Abstract:
Apparatus for improving the efficiency of a water heater includes a combination damper assembly and heat transfer baffle. The damper assembly includes a plurality of movable damper with each damper leaning outwardly from one another when the dampers are in a closed position. The baffle depends from the damper assembly and includes a truncated conical shape in this position within the flue of a water heater for directing combustion gases from the burner against a flue wall.

Description:
The present application is a continuation-in-part of U.S. Ser. No. 10/956,921 filed Oct. 2, 2004 now U.S. Pat. No. 7,000,572 and said application is incorporated herewith in its entirety herewith. 

   The present invention generally relates to apparatus for gas burning and/or oil burning water heaters and is more particularly adapted to apparatus for improving the efficiency of a gas burning and/or oil burning water heater, hereinafter commonly referred to as a gas water heater. 
   Typical fuel-burning water heaters include the combustion chamber disposed in a base of a water tank with a flue disposed within the tank for evacuation of the burner combustion gases therethrough and concomitant heating of water in the tank. The combustion gases exiting the water heater fluid typically pass through an exhaust flue for proper venting. 
   U.S. Pat. No. 5,682,842 to Schimmeyer describes a segmented heat deflector including cylindrical sections for enhancing heat transfer from the combustion gases through a flue wall and into surrounding water. This reference is to be incorporated herein in its entirety by this specific reference thereto in order to describe the benefits of the heat deflector and incorporate all the data presented therein. 
   The present invention provides apparatus for the enhancement of heat transfer from the combustion gases to the water and hot water heater through a flue with unexpected efficiencies due to a conically shaped baffle in combination with a damper. 
   A water heater damper is important in that energy losses through an exhaust flue can be significant; it is estimated that approximately 33% of the heat energy generated from the main burner and pilot light operation is lost directly up the flue. 
   In addition, an unrestricted duct allows cool room air to circulate freely through the hot water heater and its central core, thereby cooling the heated water and requiring the main burner to operate more frequently than would otherwise be necessary. 
   Thus, it is clearly desirable, for efficiency and cost considerations, to regulate the flow of gasses both in and out of a gas-fired hot water heater. 
   Numerous damping devices have been developed for use with boilers, furnaces, and other combustion gas-producing systems. Many are simply one-way mechanical valves that prevent outside air from coming down the exhaust duct. 
   While effective for that purpose, such devices often require significant exhaust flow in order to open, and thus are useable only with relatively large units, or those equipped with a fan or blower. 
   Some large commercial water heaters may include power-assisted or computer-controlled mechanical dampers. Unfortunately, such systems are too costly and cumbersome for widespread domestic use 
   Useful and effective heat conserving systems for relatively small scale water heaters, for example domestic water heaters, have been described in U.S. Pat. No. 4,770,160, U.S. Pat. No. 5,239,947, U.S. Pat. No. 5,682,841, U.S. Pat. No. 5,732,692, and U.S. Pat. No. 5,845,632 to Schimmeyer, each of which is incorporated herein by this specific reference thereto. 
   For example, U.S. Pat. No. 4,770,160 discloses a vent damper which is incorporated into an exhaust flue above a water heater. The damper comprises a lightweight, frustro-conical shaped floating poppet what is slidably mounted on a guide within a flue hood immediately above the heater. 
   When the heater burner is in operation, the hot exhaust gases lift the poppet allowing gas to escape around the poppet and into the flue. When the main burner is turned off, the poppet is lowered into a closed position where it rests atop the tank central passageway. 
   Unfortunately, while this system is effective in restricting the circulation of cool room air through the water heater, the long-term operation thereof may result in impaired movement of the poppet due to condensation and debris accumulating between the poppet and the central guide, thus inhibiting the free movement of the poppet along the guide. 
   Additionally because of the fragile, lightweight nature of the poppet, damage may occur thereto by handling of the device during installation, cleaning or maintenance thereof. 
   Although the floating poppet closure provides a substantial improvement over the prior art, the shape of the poppet tends to interrupt the vertical flow of exhaust gases, and deflects the flow away from a vertical direction. It can be appreciated that it is desirable to have a vent damper apparatus that directs a flow of exhaust gasses substantially vertically rather than deflecting the gasses, thus ensuring the hot gasses are passed into the exhaust port and not into a surrounding space. 
   U.S. Pat. No. 5,732,692 discloses a more complicated vent damper system that incorporates a floatable damper with an exhaust flue hood disposed above a water heater tank. A lightweight floating damper is movable along a faceted guide. This design tends to reduce the occurrence of condensation which could impede free movement of the damper. 
   Although these systems are effective, there remains a need for an efficient combination water heater damper/baffle. 
