Description:Water Heater
Field of the Invention
[0001] The present disclosure generally relates to water heating appliances. Further, the present disclosure particularly relates to a water heater comprising a thermoplastic container body.
Background
[0002] The background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Water heating appliances are commonly used in domestic, commercial and industrial applications for providing hot water. Such appliances generally consist of a container structure for retaining water, a heating unit for raising the temperature of the retained water and safety and mounting features. Various known systems and techniques have been developed for constructing the container structures of such appliances.
[0004] One known system employs metal containers with welded joints and metallic reinforcement structures. Such systems offer structural strength and pressure resistance but are generally associated with high manufacturing costs and increased weight. Moreover, such metallic containers are susceptible to corrosion which leads to leakage and degradation over time especially under prolonged exposure to water and heat. The metallic nature of the structure further necessitates complex insulation measures to ensure energy efficiency.
[0005] Another known system uses thermoplastic containers formed using blow moulding or injection moulding techniques. Such containers are lighter in weight and resistant to corrosion. However, such thermoplastic containers generally exhibit low mechanical strength and dimensional instability under elevated temperatures and pressures. As a result, such thermoplastic containers require additional reinforcement or thicker walls, which leads to increased material consumption and manufacturing cost. Moreover, such containers are often unable to reliably support mounting features and internal pressure, leading to failure during operation.
[0006] Other known systems also utilise combinations of materials or coatings to enhance performance. However, such approaches introduce complexity in manufacturing and potential failure at material interfaces. Further, many of such containers do not include effective means for withstanding internal steam pressure, ensuring sealing of access points or mounting the container structure in a reliable manner.
[0007] In light of the above discussion, there exists an urgent need for solutions that overcome the problems associated with conventional systems and/or techniques for constructing water heating appliances with thermoplastic containers.
Summary
[0008] The following presents a simplified summary of various aspects of this disclosure in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements nor delineate the scope of such aspects. Its purpose is to present some concepts of this disclosure in a simplified form as a prelude to the more detailed description that is presented later.
[0009] The following paragraphs provide additional support for the claims of the subject application.
[00010] An objective of the present disclosure is to provide a water heater comprising a thermoplastic container body capable of withstanding high internal temperature and pressure. Another objective of the present disclosure is to enable structural reinforcement within the container body using integrally formed elements while maintaining low weight and corrosion resistance. The water heater of the present disclosure aims to overcome drawbacks of conventional metallic or unreinforced plastic tanks by enabling thermomechanical performance, durability and secure mounting.
[00011] In an aspect, the present disclosure provides a water heater comprising a thermoplastic container body defining a water-retaining chamber, the container body comprising a cylindrical side wall and a domed top wall integrally formed with the cylindrical side wall. The container body exhibits at least two of a heat deflection temperature of at least 155°C at a load of 1.8 MPa, a tensile strength of at least 525 kg/cm², a flexural modulus of at least 2200 MPa, a melt flow index of approximately 20 g/10 min and a notched Izod impact strength of at least 5 kg·cm/cm. A plurality of reinforcement ribs project inwardly from an inner surface of the domed top wall. A recess is formed in an upper region of the domed top wall, dimensioned and shaped to receive a lid that covers and encloses an upper access region of the water-retaining chamber. A bottom-facing mounting flange extends outwardly from a lower portion of the cylindrical side wall and enables secure installation of the water heater. A heating element heats water contained within the water-retaining chamber.
[00012] Furthermore, the use of high-performance thermoplastic material in combination with reinforcement ribs and optimized wall thickness enables enhanced resistance to thermal and mechanical stresses. Moreover, integration of mounting and sealing features within the monolithic container body enables ease of assembly and installation. Further, inclusion of structural recess and lid support enables secure sealing and safe operation under high pressure.
Brief Description of the Drawings
[00013] The features and advantages of the present disclosure would be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:
[00014] FIG. 1 illustrates a water heater 100, in accordance with the embodiments of the present disclosure.
[00015] FIG. 2 illustrates a structural and dimensional representation of a thermoplastic container body 102 for a water heater 100, in accordance with the embodiments of the present disclosure.
Detailed Description
[00016] In the following detailed description of the invention, reference is made to the accompanying drawings that form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to claim those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims and equivalents thereof.
[00017] The use of the terms “a” and “an” and “the” and “at least one” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The use of the term “at least one” followed by a list of one or more items (for example, “at least one of A and B”) is to be construed to mean one item selected from the listed items (A or B) or any combination of two or more of the listed items (A and B), unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
[00018] Pursuant to the "Detailed Description" section herein, whenever an element is explicitly associated with a specific numeral for the first time, such association shall be deemed consistent and applicable throughout the entirety of the "Detailed Description" section, unless otherwise expressly stated or contradicted by the context.
[00019] As used herein, the term "water heater" refers to a fluid heating apparatus employed to elevate the temperature of water for domestic, commercial or industrial applications. Such water heater comprises structural, thermal and electrical components to retain water and facilitate thermal energy transfer to the retained water. The heating mechanism can be resistive, inductive or fluid-based, with electric heating coils, immersion rods or heat exchangers used as common examples. The water heater may be designed for vertical or horizontal installation depending on application constraints. Fluid containment is maintained using a pressure-resistant tank made from metal or plastic materials. The water heater also includes supporting structures for mechanical stability and may be fitted with safety valves, temperature regulators and thermostats for operation control. Water heaters may be powered through electric, solar, or fuel-based energy sources. The function of the water heater is to heat water to a predetermined temperature threshold and maintain said water at such temperature for on-demand use.
[00020] As used herein, the term "thermoplastic container body" refers to a vessel structure formed from a polymer material that softens when heated and hardens upon cooling without undergoing chemical change. Such thermoplastic container body is utilised for enclosing and storing fluids including water. The polymer used for manufacturing said container body includes, but is not limited to, polyethylene terephthalate, polypropylene, or polybutylene terephthalate. The thermoplastic material facilitates moulding and forming of complex shapes, thereby enabling integration of structural and mounting features. The container body retains water under elevated temperature and pressure conditions and maintains dimensional stability during thermal cycling. The container body may be produced using injection moulding, blow moulding, or rotational moulding techniques depending on shape and application. Resistance to deformation and chemical degradation is enabled by material properties such as tensile strength, flexural modulus, impact strength and heat deflection temperature. Thermoplastic container body may further include internal ribs, recesses, and mounting structures formed monolithically during the moulding process.
[00021] As used herein, the term "water-retaining chamber" refers to an enclosed internal volume formed within a structural component, such as a container body, configured to store and retain water for subsequent heating or circulation. Such water-retaining chamber may be of cylindrical, elliptical or polygonal geometry depending on dimensional and volumetric requirements. The internal chamber is bounded by walls that resist thermal expansion and fluid pressure. The water-retaining chamber is filled with water through an inlet and may include an outlet for dispensing the heated water. The water-retaining chamber may be configured for sealed or open operation depending on pressure constraints and safety requirements. Material used for surrounding said chamber is selected to withstand water-induced stress, thermal loading and chemical corrosion. The water-retaining chamber serves as the primary volume wherein heat is transferred from an energy source to the stored water. Common applications of a water-retaining chamber include storage tanks in geysers, boilers and household water heating units.
