Water Heater Construction

The present invention relates in general to water heater construction and more specifically, to the design of the outer shell for commercial and residential water heaters.

The majority of conventional commercial and residential water heaters are fabricated with an inner storage tank and an outer shell. A designed clearance space between these two generally concentric members is provided for the receipt of a suitable insulation. The outer shell is typically a singular cylindrical member which must be assembled over the tank by closely and carefully aligned axial movement of either the tank or the shell relative to the other.

One difficulty with this assembly technique is the time required due to the fact that with insulation disposed around the inner tank and a desire to compress that insulation slightly, great care must be taken with this axial sliding operating. Another concern, though related to the foregoing, is how to maximize the amount and coverage of insulation. Clearly, by increasing the thickness of insulation heat transfer losses from the tank are minimized thus reducing energy costs attributable to heating the water within the tank. However, if the thickness of insulation is too great, it will not be possible to slide the outer shell down over this insulation without significant problems of pulling and tearing the insulation to the point that the finished product is unacceptable and the insulation must be replaced and the assembly procedure repeated.

Some of the specifics as to the design of the insulation will depend upon the type of insulation used. Different design parameters exist depending upon whether the annular space between the tank and the shell is to be filled with foam insulation or an insulation blanket or both. For example, my prior, issued patents, U.S. Pat. Nos. 4,736,509 and 4,744,488 relate generally to design concepts and water heater construction concepts.

As mentioned, the annular space between the tank and the shell may also be filled by means of an insulation blanket which is draped over the tank prior to lowering the shell in place. For improved results, it is helpful to compress the insulation blanket. However, since there are difficulties in assembling the shell in a manner to achieve compression without pulling or tearing the blanket, the result is to use a relatively thin blanket of insulation so as to permit the assembly of the outer shell. Nevertheless, even with a relatively thin blanket there is some pulling and a risk of tearing and thus with insulating material such as fiberglass, it is difficult if not impossible to achieve 100% coverage.

A further option as to the insulation concept is to use a combination of a partial blanket or insulation dam or barrier and foam-in-place insulation disposed above the upper edge of the blanket or dam. My prior, co-pending applications, Ser. Nos. 177,392, 177,393 now U.S. Pat. No. 4,844,049 and 216,384 are examples of this combination insulation structure.

As various insulation concepts and construction concepts are evaluated, the speed and ease of assembly are important consideration. The appearance of the finished product is also important since attractive designs are a factor in purchasing decisions, possibly as one indicator of product quality. Since water heaters are typically mass-produced, there is a fast moving assembly line in the more efficient operations. Any design of tank, shell and insulation must keep the pace of the assembly line in mind.

Concepts and structures employed by others in the design and insulation of water heaters include the use of a bag to receive foam insulation. In one arrangement, when used with electric water heaters, the bag does not extend the full 360 degrees of the tank's circumference. Openings are left for the electrical controls. One concern with this insulation concept is the ability to get even distribution of the foam throughout the bag so that the finished product is very similar to an insulation blanket as to its uniformity and thickness. In this particular design the bag can be installed and then foamed after assembly of the shell, though again, complete coverage is a hit or miss proposition. In another arrangement, the bag may be pre-foamed and then assembled. The assembly time is though excessive with this approach and the bag even in this instance does not always foam evenly or completely thus leaving voids for heat loss leaks.

One example of the foregoing bag concept is illustrated in U.S. Pat. No. 4,527,543 which issued July 9, 1985 to Denton. In this structure a plastic envelope is wrapped entirely around the tank, or part of the tank if it is an electric water heater. After the outer shell is assembled, a foam-type insulation material (in liquid form) is injected into the envelope. A vent hole in the top cover provides an air vent during the foaming operation and also serves to provide a visual indicator for determining when the envelope is filled. Another patent to Denton, U.S. Pat. No. 4,447,377 which issued May 8, 1984, discloses a similar structure and insulation concept.

In U.S. Pat. No. 4,749,532 issued June 7, 1988 to Pfeffer there is disclosed yet another insulation concept. In Pfeffer a band of insulation is cinched to the tank such that the top and bottom edges flare outwardly beyond the location of the shell wall. In order to install the shell without tearing or pulling, a "shoe horn" type device is used to compress the outer edges inwardly as the shell is lowered into place. Thereafter the shoe horn is removed.

Although there are yet other designs where the insulation is wrapped around the tank, in each such configuration the outer shell is a singular, cylindrical member which must be assembled by axial sliding motion relative to the tank. Example of wrap-around insulation can be found in U.S. Pat No. 4,282,279 issued August 4, 1981 to Strickland and U.S. Pat. No. 4,039,098 issued August 2, 1977 to Stilts. In Strickland ('279), while the art is different and possibly unrelated to the present invention, there is disclosed an insulation blanket which is designed to be wrapped around a cylindrical tank (beverage can) and the free ends are thereafter secured together. In Stilts ('098), a thermal insulation jacket is provided where the free ends are joined by strips of tape.

