Abstract:
A high efficiency water heater comprising a generally cone shaped tank; an surrounding and spaced from the tank defining a passageway for flue gases between an inner surface of the enclosure and the outer surface of the tank, said enclosure having an outlet for flue gases; a burner communicating with the interior of said enclosure, and means for providing combustion air to said burner. The preferred embodiment includes baffle means attached to the outer surface of the tank for increasing heat transfer. One embodiment has a conduit passing vertically through the tank, and wherein the burner is disposed in an upper region and communicating with the conduit, and includes a fan for directing flue gases downward through the conduit and subsequently into and through said passageway between the inner surface of the enclosure and the outer surface of the tank.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to water heaters, and specifically to a water heater with novel geometry and associated features to provide high efficiency. 
   Applicants prior U.S. Pat. No. 6,508,208 issued Jan. 31, 2003, to Frasure, et al. discloses a water heater having a conical bottom adapted to collect and dispose of sediment. 
   Applicants prior U.S. Pat. No. 7,100,541 issued Sep. 5, 2006, and U.S. Patent Application 20050109287 filed May 26, 2005 to Frasure, et al discloses a high efficiency tank type continuous flow and self cleaning water heater, having a flue pipe extending vertically through the tank, a cylinder disposed within the flue pipe, a burner disposed in a lower region of the cylinder, and a water conducing coil disposed within the cylinder connected with the interior of the tank. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a high efficiency, tank type, fuel-fired water heater. 
   It has been found a water heater having high efficiency can be provided by using a cone shaped tank and having combustion products contact the outer surfaces as they rise upwardly and outwardly along the tank surfaces. 
   The present invention provides a water heater comprising a generally cone shaped tank operatively oriented with a smaller cross-section disposed at a lower end thereof, and having a water inlet for connection with a water supply, and an outlet for heated water; an enclosure surrounding and spaced from the tank defining a passageway for flue gases between an inner surface of the enclosure and an outer surface of the tank, said enclosure having an outlet for flue gases; a burner communicating with the interior of said enclosure and means for providing combustion air to said burner. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic sectional view of one embodiment of a water heater in accordance with the present invention. 
       FIG. 2  is a schematic sectional view of another embodiment of the invention, having a central conduit for combustion air. 
       FIG. 3  is a schematic sectional view of another embodiment of the invention. 
       FIG. 4  is a schematic sectional view of another embodiment of the invention having a central conduit for flue gases. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIG. 1 , the water heater of the present invention comprises a cone shaped tank  100  having a water inlet  210  for connection with a water supply, and a hot water outlet  215  connected to the tank interior. Surrounding and spaced from the tank  100  is an enclosure  106 . The outer surface  104  of tank  100  and the inner surface  105  of enclosure  106  define the inner and outer wall, respectively, of flue passageway  306 . 
   In the embodiment of  FIG. 1 , a flue pipe  305  extends vertically through the center of the tank  100  and exits at the bottom of the tank  100 . A down draft burner  220  is located at the top of the central flue  305 . Utilizing fan  935 , hot gases flow down the vertical flue  305 , around the outside of tank  100  through flue passageway  306  to the outlet/vent  110  located above the tank. 
   Since flue gas contacts the tank  100  both with downward flow, via the central conduit  305 , and also upon upward flow via the passageway  306 , high heat transfer to the tank with resulting high efficiency of the water heater is obtained. 
   Attached to the outside of the tank surface  104  are baffle means  308  for directing flue gas flow arranged to increase heat transfer to the tank. The baffle means  308  may be in the form of a plurality of discrete elements or in the form of a continuous spiral, as will be described in more detail below. 
   The central flue  305  will preferably also have baffle means designed to increase heat transfer. This baffle may be coated with a heat reflective material. 
   A deflector  315  is shown located below the bottom of flue  305  directing hot flue gases toward the flue passageway  306  to contact the baffle means  308  and tank  100  as the hot flue gases proceed to the outlet  110 . The deflector  315  can be supported by suitable means in the lower area of the water heater, and may be coated with a heat reflective material. 
   The flue gas venting conduit and the conduit for receiving incoming combustion air may be arranged to exchange heat and may utilize a secondary fan. 
     FIG. 1  shows a plurality of baffle elements  308  attached to the exterior surface of the tank  100 , attached for example, by welding. The baffle elements  308  are arranged to form a spiral around the tank with the desired pitch based upon the position, angle and dimension of the baffle elements  308 , which increases the amount of hot gases coming in contact with tank surface  100  through conduction of heat through the baffle elements  308 . The baffle elements  308  cause the flue gases to flow in a spiral around tank  100  to the top of the tank. 
   The baffle elements  308  will preferably be angled downward, directing the hot gases toward the surface of tank  100 . Also, the baffle elements  308  will preferably be angled to direct flow to an adjacent element in an upward spiral. 
   The baffle means  308  can be attached to tank surface  100  by welding, or other suitable means. 
