Abstract:
This gas-fired water heater has a shell sealed at opposite ends within an insulated storage tank, defining a water-tight chamber with inlet and outlet water connections thereto. The shell preferably is a one-piece casting of aluminum alloy, with a circular array of impervious passages between its opposite ends. Each passage is defined by a curved wall segment spaced inwardly adjacent the tank and a pair of side walls converging inwardly from opposite ends of each curved wall segment to an inboard corner, where the adjacent corners and side walls are spaced apart radially and circumferentially respectively yielding water contact against all exterior passage surfaces. A burner under the storage tank generates hot flue gases that vent through the passages for heating the chamber water. A rib can project inwardly from the curved wall segment into each flow passage, adding heat transfer to the wall segment and contacted water.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0001]     Not Applicable  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0002]     Not Applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Technical Field of Invention  
         [0004]     This invention relates to a water heater in which combustion products are caused to flow past a tank to heat water in the tank, particularly for domestic use such as showering and washing the dishes or clothes, as well as for space heating in a building.  
         [0005]     2. Description of the Prior Art  
         [0006]     In a conventional gas fired/fueled water heater of prior art U.S. Pat. Nos. 4,672,919; 5,020,512; 5,199,385; 5,335,646, etc., a gas burner is located beneath the lower end of the water tank in a combustion chamber. A central vertical flue pipe is provided through the tank for discharge of the waste combustion or flue gases. Water in the tank is heated by the heat from the burner in the combustion chamber and from the waste gases passing upward through the central flue pipe, which serves as a heat transfer surface for heating water. Different flue baffles are placed into the flue pipe to increase the amount of heat transmission through the flue pipe. The thermal efficiency of such water heaters is usually 76-80%. The reason for such a low thermal efficiency is the high temperature of the outlet flue gases, which can reach 200° C.  
         [0007]     A multi-flue construction can be used to increase the productivity of water heaters (e.g. by U.S. Pat. Nos. 4,157,077; 4,512,289; 4,531,509; 5,027,749). However, these constructions are very complicated, generally being expensive and complex, and contain numerous welds, which shorten a water heater&#39;s life. Moreover, special means are required to prevent sediment buildup the tank, e.g. as in U.S. Pat. No. 5,341,770.  
         [0008]     Furthermore, it is known that hot water heaters may have two separate hot water outlets, one for domestic hot water and the other for a heating system in a building. Examples of such devices are shown in U.S. Pat. Nos. 2,937,625; 4,222,350; 5,228,413; 5,372,185.  
         [0009]     3. Object and Advantages of the Invention  
         [0010]     It is an object of the present invention to provide a water heater with a constant thermal efficiency of 85-95% during a heater&#39;s life, for residential use as well as for commercial use with a manufacturing cost that is not greater than other ordinary residential models of the same productivity and much less than the cost of ordinary commercial models.  
         [0011]     The current invention provides the following advantages: 
        1) Increased water heater operating efficiency to 85-95%, by improving heat recovery from flue gases to water.     2) Increased water heater power, without decreased operating efficiency and without increased water heater dimensions.     3) Simple construction, easily implemented at low cost.     4) Replacement of a typically separate water heater and boiler with a single unit, by performing dual functions such as showering and washing the dishes or clothes, as well as a heating system in a building.     5) Reduced cost for water heating, by improving heater efficiency during the water heater&#39;s life and by dual function implementation.     6) Prolonged water heater lifespan, by eliminating sediment accumulation within the water heater tank.        
 
         [0018]     Other objects and advantages of the present invention will become apparent to those skilled in the art from the drawings, the detailed description of the preferred embodiment, and the appended claims.  
       BRIEF SUMMARY OF THE INVENTION  
       [0019]     There is a need for a dual function, relatively simple, and highly efficient water heater in which combustion products are caused to flow past a tank to heat water. In accordance with the present invention, a water heater is provided that includes an insulated water tank with a flue pipe extending vertically through the tank for the discharge of waste combustion or flue gases, a burner below the tank, and a burner control means. The flue pipe comprises a water-surrounded and radially-expanded means for increasing heat recovery from the flue gases. The radially-expanded means comprises a chamber for the flow of the flue gases. The chamber includes a means for directing the flue gases toward the inner surface of the radially-expanded means. In a further improvement, the water heater comprises a means for transferring heat from the water in the tank to an additional water line, preferably for heating potable water for domestic use such as showering and washing the dishes or clothes. In a still further improvement ( FIG. 1   c ), the burner control means possesses an additional means for adjusting burner power depending on water temperature in the water tank.  