In the present invention, the singular, cylindrical outer shell is replaced with a split generally cylindrical, wrap-around shell which may be opened and closed in a hinged movement so that the axial sliding procedure of prior shell designs can be eliminated. The construction of the present invention solves many of the current problems and provides an ease and efficiency of fabrication which is not presently available. The problems as to the integrity and completeness of the insulation which is disposed between the inner tank and the outer shell do not exist and the integrity and completeness can be confirmed before the shell is closed in place around the insulation.

The present invention contemplates an initially flat, though flexible, shell which is formed into two generally semi-cylindrical portions which are joined along one edge in a hinged fashion and the opposite free ends are secured together at the completion of the closing operation. A number of configurations are available for the hinge mechanism as well as for securing the free ends together. An alternative is simply to provide enough flexibility in the shell material that hinging-type movement can occur without using an actual hinge. A review of the cited references reveals that prior designs have never envisioned such a shell design, even in view of the many advantages and improvements which the present invention offers. It was not until the conception of the present invention that this idea came into being.

A water heater construction for commercial and residential use according to one embodiment of the present invention comprises a generally cylindrical water tank, insulation means disposed against the outer surface of the water tank, a generally cylindrical outer shell split into two hinged portions wherein each portion includes a free end and means for securing the free ends together such that the outer shell is drawn into abutment with the insulation means when closed into its generally cylindrical shape.

One object of the present invention is to provide an improved water heater construction.

Related objects and advantages of the present invention will be apparent from the following description.

FIG. 1 is a diagrammatic front elevational view of a water heater outer shell applied around an insulated tank according to a typical embodiment of the present invention.

FIG. 2 is a diagrammatic top plan view of the FIG. 1 outer shell and insulated tank.

FIG. 3 is a diagrammatic top plan view of a hinged outer shell according to a typical embodiment of the present invention.

FIG. 4 is a diagrammatic top plan view of a hinged outer shell according to a typical embodiment of the present invention.

FIG. 5 is a diagrammatic front elevational view of the FIG. 4 outer shell as assembled as part of a completed water heater.

FIG. 6 is a perspective view of a formed outer shell prior to circumferential wrapping according to a typical embodiment of the present invention.

FIG. 7 is a perspective view of the FIG. 6 outer shell with insulation applied.

FIG. 8 is a partial diagrammatic top plan view of the FIG. 7 insulated outer shell as wrapped around an inner tank according to the present invention.

FIG. 9 is a front elevational view of an alternative outer shell designed with insulation applied.

FIG. 10 is a partial diagrammatic top plan view of the FIG. 9 insulated outer shell as wrapped around an inner tank according to a typical embodiment of the present invention.

FIG. 11 is a partial diagrammatic top plan view of an alternative outer shell configuration according to a typical embodiment of the present invention.

FIG. 12 is a front elevational view in full section of the insulation structure for a water heater.

FIG. 12A is an enlarged detail from the FIG. 12 structure showing the fit between the outer shell and the bottom pan.

FIG. 13 is a perspective view of a water heater including a plastic control panel.

FIG. 14 is a perspective view of a cover for use in assembly to the FIG. 13 control panel.

FIG. 15 is a top plan view in full section showing the assembly of the FIG. 14 cover to the FIG. 13 control panel.

FIG. 16 is a top plan view in full section of an insulation jacket for a water heater according to a typical embodiment of the present invention.

FIG. 17 is a partial perspective view of the FIG. 16 insulation blanket showing the extruded panel and one of several blocks of insulation.

FIG. 18 is a partial top plan view in partial section of an alternative insulation blanket for a water heater according to a typical embodiment of the present invention.

FIG. 19 is a partial perspective view of the FIG. 18 insulation blanket as unwrapped showing the base panel and two blocks of insulation.

FIG. 20 is a partial top plan view of an alternative insulation blanket according to a typical embodiment of the present invention.

FIG. 21 is a perspective view of the FIG. 20 insulation blanket showing the panel and several insulation blocks.

FIG. 22 is a partial top plan view in diagrammatic form showing the laminations of one block of insulation comprising part of an insulation blanket associated with a water heater.

FIG. 23 is a partial top plan view of a honeycomb insulation panel according to a typical embodiment of the present invention.

FIG. 24 is a front edge elevational view of the FIG. 23 honeycomb insulation panel.

FIG. 25 is a perspective view of the FIG. 23 insulation panel with the filling insulation removed from the honeycomb.

FIG. 26 is a top plan view in full section and diagrammatic form representing the complete FIG. 23 panel as wrapped around an inner tank.