[00022] As used herein, the term "cylindrical side wall" refers to a vertically extending, generally circular wall structure forming the lateral boundary of a container, tank or housing. Such cylindrical side wall defines the height and volume of the container and is typically formed as a continuous annular surface enclosing the internal chamber. The cylindrical side wall may possess a uniform or variable thickness and may include features such as ribs, flanges or grooves for structural enhancement or component integration. The geometry of the cylindrical side wall enables ease of moulding and optimal stress distribution under internal pressure. Cylindrical side wall configurations are commonly used in fluid tanks, thermoplastic containers, and gas storage vessels due to their symmetry and resistance to buckling. Said cylindrical side wall may include regions of material reinforcement or thickening depending on load distribution or mounting interface requirements. The cylindrical side wall may also serve as an interface for attaching heating elements or external fittings.
[00023] As used herein, the term "domed top wall" refers to a curved upper structural surface integrally formed with a side wall of a container, wherein such surface forms the top enclosure of an internal chamber. Said domed top wall exhibits convex geometry that extends outwardly or upwardly from the edge of the cylindrical structure. The domed configuration enables improved stress distribution under internal pressure and prevents localized deformation. The domed top wall may be circular, elliptical or irregular in plan view and is formed from the same material as the adjacent side wall to ensure continuity of strength and barrier properties. Domed top walls are commonly used in storage tanks, pressure vessels, and water heaters to resist bulging under thermal or hydraulic expansion. The domed top wall may include integrally formed features such as reinforcement ribs, recesses, or connection ports for structural or functional purposes. Said domed top wall may be moulded along with the container in a single operation.
[00024] As used herein, the term "heat deflection temperature" refers to the temperature at which a polymer sample exhibits a specified deformation under a defined load, indicating thermal resistance of the material under mechanical stress. Such property is measured using a standard test method such as ASTM D648 wherein a specimen is subjected to a flexural load and gradually heated until deformation occurs. The heat deflection temperature is critical in determining the suitability of thermoplastic materials for applications involving exposure to elevated temperatures under load. A material with a heat deflection temperature above 155°C under a load of 1.8 MPa is suitable for use in containers that store heated water. Higher values of such temperature imply higher stability and reduced risk of material softening, warping, or collapse during service. Typical polymers possessing such characteristics include polyphenylene sulphide, polybutylene terephthalate, and polyetherimide. Heat deflection temperature guides selection of materials for housings of appliances such as kettles, coffee machines, and water heaters.
[00025] As used herein, the term "tensile strength" refers to the maximum amount of tensile stress that a material can withstand before failure, rupture or permanent deformation. Such tensile strength is expressed in units of force per unit area, such as kilograms per square centimetre or megapascals. The measurement of tensile strength is conducted using standardised procedures such as ASTM D638 wherein a sample is elongated under uniaxial tension until fracture. Tensile strength characterises the load-bearing capacity of thermoplastic materials used in structural applications such as container bodies or pressure vessels. A value of at least 525 kilograms per square centimetre is indicative of the ability of the material to resist elongation or tearing under applied pressure or weight. Polymers such as polybutylene terephthalate, polyethylene terephthalate and polycarbonate are commonly selected for their high tensile strength. Such mechanical property is relevant in components subjected to static or dynamic loading including liquid storage containers, structural tanks, and heating appliances storing pressurised fluids.
[00026] As used herein, the term "flexural modulus" refers to a measure of a material's stiffness or resistance to bending under an applied load. Such flexural modulus is expressed in units of pressure, such as megapascals, and is evaluated using standard test methods including ASTM D790. In such a test, a polymer specimen is supported at both ends and loaded at the centre, with the modulus calculated from the slope of the stress-strain curve in the elastic region. A flexural modulus of at least 2200 megapascals indicates a high degree of rigidity, enabling the material to retain shape and resist deflection when exposed to external or internal forces. Such property is critical in components like tank walls, support ribs, and flanges where dimensional stability must be maintained under operational loads. Polymers with high flexural modulus include polybutylene terephthalate and reinforced polyamide compounds. Applications requiring shape retention under bending forces employ materials selected based on flexural modulus for reliable performance.
[00027] As used herein, the term "melt flow index" refers to the mass of polymer material that flows through a capillary under specified temperature and pressure conditions within a given time interval. Such melt flow index is expressed in grams per ten minutes and is measured using standardised tests such as ASTM D1238. A melt flow index of approximately 20 grams per ten minutes characterises the flowability of the thermoplastic material during moulding operations such as injection moulding or extrusion. Such value influences processing parameters including mould filling time, pressure and cycle duration. Melt flow index is inversely related to the molecular weight of the polymer. A moderate value indicates balanced flow behaviour and mechanical performance, suitable for components requiring precision moulding and dimensional stability. Examples of polymers with comparable melt flow index values include general-purpose polybutylene terephthalate and impact-modified polyethylene terephthalate. Melt flow index is considered in the selection of materials for producing tank walls, lids, and other structural features in heating appliances.
[00028] As used herein, the term "notched Izod impact strength" refers to the amount of energy required to fracture a notched specimen of a material under sudden impact loading. Such property is expressed in units such as kilogram-centimetres per centimetre and is typically measured using standard test methods including ASTM D256. The test involves striking a notched polymer bar with a pendulum and recording the energy absorbed in breaking the sample. A notched Izod impact strength of at least 5 kilogram-centimetres per centimetre indicates the material's capacity to resist crack propagation and sudden mechanical shocks. Such impact resistance is essential in structural parts subjected to abrupt external forces, such as transportation-induced vibration, handling during installation or thermal expansion-induced stress. Polymers like polybutylene terephthalate and high-impact polystyrene are selected for such applications due to their resistance to brittle failure. Impact strength is a critical parameter in selecting materials for housing enclosures, container lids and ribbed structural reinforcements in water heaters and similar containers.
[00029] As used herein, the term "reinforcement ribs" refers to linear or grid-like projections integrally formed on or within a structural surface to increase rigidity and distribute stress. Such reinforcement ribs are configured to project from the inner surface of a wall, typically orthogonal or angled relative to the primary wall plane, and are used to improve load distribution, minimise deflection and enhance mechanical strength. Reinforcement ribs are commonly employed in thermoplastic mouldings such as containers, tanks and enclosures, especially where pressure or temperature-induced deformation may occur. The orientation of the reinforcement ribs may be radial, circumferential or grid-like depending on the stress distribution pattern. Reinforcement ribs are formed during the moulding process as raised features and may be continuous or segmented. The spacing, thickness and height of the reinforcement ribs are defined based on performance requirements. Examples of applications include top covers of pressure vessels, housing of electrical devices and enclosures of water storage units where structural integrity under thermal and hydraulic loading must be maintained.
