Patent Publication Number: US-2010107993-A1

Title: Energy efficient induced air gas water heater

Description:
TECHNICAL FIELD 
     This disclosure relates to energy efficient induced air gas water heaters. More particularly, the disclosure relates to an energy efficient damper installed on the outlet of a blower or at the top of a flue. 
     BACKGROUND 
     In water heaters that include blowers, such as induced air gas water heaters, residual heat and gases escape through the outlet of the blower when the water heater is in standby mode. Exhausting combustion gases is necessary when the burner and the blower are operating. However, when the blower is not operating and the water heater is in standby mode, the release of residual heat from the water heater is inefficient as hot air from the water heater storage tank is lost. 
     Thus, a device that allows the release of combustion gases during operation, but preventing the loss of residual heat during standby mode could be helpful. 
     SUMMARY 
     I provide an energy efficient induced air gas water heater that includes a water tank; a flue associated with the water tank; a burner that combusts fuel that creates combustion products that pass through the flue; a blower that receives the combustion products from an outlet of the flue; a damper that movably covers and uncovers the flue outlet or an outlet of the blower. The damper may be in an open position when the burner and/or the blower are operating uncovered and may be in a closed position when the burner and/or the blower are not operating. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic front view, taken in section, illustrating details of an exemplary water heater. 
         FIG. 2  is a schematic front view, taken in section, illustrating details of another exemplary water heater. 
         FIG. 3  is a top plan view of an exemplary damper that may be utilized with water heaters of the type shown in  FIGS. 1 and 2 . 
         FIG. 4  is a side view of the damper shown in  FIG. 3  with the movable disc shown oriented in multiple positions. 
         FIG. 5  is a schematic top plan view of another exemplary damper. 
         FIG. 6  is a schematic side view of the damper of  FIG. 5  in a closed position. 
         FIG. 7  is a schematic side view of the damper shown in  FIG. 5  in an open position. 
         FIG. 8  is a schematic top plan view of yet another exemplary damper. 
     
    
    
