Automated thermal recirculation valve

An automated thermally actuated valve utilizing a thermally expansive substance to substantially close the valve at a first temperature and a spring to open the valve at a second, lower temperature. A method of utilizing an automated thermally actuated valve to balance and manage hot water supply in a piping system.

BACKGROUND OF THE INVENTION

Field of the Invention

The present general inventive concept is directed to a device that provides automated regulation of hot water systems, and a method of utilizing the device to improve performance in hot water systems.

Description of the Related Art

The prior art includes spring loaded valves utilizing thermal expansion of a solid, liquid, or phase change to effect opening or closure of a valve. U.S. Pat. No. 5,816,493 to Pirkle discloses an improved thermally expansible composition that contains silicone rubber and does not require a diaphragm or seal. This concept is insufficient for use in closed systems where the automated valve is installed in-line and in contact with a fluid such as water for extended periods, and will not provide consistent operation over time. Within hot water systems such as showers and sinks, it is known to utilize a valve to direct water flow. It is a common problem that the distance between the hot water heater or hot water source and the location where the user wishes to utilize the hot water causes a delay related to the pipe volume between the source and the user divided by the flow rate. In larger structures or larger diameter pipes, the delay can be substantial. Constant recirculation of hot water within the piping system is commonly utilized to reduce the delay in the delivery of hot water. However, in addition to the delay caused by distance and pipe volume, complex systems can experience resistance to the flow of hot water including gravity. A single hot water source within a system containing many faucets or outlets may not deliver hot water to all parts of the system equally, or sufficiently, to meet demand. Typical installations include the use of a pump, mixing valves, and other manual adjustments to attain delivery to all parts of a piping system in the face of gravity, flow restrictions, and other complicating factors either fixed or dynamic.

Numerous attempts to optimize the delivery of hot water in complex systems have been made. Providing a hot water source nearer to the user is one potential solution, but can be very costly with the additional equipment needed. Providing constant recirculation can reduce the delay as well, but is difficult to regulate in large systems. For example, recirculated water will travel the path of least resistance such that in multistory buildings, the top floors will not receive sufficient recirculation flow. What is needed is an automated valve that can be installed in-line with existing piping systems, that requires no maintenance or adjustment, and can automatically adjust the recirculation flow to ensure the availability of hot water in complex piping systems.

Other attempts to address this problem have been insufficient. For instance U.S. Pat. No. 7,681,804 B2 to Lockhart discloses a temperature-controlled valve that can be inserted above a shower head. This device can be activated by a user to start the flow of water into the shower. The valve will then substantially close after the hot water arrives at the valve. This valve does not obviate the delay in the arrival of the hot water supply. It merely reduces the waste of hot water that would be caused by an inattentive user that is not present at the moment hot water supply arrives. It does allow for a large amount of water to go down the drain while waiting for hot water supply. Numerous other valves have been manufactured and some have been patented, but most require adjustment or settings that make them unsuitable for installation in a piping system behind walls or access panels. What is needed is a valve that provides automated recirculation to ensure that hot water is available soon after requested by a user

SUMMARY OF THE INVENTION

It is an aspect of the present invention to provide a flow control valve that automatically adjusts the flow of a fluid to manage the fluid flow within a piping system based on temperature.

It is a further aspect of the present invention to provide an automated hot water recirculation valve that automatically adjusts the flow of recirculated hot water within a piping system to ensure that hot water is present throughout the hot water piping system.

DETAILED DESCRIPTION

Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

The present inventive concept relates to an automated valve that provides automated flow regulation based on fluid temperatures. A valve that is preset can be installed without specific expertise in thermal valves, thereby reducing installation cost. The valve should operate automatically to increase or decrease flow to ensure proper management of fluid flow. Additionally, the valve should be made with a minimum number of components to reduce cost. Further, the valve should allow at least some flow at all temperatures so that sanitation operations such as high temperature flush or chemical flush of piping systems is not thwarted. The valve should also provide consistent performance over time and not degrade when contacted with hot water, chlorinated water, or other fluids. The above aspects can be obtained by a pipe segment containing a spring biased piston driven by a cup filled with a thermally expansive substance that drives the piston towards a closed position when it is heated to a desired temperature. The piston is surrounded by a piston casing that substantially obstructs a seat opening in the valve to reduce flow. When the thermally expansive substance is cooled, the spring provides a return force and pushes the piston casing and piston away from the seat opening to open the valve. While the automated valve of the invention can be utilized with any number of fluids, such as ethylene glycol, hydraulic oils, poly alpha olefin, or fuel oils, discussion of the valve as used within hot water systems will be utilized for clarity of explanation and as water is the most commonly used fluid.