   SUMMARY OF THE INVENTION 
   Apparatus for proving the efficiency of a water heater having a tank, a burner, and a flue being disposed within the tank for evacuation of burnt combustion gases therethrough generally includes a base and a damper assembly. 
   The damper assembly extends from the base and limits flow of ambient air from the flue. 
   More specifically, the damper assembly includes a plurality of moveable dampers with each damper leaning outwardly from one another when the dampers are in a closed position. A frame is provided for supporting the dampers and enabling pivoting of the dampers from the closed position preventing ambient air flow therepast to an open position allowing passage of exhaust gases therepast. The dampers are generally disposed parallel to the exhaust gas flow in the open position. 
   An enhancing heat transfer baffle is provided and depends from the base with the baffle having a truncated conical shape and position within the flue for directing combustion gases from the burner against a flue wall. 
   More particularly, the damper assembly frame includes a lower cylindrical portion for fitting a water heater flue and an upper cylindrical portion with angulated sidewalls for supporting the dampers in the closed position. Preferably, the upper and lower portions are formed from a thermal ceramic and a metal liner may be disposed on an inside surface of the upper cylindrical portion. 
   Still more particularly, the damper assembly frame may include a pair of parallel pivot bars with each damper having an open ended angular bottom for pivotally engaging a respective pivot bar. 
   The frame further may include an upstanding center post for supporting a transverse arm extending through openings in each of the dampers to prevent upward movement of the dampers along the longitudinal axis of the apparatus. 
   More specifically, the upper cylindrical portion may include angulated sidewalls for supporting the dampers in a closed position. In that regard, each of the dampers may include edge retaining upstanding rims for enabling and insuring flush abutting contact with the angulated sidewalls. 
   Still more particularly, the baffle in accordance with the present invention may include a tapered tube and may be segmented with each segment being a tapered tube with adjacent tapered tubes having substantially equal diameters. 
   In an exemplary embodiment, the baffle includes three segments wherein the top segment and a middle have closed tops and wherein a bottom segment includes a divider disposed at a top of the bottom segment with the divider having an opening therein. All of this structure promotes heat transfer enhancing contact between the combustion gases and the water tank flue. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages and features of the present invention would be better understood by the following description when considered in conjunction with the accompanying drawings in which: 
       FIG. 1  is a plan view, partially broken away, of the present invention generally showing a hot water tank with a flue therethrough heated by a burner in combination with a damper assembly interconnected with a baffle for enhancing heat transfer through a flue wall; 
       FIG. 2  is an enlarged plan view of the baffle shown in  FIG. 1  positioned within the flue by tabs and including three segments of conically shaped tubes; 
       FIG. 3  is an enlarged perspective view of the damper shown in  FIG. 1  generally showing a plurality of movable dampers with each damper leaning outwardly from one another when the dampers are in a closed position along with a frame for supporting the dampers and enabling pivoting of the dampers from the closed position as shown; and 
       FIG. 4  is a cross sectional view of the damper assembly shown in  FIG. 3  along with a base interconnecting the vent damper with the baffle and illustrating an open position of the dampers for exhaust of flue gases. 
   

   DETAILED DESCRIPTION 
   With reference to  FIG. 1 , there is shown a hot water heater apparatus  10  in accordance with the present invention which generally includes a tank  12 , a burner  14 , disposed at a bottom portion  16  of the tank along with a flue  18 , which provides a means for evacuation of burner gases therethrough to a vent damper  24  and thereafter to an exhaust flue  26 . 
   It should be appreciated that the tank  12 , burner  14 , and flue  18  of the apparatus  10  may be of any conventional suitable design. 
   As shown in  FIGS. 1 and 2 , a baffle  30  is provided for enhancing heat transfer from combustion gases through a flue  32  and into surrounding water  36 , as indicated by the arrows  40  in  FIG. 1 . 
   While the baffle  30  may be formed from a single piece of tubular material with a generally truncated conical shape for retrofit applications, the baffle in accordance with the present invention may generally include a top segment  44 , a middle segment  46 , and a bottom segment  48 , as more clearly shown in  FIG. 2 . Preferably, the flue segments  44 ,  46 ,  48  are formed from polished stainless steel material in order to further reflect the heat into the flue wall  32 . 
   With a clearance A between a ceiling  52  and a tank top  54 , the segments  44 ,  46 ,  48  should preferably have a length each of less than about 15 inches. For a typical flue diameter B of about 4 inches, the top segment  44  has a maximum diameter C of about 2¼ inches and the bottom segment  48  has a minimum dimension D of about 1½ inches. 
   As shown in  FIG. 2 , it should be appreciated that adjacent tapered segments, or tubes,  44 ,  46  and  46 ,  48  have substantially equal diameters junctions  58 ,  60 . 
