Abstract:
A dam assembly to protect a component mounted on a water heater tank wall while insulating foam is injected between the tank and a jacket surrounding the tank, the dam assembly comprising an outer portion, an inner portion, and a frangible web connecting the inner and outer portions, the web having a strength sufficient to withstand force applied to the inner portion to press the dam assembly into an aperture in the jacket such that the outer portion surrounds the component between the tank and the jacket, and the web breaking under the application of a pre-determined force on the inner portion, allowing the inner portion to be at least partially pushed inside the outer portion to enclose the component within the dam assembly.

Description:
BACKGROUND 
   The present invention relates to water heaters. 
   SUMMARY 
   In one embodiment, the invention provides a dam assembly to protect a component mounted on a water heater tank wall while insulating foam is injected between the tank and a jacket surrounding the tank, the dam assembly comprising an outer portion, an inner portion, and a frangible web connecting the inner and outer portions, the web having a strength sufficient to withstand force applied to the inner portion to press the dam assembly into an aperture in the jacket such that the outer portion surrounds the component between the tank and the jacket, and the web breaking under the application of a pre-determined force on the inner portion, allowing the inner portion to be at least partially pushed inside the outer portion to enclose the component within the dam assembly. 
   In another embodiment the invention provides a water heater comprising a tank, means for heating water in the tank, a component mounted on the tank, a jacket substantially surrounding the tank and including an aperture providing access to the component, foam insulation between the tank and the jacket, a dam assembly including an inner portion, and outer portion, and a frangible web connecting the inner and outer portions, the web having a strength sufficient to withstand force applied to the inner portion to press the dam assembly into the aperture in the jacket such that the outer portion surrounds the component between the tank and the jacket, and the web breaking under the application of a pre-determined force on the inner portion, allowing the inner portion to be at least partially pushed inside the outer portion to enclose the component within the dam assembly. 
   In another embodiment the invention provides a method of manufacturing a water heater, the method comprising providing a water heater including a water tank, means for heating water in the water tank, a component mounted on the tank, and a jacket substantially surrounding the tank and including an aperture providing access to the component. The method further comprises providing a dam assembly including an inner portion, an outer portion, and a frangible web connecting the inner and outer portions. The method further comprises pressing on the inner portion to push the dam assembly into the aperture such that the outer portion surrounds the component between the tank and the jacket, thereafter pressing the inner portion of the dam assembly with sufficient force to break the web and at least partially push the inner portion into the outer portion to enclose the component within the dam assembly, and injecting foam insulation between the water tank and the jacket and outside the dam assembly. 
   Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of a water heater including a dam assembly embodying the invention. 
       FIG. 2  is a partially exploded perspective view of the water heater and dam assembly of  FIG. 1 . 
       FIG. 3  is a perspective view of the dam assembly of  FIG. 1 . 
       FIG. 4  is a cross-sectional view of the dam assembly of  FIG. 1  taken along line  4 - 4  in  FIG. 3 . 
       FIG. 5  is a cross-sectional view of an alternative dam assembly of  FIG. 1  taken along line  4 - 4  in  FIG. 3 . 
       FIG. 6  is a cross-sectional view of the water heater and dam assembly of  FIG. 1 . 
   

   DETAILED DESCRIPTION 
   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. 
     FIGS. 1-6  illustrate a water heater  10  including a dam assembly  12  embodying the present invention. In the illustrated embodiment, the water heater  10  is an electric water heater. In some embodiments, the water heater  10  can be a gas water heater. The water heater  10  includes a substantially cylindrical tank  14  that defines a water chamber  16 . A cold water inlet  18  and a hot water outlet  20  extend through the top of the tank  14 . The tank  14  is substantially surrounded by foam insulation material  24  to reduce heat loss through the tank  14 . A thin jacket  26  surrounds and protects the insulation material  24 . The manner in which the insulation material  24  is placed between the tank  14  and the jacket  26  is described in greater detail below. 