[00030] As used herein, the term "recess" refers to a depression or cavity formed on a surface for the purpose of receiving or positioning another component in a nested or aligned manner. Such recess is integrally formed in a wall structure and is dimensioned to match the contour and profile of the component it accommodates. In the context of containers or enclosures, a recess is typically provided to retain a lid, cap, plug or sensor housing. The shape of the recess may be circular, rectangular, stepped or contoured depending on the mating geometry of the inserted component. The recess ensures positional alignment and minimises relative displacement during use. The depth and edge configuration of the recess provide support to vertical or axial loads and sealing forces. Recesses are widely used in mechanical assemblies, plastic housings, and liquid containment systems where closure integrity or alignment must be achieved. Formation of a recess is typically executed during injection or blow moulding processes.
[00031] As used herein, the term "lid" refers to a closure member configured to cover an opening of a container, chamber or housing for the purpose of enclosing the internal volume and restricting fluid exchange or contamination. Such lid may be circular, square or polygonal depending on the shape of the opening it encloses. The lid may be formed from thermoplastic, metal or composite materials and may include sealing elements such as gaskets, O-rings or interference-fit projections. The lid may further include reinforcement regions, mounting flanges, or engagement features for attachment with the container. Lids are commonly used in fluid storage tanks, access panels, electrical enclosures and appliances. In heated containers, the lid also functions to resist internal steam pressure and may incorporate vents or pressure-relief elements to regulate pressure buildup. Examples of lids include snap-fit caps, threaded closures, hinged covers and press-fit plates depending on application requirements. The lid interfaces with the recess to provide stable seating and axial retention.
[00032] As used herein, the term "mounting flange" refers to a projecting structural extension provided at the periphery of a container or component to enable attachment, positioning, or secure installation to a fixed surface or support frame. Such mounting flange is typically formed as an outward radial projection from a cylindrical or planar surface and includes one or more apertures, slots, or openings for insertion of fasteners such as screws, bolts, or rivets. The mounting flange maintains positional stability of the container and transmits mechanical loads from the container body to the support structure. The configuration of the mounting flange is selected based on installation orientation, operating conditions, and material properties. In applications involving thermal expansion, fluid pressure, or vibration, the flange is reinforced or thickened to resist fatigue or deformation. Mounting flanges are widely used in water tanks, boilers, electronic enclosures, and mechanical housings. The flange may be circumferential or segmental and is generally produced integrally with the container body during the moulding process to ensure strength continuity.
[00033] As used herein, the term "heating element" refers to a component designed to convert electrical energy into thermal energy for the purpose of raising the temperature of a surrounding medium, such as water, air, or fluid. Such heating element operates on resistive heating principles and comprises conductive materials such as nichrome, stainless steel, or copper that resist electrical current and generate heat. The heating element may be formed as a coil, rod, or plate and is embedded directly within the fluid-retaining container or mounted adjacent to the chamber wall. The heating element is electrically connected to an external power source through terminals or connectors and may include an insulating sheath to isolate it from the fluid. Temperature regulation is achieved using thermostats, thermal fuses, or electronic control circuits. Applications of heating elements include electric kettles, geysers, water heaters, and industrial boilers. Heating elements are selected based on wattage rating, thermal response time, corrosion resistance, and compatibility with the surrounding container material.
[00034] FIG. 1 illustrates a water heater 100, in accordance with the embodiments of the present disclosure. The water heater 100 comprises a storage and heating system that is structured to retain water and elevate its temperature for domestic or commercial use. The water heater 100 incorporates a thermoplastic container body 102 which defines a water-retaining chamber for holding a specified volume of water during both static and active heating conditions. The thermoplastic container body 102 is formed using injection or blow moulding techniques, enabling integral formation of structural and functional elements while maintaining seamless transitions between curved and flat surfaces. The thermoplastic container body 102 enables corrosion resistance and reduced mass in comparison to metallic tanks and supports moulded-in-place features that facilitate mounting, sealing, and component interfacing. The water-retaining chamber is defined internally by continuous walls of the container body 102 and is enclosed at its top and bottom. The chamber is shaped for optimal water circulation and pressure management. The material selection for the thermoplastic container body 102 enables resistance to repeated thermal cycling, dimensional deformation, and chemical degradation. The thermoplastic container body 102 may be constructed from polybutylene terephthalate (PBT) or an equivalent engineering thermoplastic compound. The container body 102 functions as both a fluid-retaining volume and a load-bearing framework, supporting associated components including a lid 112, a heating element 116, and anchoring fixtures. Integration of all structural elements during a single moulding operation ensures mechanical uniformity and eliminates interface failures associated with welding or adhesive joining. The design of the container body 102 enables manufacturing repeatability, thermal insulation layering, and assembly compatibility with external plumbing and electrical networks.
[00035] The container body 102 comprises a cylindrical side wall 104 that forms the primary vertical surface enclosing the water-retaining chamber. The cylindrical side wall 104 is generally circular in cross-section and extends between a bottom terminal region and a domed top wall 106. The cylindrical side wall 104 is integrally formed with the rest of the container body 102 and defines the volumetric capacity of the water-retaining chamber. The cylindrical geometry of the side wall 104 enables even stress distribution across the wall thickness and enhances resistance to internal hydrostatic pressure. The cylindrical side wall 104 possesses a uniform thickness ranging between 2.5 mm and 4.0 mm, where the lower range (2.5 mm to 3.0 mm) provides material economy for small capacity tanks and the upper range (3.1 mm to 4.0 mm) supports larger tank sizes and pressurized configurations. The cylindrical side wall 104 may further include integral ribs for vertical reinforcement or surface patterning for bonding insulation layers. The cylindrical side wall 104 enables straightforward integration of external components, such as sensor housings, heating bands, and control boxes. The continuous curvature of the side wall 104 eliminates geometric discontinuities, which are typically associated with crack initiation or material fatigue in pressure vessels. The surface of the cylindrical side wall 104 may also serve as an anchoring location for the bottom-facing mounting flange 114. The cylindrical side wall 104 provides not only structural stiffness but also functions to stabilize the top and bottom portions of the container body 102 during operation.
Wall Thickness (mm) Flexural Modulus Impact Resistance Pressure Resistance Wall Stability
2.0 – 2.4 mm * * * *
2.5 – 3.0 mm ** ** ** **
3.1 – 3.5 mm *** *** *** ***
3.6 – 4.0 mm *** *** *** ***
4.1 – 4.5 mm ** ** ** **
4.6 – 5.0 mm * * * *
Table 1
[00036] Table 1 illustrates the influence of wall thickness variation in the cylindrical side wall 104 on structural performance metrics of the water heater 100. The water heater 100 comprises a thermoplastic container body 102 featuring the cylindrical side wall 104 integrally formed with a domed top wall 106, enclosing a chamber dimensioned to store approximately 80 liters of heated water. The assembled height and diameter of the container body 102 are approximately 700 mm and 400 mm, respectively, and the water heater 100 is configured for residential operation at up to 0.6 MPa pressure and sustained water temperatures between 60°C and 80°C. To examine the effect of varying wall thickness, six variants of the cylindrical side wall 104 were molded with average wall thicknesses from 2.0 mm to 5.0 mm. Structural uniformity is evaluated using ultrasonic wall profiling at multiple vertical sections to identify deviations in material density and continuity. To measure hoop expansion behavior under thermal stress, circumferential strain gauges were bonded onto the external surface of the cylindrical side wall 104 and monitored during hot-water fill cycles at 75°C. Out-of-round deformation under compressive base loading is tested using a vertical platen compression setup, recording elliptical distortion using laser displacement sensors positioned at orthogonal axes. Resistance to thermal creep is assessed by sustaining the container body 102 in a filled and heated condition for 72 hours and measuring permanent radial displacement. As shown in Table 1, wall thicknesses below 2.5 mm exhibited irregular hoop strain, excessive ovalization under axial compression, and long-term creep under thermal stress. Thicknesses in the range of 2.5 mm to 4.0 mm showed stable hoop strain behavior, uniform ultrasonic profiles, and low residual deformation, indicating optimal structural integrity. Specimens with thicknesses above 4.0 mm showed minor improvement in hoop behavior but introduced processing drawbacks such as inconsistent cooling and internal stress zones. These findings validate that the 2.5 mm to 4.0 mm range represents the structurally balanced and practically efficient wall thickness for the cylindrical side wall 104 of the water heater 100.