     DETAILED DESCRIPTION 
     It will be appreciated that the following description is intended to refer to specific examples of structure selected for illustration in the drawings and is not intended to define or limit the disclosure, other than in the appended claims. 
     This disclosure relates to a water heater, such as an induced air gas water heater, to allow for the release of combustion gases from a flue when a blower and burner are running and to prevent the loss of residual heat from a heated water tank when the blower and burner are not operating, i.e., in standby mode. 
     With reference to  FIGS. 1 and 2 , exemplary water heaters  100  are illustrated. Water heater  100  includes jacket  104  which surrounds a water tank  106 , a main burner  114  in a combustion chamber  115 . Passing through the center of the tank  106  is a substantially vertically oriented flue  110 , which may incorporate a series of baffles (not shown) to better transfer heat generated by the main burner  114  to water in water tank  106 . Water tank  106  is preferably of mains pressure capability and capable of holding heated water. Water tank  106  is preferably insulated by foam insulation  108 . Alternative insulation may include fiberglass or other types of fibrous insulation and the like. Fiberglass insulation  109  surrounds combustion chamber  115  and the lowermost portion of water tank  106 . It is possible that heat resistant foam insulation can be used if desired. A foam dam  107  or other means separates foam insulation  108  and fiberglass insulation  109 . 
     Located underneath the water tank  106  is the main burner  114  which uses natural gas or other gases, such as LPG, for example. Other suitable fuels may be substituted. Main burner  114  combusts a gas and air mixture and the hot products of combustion resulting rise up through flue  110 , possibly with heated air. 
     The products of combustion pass upwardly and out the top of jacket  104  via flue outlet  116  after heat has been transferred from the products of combustion. The flue outlet  116  discharges into a blower/air inducer  120 . Blower  120  includes a fan  122  that induces combustion products upwardly through flue  110  and into the housing of blower  120 . Those hot combustion products are mixed with ambient air that is introduced into blower  120  through inlet  135 . Mixture of those two components reduces the temperature of the combustion products and allows that mixture to be discharged from outlet  125  at a temperature that is low enough to be compatible with materials that are not resistant to very high temperatures such as PVC pipe, as one example. This allows for the increased flexibility of installing water heater  100 . 
     With reference to  FIGS. 1 and 2 , an exemplary damper  200  is illustrated. The damper  200  is sized and shaped to securely cover the blower outlet  125  as shown in  FIG. 1 . Alternatively, the damper  200  is sized and shaped to securely cover the flue outlet  116  as shown in  FIG. 2 . 
     The damper  200  has an open position and a closed position. In an open position, combustion products, such as gases and heat, exit from the water heater  100  via the flue  110 . The damper  200  is in the open position when the burner  114  and the blower  120  are operating and combustion products are being produced to heat water in the storage tank  106 . In a closed position, heat is prevented from leaving the water heater  100  as the damper  200  closes either the blower outlet  125  ( FIG. 1 ) or the flue outlet  116  ( FIG. 2 ). The damper  200  is in the closed position when the burner  114  and the blower  120  are not operating and loss of the heat from the storage tank  106  is undesirable. 
       FIGS. 3 and 4  show a representative or exemplary damper  300  which may be used as one construction of a damper  200  as shown in  FIGS. 1 and 2 . The damper  300  includes a frame  310 , a substantially flat and round disc or plate  320 , and a pivot member or pin  330 . Frame  310  is attached to the outlet  125  of blower  120  or the outlet  16  of flue  110 . This connection may be made by any means depending on the material of the frame  310 . For example, if  310  is a metal such as the same type of metal as flue  110 , frame  310  may be spot welded or fixed to the outlet  116  by any other known methods of fixing materials together. 
     The frame  310  can be located entirely within outlet  116  or can also be connected to outlet  116  at bevelled side portions  340  that can be sized and shaped to match complementary sizes and shapes of outlet  116  to facilitate an easy connection between the two devices. 
     Moveable disc  320  connects to pivot member  330  and is moveable between a closed, substantially horizontal position and a substantially vertical open position as shown by the range of motion indicated by arrow A in  FIG. 4 . It is preferred to size disc  320  to have an outer diameter that is slightly smaller than the inner diameter of frame  310  as shown by the gap indicated at arrow B in  FIG. 4 . This allows for expansion and contraction of the various structures such as frame  310  and disc  320  depending on the heating and cooling conditions and allows for complete freedom of movement along the range indicated by arrow A of  FIG. 4 . Moveable disc  320  should also be manufactured from a heat resistant material such as metal. While frame  310  and disc  320  are depicted as round, other shapes may be used as appropriate. 
     With reference to  FIGS. 5-7 , another exemplary damper  400  is illustrated. Damper  400  is sized and shaped to securely cover the blower outlet  125  or the flue outlet  116 . Similar to the exemplary damper  300 , damper  400  has an open position in which combustion products exit the water heater  100  and a closed position when the water heater is in standby mode. 
     The damper  400  includes a frame  410 , multiple flaps  420  and a support frame  430 . Damper  400  has a substantially circular frame  410  that is fixed to the substantially circular outlet  116  or  125 . Four flaps  320  connect to the frame  410  and are made from a flexible, but heat resistant material such as santoprene, for example. The flexible flaps  420  are maintained in a closed position by support frame  430  which is essentially comprises support members that form a “cross” or “X” and connect interiorly of frame  410 . The support frame  430  allows the four flaps to lie in a closed position when the water heater is in standby mode. This is particularly well shown in  FIG. 6 . 
       FIG. 7  shows flaps  420  having been displaced into a more vertical position by the induction of air and the passage of combustion products from outlet  125  or outlet  116 . Support frame  430  remains in a constant position whether the water heater is operating or in standby mode. 
       FIG. 8  shows a top plan view of another damper  500  which is similar to damper  400  of  FIG. 5 . However, instead of four flaps  420 , damper  500  has six flaps  520  and a corresponding support frame  530  that accommodates the two additional flaps. Damper  500  operates substantially in the same manner as damper  400 . Alternate numbers of flaps may be utilized as desired. 
     Water heater  100  may be in an operating condition or in a standby mode. When the temperature of water in water tank  106  falls below a preselected temperature level, a controller  130  activates blower  120  to induce the flow of air through  110  by way of combustion chamber  115  which typically has an access opening to draw ambient air into combustion chamber  115 . Then, upon receiving a signal that air is successfully moving through water heater  100 , controller  130  activates burner  114 . Burner  114  produces combustion products that pass upwardly through flue  110  and outwardly of flue  110  to outlet  116 . Those combustion gases mix with ambient inlet air passing through inlet opening  135  which then combine with the combustion products and exit through blower outlet  125 . 
     When the temperature of water within tank  106  again reaches approximately the preselected temperature, the controller terminates operation of burner  114  and typically shortly thereafter terminates operation of blower  120 . 
     During standby mode when burner  114  is not operating, there is no induction of combustion products and air through flue  110 . However, due to the “open” nature of water heater  100  wherein ambient air may enter combustion  115  and there would ordinarily be an opening at the top  104  of water heater  100 , such ambient air would tend to enter combustion chamber  115 , pass through flue  110  and exit outwardly at outlet  116  and outlet  125 . This creates a passage of cooling air that reduces the efficiency of the water heater by as much as 7 percent. This is undesirable. 
     As shown in  FIG. 1 , placing a damper such as damper  200  at outlet  125  prevents this natural flow of ambient air into water heater  100  that would otherwise pass cooling air through flue  110  and reduce energy efficiency. The presence of damper  200  substantially prevents this free-flow of cooling air, retains the heat within tank  110 , thereby increasing energy efficiency by as much as 7 percent as shown in the Example and Comparative Example below. 
     Tank Capacity, Measured/Rated: 47.8/50.00 
     EXAMPLE 
       
