (e.g., flame retardant 4 (FR-4) circuit board material, etc.), G-10 phenolic sheet material, or other suitable thermally insulating materials.
By way of example only, exemplary embodiments including the thermal insulators disclosed herein (e.g., thermal insulator 120 (
To determine the effects that the inventors' insulators have when installed between a flange and body of a control on temperature calibration accuracy, DOE stacking tests were performed on a 37C73U-836 mechanical water heater control with and without a stainless insulator. Notably, the control without the insulator (standard production) overshot the target temperature by 14° F. But the control with the insulator overshot the target temperature by 6.6° F. Thus, the stainless steel insulator significantly decreased the amount by which the control overshot the target temperature. In other exemplary embodiments, a thicker stainless steel insulator or other thermal insulator (e.g., thickness greater than or equal to about 0.020 inches, etc.) may be used that is operable to eliminate or reduce (e.g., less than 6.6° F., etc.) the amount the water heater control overshoots a target temperature. These testing results are provided to further illustrate aspects of the present disclosure as they do not limit this disclosure to only configurations that can achieve these particular test results.
Additional testing was also performed on the exemplary embodiment of a thermal insulator or gasket 320 shown in
For this particular testing, the thermal insulator or gasket 320 was formed from a FR-4, G-10 phenolic sheet having a thickness of about 0.021 inches and having a thermal conductivity of about 0.27 Watts per meter Kelvin (W/mK).
Heat transfer from a water heater through a control is a significant portion of the heater's energy loss. By adding the thermal insulator 320, the percentage of heat loss through the control may be reduced (e.g., from about 6.8 percent down to 3.9 percent, etc.). Typically, the valve temperature is the average of the tank temperature and the room temperature. Based on the valve's approximately 2.5 percent contribution to standby loss, adding a thermal insulator should represent about one percent overall energy savings for the hot water tank in standby mode.
In addition,
These testing results shown in
It should also be noted that although various exemplary embodiments are described with reference to gas water heaters, exemplary embodiments may also be used with other controllers, controls, and control systems for other types of fluid heaters and/or devices. For example, exemplary embodiments may be used in conjunction with electric heaters for water and other fluids.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms (e.g., different materials may be used, etc.) and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail. In addition, advantages and improvements that may be achieved with one or more exemplary embodiments of the present disclosure are provided for purpose of illustration only and do not limit the scope of the present disclosure, as exemplary embodiments disclosed herein may provide all or none of the above mentioned advantages and improvements and still fall within the scope of the present disclosure.
Specific dimensions, specific materials, and/or specific shapes disclosed herein are example in nature and do not limit the scope of the present disclosure. The disclosure herein of particular values and particular ranges of values for given parameters are not exclusive of other values and ranges of values that may be useful in one or more of the examples disclosed herein. Moreover, it is envisioned that any two particular values for a specific parameter stated herein may define the endpoints of a range of values that may be suitable for the given parameter (i.e., the disclosure of a first value and a second value for a given parameter can be interpreted as disclosing that any value between the first and second values could also be employed for the given parameter). Similarly, it is envisioned that disclosure of two or more ranges of values for a parameter (whether such ranges are nested, overlapping or distinct) subsume all possible combination of ranges for the value that might be claimed using endpoints of the disclosed ranges.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.
When an element or layer is referred to as being “on”, “engaged to”, “connected to” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to”, “directly connected to” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The term “about” when applied to values indicates that the calculation or the measurement allows some slight imprecision in the value (with some approach to exactness in the value; approximately or reasonably close to the value; nearly). If, for some reason, the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein indicates at least variations that may arise from ordinary methods of measuring or using such parameters. For example, the terms “generally”, “about”, and “substantially” may be used herein to mean within manufacturing tolerances.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”, “lower”, “above”, “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. Spatially relative terms may be intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the example term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements, intended or stated uses, or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