   The number and dimensions of the baffle elements  308  will be determined based on the appropriate number necessary to most effectively extract the maximum heat from the hot gases, and on the specific application, the desired flow pattern, water heater size, and flue gas volumes. The size of baffle elements  308  can vary, but would typically be 1 to 6 inches long and 1 to 6 inches wide depending on the particular water heater size or design and extend out into the flow of hot gases. The baffle elements  308  would extend to within typically 0.5 to 1 inch of the outer flue wall  106  but the distance would vary depending on the size and application of the water heater. The location and arrangement of baffle elements  308  may be varied, and may be limited to specific areas of the tank. 
   The baffle elements  308  may be provided with a crease, or bent at an angle for rigidity and to provide desired heat flow control. 
   In another embodiment of the baffle elements  308 , the edge that extends from the tank surface toward the outside flue wall would contain a downwardly pointing lip/protrusion running the entire length of the side of the baffle means. The lip/protrusion would prevent the heat flow from backing up and exiting the under side of the baffle element in the wrong direction. The opposite side of the baffle element would contain a lip of the same length, but it would not extend as far. 
   Condensation forming on the baffle elements  308  would drip from the baffle means  308  onto the outer flue wall  106  and collect in the area of drain  125  located at the bottom of the water heater  107 . The bottom of the water heater  107  would contain a drain  125  leading to a building drain. The drain  125  would contain a check valve  130  which would allow water to exit to a drain, but prevent combustible gases from entering the drain tube/pipe or combustion area of the water heater. The bottom of the tank  100  would contain a drain pipe  295 . The drain pipe would contain an appropriate shut of valve. 
   In another embodiment, the baffle means  308  may be in the form of a raceway arranged in a continuous spiral around the tank  100 . The raceway is preferably angled downward for increasing the contact of flue gas with the tank while flowing upward around the outside of the tank. The bottom side of the raceway and the tank surface will preferably be provided with protrusions to slow the flow rate of the hot gases allowing for enhanced heat transfer to the tank  100  surface. 
   In another embodiment, the flue utilizes a water conducing coil in the flue  305  or in the exit vent pipe  110 . Baffle means may be utilized to increase the amount of hot gases coming in contact with the flue wall and or the water conducing coil. 
   In the embodiment shown in  FIG. 2 , the incoming air passes through a heat exchanger  920  which would be located in the flue  110  above tank  100 , through the vertical flue  305  up flue  306  and past or through heat exchanger  920  to the exit air vent  110 . A fan  935  may be used at the inlet or outlet to facilitate flow. Baffle means  308  would be attached to the outside surface of tank  100  as described in  FIG. 1 . The incoming air would have the option of being piped in from outside and entering the combustion chamber from the bottom of the water heater. The condensation would drain through the drain  125  located in the bottom of the water heater. The drain  125  would contain an optional check valve  130  to prevent combustible gases from entering. 
   The bottom of the tank would contain a drain pipe  295 . The drain pipe would contain an appropriate shut of valve 
   In the embodiment shown in  FIG. 3 , the incoming air enters the combustion chamber of the water heater in the area below the burner located at the bottom of or lower area of the tank. The burner  820  would preferably be a ring burner. The hot gases flow from the burner up through baffle elements located in flue  306  as described in  FIG. 1  and the air flow then proceeds to the exit air vent  110 . 
   A lip  130  is shown located around the inside of the lower section of the wall of the water heater to catch condensation and direct it to a drain  132  attached to the lip. The drain would contain an optional check valve to prevent combustible gases from entering the combustion area. The lowest point of the tank would contain a drain pipe  295  leading to a drain. The drain pipe  295  would contain an appropriate shut of valve. 
   In the embodiment shown in  FIG. 4 , the incoming air enters in the bottom area of the water heater below the burners. The hot gases then proceed up flues  306  and  305  and exit through exit vent  110 . Flue  305  would contain baffle means and or water conducing coil. The burner could be a ring burner or one of various types of burners. Condensate from flue  305  is collected at drain  125 . 
   It will be understood that features described in one of the embodiments described herein may be utilized in another embodiment. Following are additional features which may be utilized. 
   All embodiments may include a heat exchanger that transfers heat from the outlet vent to incoming air. This can achieved by having the outlet vent pass through the air inlet conduit. Heat transfer fins could be added to the outside of the outer wall of flue  106  and extend to the outside of the water heater skin to allow the heat to be utilized to heat the room it is located in. 
   All embodiments can include a raceway leading to drain  295  at bottom of the tank  100  to reduce scale build up as described in patent applicant&#39;s U.S. Pat. No. 6,508,208. There are a number of methods currently used to remove sediment from water heater tanks that can be utilized. Also, various methods can be utilized to drain condensation from the bottom of the water heater. Also suitable means can be employed to prevent an explosion from occurring due to a combustible gas entering the combustion chamber from outside the water heater 
   In all embodiments, the baffle element can be in the in form of a stud, preferably a rectangular stud. 
   Any of the embodiments herein may utilize features presently used in water heaters, such as: sensors, controls and pressure relief valves to control the temperature and prevent overheating and explosion, an anode rod  250 , condensate traps, the use of corrosion resistant materials, a water conducting coil in the flue or vent pipe, etc. 
   The burner of the embodiments herein may operate on oil, natural gas, propane or other fuel.