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Summary 
                 Measured 
                 Minimum Gama Listing 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Recovery Efficiency 
                 0.89 
                   
               
               
                   
                 Energy Factor 
                 0.700 
                 0.58 
               
               
                   
                 First Hour Supply 
                 0.00 
               
               
                   
                   
               
            
           
         
       
     
     Simulated Use Test 
       
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 Correction Factor/Heating Value (Gas only) 
                 0.9489/1,044.68 
               
               
                 Total gallons drawn during test 
                 64.43 
               
               
                 Gallons drawn during first cycle 
                 10.73 
               
               
                 Outlet minus inlet water temperature for first cycle, 
                 83.68 
               
               
                 Fahrenheit 
               
               
                 Average of outlet minus inlet water temperature 
                 82.70 
               
               
                 during all draws, Fahrenheit 
               
               
                 Total energy used during 24 hour simulated use 
                 62,274.73 
               
               
                 test, Btu 
               
               
                 Energy consumed during recovery test (first cycle), 
                 8,702.36 
               
               
                 Btu 
               
               
                 Energy consumed after draw/recovery period, Btu 
                 3,443.40 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Initial 
                 First Cycle 
                 After recovery 
                 Final 
               
               
                   
               
               
                 Mean tank 
                 136.08 
                 136.84 
                 136.61 
                 129.50 
               
               
                 temperatures, 
               
               
                 Fahrenheit 
               
               
                   
               
            
           
           
               
               
            
               
                 Time from last draw/recovery Tmax to 24 hours, 
                 18.50 
               
               
                 hours 
               
               
                 Total standby time, hours 
                 23.69 
               
               
                 Average ambient temperature during all standby, 
                 68.40 
               
               
                 Fahrenheit 
               
               
                 Average mean tank temperature during all standby, 
                 132.00 
               
               
                 Fahrenheit 
               
               
                 Average ambient temperature from last draw/ 
                 68.33 
               
               
                 recovery Tmax to 24 hours, Fahrenheit 
               
               
                 Average mean tank temperature from last draw/ 
                 133.23 
               
               
                 recovery Tmax to 24 hours, Fahrenheit 
               
               
                   
               
            
           
         
       
     
     First Hour Draw Test 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Average outlet temperature, Fahrenheit 
                 0 
               
               
                   
                 Average inlet temperature, Fahrenheit 
                 0 
               
               
                   