FIG. 27 is a diagrammatic front elevational view of one insulation option for the honeycomb of the FIG. 23 panel.

For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Referring to FIGS. 1 and 2 there is illustrated in diagrammatic form a partially disassembled hot water heater 20 which includes inner water tank 21, a blanket of insulation 22 which is wrapped around the exterior surface of the inner water tank, and a two-part outer shell 23 with hinged halves 23a and 23b which close together in the direction of arrows 24 in order to complete the assembly of the water heater.

In the preferred embodiment the two halves 23a and 23b of outer shell 23 are configured such as when their corresponding, axially-extending free ends 27 and 28 are hinged together so as to completely enclose or encircle tank 21 and insulation 22, the completed outer shell is of a generally cylindrical structure and is positioned relative to tank 21 in a generally concentric fashion. In this regard, a substantially uniform annular space 29 is created between the outer surface of the tank and the inner surface of the shell. It is within this annular space that the blanket of insulation 22 is disposed. Due to the opened nature of shell 23 the annular space 29 is not completely defined. Broken line 29a provides an indication of the outer edge of space 29 once shell 23 is closed. Although only a small section of insulation is illustrated, it is to be understood that this blanket or band of insulation could extend the full height of the inner water tank and could even be draped over the top surface of the tank.

It is also to be understood that the radial thickness of the blanket of insulation 22 is slightly greater than the radial thickness of annular space 29 such that when the two halves of outer shell 23 are hinged together so as to complete their cylindrical enclosure, the blanket of insulation will be compressed in the direction of the tank. Obviously the greater the radial thickness of the blanket of insulation relative to the size of annular space 29 the greater the degree or extent of compression required in order to close the outer shell. This compression of the blanket of insulation will occur throughout the full height of the blanket even if it is extended from top to bottom completely around the entirety of the inner water tank. Furthermore, this blanket of insulation may be secured directly to the tank or may be attached by bands or similar mechanical structures in order to hold the blanket in its desired location.

As discussed in the Background of the Invention, a number of insulation concepts are envisioned for use with the present invention and the blanket of insulation illustrated in FIG. 1 may be used in combination with a foam-in-place insulation (initially in liquid form) which is injected above blanket of insulation 22 into the annular space 29.

One advantage of the hinged outer shell design of FIGS. 1 and 2 is that it eliminates the need to axially slide either the tank into the outer shell or the outer shell over the tank. As previously mentioned in the Background of the Invention, this sliding action creates the risk that the insulation will be pulled or torn or in some manner disturbed such that it does not provide the maximum insulation nor complete or adequate coverage around the tank. As mentioned, an earlier approach attempted to "shoe horn" the outer cylindrical shell down over a thickness of insulation which is radially thicker than the dimension from the tank to the shell. Some approaches have tried to use insulation which is radially compressed and then the shell put in place before that insulation can expand back outwardly. These approaches are marginal in that the excess thickness of insulation must be tightly controlled and if too much is used it will either expand back to full size too quickly or will be stretched or torn when the shell and tank axially slide together into their final assembly.

The manner or nature of joining halves 23a and 23b together is illustrated in FIG. 2 includes a hinge 30 which includes on opposite ends, receiving channels 31 and 32, which rigidly and securely attach to the ends of outer shell halves 23a and 23b, respectively. The center portion of hinge 30 has a suitable flexibility to act as a type of living hinge in order for halves 23a and 23b to be spread apart such that with the blanket of insulation first applied directly to the inner water tank's outer wall, the shell can thereafter be moved into position, the halves then closed so as to create a clamping action radially inward, around the blanket of insulation 22. As the free ends 27 and 28 are hinged or pivoted towards one another so as to complete the generally cylindrical outer shell, it is to be understood that a two-part latch mechanism is employed at a plurality of locations from top to bottom along these free ends. Each latch assembly includes a latch portion 35 adjacent free end 27 and a cooperating and engaging latch portion 36 adjacent free end 28. These two latch portions 35 and 36 are configured so as to provide a type of cam action similar to the latches on a tool box or luggage such that although there is slight resistance to the closing of the two halves due to the compression of the blanket of insulation, initial connection can be made and thereafter the mechanical advantage of the cam or levering action used to securely join halves 23a and 23b together with a tight and flush joined seam.

It is also envisioned that halves 23a and 23b can be hinged together by a conventional piano hinge, though with slightly curved flanges so as to approximate the general cylindrical curvature of the completed shell. It is also to be understood that whatever hinge mechanism is utilized that it should extend the full height of the outer shell so that the enclosing of the insulation and tank is complete. The top and bottom of the water heater 20 may be fabricated in any of the presently well known techniques.