The automated valve will open to allow flow of hot water in a piping system when the assembly is cooled, ensuring the additional flow of water in that part of the piping system. When the flow of water is sufficiently warm, the piston and piston casing are driven towards the closed position, substantially reducing the flow of water within that portion of the piping system. Thus, the valve ensures that flow is substantial when the temperature is below a set point in order to enable the movement of hot water in the recirculation system. When the hot water is present, the valve automatically reduces flow to a small amount so that unnecessary recirculation of hot water in that portion of the piping system is avoided. The recirculation pump of the system will need to pump less water as the warm parts of the system will automatically allow reduced recirculation flow. The valve does not completely close to ensure thermal communication with the system and to provide other safety features including access of all parts of the piping system to hot water flush or chemical flush to ensure sanitary conditions. The present inventive concept can be specifically adapted to provide automated regulation of hot water systems, and a method of utilizing the device to improve performance in hot water systems. The automated valve can automatically open and allow water (or other liquid) flow when the liquid is below a certain temperature, and the automated valve can automatically close and block water (or other liquid) when the liquid is above a certain temperature. In one embodiment, a series of these automated valves can be utilized in a piping system to optimally and automatically distribute water order to provide showers, faucets, and other receiving elements with immediate hot water when possible. The valve can be placed at the end of a piping run in a building for instance having a piping run on each floor. In a basic system, all of the piping runs return to a single recirculation pump. The valve can be installed into the piping at the end of each run before it joins the common return pipe. In this way, flow can be restricted by the valve in piping runs that are satisfactorily hot, thereby ensuring that flow is distributed to the runs in which the valve is open. A valve experiencing cool fluid flow or flow below a desired set point would be in an open position, allowing additional flow through that section of the system or that piping run. In this way, a set of valves can automatically balance fluid flow in a system subject to dynamic changes in demand and usage.

An embodiment of the invention comprises a casing10that is suited for installation within a line of conventional piping.FIG. 1shows a cross section of the casing10. The casing10is preferably constructed of metal, more preferably303stainless steel as it is machineable and it does not contain lead. The casing body12is cylindrical and substantially hollow. Casing first end20is preferably configured in a substantially hexagonal circumference (seeFIG. 2) to accept conventional wrenches and tools. Casing first end20is threaded in the interior of the casing with conventional pipe threading to form first end pipe threads22. Casing second end30is positioned opposite first end20and is preferably configured in a substantially hexagonal circumference (seeFIG. 2) to interface with conventional tools used to rotate casing10. Casing second end30is threaded in the interior of the casing with conventional pipe threading to form second end pipe threads32. Disposed within casing body12and located proximal to first end pipe threads22is seat40containing seat opening44. Seat40effects a reduction of cross sectional void within casing10.

Dimensions are given for a one inch internal diameter valve for clarity only. The valve can be configured in a number of sizes for installation within a variety of plumbing systems. As one inch internal diameter (ID) piping is commonly used, representative dimensions will be given for elements within the figures corresponding to a device that is configured for one inch ID piping. This configuration will be referred to as a “one inch ID configuration” when providing dimensions. The diameter of seat opening44can be 0.1 to 0.5 inches and in a one inch ID configuration can be for example 0.393 to 0.394 inches. Casing interior diameter60can be 0.5 inches to 1.2 inches and can be for example about 0.9 inches. In a one inch ID configuration, casing interior diameter60can be fabricated to 0.906 plus or minus 0.002 inches. Seat interface50is the surface of seat40facing towards casing second end30. Seat interface50is preferably smooth and has a seat interface diameter shown as51. In a one inch ID configuration seat interface diameter51can be machined within a range of 0.735 to 0.745 inches. Seat ramp55in the interior of the casing body12increases the interior diameter of the casing from seat interface diameter51to casing interior diameter60. The inner surface of the casing body12is smooth and designed to accept a thermal assembly (not shown inFIG. 1). Retaining groove38is disposed within the casing body12adjacent to casing second end30. In a one inch ID configuration, retaining groove38can be approximately 0.054 inches deep, is approximately 1/20thof an inch wide (within a tolerance of 0.046 to 0.051 inches wide), and forms a complete loop. Casing first end20can be threaded to a depth of 0.69 inches, and casing second end30can be threaded to a depth of 0.655 inches.