[00037] The domed top wall 106 is integrally formed with the cylindrical side wall 104 and forms the upper enclosure boundary of the water-retaining chamber. The domed top wall 106 includes a convex curvature extending outward from the central axis of the container body 102, the geometry of which is selected to reduce stress concentration caused by internal steam or thermal expansion. The domed top wall 106 is formed monolithically with the container body 102 and exhibits enhanced material thickness in comparison to the cylindrical side wall 104. Specifically, the thickness of the domed top wall 106 is greater by a range of approximately 25% to 40% than that of the cylindrical side wall 104. This thickness range is further delineated into bracketed values of 25% to 30% and 31% to 40%, where the lower bracket addresses applications requiring moderate pressure retention and the upper bracket supports stea

integrally during the molding of the container body 102. The recess 110 includes a stepped inner ledge designed to support the downward vertical force imposed by the lid 112 under thermal expansion or internal pressure buildup. The diameter and depth of the recess 110 are configured to match the seating flange of the lid 112, enabling secure fitment and pressure sealing. The shape of the recess 110 may be contoured to include a flat shoulder, tapered sidewalls, or O-ring engagement grooves depending on sealing requirements. The stepped geometry permits containment of compressible seals such as silicone gaskets or elastomeric rings that compress radially and axially to prevent leakage. The recess 110 facilitates the axial alignment of the lid 112 during assembly and maintains sealing integrity during heating cycles or pressure fluctuations. The structural design of the recess 110 allows the dome to distribute lid loads circumferentially, reducing localized stress concentrations. The recess 110 may further include alignment notches, interlocking tabs, or sensor guide slots depending on application. Because the recess 110 is formed from the same material as the domed top wall 106, it exhibits matched thermal expansion behavior, ensuring consistent sealing under varying operational conditions.
[00044] The lid 112 is dimensioned to enclose and cover the upper access region of the water-retaining chamber defined by the thermoplastic container body 102. The lid 112 is circular in plan view and features a downward-projecting engagement surface that mates with the stepped ledge of the recess 110. The lid 112 is formed from a polymer or composite material capable of resisting heat and pressure, optionally reinforced with glass fibers or metal inserts. The outer edge of the lid 112 may include a gasket groove configured to retain a compressible sealing element such as a fluoropolymer or silicone ring. The lid 112 may be removably secured via a twist-lock mechanism, snap-fit tabs, or threaded engagement, depending on desired sealing strength and access frequency. The upper surface of the lid 112 may include integrated features such as a pressure-relief vent designed to activate above a threshold value of internal pressure, preventing structural failure of the container body 102. In some embodiments, the lid 112 also accommodates a sensing module configured to monitor one or more operational parameters including temperature, water level, or internal pressure. Such sensors may include thermistors, reed switches, or resistive pressure devices mounted within the lid body or on an external interface. The thickness of the lid 112 may vary, with a reinforced periphery that is at least 20% greater in thickness compared to the central region. This reinforcement range is subdivided into two brackets of 20% to 25% and 26% to 30%, enabling structural tuning based on the container size and pressure profile. The lid 112 provides both mechanical closure and operational monitoring interface.

Peripheral Thickness Increase (%) Flexural Modulus Impact Strength Steam Load Endurance Sealing Surface Stability
18% – 19% * * * *
20% – 22% ** ** ** **
23% – 25% ** ** ** **
26% – 28% *** ** *** **
29% – 30% *** *** *** ***
31% – 33% ** ** ** *
Table 6
[00045] Table 6 illustrates the influence of peripheral thickness increase of the lid 112 relative to its central region on mechanical and sealing performance parameters in the water heater 100. Six lid 112 variants are examined with peripheral thickness enhancements of 18%–19%, 20%–22%, 23%–25%, 26%–28%, 29%–30%, and 31%–33% over the central region thickness. Each lid 112 is seated into the recess 110 formed within the domed top wall 106 of the container body 102 and subjected to targeted evaluation under controlled environmental and mechanical loading conditions. Flexural modulus is assessed by applying a distributed vacuum field beneath the lid 112 while centrally loading the structure with a ring mass, allowing for vertical displacement tracking via equidistant optical sensors placed around the periphery. Impact strength is characterized by a controlled hammer pulse test, in which dynamic contact at the lid 112 edge is followed by time-gated infrared thermal mapping to detect internal fracture paths. Steam load endurance is evaluated by maintaining elevated chamber saturation at 0.4 MPa for 16 hours followed by a vacuum cooldown phase, during which contour shifts and lid edge separation are recorded using edge gap sensors. Sealing surface stability is assessed by installing a sensing film between the lid 112 and recess 110, compressing the closure, and analyzing micro-contact dispersion using topography mapping software. As indicated in Table 6, peripheral thickness increases of 18%–19% result in poor edge rigidity and premature leakage under mild internal pressure buildup. The 20%–22% and 23%–25% ranges show acceptable performance with reduced flexural distortion and improved steam retention, though minor sealing inconsistencies persist under thermal cycling. Lid 112 variants with a 26%–28% increase exhibit strong mechanical control with partial improvement in contact stability. The 29%–30% configuration provides the best overall outcome, offering consistent structural retention, high resistance to crack initiation, and stable sealing engagement throughout multiple thermal-pressure cycles. Beyond this threshold, variants with 31%–33% peripheral thickness increase begin to demonstrate over-stiffening effects, reduced compliance at the recess interface, and increased edge misalignment following closure. These observations support that a peripheral thickness increase of 29%–30% over the central region of the lid 112 offers the most balanced and functionally effective configuration for the water heater 100.