Referring to FIG. 3 an alternative hinge configuration is illustrated wherein outer shell 39 includes a first portion 40 and a second portion 41 each of which are specifically shaped and contoured at their free ends so as to provide an interlock hinge arrangement on one side and a connecting arrangement on the opposite side. In order to achieve this combination, outer shell portion 40 includes along one edge an axially extending generally cylindrical rib 42 and outer shell portion 41 includes at its adjacent and cooperating free end a part cylindrical and hollow channel 43 which extends axially the full height of outer shell portions 40 and 41. As is illustrated, rib 42 and channel 43 interfit with each other such that outer shell portions 40 and 41 can be opened and closed in a clam shell-type arrangement where rib 42 and channel 43 serve as the hinge for that opening and closing action. To enhance the security and integrity of this two-part hinge arrangement, it is possible to form channel 43 with a circumferential extent of at least 300 degrees. As a result, the opening left (approximately 60 degrees of circumference) is not adequate for rib 42 to pass through and thus the assembly of outer shell portions 40 and 41 must be done by axially sliding rib 42 down into channel 43 prior to application of the shell around tank 21 and insulation 22.

At the opposite side the other free ends of outer shell portions 40 and 41 are interlocked though in a slightly different manner. By creating a type of curved or spiral wrap at free end 44 and a complementing curved or spiral wrap at free end 45, these two ends are able to be latched together simply by compressing the outer shell portion 40 and 41 together until there is clearance for the interfit of ends 44 and 45, making that interfit and then allowing the outer shell portions to spring back into their normal cylindrical configuration as illustrated in FIG. 3. It is also to be understood that this curved and spiral interfit of free ends 44 and 45 could be used with the hinge arrangement of outer shell halves 23a and 23b. Similarly, the latch configuration in FIG. 1 could be used as part of outer shell portions 40 and 41. What is being illustrated in these first three figures is the concept and design of providing a water heater outer shell in two halves or portions which are hinged together along one end and latched or interlocked with one another along the opposite side edge. The specific design of the hinge and the specific technique used to interlock or secure together the free ends while important, are able to be satisfied in a number of different ways. Characteristics which are of interest and should be provided include a hinge design relative to the two portions of the outer shell such that once assembled into their hinged relationship can be opened sufficiently wide so as to be placed around the inner tank and layer of insulation. Only in this manner can the integrity and completeness of the insulation be preserved such that the only forces acting upon the insulation by the assembly of the shell will be radially compressive forces pushing inwardly in the direction of the tank. With the present invention there is no axial sliding required between the shell and the tank thus eliminating the earlier problems of insulation pulling and tearing.

Referring to FIGS. 4 and 5, a still further alternative embodiment for the present invention is illustrated. Water heater 48 includes an inner water tank 49, insulation 50 which is disposed around the water tank, a two-part outer shell 51 including first portion 51a and second portion 51b and a closing or latching panel 52 with heater control access openings 53 and 54. First and second portions 51a and 51b are hinged together by means of piano hinge 57 which is disposed on one side of the water heater and which extends axially for substantially the full height of the water heater. As is consistent with the design of the present invention, first and second portions may be hinged outwardly so as to open outer shell 51 as illustrated by broken lines 58. When the outer shell is opened in this manner by the hinged separation of its two portions, the shell may be fit around insulation 50 and thereafter the first and second portions are closed together creating slight compression in the insulation and resulting in an improved water heater design.

With regard to closing panel 52, it is to be understood that first and second portions do not create a full 360 degrees or circumference for the outer shell. Approximately 30 degrees of circumference are covered by closing panel 52 whose outer edges are each formed with a curved metal channel which is directed inwardly. In a complementing nature, the free ends 59 and 60 of the first and second portions, respectively, are formed with curved axial channels which open outwardly. As the first and second portions are hinged together in a closing manner, the first channel 61 of closing panel 52 is hooked into channel 59 and at that point is then drawn towards channel 60 at which point channel 62 of closing panel 52 is hooked into channel 60. The hooked interfit between these four channels completes the outer shell providing 360 degrees of coverage around the water heater insulation and tank and permits the hinged, two-part design of the present invention to be incorporated in a design where front panel access openings such as 53 and 54 are required.

Referring to FIGS. 6 and 7, a still further alternative embodiment of the present invention is illustrated. In FIG. 6, outer shell skin 65 is shown as an extrusion which may be either metal or plastic and is coming from the extruding dies in the direction of arrow 66. If metal is used for outer shell skin 65 then the curved flanges defining longitudinal channels 67 and 68 may be formed in flat sheet stock coming off of a roll as part of an automated forming process, though not necessarily an extrusion. The point being illustrated and described is that it is possible to automate the process of fabricating a metal or plastic skin which will be used so as to create the outer shell for water heater construction. It is envisioned that at some point downstream in the fabrication process, the formed or extruded skin 65 will be cut to a desired length along broken line 69 and this length which is marked by the letter H represents the height of the outer shell for use in the water heater construction. Either before or after cutting the skin to the desired length (height), insulation may be applied directly to the skin as is illustrated in FIG. 7. Insulation 70 may be either poured foam insulation or sprayed-on fiberglass or cellulose insulation. Alternatively, insulation 70 may be from a roll of flexible foam or fiberglass batting and simply rolled out on the skin and cut to length equal to the length or height of the portion cut for the water heater construction. Inasmuch as it is desirable to fabricate the skin and insulation as a single assembly, some adhesive or bonding agent is applied to the surface of the skin prior to application of the insulation.