   The water heater  10  includes two heating elements  28 . In some embodiments, the water heater  10  can include one, three, or more heating elements  28 . In the illustrated embodiment, the heating elements  28  are U-shaped tubes that conduct electricity to heat water in the tank  14 . The heating elements  28  include a threaded portion at one end that permit the heating elements  28  to thread into spuds (not shown) which are connected to the wall of the tank  14 . In the illustrated embodiment, a thermostat  34  is positioned on the wall of the tank  14  over each spud and communicates with the heating elements  28 . In some embodiments, a single thermostat  34  can be used to communicate with both heating elements. The thermostats  34  monitor the temperature of the water in the tank  14 , and turn the corresponding heating elements  28  on and off to maintain a desired water temperature in the tank  14 . In the illustrated embodiment, the thermostats  34  permit an operator to adjust the desired water temperature. The thermostats  34  are accessible to an operator through apertures  36  defined by the jacket  26 . In the illustrated embodiment, the apertures  36  are oval-shaped. In some embodiments, the apertures  36  can be round, square, rectangular, or any other desired shape. 
   In the illustrated embodiment, the insulation material  24  is injected between the tank  14  and the jacket  26 , and expands to fill the volume between the tank  14  and the jacket  26 . A dam assembly  12  is inserted into each of the apertures  36  prior to injecting the insulation material  24  to help prevent the foam from potentially damaging the thermostats  34  and escaping through the apertures  36 . 
   As best shown in  FIGS. 2-5 , the dam assembly  12  includes an outer portion  38  and an inner portion  40 . The outer portion  38  includes a wall  42  defining an oval-shaped perimeter, and a lip  44  extending outwardly from the top of the wall  42 . The outer portion  38  also includes tabs  46  extending from the lip  44  at opposite ends of the outer portion  38 . The tabs  46  are discussed in greater detail below. A resilient seal  45  is positioned on the inner surface of the wall  42 . The wall  42  tapers from the outside or top of the wall  42  toward the inside or bottom of the wall  42  to ease insertion of the dam assembly  12  into the aperture  36  and to ease removal of the dam assembly  12  from a molding die during manufacturing. The inner portion  40  is oval shaped and is connected to the top surface of the outer portion  38  by a frangible web  48 . The inner portion  40  includes a handle  50  and recesses  52 , which are explained in greater detail below. 
   In the illustrated embodiment the outer portion  38 , the inner portion  40 , and the web  48  are constructed from expanded polystyrene foam, and are molded together as a single piece in a single operation. Unassembled dam assemblies  12  constructed in this manner can nest together, and are stackable for convenient storage. In some embodiments, either or both of the outer portion  38  and the inner portion  40  can be constructed from other materials such as, for example, polyethylene, polypropylene, or polyurethane, and are not necessarily molded as a single piece. In the illustrated embodiment, the seal  45  is constructed from open-cell polyurethane. In some embodiments, the seal  45  can be formed from other materials such as, for example, a hot melt adhesive that is flexible enough to form a seal around wires. In the illustrated embodiment, the seal  45  is applied to the bottom of the outer portion  38  with adhesive after the outer portion  38  and inner portion  40  are molded. As shown in  FIG. 5 , the seal  45  could also be stretched around a small flange  47  on the bottom of the outer portion  38  and held in place by elasticity rather than adhesive. In some embodiments, the seal  45  can be molded in a two-stage molding operation at the same time the outer portion  38  and inner portion  40  are molded. In such embodiments, the outer portion  38  and the inner portion  40  are molded separately from the seal  45 , but in the same molding die such that the seal  45  is molded directly onto the outer portion  38 , or the outer portion  38  is molded directly onto the seal  45 . 