[00046] A bottom-facing mounting flange 114 extends radially outward from a lower portion of the cylindrical side wall 104 and provides a structural interface for mounting the water heater 100 onto a base surface. The mounting flange 114 is integrally formed during the molding of the thermoplastic container body 102 and is planar or slightly contoured to match expected installation geometries. The flange 114 includes a plurality of preformed apertures distributed circumferentially, each aperture configured to accept a mechanical fastener such as a bolt, screw, or rivet. The preformed apertures may be countersunk or chamfered to facilitate secure attachment. The radial width of the flange 114 is selected based on expected installation torque and static loading. The flange 114 may be reinforced by localized thickening of the adjoining cylindrical side wall 104 or by integration of radial support ribs extending between the flange 114 and the wall 104. During installation, the flange 114 transfers the weight of the filled container body 102 and any external loads (such as piping or wiring) directly to the mounting surface. The flange 114 ensures positional stability of the water heater 100 and enables consistent vertical alignment with gravity-driven flow elements. The flange 114 may further incorporate drainage features, alignment pins, or cushioning pads depending on floor material or anchoring strategy. The integration of the mounting flange 114 as a monolithic extension of the cylindrical side wall 104 eliminates the need for fastened brackets or secondary mounting accessories, improving structural cohesion and reliability under dynamic service conditions.
[00047] The heating element 116 is disposed within the water-retaining chamber defined by the thermoplastic container body 102 and is configured to heat the water to a predetermined operational temperature. The heating element 116 comprises a metallic coil or rod formed from a resistive material such as nichrome, stainless steel, or copper alloy, and is enclosed within a sheath for electrical insulation and corrosion resistance. The heating element 116 is mounted internally within the container using threaded ports, molded brackets, or press-fit grommets. The power rating of the heating element 116 is selected based on the container volume and heating cycle time, typically ranging between 500 watts and 3000 watts. This rating may be subdivided into brackets of 500 to 1000 watts for compact domestic models, 1100 to 2000 watts for standard household units, and 2100 to 3000 watts for commercial or rapid-heating applications. The heating element 116 is connected to an external control circuit via waterproof electrical terminals, and is operable using a thermostat or digital temperature controller. Temperature feedback may be provided by a thermocouple or a negative temperature coefficient (NTC) thermistor placed in close proximity to the heating element 116. Safety features including thermal cutoffs or current-limiting fuses may be embedded to prevent overheating or dry-run conditions. The placement of the heating element 116 below the waterline ensures direct contact with water, facilitating efficient thermal energy transfer. The geometry, power profile, and mounting of the heating element 116 are selected to achieve rapid and uniform heating with low energy loss and minimal stratification.
Power Rating (Watts) Heating Speed Thermal Stratification Energy Consumption Cycle Time (to 60°C)
500 – 1000 W * *** * ***
1100 – 2000 W ** ** ** **
2100 – 3000 W *** * *** *
Table 7
[00048] Table 7 illustrates the relationship between the power rating of the heating element and key thermal performance parameters including heating speed, thermal stratification, energy consumption, and cycle time required to reach 60°C. The lowest power range of 500–1000 W delivers minimal heating speed and energy input, resulting in longer cycle times but low thermal gradient variation, hence excellent thermal stratification control. The intermediate range of 1100–2000 W offers a balanced performance across all parameters, enabling moderate heating rates, reasonable energy use, and reduced stratification effects. The highest range of 2100–3000 W provides the fastest heating speed and shortest cycle times, but at the cost of higher energy consumption and less uniform temperature distribution within the water volume. This classification aids in selecting the appropriate heating element rating based on application-specific needs, such as energy efficiency, heating uniformity, or rapid temperature attainment in residential or commercial water heating scenarios.
[00049] In an embodiment, the reinforcement ribs 108 are oriented in a radial or grid-like pattern across the inner surface of the domed top wall 106 to distribute stress caused by thermal expansion or pressurization. The radial configuration comprises ribs extending from a central apex of the dome outward toward the peripheral edge at angular intervals, while the grid-like configuration includes intersecting ribs arranged orthogonally or diagonally. The reinforcement ribs 108 are molded integrally with the domed top wall 106 and typically extend inward with a rib depth in the range of 5 mm to 12 mm. These depths may be segmented into sub-ranges of 5–6 mm for light-load applications, 7–9 mm for moderate pressurization, and 10–12 mm for high-pressure containment. The reinforcement ribs 108 function to stabilize the dome against inward deflection due to internal steam buildup and provide structural anchorage for the seating region of the lid 112. The rib distribution ensures that no unsupported dome segment exceeds a span of 40 mm. The ribs may also promote turbulent water flow during heating, aiding in thermal homogenization. Integration of these reinforcement ribs 108 enhances mechanical performance of the domed top wall 106 under cyclic temperature and pressure variations.
Rib Depth (mm) Buckling Resistance Dome Rigidity Thermal Load Tolerance Water Mixing Effect
5–6 mm * * * *
7–9 mm ** ** ** **
10–12 mm *** *** *** ***
Table 8
[00050] Table 8 outlines the impact of varying rib depth on the performance of reinforcement ribs integrated within the domed top wall of the thermoplastic container body. As the rib depth increases from 5–6 mm to 10–12 mm, a corresponding enhancement is observed in buckling resistance, dome rigidity, thermal load tolerance, and water mixing effect. The shallow rib depth range of 5–6 mm provides minimal reinforcement, sufficient only for low-pressure or small-capacity containers. Increasing the rib depth to 7–9 mm results in improved structural resistance to dome deflection and better distribution of thermal and mechanical loads. The deepest range of 10–12 mm delivers the highest performance across all parameters, supporting the dome against internal pressure surges, improving structural stiffness under steam exposure, and enhancing internal fluid turbulence during heating. This classification supports structural optimization of dome-integrated ribs based on anticipated load conditions and desired water circulation characteristics.
[00051] In an embodiment, the bottom-facing mounting flange 114 extends circumferentially outward from the lower portion of the cylindrical side wall 104 and comprises a plurality of preformed apertures to support mechanical fastening. The flange 114 is molded integrally with the thermoplastic container body 102 and extends radially in the range of 15 mm to 25 mm from the outer wall surface. These dimensions may be divided into sub-ranges of 15–17 mm for compact installations, 18–21 mm for standard domestic use, and 22–25 mm for high-load or commercial configurations. The apertures are evenly spaced along the periphery and are configured to accept fasteners such as M6 or M8 bolts. Each aperture may be reinforced with an annular boss having a wall thickness increase of approximately 20% to prevent crack initiation under torque. The flange 114 ensures that vertical and torsional forces acting on the water heater 100 are transferred to a base surface or mounting bracket without overstressing the cylindrical side wall 104. Multiple apertures support distributed load transfer and alignment accuracy. The design of the mounting flange 114 also facilitates installation repeatability and accommodates tolerance variations in anchoring platforms or surfaces.
Flange Width (mm) Fastener Stability Load Transfer Deformation Resistance Mounting Accuracy
15–17 mm * * * *
18–21 mm ** ** ** **
22–25 mm *** *** *** ***
Table 9
[00052] Table 9 illustrates the effect of flange width on mounting-related performance parameters of the bottom-facing mounting flange of the thermoplastic container body. As the flange width increases from 15–17 mm to 22–25 mm, there is a clear improvement in fastener stability, load transfer efficiency, deformation resistance, and mounting accuracy. The narrow width range of 15–17 mm provides basic anchoring capability suitable for lightweight or stationary installations. A moderate width of 18–21 mm enhances the flange's ability to distribute mechanical loads, improves resistance to flexural distortion during fastening, and ensures better alignment with pre-drilled mounting surfaces. The widest range of 22–25 mm offers maximum support, enabling precise positioning, robust load transmission to the mounting base, and superior resistance to mechanical or thermal deformation during installation or service. This classification enables rational selection of flange dimensions based on expected mounting forces, surface conditions, and durability requirements in water heater applications.