Once the desired length is determined and a cut made along line 69, assuming that the insulation has been applied or will be applied, this panel is then curved and wrapped around the water heater tank such that curved channels 67 and 68 are drawn into interlocking engagement with each other as is illustrated in FIG. 8. The outermost edges of channels 67 and 68 are opposing free edges of the generally rectangular panel created by the cut along line 69. When the panel is flexed into a generally cylindrical shape around the inner water tank, these free edges are axially extending. It should be understood that to accomplish this interlock of channels 67 and 68 some unique shaping and contouring is required so that the finished product has an aesthetically pleasing exterior appearance. It is also to be understood that in this particular configuration, a hinge is not provided but rather the flexibility of the metal or plastic skin provides the necessary flexibility for the outer shell to begin as a substantially flat member and simply formed into a generally cylindrical configuration as it is placed around the water heater tank 21. The width of skin 65 as indicated by dimension line C equals the circumference of the outer shell when formed about the water heater tank and with channels 67 and 68 interlocked. It is also important that the insulation 70 which is applied, be applied in a manner so as to prevent any gap or void along the seam where channel 67 and 68 are interlocked.

With regard to the assembly technique, it is envisioned the flexible bands may be used in order to draw the outer shell skin 65 into its assembled generally cylindrical configuration. Thereafter, once channel 67 and 68 are interlocked, the bands are released and the assembly is completed.

Referring to FIG. 9, an alternative skin and insulation structure is disclosed wherein skin 73 includes similarly configured free ends turned of formed to define outer curved channels 74 and 75 which are oriented in the same direction relative to each other rather than opposite directions as was previously the case with regard to skin 65. This particular configuration is intended for use with a closing panel such as panel 52 as illustrated in FIG. 4. It is also to be understood that the free end channels 74 and 75 can be turned in either direction depending on the orientation of the free end channels as part of the closing panel. Conceivably, even the free end channels 74 and 75 could be reversed from one another similar to FIG. 7 if the closing panel had its free ends alternated so as to be compatible. The assembly of outer shell skin 73 and insulation 76 to a water tank 77 and in combination with a closing control panel 78 is illustrated in FIG. 10. Panel 78 includes insulation 78a and filler portion 78b to fill in the void between the free ends of skin 73 so that the exterior of the assembly appears continuous.

Referring to FIG. 11, a still further alternative embodiment of the present invention is illustrated. In this arrangement, a one-piece outer shell skin 80 similar to skin 65 or skin 73 has a layer of insulation 81 applied and is wrapped around an inner water tank 82. The free ends 83 and 84 are formed with outwardly opening curved channels which are of opposite orientation to free end channels 74 and 75 and thus rather than being directed inwardly towards the tank, these channels open outwardly on the exterior surface of the outer shell. In order to complete the closing of the outer shell skin around the water tank, a heavy band or channel member 85 which extends the full height of the water heater is used to slide down over and clamp together free ends 83 and 84. Clamp 85 has its free ends 86 and 87 turned inwardly so as to create an oblong channel 88 whose width is set small enough so as to draw free ends 83 and 84 tightly toward each other. If the sizes and spacing of these various members is such that free ends 83 and 84 are not designed to abut, then insulation strip 89 is provided to fill the clearance space.

While the use of clamp or band 85 has been illustrated in FIGS. 11 with a single piece outer shell skin, this particular clamping configuration is equally suitable for use with the two-part or two-half hinged arrangement of FIG. 1. Again, while it is important to consider all of the various permutations and alternatives for the present invention, the key is the two-part or wrap-around skin whether hinged or simply sufficiently flexible to be formed as an integral member. The assembly of this skin to the inner water tank is in a circumferential or radial direction rather than axially. Consequently, insulation of greater thickness can be used with greater compression.

Referring to FIGS. 12 and 12A, additional construction details are shown relative to water heater 100. Water heater 100 includes tank 101, outer shell 102, insulation 103, top pan 104 and bottom pan 105. Top pan 104 includes a hard plastic cover 108 and a generally circular pad of insulation 109 which is recessed in its center to receive the top cylindrical end of tank 101. Since cover 108 is completely fabricated when it is set down over the top edge of shell 102, it may be fabricated of virtually any material since the fabrication options are numerous. Insulation 109 may be either a section cut from a batt or mat of fiberglass (several sections if needed for the requisite thickness) or precast to the specific size and shape desired.