FIG. 2presents a perspective view of the casing10. Casing body12is cylindrical, casing first end20is shown with substantially hexagonal circumference24and first end pipe threads22. Similarly, second end30is shown with substantially hexagonal circumference34. Interior to the casing10and viewable through the cutaway in casing first end20is seat40and seat opening44.

FIG. 3Apresents a cross section of the thermal assembly of the invention in a compressed configuration.FIG. 3Arepresents the open position in which water can flow through the valve because the thermal assembly is in a compressed or open configuration. In order to create a thermally responsive automated valve, a material that exhibits a phase change can be utilized. A preferable material will change from a solid to a liquid at a temperature near, but less than, the desired recirculated fluid temperature of the system. The phase change effects an expansion and change in volume. Paraffin, an aliphatic hydrocarbon, is a suitable material. In particular, twenty two carbon length docosane has a suitable melting point of approximately 44.4 degrees C. or 112 degrees F. Longer chain carbon molecules exhibit higher melting points, and shorter chain carbon molecules exhibit lower melting points as is known in the art, and these alternatives can be adapted to achieve a phase change at other temperatures. For example, n-Heptadecane exhibits a melting point of 22.0 degrees C., whereas n-Octacosane exhibits a melting point of 61.4 degrees C. For regulation of hot water systems, cup102can be filled with thermally expansive substance110, for example paraffin, namely n-Docosane. The melting point of thermally expansive substance110corresponds to a set point for the valve. Fluid flowing through the valve with a temperature above the set point will cause the thermally expansive substance110to melt and cause the automated valve substantially close. Fluid temperatures below the set point will cause thermally expansive substance110to solidify and cause the automated vale to open. The selection of a thermally expansive substance110will provide a set point for the thermal assembly approximate to the melting point of the thermally expansive substance110. Cup102is configured with cup collar104to interface with other parts of the invention. Molded diaphragm120is preferably made of an elastomer material such as fluorocarbon elastomer that can deform and allow expansive substance110to push the diaphragm towards plug130. In one embodiment, the molded diaphragm120is prepared using a compression mold die set in the form of the desired shape, roughly disc-shaped. The die is filled with polymer, preferably Viton Brand GF600S fluorocarbon elastomer and compression molded under heat and pressure. The material can be cooled within the die to produce a molded part. The molded part can be trimmed of excess material to a desired shape. The molded part then can be post cured at 450 degrees Fahrenheit for up to five hours to increase molecular cross linking to add strength and flexibility and create a molded diaphragm. Molded diaphragm120can be held in place by threaded guide140which is in turn retained by the crimping of cup lip106. Thus, elements102,120, and140can be fixedly connected and positions of elements102and140can be fixed relative to each other. Molded diaphragm120can comprise a sealing bead121about the exterior circumference. Sealing bead121interfaces with annular groove141within the threaded guide140, and each are formed of corresponding shape, thickness, and depth to ensure a seal between the diaphragm120and threaded guide140. Elements102,140, and121are fixed relative to each other while the center of molded diaphragm120is able to move or deflect as needed.

Plug130is preferably composed of an elastic material including silicone or rubber or other suitable elastomer. In an embodiment, plug130can be made of fluorocarbon elastomer, e.g. Viton brand, 600LF. [Available from DuPont Elastomers. Plug130can be roughly cone shaped to fit within threaded guide140. The cone shape accentuates the lateral movement of the molded diaphragm as the larger diameter of the plug is forced into threaded guide140. The additional material of the progressively larger conical diameter elongates when entering the restrictive opening to provide increased lateral movement of the piston160. In one embodiment, diaphragm120displacement of 0.1 inches is translated to 0.15 inches of piston travel through the function of the conical shaped plug130. Anti-extrusion disk150is made of a non stick material, and in an embodiment, Teflon brand PTFE, and is positioned between plug130and piston160to prevent deformation of plug130at the interface of plug130and anti-extrusion disk150. Piston160is positioned within threaded guide140and adjacent to anti-extrusion disk150. Piston casing170is generally cylindrical in shape and positioned about piston160and threaded guide140. Piston casing170can be biased towards cup102by spring180. Piston casing collar176projects outward from piston casing170and engages spring second end184. The elements inFIG. 3Acomprise the thermal assembly. The elements ofFIG. 3Aare shown in a compressed configuration that corresponds to an “open” position and a cool, or solid, thermally expansive substance110.