         [0020]     In accordance with the invention, in the second alternative preferred embodiment as shown in ( FIG. 1   a ,  FIG. 1   b , and  FIG. 1   c ), the means for directing the flue gases constitutes a tank containing water in a heat exchange relationship with the water in the main heater tank of the water heater. In a still further modification ( FIG. 1   c ), the tank for directing the flue gases comprises at least two interconnected sections.  
         [0021]     In accordance with the invention, the third alternative preferred embodiment ( FIG. 2  and  FIG. 3 ) provides a water heater having an additional heat exchanger for heating water for potable use, a burner with control means, and a water housing containing the water to be heated. The water housing comprises an inner ribbed means and a separate outer shell tightly interconnected and sealed together, between which is contained the water to be heated and the heat exchanger. In the preferred embodiment, the outer shell is in the shape of a cylinder with one partially closed top end and one open bottom end. The partially closed top end possesses a machined flange face sealing surface on the inside surface of the top end, and the open bottom end possesses a machined flange face sealing surface on the bottom side of a lip perpendicularly extending from the outside of the outer shell. The inner ribbed means is preferably in the shape of a truncated cone with one partially closed top end and one open bottom end. The partially closed top end possesses a machined flange face sealing surface on the outside surface of said top end, and said open bottom end possesses a machined flange face sealing surface on the top side of a lip extending from the outside of the inner ribbed means. The flange face sealing surface on the top end of both the inner ribbed means and outer shell are tightly sealed and connected together, and the flange face sealing surface on the lip of the bottom end of both the inner ribbed means and outer shell are tightly sealed and connected together. The opening of the partially closed top end of both the inner ribbed means and outer shell provides for the discharge of the combustion gases from the water heater, and the opening of the bottom end of the inner ribbed means provides for the entry of the hot combustion gases to the water heater.  
         [0022]     In a further improvement, the burner control means possesses an additional means for adjusting burner power, depending on water temperature in the water housing.  
         [0023]     In a still further improvement, the inner ribbed means constitutes a cast shell comprising a plurality of ribs for absorbing and transferring heat from the combustion gases.  
         [0024]     In a still further improvement, the ribs are radially-starlike situated in the inner cast shell.  
         [0025]     In a still further improvement, at least some of the ribs possess inner water cooling passages to maximize heat transfer. 
     
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
       [0026]     In the drawings which illustrate the present invention,  
         [0027]      FIG. 1  is an elevated cross-sectional view showing a first preferred embodiment of a water heater according to the present invention.  
         [0028]      FIG. 1   a  is an elevated cross-sectional view illustrating a second preferred embodiment of a water heater according to the present invention.  
         [0029]      FIG. 1   b  is an elevated cross-sectional view illustrating a similar embodiment to  FIG. 1   a.    
         [0030]      FIG. 1   c  is an elevated cross-sectional view illustrating a second similar embodiment to  FIG. 1   a.    
         [0031]      FIG. 2  is a side elevated cross-sectional view illustrating a third preferred embodiment of the water heater according to the present invention.  
         [0032]      FIG. 3  is a top cross sectional view taken along line A-A of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]     The detailed description is presented to illustrate the present invention but is not intended to limit it.  