It is to be understood that bottom pan 105 is configured and constructed in a manner virtually identical to top pan 104 except for possibly the depth of the generally cylindrical recess in insulation 110 which receives the lower end of tank 101. Cover 111 may also be fabricated from plastic or metal and is prefabricated with insulation 110 prior to receipt of tank 101 and outer shell 102.

As illustrated in the enlarged detail of FIG. 12A, the inner and upper edge of cover 111 is provided with a receiving lip 112 which is an offset band of material, plastic or metal, formed into an annular ring and then joined to the inside surface of cover 111. The offset configuration of lip 112 creates a generally annular channel 113 which has a radial width just slightly larger than the wall thickness of the lower edge 114 of the outer shell 102. The lower edge 114 fits snugly within channel 113 and this assembly technique is virtually duplicated for the upper edge of the outer shell which fits into channel 115 formed by the assembly of lip 116 to cover 111. When incorporating the hinged shell structure of FIG. 1, for example, or the flexible, wrap-around shell structure of FIG. 6 into the FIG. 12 assembly, channel 113 may be used as a retention means and as a guide for the shell 102 as it is shaped and moved into its desired cylindrical configuration. In the event the outer shell is formed and its free ends (edges) secured together prior to assembly of the top and bottom pans, the channels 113 and 115 serve to help hold and retain the cylindrical shape of the outer shell 102.

Referring to FIGS. 13-15, further construction details and options of the present invention are illustrated. Water heater tank 120 includes a raised plastic panel 121 which is secured to the outer surface of the tank. Plastic panel 121 includes various controls associated with the operation and control of the water heater. Controls blocks 122 and 123 represent portions of panel 121 where the controls are assembled. Panel 121 includes a pair of full-height substantially straight and parallel grooves 124 and 125. These two grooves provide a simple and convenient means to secure the free ends (edges) of the outer plastic shell 126 which is wrapped around the tank 120 and the layer of insulation 127 (see FIG. 15). Free ends 128 and 129 fit securely within grooves 124 and 125, respectively, and are anchored therein by heat-welding or staking of plastic to plastic. Alternatively, the free ends may be adhesively secured within the grooves.

Referring to FIG. 14 an appearance cover 132 is illustrated and includes access doors 133 and 134, outer skin 135, filler block 136 and a series of screw holes 137. The assembly of appearance cover 132 to outer shell 126 and plastic panel 121 is illustrated in FIG. 15. The wedge-shaped recess created by the differing thicknesses of panel 121 and insulation 127 and the angularity of free ends 128 and 129 when received by the corresponding grooves, is plugged or filled by filler block 136. The outer edges of skin 135 overlap the outer surface of shell 126 adjacent free ends 128 and 129. The skin is secured to shell 126 by the use of self-tapping screws 140 which are inserted through hole 137 and anchored into shell 126. Cover 132 covers up the assembly of the free ends to panel 121 and provides a more attractive and pleasing appearance to the overall construction of the water heater. Access door 133 is disposed over block 122 and access door 134 is disposed over block 126. Opening or removal of the doors enables the corresponding controls positioned within the blocks 122 and 123 to be accessed for operation and control of the water heater.

Referring to FIGS. 16 and 17, an alternative construction to the outer shell is illustrated. Employing a wrap-around plastic shell 144, water heater 145 includes a tank 146, panel 147 and insulation blocks 148. The free ends (edges) 149 and 150 of shell 144 are anchored within corresponding channels in panel 147 consistent with the foregoing description relative to FIGS. 13-15. Appearance cover 151 is used to cover the assembly of the shell 144 to the panel 147 and is assembled thereto consistent with the foregoing description relative to FIGS. 13-15.

Shell 144 is an extruded plastic member formed as an integral, unitary sheet with a plurality of substantially flat and parallel spaced ribs 152. The distance or height of the ribs 152 above shell panel 153 corresponds generally to the radial distance between the outer surface of tank 146 and panel 153, or vice versa, and this annular space (arrow 154) is filled with insulation blocks 148 thereby creating an insulation blank (shell 144). When shell 144 is flexed into a generally cylindrical shape around the inner water tank, the free ends 149 and 150 and the insulation blocks are oriented so as to extend in axial direction. By first fabricating the plastic shell and then installing insulation blocks 148 between each rib and end blocks of insulation between the free ends 149 and 150 and their immediately-adjacent ribs, the assembly of FIG. 16 is able to be achieved. Each insulation block 148 begins with a size somewhat higher than the height of ribs 152. Then, since the insulation for insulation blocks 148 is flexible and compressible, as the shell is wrapped around the tank, the insulation blocks are slightly compressed so as to create a packed thickness of insulation between the shell and tank contributing to an improved and more efficient design. More insulation is able to be included due to the wrap-around design of the shell and its ability to compress the excess insulation into a smaller space as the free ends of the shell are secured to panel 147. As an alternative, shell 144 may be fabricated in two curved sections and then hinged together similar to what is illustrated in FIGS. 1 and 2.