   To install the dam assembly  12 , an operator inserts the outer portion  38  in the aperture  36  and applies force to the inner portion  40 . The force is transferred to the outer portion  38  through the web  48 . As best shown in  FIG. 6 , when the outer portion  38  is installed in the aperture  36 , the outer portion  38  surrounds the thermostat  34  between the tank  14  and the jacket  26 , and the inner portion  40  substantially covers the thermostat  34 . As the dam assembly  12  is inserted into the aperture  36 , the tapered wall  42  of the outer portion  38  forms an interference fit with the jacket  26  about the aperture  36  and the seal  45  is compressed into sealing engagement with the tank  14 . The interference fit between the wall  42  and the jacket  26  helps prevent the insulation material  24  from leaking through the aperture  36  around the outer portion  38 , and the seal  45  helps prevent the insulation material  24  from leaking between the tank  14  and the outer portion  38  to protect the thermostat  34 . The oval shape of the outer portion  38  also resists deformation during injection and expansion of the insulation material  24  because the convex shape of the wall  42  can withstand greater force than a flat or square wall of similar thickness. 
   The web  48  can withstand sufficient force applied to the inner portion  40  to seat the dam assembly  12  in the aperture  36 . Application of additional force causes the web  48  to rupture and the inner portion  40  to be pressed inside the wall  42  of the outer portion  38 . The inner portion  40  forms an interference fit with the wall  42  of the outer portion  38 , and forces the wall  42  into tighter interference with the jacket  26 , thereby improving the seal between the wall  42  and the jacket  26 . After the web  48  breaks, the outer portion  38  remains installed in the aperture  36  in the jacket  26 . The inner portion  40  is removable from the outer portion  38 , but the inner portion  40  should remain inside the wall  42  of the outer portion  38  during injection and expansion of the insulation material  24  to ensure the best seal between the outer portion  38  and the jacket  26 . An operator can grasp the handle  50  near the recesses  52  to remove of the inner portion  40  from the outer portion  38  and provide access to the thermostat  34 . 
   A lid  60  is installed over the dam assembly  12  to further increase the seal between the wall  42  and the jacket  26  and between the seal  45  and the tank  14  during injection of the insulation material  24 . The lid  60  improves the seal by engaging the handle  50  of the inner portion  40  and pressing and holding the inner portion  40  within the outer portion  38 . The lid  60  also helps prevent unwanted access to the dam assembly  12  without tools by substantially covering the dam assembly  12 . As best shown in  FIGS. 1 and 2 , the lid  60  is a substantially flat plate with a locking tab  62  and a fastening tab  64 . The lid  60  is positioned over the dam assembly  12  after the dam assembly  12  is installed in the aperture  36 . The locking tab  62  is inserted into a locking aperture  66  adjacent the aperture  36 , and a fastener  68  is inserted through the fastening tab  64  and into an aperture  70 , also adjacent the aperture  36 . In the illustrated embodiment, a single fastener  68  is used, and is a screw. In some embodiments, multiple fasteners of various forms can be used to connect the lid  60  to the jacket  26 , or the lid  60  can include locking or sliding tabs such that no fasteners are required to connect the lid  60  to the jacket  26 . The lid  60  is rigidly connected to the jacket  26  and substantially covers the dam assembly  12  when the locking tab  62  is engaging the locking aperture  66  and the fastener  68  is engaging the aperture  70 . The lid  60  can be removed from the jacket  26  by removing the fastener  68 . 
   One of the tabs  46  on the outer portion  38  extends to the locking aperture  66  when the dam assembly  12  is installed in the aperture  36 . The lid  60  compresses the tab  46  when the locking tab  62  of the lid  60  engages the locking aperture  66  and the lid  60  is installed as described above. The compressed tab  46  forms a seal between the lid  60  and the jacket  26  adjacent the locking aperture  66  to help prevent injected insulation material  24  from leaking through the locking aperture  66 . The outer portion  38  includes tabs  46  at opposite ends so that the dam assembly  12  cannot be inserted in an incorrect orientation in the aperture  36 .