Abstract:
A method of manufacturing a water heater includes the steps of providing a water heater tank having an interior and an exterior, the tank also including a first aperture communicating between the interior and exterior, providing a spud having an internally threaded aperture and placing a membrane between the spud and the tank such that the membrane covers the first aperture. Thereafter, the method also includes the steps of welding the spud and the membrane to the tank, and thereafter forming a second aperture in the membrane so that the threaded aperture of the spud communicates with the interior of the tank via the first and second apertures.

Description:
BACKGROUND 
       [0001]    The present invention relates to a water heater and a method of manufacturing the water heater 
       SUMMARY 
       [0002]    In one embodiment, the invention provides a method of manufacturing a water heater, the method comprising: providing a water heater tank having an interior and an exterior, the tank also including a first aperture communicating between the interior and exterior; providing a spud having an internally threaded aperture; placing a membrane between the spud and the tank such that the membrane covers the first aperture; thereafter welding the spud and the membrane to the tank; and thereafter forming a second aperture in the membrane so that the threaded aperture of the spud communicates with the interior of the tank via the first and second apertures. 
         [0003]    In another embodiment, the invention provides a method of manufacturing a water heater, the method comprising: providing a water heater tank having an interior and an exterior, the tank also including a first aperture communicating between the interior and exterior; providing a spud having an internally threaded aperture; placing a membrane between the spud and the tank such that the membrane covers the first aperture; thereafter welding the spud and the membrane to the tank; thereafter spraying unfired glass to the interior of the tank; thereafter applying heat to the unfired glass; thereafter pressure testing the interior of the tank with the membrane covering the first aperture; and thereafter forming a second aperture in the membrane so that the threaded aperture of the spud communicates with the interior of the tank via the first and second apertures. 
         [0004]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1A  is a perspective view of a water heater embodying the invention. 
           [0006]      FIG. 1B  is an enlarged portion of the water heater in  FIG. 1A . 
           [0007]      FIG. 2  is an exploded view of a spud, a membrane and a portion of the tank in  FIG. 1A  prior to a welding process. 
           [0008]      FIG. 3A  is a section view of the spud, membrane and portion of the tank in  FIG. 2  in position for the welding process. 
           [0009]      FIG. 3B  is a section view of the spud, membrane and portion of the tank subsequent to the wending process. 
           [0010]      FIG. 3C  illustrates the elements in  FIG. 3B  plus a coating on the interior of the tank. 
           [0011]      FIG. 3D  is a perspective view of the elements in  FIG. 3C  with a portion of the membrane removed. 
           [0012]      FIG. 4  is a flow diagram illustrating one method of manufacturing the water heater in  FIG. 1A . 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0014]      FIGS. 1A and 1B  illustrate a water heater  10  according to one embodiment of the present invention. Particularly,  FIG. 1A  illustrates the water heater  10  including a base pan  15 , a metal water tank  20  with a bottom head  22 , an insulating jacket  25  surrounding the tank  20 , and insulating material  27  between the outer surface of the tank  20  and jacket  25 . The top of the jacket  25  is cut away to show the insulation  27 . The water heater  10  also includes a burner  30  disposed in a combustion chamber  32  beneath the bottom head  22  of the tank  20 , a water inlet pipe  35 , a water outlet pipe  37 , and a flue tube  40  extending from the combustion chamber  32  and through the tank  20 . During operation of the water heater  10 , gas fuel is provided to the burner  30  through a conduit  45 . Products of combustion or hot gasses flow up from the combustion chamber  32  and through the flue tube  40  to heat the water in the tank  20 . Other constructions of the water heater also fall within the scope of the invention. 
         [0015]      FIG. 1B  illustrates a detailed portion of the water heater  10 . Particularly,  FIG. 1B  illustrates a connection  50  between the inlet pipe  35  and the tank  20  according to one embodiment of the present invention. In the illustrated construction, the connection  50  is the same as a connection between outlet pipe  37  and the tank  20 , thus the following description applies to both connections between either inlet pipe  35  or outlet pipe  37  and the tank  20 . The connection  50  is defined by a spud  55  as further described below. 