Ribs 152 provide a ready-made mold for a foam-in-place insulation. All that is required is to close off the ends of the extrusion between the adjacent ribs to create a generally rectangular volume. If an increased thickness of insulation is desired (above the height of ribs 152), then a temporary extension or lip must be applied to the top of each rib for the increased thickness of the foam-in-place insulation. The ribs also significantly contribute to the strength and rigidity of the shell enabling the shell to hold or maintain its generally cylindrical shape. A further variation to the structure of FIG. 16 and 17 is to install shell 144 around tank 146 without insulation blocks 148 installed and without any foam-in-place insulation preformed as part of shell 144 prior to assembly of the shell. In this approach, after the shell 144 is assembled and prior to installing the top pan, the enclosed hollow troughs which are thus defined by the shell panel 153, the tank 146 and each pair of adjacent ribs 152, is filled with a foam-in-place (liquid) foam insulation.

Referring to FIGS. 18 and 19, a further variation for the present invention is illustrated. In lieu of the spaced ribs 152 of FIGS. 16 and 17, a series of spaced insulation blocks 157 are attached to panel 158 of shell 159. The height or thickness of each block 157 is determined based upon the diametral size of the tank 160 relative to the diameter of shell 159. The difference is the radial thickness of annular clearance space 161. The voids of clearance space 161 on either side of blocks 157 are filled with additional insulation, such as foam-in-place insulation 162. In order to add to the strength and rigidity of shell 159, blocks 157 are fabricated from polystyrene or a similar rigid insulation material. This type of relatively rigid material helps the shell conform to and maintain the desired generally cylindrical shape.

In the FIGS. 18 and 19 illustrations, only a portion of the total construction of shell 159 is illustrated. Omitted from these illustrations are several other blocks 157, free ends (edges) of panel 158 which are used to secure the shell to the raised control panel on the tank. It is also to be noted that blocks 157 extend virtually the entire length of panel 158. In lieu of foam-in-place insulation 162 which is applied after the shell is assembled, it is also envisioned the flexible, compressible blocks of insulation, such as fiberglass mats of batts will be assembled between blocks 157 prior to wrapping or hinging shell 159 around tank 160.

Referring to FIGS. 20 and 21, a further variation of the present invention is illustrated. Shell 165 includes a plastic panel 166 and a series of insulation blocks 167 which are adhesively joined to each other and adhesively joined to panel 166. A suitable insulation for blocks 167 is fiberglass and the blocks for shell 165 are cut from a larger block. This larger block begins with a series of relatively large fiberglass panels and adhesive is applied between each pair of panels. The generally cubic mass which results has a single layer cut from the top of the cube and it is this layer which provides the adhesively bonded blocks 167 illustrated in FIGS. 20 and 21. In order to fabricate additional insulation blankets (shell 165), another single layer is cut from the top of the cube which remains after the first layer is removed. Additional cuts and removal of layers provide the type of adhesively bonded blocks 167 in multiple count for a multiple number of insulation blankets.

Consistent with all of the foregoing descriptions of the shell, the free ends and the assembly of these free ends to the plastic control panel, shell 165 is designed and assembled in a virtually identical fashion, the only difference being limited to the blocks of insulation versus earlier-disclosed approaches of ribs and spaced blocks of rigid insulation. These similarities in construction are referenced in this manner since shell 165 is only illustrated in partial form.

Shell 165 is wrapped around tank 168 as illustrated in top plan and full section form in FIG. 20. As would be expected, as panel 166 is curved into a cylindrical shape the top (inner) edges of blocks 167 which abut against tank 168 must be circumferentially compressed due to their generally straight and parallel sides and the differing circumferential sizes between the shell panel and the tank. In other words, the same length of insulation (blocks 167) is disposed into two different circumferential dimensions. Since the blocks are bonded to the panel, there is no relative motion at this interface and the only option is for the outer surface (top) of the insulation blocks 167 (the surface against the tank) to be compressed in order to fit.

As is to be understood, the generally rectangular solid form for the box 167 undergoes a differing degree of compression between the outer surface 171 which is adhesively bonded to the panel 166 and the free surface 172 which is placed in abutment against tank 168.

Referring specifically to FIG. 22 and to insulation block 167a, the layering effect of fiberglass insulation is diagrammatically illustrated. There is a radiating pattern created whereby the spacing of the fiberglass layers adjacent surface 171 is farther apart than the spacing of the layers adjacent surface 172, fully consistent with the foregoing description of how the differing circumferential sizes result in differing degrees of compression between the outer surface 171 and the free opposite surface 172. The laminar nature of fiberglass insulation provides much greater compressive strength in the radial direction of the shell to the tank. This helps to provide a true cylindrical shape for the shell and should enable a thinner and thus less-costly outer shell.