[00053] In an embodiment, the recess 110 formed in the domed top wall 106 is circular in plan view and comprises a stepped inner ledge configured to seat the lid 112 and prevent vertical displacement under axial loading. The recess 110 is concentrically located at the topmost portion of the domed structure and is formed as an integral depression. The stepped ledge defines a flat horizontal shoulder recessed by a depth in the range of 5 mm to 8 mm, with sub-ranges of 5–6 mm for low-pressure applications, 7 mm for general-purpose configurations, and 8 mm for pressure-retentive sealing. The ledge supports the sealing flange of the lid 112 and provides resistance against upward displacement due to internal steam force. The geometry enables uniform compression of gaskets or sealing rings positioned between the lid 112 and the ledge. The vertical contour of the recess 110 may be tapered to promote a centering effect during lid engagement. The structure supports axial stability while eliminating the need for external clamps or fasteners. The formation of the recess 110 ensures alignment repeatability and enhances dome integrity by uniformly distributing lid pressure across the surrounding dome surface.
Shoulder Depth (mm) Lid Seating Stability Steam Seal Reliability Axial Force Absorption Gasket Compression Consistency
5–6 mm * * * *
7 mm ** ** ** **
8 mm *** *** *** ***
Table 10
[00054] Table 10 presents the influence of shoulder depth—formed within the recess on the domed top wall—on critical sealing and structural performance attributes related to lid engagement. As the shoulder depth increases from 5–6 mm to 8 mm, significant enhancements are observed in lid seating stability, steam seal reliability, axial force absorption, and gasket compression consistency. The shallow depth range of 5–6 mm provides minimal surface engagement and limited axial load bearing, making it suitable for low-pressure applications. At 7 mm, the shoulder offers improved geometric locking of the lid, better distribution of sealing forces, and more reliable gasket compression. The 8 mm depth delivers the highest performance, enabling uniform and secure seating of the lid under operational loads, enhanced steam retention through consistent gasket deformation, and increased ability to absorb pressure-induced axial forces without displacement. This classification supports the optimization of shoulder design for pressure-containment systems requiring durable and repeatable sealing engagement.
[00055] In an embodiment, the cylindrical side wall 104 comprises at least one localized wall thickening region proximate to the mounting flange 114 to enhance load transfer and prevent material failure at the anchoring interface. The thickening is formed monolithically during the molding process and is applied selectively to the lower 20 mm to 30 mm of the cylindrical side wall 104. The thickness of this reinforced region may range from 4.5 mm to 6.0 mm, segmented into sub-ranges of 4.5–5.0 mm for lightweight containers, 5.1–5.5 mm for standard units, and 5.6–6.0 mm for high-load installations. This thickening compensates for concentrated torque applied during fastener engagement through the mounting flange 114 and resists flexural displacement caused by container weight or thermal expansion. The reinforcement region may also support auxiliary structures such as drainage ports or bracket interfaces. The outer contour of the wall remains compatible with insulation cladding or enclosure housings. This structural modification extends the operational life of the container body 102 by suppressing creep, stress cracking, and plastic deformation under repeated heating and load cycles.
Increased Wall Thickness (mm) Load Resistance Torque Handling Mounting Flange Integrity Thermal Cycle Durability
4.5–5.0 mm * * * *
5.1–5.5 mm ** ** ** **
5.6–6.0 mm *** *** *** ***
Table 11
[00056] Table 11 highlights the effect of increased wall thickness—particularly in localized reinforced regions near the mounting flange—on mechanical and thermal performance characteristics of the container body. As wall thickness increases from 4.5–5.0 mm to 5.6–6.0 mm, there is a marked improvement in load resistance, torque handling capability, mounting flange integrity, and thermal cycle durability. The lower range of 4.5–5.0 mm offers minimal reinforcement, suitable for low-load static installations with limited thermal stress. The intermediate range of 5.1–5.5 mm provides balanced mechanical stability, enabling moderate resistance to installation torque, flange distortion, and material fatigue under cyclic heating. The upper range of 5.6–6.0 mm delivers maximum structural reliability, ensuring rigid anchoring, high load tolerance, sustained shape retention, and reduced risk of crack propagation in repeated service cycles. This classification guides localized wall design in thermoplastic water heaters subjected to mechanical fastening and long-term thermal fluctuation.
[00057] In an embodiment, the domed top wall 106 is associated with a convex curvature extending outward from the central axis of the container body 102, forming a geometrically smooth shell profile. The curvature is defined by a continuous radial transition from the center of the dome to its periphery and serves to distribute internal pressure uniformly across the surface. The radius of curvature may fall within the range of 80 mm to 150 mm, with sub-ranges of 80–100 mm for compact tanks, 101–125 mm for medium-volume units, and 126–150 mm for high-capacity or elevated-pressure configurations. The convex shape minimizes stress concentration and avoids sharp transitions that may induce fracture under pressure cycling. The profile also promotes condensation runoff and prevents water pooling at the lid interface. Formation of the convex geometry occurs during molding, ensuring surface continuity and structural cohesion with the adjoining side wall 104 and recess 110. The convex dome enhances buckling resistance and forms a mechanically resilient interface for attachment of reinforcement ribs 108, sensor recesses, or lid structures.
[00058] In an embodiment, the lid 112 further comprises a pressure-relief vent structured to release internal steam buildup above a specified threshold pressure. The vent may comprise a spring-loaded valve, thermally responsive membrane, or fusible element and is integrated into the lid 112 to maintain structural compactness. The release threshold is typically set within the range of 1.5 bar to 3.0 bar, with sub-ranges of 1.5–2.0 bar for domestic units, 2.1–2.5 bar for general-use systems, and 2.6–3.0 bar for high-pressure industrial or commercial applications. The vent ensures that pressure within the container body 102 remains below structural failure limits of the thermoplastic material. When internal steam pressure exceeds the preset threshold, the vent opens to allow discharge, thereby relieving axial load on the dome and the lid 112. The orientation of the vent is selected to direct steam safely away from users or sensitive components. The pressure-relief mechanism ensures compliance with overpressure safety standards and prevents catastrophic rupture during thermal malfunction or electrical control failure.
[00059] In an embodiment, the cylindrical side wall 104 is formed with integral vertical ribs molded into the outer surface to increase stiffness and load distribution. These ribs extend parallel to the axis of the cylinder and are evenly spaced circumferentially. The rib depth typically ranges from 3 mm to 6 mm, with sub-ranges of 3–4 mm for light-duty tanks, 4.1–5 mm for medium-strength designs, and 5.1–6 mm for high-strength applications. The width of each rib may be 6 mm to 10 mm depending on load requirements. The ribs act as reinforcement beams, minimizing hoop deformation under hydrostatic pressure. The configuration also resists outward bulging during thermal expansion and supports insulation bonding or external bracket alignment. The continuous formation of ribs along the vertical profile does not interfere with sealing or mounting features and enhances overall structural uniformity of the container body 102 under operational loads.