         [0016]    In the illustrated construction, the spud  55  is manufactured of a metal material. As illustrated in  FIGS. 2 and 3A , the spud  55  includes a threaded inner surface  65  and a beveled lower portion  70 . The threaded surface  65  defines an aperture  75  extending through the spud  55 . A substantially circular membrane  60  is manufactured from a flat metal sheet having a substantially uniform thickness between about 0.002 inches and about 0.006 inches. The membrane  60  is located between the spud  55  and an exterior surface  85  of the tank  20  and has a periphery  80  extending outward of the spud  55  prior to a welding process, as further explained below. In other constructions, the membrane  60  can include different shapes and thicknesses based on desired specifications and manufacturing parameters of the water heater  10   
         [0017]    FIGS.  2  and  3 A- 3 D help illustrate the steps of a manufacturing process of the water heater  10  according to one embodiment of the present invention. With reference to  FIGS. 2 and 3A , the manufacturing process includes providing the tank  20 , one spud  55  and one membrane  60  to form one connection  50  (as illustrated in  FIG. 1B ). In the illustrated construction, the membrane  60  is placed between the spud  55  and a portion of the tank  20  defining an aperture  90 , which connects the exterior and interior of the tank  20  ( FIG. 3A ). The spud  55  and membrane  60  are aligned with respect to the aperture  90  such that the membrane  60  is pressed between the lower portion  70  of the spud  55  and the exterior surface  85  of the tank  20 . The membrane  60  substantially covers aperture  90  of the tank  20  and aperture  75  of the spud  55 . In other constructions, the spud  55  and membrane  60  can be aligned differently based on desired manufacturing parameters of the water heater  10 . 
         [0018]    The manufacturing process also includes welding the spud  55  to the membrane  60  and tank  20 , as illustrated in  FIG. 3B . As a result of the welding process, at least part of the lower portion  70  of the spud  55 , the periphery  80  of the membrane  60  and a portion of the tank  20  defining aperture  90  and adjacent the periphery  80  form a welding nugget  95 . The membrane  60  welded between the spud  55  and the tank  20  separates the interior and exterior of the tank  20 , thus sealing the aperture  90 . In a preferred embodiment, the tank  20 , spud  55  and membrane  60  are manufactured of a metal material. However, the invention provides for the tank  20 , spud  55  and membrane  60  to include materials other than metals to facilitate other types of welding processes (e.g., ultrasonic welding). In one construction, the membrane  60  can further include a permeable material that permits a relatively small amount of fluid (e.g., air) to flow therethrough. 
         [0019]    Subsequent to the welding process, the manufacturing process includes (see  FIGS. 3B  and C) applying a coating  100  to the interior surface  105  of the tank  20  to help prevent the tank  20  from rusting, as is known in the art. In one preferred construction, applying the coating  100  to the inner surface  105  of the tank  20  includes spraying unfired glass on the interior of the tank  20 . In other constructions, applying the coating  100  to the interior of the tank  20  includes applying a coating of porcelain, ceramic, polymer, organic material, a lining formed by electroplating or other materials suitable to prevent the surface of the tank  20  from rusting. In the manufacturing process of the water heater  10 , it is desirable to prevent materials forming the coating  100  to come into contact with or settle on the threaded inner surface  65  of the spud  55 . Because the membrane  60  covers the aperture  90 , the membrane  60  helps prevent the coating material  100  from contacting the threaded surface  65  of the spud  55 , as illustrated in  FIG. 3C . 
         [0020]    Optionally, the manufacturing process can include applying a dust coating to the exterior surface  85  of the tank  20 . In applying the dust coating, part of the material being applied also coats or comes into contact with the threaded surface  65  of the spud  55  and outer surface  110  of the membrane  60 . The dust coating forms a relatively thin layer in comparison to the coating  100  applied to the interior surface  105  of the tank  20 . However, the dust coating is sufficient to help prevent oxidizing of the exterior surface  85  of the tank  20  and the membrane  60 , as further explained below. Because the dust coating forms a relatively thin layer in comparison to the coating  100 , there is no detriment to the manufacturing process if the dust coating is formed on the threaded surface  65  of the spud  55 . In some constructions, the dust coating is formed of the same material as the coating  100 . However, in other constructions, the dust coating includes other materials that permit forming a relatively thin layer on the surface of the tank  20  and also help prevent oxidizing the tank  20  and membrane  60  surfaces. 