FIG. 3Billustrates the thermal assembly in the warm, or substantially closed position, because the water flowing through is at or above the melting point which automatically causes the thermal assembly to expand. When thermally expansive substance110warms past the melting point, it changes phases and expands, deforming the central portion of the molded diaphragm120and in turn forcing elements130,150,160, and170away from the cup102. When extended, piston casing end174substantially obstructs seat opening44(not shown), to reduce fluid flow. Dimensions are given for a configuration designed to interface with conventional one inch diameter piping. An embodiment of the invention can be scaled up or down to meet other needs and other piping sizes. As the one inch diameter piping is common, dimensions are provided to enable the practice of an embodiment of the invention, but the function and scope of an embodiment of the invention are not limited to these specific dimensions or configuration. The diameter of174is preferably less than seat opening44to allow minimum flow in substantially closed position. In a one inch ID configuration, where seat opening44is approximately 0.393 inches wide, piston casing end174can be machined to a diameter of 0.392 to 0.3925 inches to provide a minimum clearance of 0.0005 inches. This opening is sufficient to allow fluid flow in pressurized systems. Piston casing ramp175aids in the insertion of piston casing170into spring180. The distance from piston casing ramp175to piston casing end174can be about 0.188 inches. Piston160can have a diameter of 0.155 inches. Piston casing collar176can have an exterior diameter of about 0.720 inches, and piston casing170can have a length of 0.843 inches. Cup length can be about 0.555 inches. When thermally expansive material110cools and changes to a solid with decreased volume, piston casing170and adjacent elements are forced towards cup100by spring180, returning thermal assembly to the positions shown inFIG. 3A. Spring first end182contacts seat interface50(not shown). Spring180including ends182and184, can be approximately equal in diameter to seat interface diameter51(not shown). Spring180provides a return force to push the elements of the valve into an open position when the valve is cooled.

Additional elements of an embodiment of the present invention are utilized to position thermal assembly100within the casing10.FIG. 4Apresents a side view of a carrier200. Carrier200is generally cylindrical and sized to fit within casing10, not shown. Carrier holes230are present around the circumference of the carrier and allow a fluid to flow through the carrier assisting thermal communication throughout the interior of the valve. In one embodiment shown inFIG. 4A, eight carrier holes230are present, but other numbers and placements can be utilized. Bevel220is present on a first side of carrier200, and provides a smooth edge. Carrier collar210is present on a second side of carrier200. Carrier collar210has a diameter greater than the interior diameter of retaining ring inFIG. 4B. In a one inch ID configuration, carrier has a minimum interior diameter of 0.510 inches. Collar210can have an interior diameter of 0.640 inches and an exterior diameter of 0.092 inches. Carrier holes230each can have a diameter of 0.140 inches.

FIG. 4Bshows a perspective view of retaining ring250comprising first eyelet260and second eyelet270. Retaining ring250can be configured to sit within retaining groove38as shown inFIG. 1. When positioned, retaining ring250prevents the movement of carrier200inFIG. 4Apast the position of retaining ring250. In a one inch ID configuration, the interior diameter of retaining ring250can be 0.803 inches, the exterior diameter can be 0.971 inches, and carrier outside diameter ofFIG. 4Acan be 0.900 inches.

FIG. 4Cshows a perspective view of carrier200showing the circular nature of the element.

FIG. 5Apresents a side view of a thermal assembly positioned within a cross section of the casing body12. The thermal assembly is shown in a compressed configuration corresponding to an open valve position or a “cold” configuration. Threaded guide140is shown within piston casing170. Piston casing170is positioned within spring180. Piston casing end174is shown separated from seat interface50. Cup102contacts carrier200which is held in place by retaining ring250inserted within retaining groove38. Unlike second end pipe threads32which are oriented in a spiral, retaining groove38comprises a single groove suitable for insertion of a ring. Retaining ring250can be compressed and inserted into retaining groove38. This configuration prevents spring180from forcing the elements of the valve out of position. The maximum travel of the elements within the casing body12towards casing second end30is determined by the position of retaining ring250which is determined by the position of retaining groove38. Carrier200has a diameter greater than the inside diameter of retaining ring250and thus carrier200cannot pass retaining ring250. Cup102sits partially within carrier200. Cup collar104has a diameter sufficient to interface with carrier200and prevent movement of the thermal assembly past the carrier200.