[00060] In an embodiment, the lid 112 receives a sensing module configured to monitor one or more operational parameters such as water temperature, internal pressure, or fluid level within the container body 102. The sensing module is positioned in a recessed housing on the lid 112 and is sealed using elastomeric gaskets or epoxy resin to ensure steam resistance. The module may comprise a thermistor or RTD sensor for temperature measurement, a capacitive or float-based level sensor for water level detection, and a pressure transducer with a membrane interface for steam pressure monitoring. Output from the sensing module may be transmitted via wired terminals or wireless communication protocols such as Bluetooth Low Energy (BLE) or ZigBee. Measurement ranges may include 20°C to 95°C for temperature, 0.2 bar to 3.0 bar for pressure, and 0–3 litres for water volume. The sensing module may operate autonomously or interface with a microcontroller for real-time feedback control of the heating element 116. The presence of this module enables active safety regulation, predictive maintenance, and operational monitoring of the water heater 100 in both domestic and commercial contexts.
[00061] In an embodiment, the cylindrical side wall 104 comprises external helical ribs that extend longitudinally along the wall surface in a spiral pattern. The helical ribs are molded integrally during formation of the thermoplastic container body 102 and are configured to provide distributed reinforcement across both the vertical and circumferential axes. The helix pitch may range from 20 mm to 40 mm, divided into sub-ranges of 20–25 mm for dense ribbing, 26–32 mm for balanced structural enhancement, and 33–40 mm for lighter reinforcement. The rib depth ranges from 2 mm to 5 mm depending on tank size and pressurization requirements. The helical pattern resists torsional and axial buckling and supports alignment of insulation layers or external sleeves. The angled rib geometry improves energy dispersion under lateral loading and thermal gradient fluctuation. The continuous nature of the helical ribs also reduces stress concentration zones compared to discrete ribs. This structure contributes to long-term shape retention and mechanical reliability of the container body 102 under thermal and hydraulic operating cycles.
[00062] In an embodiment, the cylindrical side wall 104 comprises an average wall thickness in the range of 2.5 mm to 4.0 mm to maintain structural integrity under heating and pressurization conditions. This thickness range is critical for ensuring that the side wall 104 can retain water at elevated temperatures while withstanding cyclic pressure variations without material fatigue. The range may be further segmented into sub-ranges of 2.5–3.0 mm for lightweight or compact water heater designs, 3.1–3.5 mm for medium-capacity containers, and 3.6–4.0 mm for high-performance or high-capacity vessels. These wall thickness values contribute directly to flexural modulus, impact resistance, and pressure containment. For example, containers with a 3.2 mm wall exhibit improved hoop strength while maintaining reasonable material cost and weight. The thermoplastic resin used in the cylindrical side wall 104, such as polybutylene terephthalate, enables injection molding of such calibrated wall profiles with consistent dimensional stability. Increased thickness not only prevents localized deformation under hydrostatic load but also ensures surface compatibility with insulation and mounting features. Selection of appropriate thickness within the specified range allows optimization of thermal retention, manufacturing cost, and durability across various operational and structural applications of the water heater 100.
[00063] In an embodiment, the domed top wall 106 comprises a thickness greater than the cylindrical side wall 104, such that the thickness of the domed top wall 106 is in the range of approximately 25% to 40% greater than that of the cylindrical side wall 104. This relative increase in thickness is necessary to withstand internal steam pressure, support reinforcement ribs 108, and prevent localized deformation at the dome’s apex and flange junctions. The range may be divided into sub-ranges of 25%–30% for standard applications, 31%–35% for higher structural demand, and 36%–40% for heavy-duty steam-containing environments. For example, if the side wall 104 has an average thickness of 3.0 mm, the domed top wall 106 may be formed with a thickness between 3.75 mm and 4.2 mm depending on load requirement. This increase ensures axial stiffness, particularly near the recess 110 and the anchoring points of the reinforcement ribs 108. The additional thickness also helps dissipate radial stress away from the lid 112 engagement region, supporting long-term dome integrity under temperature cycling and internal fluid pressure. The integral molding of the thicker dome section ensures uniform material properties and eliminates the risk of seam or weld failures during operational service.
[00064] In an embodiment, the lid 112 comprises a reinforced periphery having a thickness at least 20% greater than a central region of the lid 112 to improve resistance to vertical force exerted during closure or pressure buildup. The peripheral reinforcement ensures that sealing integrity is maintained when axial load is applied during fastening or internal steam expansion. The increase in peripheral thickness is categorized into sub-ranges of 20%–22% for basic sealing enhancement, 23%–25% for intermediate steam containment performance, 26%–28% for balanced structural load management, and 29%–30% for high-sealing force applications. For instance, if the central region of the lid 112 measures 2.5 mm in thickness, the peripheral edge may be formed with a thickness ranging from 3.0 mm to 3.25 mm depending on required closure force absorption. The added material in the reinforced zone functions as a structural barrier against radial distortion, improving fitment over the stepped recess 110 and preventing gasket extrusion or leakage. The peripheral reinforcement may be molded integrally using increased material deposition or through geometry profiling of the lid flange. This reinforcement increases the lid’s ability to resist deflection, maintains gasket compression, and extends sealing performance under repeated thermal expansion and contraction cycles.
[00065] The thermoplastic container body 102 defines a closed water-retaining chamber while allowing integral formation of cylindrical side wall 104 and domed top wall 106. The integration enables uniform material distribution and avoids interface stress between intersecting planes, improving reliability under cyclic thermal and pressure loading. Material properties specified—such as a heat deflection temperature of ≥155°C at 1.8 MPa, tensile strength ≥525 kg/cm², flexural modulus ≥2200 MPa, MFI ≈20 g/10 min, and notched Izod impact strength ≥5 kg·cm/cm—enable the container body 102 to retain shape and function at elevated temperatures, resist cracking, and allow detailed molding without mechanical loss. Reinforcement ribs 108 inwardly projecting from domed top wall 106 reduce bulging and increase rigidity of the top surface. Recess 110 in the top wall 106 receives lid 112 to seal the access region while maintaining vertical alignment. Bottom-facing mounting flange 114 supports secure anchoring and vertical stress transfer. Heating element 116 enables direct thermal transfer to water within the chamber, completing the functional loop.
[00066] Reinforcement ribs 108 oriented in a radial or grid-like pattern deliver uniform stress dissipation from the central dome area outward or across intersecting spans. The radial layout enhances dome stiffness by directing pressurization loads along predefined structural paths, reducing dome deflection. The grid-like orientation enables biaxial support, critical for larger diameters. These positional orientations of ribs enhance dome rigidity and prevent fatigue under thermal cycling, extending container service life.