         [0021]    Once the coating  100  is applied to the interior surface  105  of the tank  20 , the tank  20  is put through a heating process. As indicated above, one preferred construction includes spraying unfired glass to form coating  100  on the interior surface  105 . In this construction, the heating process includes placing the tank  20  through a furnace and heating/firing the unfired glass coating  100  to about 1600 degrees Fahrenheit. Firing the glass coating  100  allows fusing the elements forming the coating (e.g., silica and metals) to the surface  105  of the tank  20 . As a result, the coating  100  is firmly fused to the surface  105  to help prevent rusting of the tank  20  during manufacturing and normal use of the water heater  10 . The membrane  60  welded to the spud  55  and tank  20  is formed to withstand such temperatures. In other constructions, the membrane characteristics (e.g., diameter, periphery shape, thickness, material) can be adjusted for other heating processes that include heating the tank  20  to different temperatures. 
         [0022]    Depending on the characteristics (e.g., materials and/or thicknesses) of the tank walls and membrane  60 , the heating process can cause oxidation of the surface of the tank  20  and portions of the membrane  60  not protected by coating  100 . In such cases, the dust coating helps prevent oxidation of the tank  20  and membrane  60 , thus preserving the integrity of the tank  20  and membrane  60  during subsequent steps of the manufacturing process of the water heater  10 . 
         [0023]    The manufacturing process also includes pressure testing the tank  20  for detection of leaks or structural damage to the tank  20 . In one process, the tank  20  is pressurized to about 35 pounds per square inch (psi). The membrane  60  welded to the spud  55  and tank  20  is formed to withstand such pressure, allowing proper testing of the tank  20 . In other constructions, the membrane characteristics (e.g., diameter, periphery shape, thickness, material) can be adjusted to test the tank  20  at different pressures. In one preferred embodiment, the membrane  60  welded to the tank  20  prevents leaks or flow of fluid (e.g., pressurized air) therethrough. However, in other constructions the membrane  60  can include one or more relatively small apertures or a permeable material allowing fluid to flow therethrough. It is to be understood that for the purposes of pressure testing the tank  20 , such characteristics of the membrane  60  are taken into consideration and are not detrimental to the testing process or manufacturing process in general of the water heater  10 . 
         [0024]    The heating process and pressure testing of the tank  20  can be done in a different order. For example, the tank  20  can be pressure tested prior to applying and firing the coating  100  to the surface  105  of the tank  20 . 
         [0025]    Once the tank  20  has gone through the heating process and has been pressure tested, the manufacturing process includes creating or forming an aperture through the membrane  60  to allow the flow of fluid (e.g., water) during operation of the water heater  10 . In the construction illustrated in  FIG. 3D , a hole saw (not shown) is utilized to remove at least a portion of the membrane  60  for forming aperture  115 . The hole saw may be inserted through aperture  75  of the spud  55  or applied to inner surface  120  of the membrane  60 . In another construction, a perforating element is inserted through aperture  75  of the spud  55  with a sufficient amount of force to rupture the membrane  60  without removing a portion of the same. 
         [0026]      FIG. 4  is a flow chart illustrating an exemplary process for manufacturing the water heater  10 . It is to be understood that some of the steps comprised in the following process can occur in a different order. The process includes providing a water heater tank having an aperture communicating the interior and exterior of the tank (step  200 ), providing a spud with a threaded aperture (step  205 ) and placing a membrane between the spud and the tank such that the membrane covers the aperture of the tank (step  210 ). The process also includes welding the spud and the membrane to the tank (step  215 ), spraying a coating, such as unfired glass, to the interior of the tank (step  220 ) and applying heat to the coating (step  225 ). Finally, the process includes pressure testing the tank with the membrane covering the aperture of the tank (step  230 ) and forming an opening in the membrane for allowing fluid flow therethrough (step  235 ). 
         [0027]    Various features and advantages of the invention are set forth in the following claims.