FIG. 5Bshows a side view of a thermal assembly positioned within a cross section view of casing body12corresponding to an “expanded” or “hot” configuration. The piston casing170is shown displaced to the left so that piston casing end174substantially obstructs seat opening44. When the thermal assembly is warmed above the desired set point, the valve is substantially closed, allowing only a small amount of fluid to flow through the valve.

FIG. 6presents a schematic of a piping system. The configuration of the automated valve within a piping system is shown. The schematic inFIG. 6represents a hypothetical four story building, however, any piping system size or configuration is contemplated by the invention. Hot water heater600is connected to pump620through any conventional means including piping. Pipe625is connected to four different branches601,602,603, and604representing the four stories of a building. Each floor contains multiple shower heads for illustration. The multiple fixtures are connected as the piping system is united in one return pipe630that returns unused, recirculated hot water to the hot water heater600. At the end of branch601, automated valve631is installed in line. At the end of branch602, automated valve632is installed in line. At the end of branch603, automated valve633is installed in line (“automated valve” refers to the valve shown inFIGS. 1-5and their accompanying description herein). At the end of branch604, automated valve634is installed in line. Each valve is configured so that it will be substantially open to the flow of water when below a set point or “cold.” In this way, the pressure created by pump620will cause water to flow through the associated branch of the piping system that contains an automated valve in a “cold” or substantially open position. The automated valve will warm up upon the arrival of hot water and will substantially close. This will prevent large amounts of water being recirculated through the branch of the piping system that contains the substantially closed automated valve. Thus, if pipe runs601,602, and603are sufficiently warm, automated valves631,632, and633will be substantially closed, limiting the recirculation flow through the respective portions of the piping system. If the top floor represented by pipe run604is receiving insufficient hot water flow, automated valve634will be at a temperature below the set point and cause the automated valve to open to effect the flow of hot water through pipe run604, or the fourth floor of the building. At the point where recirculated hot water flow in pipe run604is sufficiently warm to cause the automated valve to close, recirculated water in pipe run604is substantially reduced. These movements automatically occur within the valve based on temperature of fluid flow. In this way, the valve is automated and operates continuously, dynamically, and without the need for user intervention.

Additionally, in another embodiment, a thermally expansive mixture can also be employed. Instead of a single substance such as paraffin, the thermally expansive substance can comprise a thermally expansive mixture. A thermally expansive mixture can be employed that provides improved responsiveness and reliability. One thermally expansive mixture is composed of an elastomer, a thermally conductive material, and a thermally expansive substance. In an embodiment the thermally expansive mixture comprises a thermally conductive material namely copper powder, a thermally expansive substance namely paraffin, preferably C22 or docosane, and an elastomer such as Elastol, a viscoelastic polymer available at www.elastol.com. Elastomers, including Elastol, add to the cohesion of the mixture and increasing the workability of the mixture. One suitable composition of the thermally expansive mixture is accomplished by mixing by weight 20% paraffin, 4% viscoelastic polymer, and 76% copper powder. The thermally expansive mixture is placed within cup102. The device of the invention functions as described in the preceding figures. When heated, the wax expands and melts, experiencing a phase change and accompanying increase in volume. The phase change and increase in volume provide and sufficient force to cause movement of the diaphragm, plug, and piston. The phase change occurs at the melting point of the thermally expansive mixture. The melting point of the thermally expansive mixture corresponds to the “set point” of the valve in that the valve will activate or function at the “set point.” The conductive material increases thermal conductivity within the mixture and increases the responsiveness of the invention by reducing the time required for the wax to melt. The elastomer increases the viscosity of the mixture and aids in shaping the mixture in constructing the valve, as well as coalescing the mixture upon cooling. The thermally expansive mixture can be created by thoroughly mixing elastomer and thermally conductive material in a container such as a mixing bowl. In one composition, 4% of the total batch weight of Elastol is combined with 76% of the total batch weight of copper powder. Simple mechanical mixing and sifting are sufficient to distribute the materials. Paraffin materials with a melting point below room temperature must be heated to create a thermally expansive mixture. For example n-docosane must be heated to a liquid state. Utilizing a metal mixing bowl on a hot plate or flame burner is sufficient to melt the paraffin. A standard mixer with a hook attachment can be utilized at 60 to 120 rpms for 15 minutes to sufficiently blend the Elastol, n-docosane, and copper powder. Heat should be applied to the mixing container to prevent the paraffin component from solidifying. Faster mixing speeds are not desired as they may result in aeration of the mixture.