Abstract:
An outside balanced flue water heater including a water tank; a jacket surrounding the water tank; a combustion chamber containing a burner positioned adjacent the water tank; a flue extending from the combustion chamber through an upper portion of the water tank; a water inlet and a water outlet connected to the water tank; a combustion air passageway positioned between the jacket and the water tank, the combustion air passageway communicating with the combustion chamber to supply combustion air from the combustion air passageway to the combustion chamber; a combustion air inlet chamber above the water tank and adapted to directly receive outside air, the combustion air inlet chamber communicating with the combustion air passageway; and a flue gas exhaust chamber above the combustion air inlet chamber and adapted to receive flue gases from the flue and to directly exhaust flue gases, the flue gas exhaust chamber communicating with the flue.

Description:
This application is a continuation-in-part of application Ser. No. 08/395,759, filed Feb. 28, 1995, and now U.S. Pat. No. 5,533,495. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a gas-fired water heater, particularly to a gas-fired balanced flue water heater capable of installation and long term operation outdoors. 
     BACKGROUND OF THE INVENTION 
     Typical gas-fired water heaters are constructed for installation and operation in indoor spaces such as basements, laundry rooms and closets, for example. As a result, the materials selected for water heater components and construction of such water heaters do not lend themselves to installation and operation of water heaters outside of such buildings. Exterior operation subjects water heaters to the elements which can reduce water heater longevity and reduce operating efficiency. 
     There is a growing need for water heaters capable of exterior installation and operation in view of increasing regulation of placement and operation of water heaters in interior spaces. For example, many localities now have regulations concerning the need to supply combustion air from outside the structure instead of the traditional means of supplying combustion air from the interior space itself. A number of water heaters have been developed to address these problems, such as the water heater disclosed in U.S. Pat. No. 5,020,512. That water heater uses a first concentric tube to supply combustion air from outside of the building in which the water heater is located and a second concentric tube to exhaust combustion gases outwardly of the building. Combustion air is channeled from the outer concentric tube into an outer jacket surrounding the water heater, the outer jacket forming a space communicating with the combustion chamber of the water heater. 
     Such water heaters typically require cumbersome concentric or multiple tubing with the necessary associated boring or cutting through the wall of the structure and then mounting vents to the wall. This additional apparatus is expensive and sometimes not easy to install because of the distance to the wall or obstacles between the wall and the water heater. Thus, exterior installation would be a possible alternative. However, such water heaters are constructed from materials suitable for indoor use which does not account for harsh exterior conditions likely to be encountered by an outdoor water heater. 
     Another problem necessitating water heaters for exterior installation and operation is the lack of suitable interior space for water heaters. Many dwellings are constructed without basements and, since space is at a premium, many dwellings seek to minimize or eliminate the space occupied by bulky water heaters. Multiunit dwellings are especially frequently space deficient and can benefit by exterior installation of water heaters. Also, since many dwellings are constructed without masonry chimneys, exhausting the hot flue gases can become a significant problem if the water heater is not designed to reduce flue gas temperatures. 
     Although many typical water heaters have been installed outside of living spaces, such as in garages, out buildings and the like, attempts to employ such water heaters completely outside have not been successful. The materials of construction of the water heaters lend themselves to premature corrosion of exterior parts. Installation of water heaters outside severely reduces energy efficiencies, especially in northern locations wherein combustion air often is very low in temperature and the entire unit is subjected to very severe low temperatures. Installation of water heaters outside can lead to reduced operating efficiencies because of the cold temperatures or because of excess wind blowing out pilot lights and accumulation of debris, such as leaves and the like around the base of the water heater, thereby reducing a balanced supply of combustion air to the water heater. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a water heater capable of installation and operation outside for prolonged periods of time. 
     It is another object of the invention to provide a water heater capable of withstanding harsh exterior elements and,operate in an energy efficient mode. 
     It is yet another object of the invention to provide a water heater suitable for exterior use that is self-contained without extraneous flue gas exhaust apparatus. 
     Other objects and advantages of the invention will become apparent to those skilled in the art from the drawings, the detailed description of the invention and the appended claims. 