         [0034]     In more detail, a typical water heater, in which combustion products are caused to flow past a tank to heat water in the tank, comprises a gas burner located beneath the lower end of the tank in a combustion chamber. A central vertical flue pipe is provided through the tank for discharge of the waste combustion or flue gases. Water in the tank is heated through the bottom end of the tank by the heat from the burner in the combustion chamber and from the waste gases passing upwardly through the central flue pipe, the walls of which also serve as a heat transfer surface for heating water. In order to increase the amount of heat transmission through the flue pipe, and to increase the productivity and efficiency of the water heater, a preferred embodiment of a water heater is shown best in  FIG. 1 . According to the invention, the improved water heater includes a water chamber  21  surrounded by a typical cylindrical tank  11  with upper concave shaped end  22  and lower convex shaped end  14 . The water tank  11  having a water inlet stub pipe  31  leads to the lower portion of the tank, and water outlet stub pipe  30  located at the upper end  22  of tank  11  is surrounded by a layer of insulation  32  on the side and top. An outer jacket  33  surrounds the insulation  32  to protect it from mechanical damage. A burner  12  situated in a burning chamber  13  and located under the lower end  14  of the tank  11  is adapted to combust gas such as natural gas or propane or some other combustible material such as oil. While the invention is disclosed in respect to a gas-fired water heater, it is equally applicable to water heaters which burn other combustible fuels. Such water heaters are intended to fall within the scope of the claims. A cylindrically shaped steel flue pipe  16  passes through the bottom end  14  extending vertically through the tank  11  for removing flue gases from the burning chamber  13 . The concave shaped bottom end  14  directs hot gases into the flue pipe  16 . The flue pipe  16  comprises a water surrounded inner tank (means)  18  for increasing heat recovery from the flue gases. The water surrounded inner tank  18  in the shape of a boiler drum with openings in the covers  19  and  20  is welded on a part of the length of the flue pipe  16 , dividing the flue pipe  16  into two separate pieces  16   a  and  16   b . The inner tank  18  comprises a chamber  18   a  for the flow of the hot flue gases, and the chamber  18   a  comprises a thin-walled steel container (means)  25  for directing the flue gases toward the inner surface of the water surrounded inner tank  18 . The thin-walled steel container (means)  25  is in a shape similar to the water surrounded inner tank  18  and is filled with thermal insulation  26 . The container is equipped with two spacers  27  and  27   a  for its central positioning in the water surrounded inner tank  18 . The water heater also comprises a copper helically coiled heat exchanger  17  for transferring heat from the water in the water chamber  21  to an additional water line, preferably for heating water for domestic use such as showering and washing the dishes or clothes. A helically coiled heat exchanger  17  is placed in the water space between the top ends  20  and  22  of the two cylindrical pressure tanks  11  and  18  and is connected to couplings  23  and  24  which are welded into the top end  22  of the outer water tank  11 . The stud pipes  30  and  31  of the outer water tank  11  allow connectivity to the home&#39;s heating system. The water heater contains a typical gas burner  12  placed in the burner chamber  13 . The gas burner  12  is operated with an improved burner control means  15  similar to a typical gas control valve. The burner control means  15  possesses an additional valve (means) (not shown) for adjusting the power of the burner  12  depending on water temperature in the water tank  11 , whereby increasing the efficiency of the water heater. The outer jacket  33  surrounding the insulation  32  also constitutes a base  34  supporting the water heater construction over the floor&#39;s surface. The lower uninsulated part of the base  34  possesses air flow openings  35  supporting the gas burning process in the burning chamber  13 .  
         [0035]     Heated combustion gases produced by the burner  12  impinge against the bottom  14  of the outer tank  11  to cause heat transfer therethrough to the water in the chamber  21 . The hot burned gases further rise upward from the burning chamber  13  through the opening  36  in the flue pipe  16   a  to the chamber  18   a  of the inner tank  18  where they flow along the walls of the inner tank  18  to the flue pipe  16   b  allowing the gases to flow out from the water heater to a chimney (not shown).  
         [0036]     A second alternative embodiment of the water heater according to the invention is shown in  FIG. 1   a ,  FIG. 1   b , and  FIG. 1   c . The alternative embodiments are similar to the embodiment shown in  FIG. 1 . In the second alternative embodiment, the means  25  for directing the flue gases toward the inner surface of the inner tank  18  constitutes a tank containing water in a heat exchange relationship with the water in the water chamber  21 . The tank  25  directing the flue gases is connected in a flow-through manner to the water in the water chamber  21  with two pipes—an inflow pipe  28  and an outflow pipe  29 . As shown in  FIG. 1   a , the inflow pipe  28  is connected to the water chamber  21  with an inflow stub tube  31  and the outflow pipe  29  is connected to the water chamber  21  with an outflow stub tube  30  delivering the hot water to the home heating system (not shown). As shown in  FIG. 1   b , the inflow pipe  28  of the tank is connected to the water chamber  21  through the concave bottom end  14  of the tank  11 . As shown in  FIG. 1   c , the tank (means)  25  directing the flue gases toward the inner surface of the inner tank  18  comprises three interconnected sections  25   a . Such a structure further increases contact area between flue gases and the water surrounded walls to maximize heat transfer.  