   In order to effect proper heat deflection into the flue wall  32  while at the same time properly heating the baffle  32  to promote such heat transfer, the lower, or bottom, segment  42  includes a pan  62  disposed at a bottom  64  of the segment  48  with the pan  62  including an opening  66 . 
   In addition, the middle segment  46  may include a pan, or closure,  68  disposed at a bottom  70  thereof and the top segment  44  includes a pan, or closure,  72  at a bottom  74  thereof, with the pans  68 ,  72  having holes  76 ,  78  therein. The top segment may include a cap  80 . In order to center the baffle  30  within the flue  18 , tabs  82 ,  84  disposed at 120° intervals around a centerline  86  on the bottom segment  48  and top segment  44  respectively, only two being shown in  FIG. 2 . 
   While similar in structure to the baffle shown in U.S. Pat. No. 5,787,846, the conical shape of the baffle  30  produces remarkable and unexpected efficiency when compared to the segmented cylindrical baffle described in U.S. Pat. No. 5,787,846, as hereinafter set forth in the hereinafter example. 
   EXAMPLE 
   In a 40 gallon gas fired water heater  10  with the baffle described in U.S. Pat. No. 5,682,841, the control setting was moved from a vacation setting to a normal hot water temperature after withdrawal of 5 gallons of hot water. The recovery time for the heater  10  to bring the water temperature to the set temperature was 5 minutes. 
   In a comparative test, the baffle described by U.S. Pat. No. 5,682,841 was removed in a baffle in accordance with the present invention installed into the water heater and the heater moved from a vacation to the same set temperature. The recovery time was 3 minutes and 30 seconds. This is about a 30% reduction in time or savings of 23% of gas usage, which is certainly unexpected in view of the shape difference between the two baffles. 
   With reference to  FIGS. 3 and 4 , there is shown an enlarged view of the damper  24  in accordance with the present invention. A base  100  is provided and a damper assembly  102  extends from the base  100  for limiting full of ambient air from the flue  32 . 
   A damper assembly  102  generally includes a frame  102  extending outwardly from the base  100  and affixed thereto by a suitable binder. Alternatively the base  100  and frame  102  may be formed from the single piece of material, preferably from the thermal ceramic such as, for example, Kaowool TBM®, this thermal insulating material improves efficiency on the damper by limiting heat loss by radiation from the damper assembly  102 . 
   With particular reference to  FIG. 4 , the frame  102  includes a lower cylindrical portion  106  fitting the water heater flue  32  in an upper cylindrical portion  108  with angulated sidewalls  112 ,  114  for supporting dampers  118 ,  120  which lean outward from one another in a closed position, as shown in  FIGS. 3  and solid line in  FIG. 4 . A metal lining  124  may be provided for facilitating assembly of the damper  24 . 
   Fixed to the liner  124 , preferably by welding, is a cross channel  126  which includes an upstanding post  128  which supports transverse arms  130 ,  132  extending through openings  136 ,  138  and the dampers  118 ,  120  in order to prevent upward movement of the dampers along a longitudinal axis  142 . 
   The post  128  may be fixed to the cross channel by any conventional means such as, for example, a nut  144 . A cross by in turn includes a pair of upstanding pivot bars  148 ,  150  and each damper  118 ,  120  includes open angulated bottoms  154 ,  156  for pivotally engaging a respective pivot bar  148 ,  150 . 
   This pivotal arrangement enables pivoting of the dampers  118 ,  120  from the closed position shown in  FIGS. 3 and 4  to an open position shown in dashed line in  FIG. 4  to all passage of exhaust gases therepast, as indicated by the arrows  160 ,  162 . 
   In the open position the dampers  118 ,  120  are in a generally parallel configuration while in a closed position the dampers  118 ,  120  lean outwardly from one another, as shown. 
   The dampers  118 ,  120  preferably made from a light weight material, such as aluminum or the like suitable in thickness and weight for being open by the flue gases  160 ,  162  to insure a secure abutting relationship between the dampers  118 ,  120  and sidewalls  112 ,  118 , the dampers  118 ,  120  may include entertaining upstanding rims  170 , which may be formed by bending of the damper edges  176 ,  178  or otherwise attached. 
   Although there has been hereinabove described a specific gas water heater damper in accordance with the present invention for the purpose of illustrating the manner in which the invention may be used to advantage, it should be appreciated that the invention is not limited thereto. That is, the present invention may suitably comprise, consist of, or consist essentially of the recited elements. Further, the invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Accordingly, any and all modifications, variations or equivalent arrangements which may occur to those skilled in the art, should be considered to be within the scope of the present invention as defined in the appended claims.