     SUMMARY OF THE INVENTION 
     The water heater of the invention includes a tank, a jacket surrounding the tank, insulation positioned between the jacket and the tank, a combustion chamber containing a burner positioned adjacent the tank, a flue extending from the combustion chamber through an upper portion of the tank, a water inlet and a water outlet connected to the tank. The water heater also includes a passageway located between the jacket and tank which extends from the top of the water heater to the combustion chamber to supply combustion air to the combustion chamber. A perforated jacket connects to the jacket and forms an upright extension. A shelf connects to the perforated jacket, is spaced above the top of the water heater, and communicates with the passageway. A divider connects to the perforated jacket and is spaced above the shelf. The divider also connects to a flue extension connected to the flue, which extends through a hole in the divider to form a combustion air inlet chamber. A cover is spaced above the divider at the top of the perforated jacket. The cover, the divider and the perforated jacket form a flue gas exhaust chamber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a front elevational view, taken in section, of a water heater in accordance with aspects of the invention. 
     FIG. 2 shows a perspective view of the water heater of FIG. 1, taken partially in section. 
     FIG. 3 shows a top plan view-of a divider plate having form stiffening ribs in accordance with aspects of the invention. 
     FIG. 4 shows a bottom plan view of a shelf having an air inlet. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It will be appreciated that the following description is intended to refer to the specific embodiments of the invention selected for illustration in the drawings and is not intended to define or limit the invention, other than in the appended claims. 
     Turning now to the drawings in general, in FIGS. 1 and 2 in particular, the number 10 designates a balanced flue outdoor water heater of the invention. Water heater 10 is formed from a water tank 12 having a flue tube 14 extending between tank bottom 16 and tank head 18. A combustion chamber 20 is located beneath tank bottom 16 and formed from side wall 22, bottom pan 24 and tank bottom 16. A gas-fired burner 26 is located within combustion chamber 20 and connects to a fuel line 28 which connects to a controller 30. The controller 30 contains a thermostat and is mounted onto jacket 32 which connects to a sensor 34. 
     A top pan 46 connects to the upper portion of jacket 32 and contains opening 48 through which flue tube 14 extends. A water inlet 40 extends into a lower portion of tank 12 through jacket 32. Similarly, a water outlet 42 extends into an upper portion of tank 12 and outwardly of jacket 32. Foam insulation 44 is located between jacket 32 and tank 12, and between top pan 46 and tank head 18. A passageway 76 extends between jacket 32 and water tank 12. The thickness or depth of passageway 76 may or may not extend the entire distance between jacket 32 and water tank 12, and space not occupied by passageway 76 may be filled with foam insulation or any suitable material. 
     Jacket 32 is closed and substantially air tightly sealed on the bottom by a bottom pan 24. A sealed access door 52 permits access to controller 30. Bottom pan 24 and tank bottom 16 form a combustion chamber 20 that communicates with passageway 76. Perforated jacket 68 connects to and extends upwardly from top pan 46. Shelf 56 is spaced above top pan 46 and connects to perforated jacket 68. Top pan 46 and shelf 56 form an upper space 79 that communicates with passageway 76 through hole 63. Shelf 56 contains air inlet 58 and is sealed at seal 60 to perforated jacket 68. Divider plate 64, having a multiplicity of form stiffening ribs 65, is spaced above shelf 56 and is sealed at seal 66 to flue extension 62. Flue extension 62 connects to and extends upwardly from flue robe 14. Water inlet 40 and water outlet 42 are sealed to jacket 32 by seals 72. 
     Perforated jacket 68 contains perforations 67 and connects to shelf 56, divider plate 64 and cover pan 70. Perforations 67 may preferably be round, or any geometric configuration. Shelf 56, divider plate 64 and perforated jacket 68 form a combustion air inlet chamber 69 which communicates with passageway 76 through air inlet 58, upper space 79 and with exterior air through perforations 67. Cover pan 70, divider plate 64 and perforated jacket 68 form a flue gas exhaust chamber 71. 
     FIG. 3 shows divider plate 64 from FIG. 1 having heat exchange ribs 65 extending radially outwardly along the surface of divider plate 64. Divider plate 64 is shown in a preferred configuration wherein four sections are combined to formed the entire divider plate 64. 
     FIG. 4 shows jacket top pan 56 having an opening 57 through which flue extension 62 passes. Jacket top pan 56 also has air inlet 58. 
     Operation of the water heater of the invention will now be described below in connection with the drawings. 
     Withdrawal of hot water from water outlet 42 results in simultaneous introduction of cold water into tank 12 through water inlet 40. Sensor 34 detects temperature changes and controller 30 causes fuel to be supplied through fuel line 28 to burner 26. Ignition of fuel at burner 26 requires combustion air. Combustion air is supplied to combustion chamber 20 by way of perforations 67 in perforated jacket 68, combustion air inlet chamber 69, air inlet 58 in shelf 56, upper space 79 and into passageway 76 through hole 62 in top pan 46. Combustion air travels downwardly through passageway 76, past access door 52 and controller 30, and into combustion chamber 20 by way of combustion air inlet 36. There is no need for separate or additional apparatus to conduct combustion air through a wall or other exterior structure. There is also no need for separate combustion air inlets through bottom pan 24 or side wall 22. 