         [0037]     The water heater as shown in  FIG. 1   c , comprises an additional control means  15   a  situated on the side of the water heater and connected to the main burner control means  15 . The additional control means  15   a , constitutes a temperature sensor that sends a signal to the additional gas control valve (not shown) in the burner control means  15  depending on the water temperature in the water chamber  21  to adjust the power of the burner  12 .  
         [0038]     In a third alternative embodiment of the water heater shown in  FIG. 2  and  FIG. 3 , the water heater comprises a heat exchanger  17 , a burner  12  with a burner control means  15  and a water housing  10 . The water housing  10  comprises a separate inner cast shell  41  (inner ribbed means) and separate outer shell  40 , which are tightly sealed and interconnected on their ends  42 ,  44  and  43 ,  45 . The chamber  21  between the inner cast shell  41  and the outer shell  40  contains circulated water to be heated and a heat exchanger  17 , which constitutes a copper pipe helically coiled around the inner cast shell  41 . The inner cast shell  41  comprises sixteen ribs  48  for absorbing and transferring heat from the combustion gases to the circulated water, which is located in the chamber  21  between shells  40  and  41 . Eight of the ribs  48  possess channels  49  filled with circulating water to maximize heat transfer from the flue gases. The ribs  48  are radially placed, starlike, in the inner cast shell  41 . The inner cast shell  41  made out of an aluminum alloy is in the shape of a truncated cone with one partially closed top end  45  and one open bottom end  44 . The partially closed top end  45  possesses a machined flange face sealing surface on the outside surface of the top end  45 . The open bottom end  44  also possesses a machined flange face sealing surface on the top side of the lip extending out from the bottom end  44 .  
         [0039]     The outer shell  40  made of cast iron is in the shape of a cylinder with one partially closed top end  43  and one open bottom end  42 . The partially closed top end  43  possesses a machined flange face sealing surface on the inside surface of the top end  43 . The open bottom end  42  possesses a machined flange face sealing surface on the bottom side of a lip  42  that perpendicularly extends from the outside of the bottom end  42  of the outer shell  40 .  
         [0040]     The flange face sealing surface on the top end of both shells  40  and  41  are connected together with bolts  46  and sealed with a sealing ring  47   a  installed between the sealing surfaces.  
         [0041]     Also the flange sealing surface on the lip of the bottom end  42  and  44  of both shells  40  and  41  are connected together with the same kind of bolts  46  and sealed with a sealing ring  47  located between their sealing surfaces.  
         [0042]     The coiled heat exchanger  17  is connected to the inflow and outflow couplings  23  and  24  placed in the partially closed top end  43  of the cast iron outer shell  40 . The water heated by the exchanger  17  is for potable use.  
         [0043]     The outer shell  40  also includes two stub tubes  30  and  31  for connecting to a heating system in a building (not shown). The water heater contains a typical gas burner  12  placed in the burning chamber  13 , which is controlled with an improved gas control valve  15  placed on the side of the outer shell  40 . The improved gas control valve possesses an additional valve (not shown) for adjusting the power of the burner  12  depending on water temperature in the water chamber  21 . The outer shell  40  is surrounded by a layer of insulation  32  on the side and top. An outer jacket surrounds the insulation  32  to protect it from mechanical damage. The outer jacket  33  also constitutes a base  34  supporting the water heater construction over the floor&#39;s surface. The lower uninsulated part of the base  34  possesses air flow openings  35  supporting the gas burning process in the burning chamber  13 .  
         [0044]     Hot combustion gases produced by the burner  12 , in the burning chamber  13 , impinge against the ribbed surface  50  of the inner cast shell  41 , which allows for heat transfer therethrough to the water in the chamber  21 . The hot burned gases rise upward along the ribs  48  and ribbed surface  50 , transmitting its heat through the walls  51  ( FIG. 3 ) to the water chamber  21 . The flue gases flow out through the flue channels  52  to the pipe  53  and outside to the chimney (not shown).