[00067] Bottom-facing mounting flange 114 extending in a circumferential manner distributes the weight of the water heater 100 evenly over its supporting base. The uniform geometry prevents torsional twisting and supports symmetric torque handling during installation. The inclusion of preformed apertures facilitates consistent fastener alignment, enhances fixture stability, and avoids manual drilling-induced inconsistencies. This configuration reduces deformation risk under mechanical fastening and promotes accurate positional locking.
[00068] Recess 110 being circular in plan view ensures that lid 112 achieves rotational symmetry for axial load distribution and gasket sealing efficiency. The stepped inner ledge provides a radial seating surface, preventing downward displacement of lid 112 under steam pressure. This stepped profile acts as a mechanical stop and promotes even gasket compression. The ce

Claims
I/We Claim:
1. A water heater 100 comprising:
a thermoplastic container body 102 defining a water-retaining chamber, said container body 102 comprising:
a cylindrical side wall 104; and
a domed top wall 106 integrally formed with the cylindrical side wall 104;
wherein the container body 102 exhibits at least two from:
a heat deflection temperature of at least 155°C at a load of 1.8 MPa
a tensile strength of at least 525 kg/cm²
a flexural modulus of at least 2200 MPa
a melt flow index of approximately 20 g/10 min; and
a notched Izod impact strength of at least 5 kg·cm/cm
a plurality of reinforcement ribs 108 projecting inwardly from an inner surface of the domed top wall 106;
a recess 110 formed in an upper region of the domed top wall 106, said recess 110 dimensioned and shaped to receive a lid 112 that covers and encloses an upper access region of the water-retaining chamber;
a bottom-facing mounting flange 114 extending outwardly from a lower portion of the cylindrical side wall 104 and configured for secure installation of the water heater 100; and
a heating element 116 to heat the water contained within the water-retaining chamber.
2. The water heater as claimed in claim 1, wherein the reinforcement ribs 108 are oriented in a radial or grid-like pattern to distribute stress caused by thermal expansion or pressurization.
3. The water heater as claimed in claim 1, wherein the bottom-facing mounting flange 114 extends outwardly in a circumferential manner and comprises a plurality of preformed apertures.
4. The water heater as claimed in claim 1, wherein the recess 110 formed in the domed top wall 106 is circular in plan view and comprises a stepped inner ledge configured to seat the lid 112 and prevent vertical displacement under axial loading.
5. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises at least one localized wall thickening region proximate to the mounting flange 114.
6. The water heater as claimed in claim 1, wherein the domed top wall 106 is associated with a convex curvature.
7. The water heater as claimed in claim 1, wherein the lid 112 further comprises a pressure-relief vent to release internal steam buildup above a threshold pressure.
8. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 is formed with integral vertical ribs.
9. The water heater as claimed in claim 1, wherein the lid 112 receives a sensing module to sense at least one of a temperature, a pressure level, or a water level.
10. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises external helical ribs extending longitudinally along the wall.
11. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises an average wall thickness in the range of 2.5 mm to 4.0 mm to maintain structural integrity under heating and pressurization conditions.
12. The water heater as claimed in claim 1, wherein the domed top wall 106 comprises a thickness greater than the cylindrical side wall 104, such that the thickness of the domed top wall 106 is in the range of approximately 25% to 40% greater than that of the cylindrical side wall 104, to withstand internal steam pressure and support the reinforcement ribs 108 without localized deformation.
13. The water heater as claimed in claim 1, wherein the lid 112 comprises a reinforced periphery having a thickness at least 20% greater than a central region of the lid 112 to improve resistance to vertical force exerted during closure or pressure buildup.
 

Water Heater
Abstract
The present disclosure provides a water heater comprising a thermoplastic container body defining a water-retaining chamber, the container body comprising a cylindrical side wall and a domed top wall integrally formed with the cylindrical side wall. The container body exhibits at least two of a heat deflection temperature of at least 155°C, a tensile strength of at least 525 kg/cm², a flexural modulus of at least 2200 MPa, a melt flow index of approximately 20 g/10 min and a notched Izod impact strength of at least 5 kg·cm/cm. Reinforcement ribs project inwardly from the domed top wall. A recess receives a lid that encloses an upper access region. A bottom-facing mounting flange extends from the cylindrical side wall. A heating element heats the water.
Fig. 1

  , C , Claims:Claims
I/We Claim:
1. A water heater 100 comprising:
a thermoplastic container body 102 defining a water-retaining chamber, said container body 102 comprising:
a cylindrical side wall 104; and
a domed top wall 106 integrally formed with the cylindrical side wall 104;
wherein the container body 102 exhibits at least two from:
a heat deflection temperature of at least 155°C at a load of 1.8 MPa
a tensile strength of at least 525 kg/cm²
a flexural modulus of at least 2200 MPa
a melt flow index of approximately 20 g/10 min; and
a notched Izod impact strength of at least 5 kg·cm/cm
a plurality of reinforcement ribs 108 projecting inwardly from an inner surface of the domed top wall 106;
a recess 110 formed in an upper region of the domed top wall 106, said recess 110 dimensioned and shaped to receive a lid 112 that covers and encloses an upper access region of the water-retaining chamber;
a bottom-facing mounting flange 114 extending outwardly from a lower portion of the cylindrical side wall 104 and configured for secure installation of the water heater 100; and
a heating element 116 to heat the water contained within the water-retaining chamber.
2. The water heater as claimed in claim 1, wherein the reinforcement ribs 108 are oriented in a radial or grid-like pattern to distribute stress caused by thermal expansion or pressurization.
3. The water heater as claimed in claim 1, wherein the bottom-facing mounting flange 114 extends outwardly in a circumferential manner and comprises a plurality of preformed apertures.
4. The water heater as claimed in claim 1, wherein the recess 110 formed in the domed top wall 106 is circular in plan view and comprises a stepped inner ledge configured to seat the lid 112 and prevent vertical displacement under axial loading.
5. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises at least one localized wall thickening region proximate to the mounting flange 114.
6. The water heater as claimed in claim 1, wherein the domed top wall 106 is associated with a convex curvature.
7. The water heater as claimed in claim 1, wherein the lid 112 further comprises a pressure-relief vent to release internal steam buildup above a threshold pressure.
8. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 is formed with integral vertical ribs.
9. The water heater as claimed in claim 1, wherein the lid 112 receives a sensing module to sense at least one of a temperature, a pressure level, or a water level.
10. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises external helical ribs extending longitudinally along the wall.
11. The water heater as claimed in claim 1, wherein the cylindrical side wall 104 comprises an average wall thickness in the range of 2.5 mm to 4.0 mm to maintain structural integrity under heating and pressurization conditions.
12. The water heater as claimed in claim 1, wherein the domed top wall 106 comprises a thickness greater than the cylindrical side wall 104, such that the thickness of the domed top wall 106 is in the range of approximately 25% to 40% greater than that of the cylindrical side wall 104, to withstand internal steam pressure and support the reinforcement ribs 108 without localized deformation.
13. The water heater as claimed in claim 1, wherein the lid 112 comprises a reinforced periphery having a thickness at least 20% greater than a central region of the lid 112 to improve resistance to vertical force exerted during closure or pressure buildup.