     Combustion of fuel at burner 26 results in the production of flue gases, the flue gases moving upwardly into and through flue tube 14. The flue gases then continue upwardly and travel through flue extension 62 and into flue gas chamber 71. The flue gases then flow outwardly of flue gas chamber 71 to the outside air by way of perforations 67 in perforated jacket 68. There is no need for separate or additional apparatus to conduct flue gases through a wall or other structure. This system of introduction of combustion air and exhausting of flue gases from the top of water heater 10 results in a balanced flue water heater. 
     Heat exchange ribs 65 are heated by flue gases in flue gas chamber 71. This assists in equalizing the temperature between combustion air and flue gases. The location of air inlet 58 adjacent opening 57 and inside shelf 56 as shown in FIG. 4 improves this effect. Incoming air combustion travels along the full length of heat exchange ribs 65 and has its temperature raised. It has been surprisingly discovered that water heater 10 of the invention is highly fuel efficient, despite the fact that incoming air, which at times is relatively very cold, travels inside jacket 32. It was previously believed that such air travelling in passageway 76 would severely impair energy efficiency. Assistance of heat exchange ribs 65, coupled with use of foam insulation 44 eliminates possible energy inefficiencies. It has also been discovered that the flow of such air through passageway 76 is relatively very slow compared to exterior winds which are capable of causing severe heat loss. Passageway 76, lower space 77 and upper space 79 act as a type of insulation because of the relatively still air in those spaces. Retention of flue gases by cover pan 70 also helps water heater 10 retain heat at the top of the unit where the hottest water is located to thereby assist in heat retention. 
     Water heater 10 of the invention is fully capable of exterior use over long periods of time with a high degree of reliability. The lower portion of water heater 10 is sealed from the elements so that a continuous supply of moderate temperature combustion air is available without the possibility of obstruction or clogging due to accumulation of leaves, debris and the like. 
     Although this invention has been described in connection with specific forms thereof, it will be appreciated that a wide variety of equivalents may be substituted for the specific elements described herein without departing from the spirit and scope of this invention as described in the appended claims. For example, water tank 12 may be of any number of sizes and shapes and may be made from a wide variety of materials such as metals and/or plastics. Foam insulation 44 may similarly be made from any number of foam insulations well known in the art. 
     Cover pan 70, shelf 56 and bottom pan 24 may be made from coated steel, plastics or the like so long as they are weather resistant. Perforated jacket 68 is preferably made from stainless steel or powder painted metal and should be weather resistant. Perforated jacket 68 may be made with slits, slots or other shaped holes and may be made from alternate types of materials such as mesh, for example, so long as it is structurally sound and provided with means making it air and flue gas permeable in the desired locations. Divider plate 64 is preferably made from galvanized steel or other heat conductive material. Divider plate 64 may have any number of heat exchanging ribs 65, the ribs being formed from a wide variety of shapes and heat conducting materials. 
     The thickness or depth of passageway 76 is not critical, so long as sufficient quantities of combustion air can pass through. A passageway depth of one inch in a two inch cavity (distance between tank 12 and jacket 32) is preferred. The geometrical shape of its cross-section is also not critical. Passageway 76 may be formed by any number of means including preformed and molded insulation, tubing made from any number of materials such as PVC, styrofoam, stainless steel and the like. Passageway 76 may also be formed by inserting a rod or the like of the appropriate length at the appropriate position for the passageway, injecting foam insulation around the rod, and removing the rod, thus leaving a passageway that communicates with upper space 79 and combustion chamber 20. Combustion air inlet chamber 69 and flue gas chamber 71 may have varied shapes and sizes as desired. 
     Flue tube 14 can extend upwards to divider plate 64, thus removing the need for flue extension 62. While air inlet 58 is shown in FIGS. 1, 2 and 4 as extending around the entire circumference of flue extension 62, it should be appreciated that air inlet 58 may be limited to an opening which surrounds flue extension 62 only partially. 
     Burner 26 may be operated with a wide variety of fuels, including natural gas, propane, liquified natural gas, oil and the like. Any type of seals 72 may be used so long as they are capable of being substantially air tight. Flue extension 62 should be made from heat resistant material, preferably the same as flue tube 14, and may be connected to flue tube 14 by any known means such as by welding, screws, bolts and the like. Similarly, flue extension 62 may be sealed to divider plate 64 by any known means such as by welding, for example.