Referring to FIGS. 23-27 there is illustrated a honeycombed insulation panel 180 which includes a first cover or skin 181 and a series of interconnected honeycombed pockets 182, the majority of which are each generally cubic (or a rectangular solid) and defined by two substantially parallel walls diagonally extending in a first direction and which respectively intersect with two substantially parallel walls diagonally extending in a second direction at right angles to the first direction.

Looking at one honeycomb pocket, honeycomb walls 183 and 184 extend in the first direction and honeycomb walls 185 and 186 extend in the second direction. The four-sided intersection defines pocket 182a which is shown filled with thermal insulation. With diagonally-extending honeycomb walls there are edge pockets 187 which are of a partial or incomplete triangular shape. These edge pockets may either be ignored or may be enclosed so that these edge pockets can receive and retain insulation. An enclosing wall 188 is drawn along the left edge of panel 180 for illustrative purposes of how such an enclosing edge wall would appear as part of panel 180. The diagonally extending walls may be varied as to their angle, but if walls 183 and 184 do not cross walls 185 and 186 at right angles, the pockets 182 will not be cubic or a rectangular solid but rather diamond-shaped (parallelogram).

Referring to FIG. 24, panel 180 is shown as a front elevational view with more of the top cover 192 illustrated. The edges of the walls which create the honeycomb pockets 182 are shown and each pocket is enclosed by the walls and by first cover 181 and top cover 192. If the honeycomb pockets are filled with loose, discrete insulation material, it is necessary to encase that insulation and thus the need for both top and bottom covers or skins.

An alternative to loose, discrete insulation is to place a block of fiberglass insulation in each pocket 182 in which case there is less need for top cover 192 because if the blocks of insulation are cut closely to the size of the pockets or slightly oversized, they will remain in their respective honeycomb pockets.

Prior to being filled with insulation, the honeycomb walls have the appearance of FIG. 25 wherein skin 181, top cover 192, walls 183 and 184 and walls 185 and 186 are all illustrated. Although only a small portion of panel 180 is illustrated and although none of the honeycomb pockets are filled with insulation, FIG. 25 provides possibly the best view of the honeycomb configuration of panel 180. The honeycomb walls such as walls 183-186 may begin as substantially flat panels which are slotted half-way with the slotting reversed from top to bottom so that the differently directed walls can interlock with each other by mutual receipt within the slots. Alternatively, the entire honeycomb may be molded as a single, integral member. It is also envisioned that the criss-crossing and interlocked arrangement of honeycomb walls can be used as a pattern or die for a mat or batt of fiberglass insulation in order to size and cut the individual insulation blocks which are to be placed into pockets 182 so that these blocks will have a precisely matching contour.

It is important for the first cover (skin) 181 to be relatively flexible though stiff enough and strong enough to both support the honeycomb structure and provide a suitable outer shell for a water heater construction. As illustrated in FIG. 26, panel 180 with both covers 181 and 192 is wrapped around and inner tank 195. In accordance with the hinged and wrap-around constructions which are typical of FIGS. 1, 2, 7, 16, 18 and 20 herein, panel 180 is assembled to inner tank 195 for a finished water heater construction. In the illustrated arrangement clasp 196 joins together the outer free ends (edges) 180a and 180b of panel 180 in order to conform the otherwise substantially flat panel into a cylindrical sleeve.

The height or thickness of the honeycomb walls (i.e., the depth of each honeycomb pocket) will vary depending on the acceptable outside diameter size for the water heater and the amount of insulation desired. Since these honeycomb pockets are flexed into a cylindrical shape, the specific material must be considered relative to the height and wall thickness in order to provide the necessary flexibility for wrapping around the inner tank.

A still further embodiment related to the use of a honeycomb network is illustrated in FIG. 27 wherein top cover 192 is omitted and the various blocks 197 (plugs) of fiberglass insulation are cut into the peripheral shape of the corresponding pockets, but each block has a height which is noticeably higher than the upper edge of the honeycomb pocket. As the panel of FIG. 27 is formed around the inner tank (such as tank 195) into a cylindrical shell and the latch 196 is closed and locked, it is intended for the fiberglass blocks to be compressed thereby increasing the amount of insulation which is disposed around the tank. If the honeycomb walls are sized to fit up against the outer surface of the inner tank 195, then the increased height portion (t) of each block 197 of insulation which extends above the honeycomb pocket by dimension "t" is compressed completely down into its corresponding honeycomb pocket as the panel is locked around the inner tank and secured thereto by the clasp.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.