                 Water drawn during test, gallons 
                 0 
               
               
                   
                 Total elapsed time of test, minutes 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     Calculated Values 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Hourly standby losses, Btu/hour 
                 334.12 
               
               
                   
                 Standby heat loss coefficient, Btu/hour-Fahrenheit 
                 5.15 
               
               
                   
                 Daily water heating energy consumption, Btu/day 
                 62,182.75 
               
               
                   
                 Adjusted daily water heating energy consumption, 
                 62,657.71 
               
               
                   
                 Btu/day 
               
               
                   
                 QHW - Energy used to heat water, Btu/day 
                 49,837.82 
               
               
                   
                 QHW77 - Energy used to heat water over 77 
                 46,293.85 
               
               
                   
                 degrees Fahrenheit rise, Btu/day 
               
               
                   
                 Modified daily water heating energy consumption, 
                 59,113.73 
               
               
                   
                 Btu/day 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Delivery: 
                 Inlet: 
               
               
                   
                   
               
               
                   
                 Average temperatures, Fahrenheit 
                 140.63 
                 57.93 
               
               
                   
                   
               
            
           
         
       
     
     Tank Capacity, Measured/Rated: 47.8/50.00 
     COMPARATIVE EXAMPLE 
       
     
       
         
           
               
               
               
               
             
               
                   
                   
               
               
                   
                 Summary 
                 Measured 
                 Minimum Gama Listing 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 Recovery Efficiency 
                 0.87 
                   
               
               
                   
                 Energy Factor 
                 0.657 
                 0.58 
               
               
                   
                 First Hour Supply 
                 0.00 
               
               
                   
                   
               
            
           
         
       
     
     Simulated Use Test 
       
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 Correction Factor/Heating Value (Gas only) 
                 0.9415/1,043.68 
               
               
                 Total gallons drawn during test 
                 64.54 
               
               
                 Gallons drawn during first cycle 
                 10.75 
               
               
                 Outlet minus inlet water temperature for first cycle, 
                 82.48 
               
               
                 Fahrenheit 
               
               
                 Average of outlet minus inlet water temperature 
                 85.90 
               
               
                 during all draws, Fahrenheit 
               
               
                 Total energy used during 24 hour simulated use 
                 72,946.09 
               
               
                 test, Btu 
               
               
                 Energy consumed during recovery test (first cycle), 
                 9,809.46 
               
               
                 Btu 
               
               
                 Energy consumed after draw/recovery period, Btu 
                 8,112.64 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Initial 
                 First Cycle 
                 After recovery 
                 Final 
               
               
                   
               
               
                 Mean tank 
                 137.86 
                 140.70 
                 142.17 
                 139.95 
               
               
                 temperatures, 
               
               
                 Fahrenheit 
               
               
                   
               
            
           
           
               
               
            
               
                 Time from last draw/recovery Tmax to 24 hours, 
                 18.50 
               
               
                 hours 
               
               
                 Total standby time, hours 
                 23.64 
               
               
                 Average ambient temperature during all standby, 
                 68.54 
               
               
                 Fahrenheit 
               
               
                 Average mean tank temperature during all standby, 
                 137.01 
               
               
                 Fahrenheit 
               
               
                 Average ambient temperature from last draw/ 
                 68.40 
               
               
                 recovery Tmax to 24 hours, Fahrenheit 
               
               
                 Average mean tank temperature from last draw/ 
                 139.46 
               
               
                 recovery Tmax to 24 hours, Fahrenheit 
               
               
                   
               
            
           
         
       
     
     First Hour Draw Test 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Average outlet temperature, Fahrenheit 
                 0 
               
               
                   
                 Average inlet temperature, Fahrenheit 
                 0 
               
               
                   
                 Water drawn during test, gallons 
                 0 
               
               
                   
                 Total elapsed time of test, minutes 
                 0 
               
               
                   
                   
               
            
           
         
       
     
     Calculated Values 
       
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Hourly standby losses, Btu/hour 
                 471.72 
               
               
                   
                 Standby heat loss coefficient, Btu/hour-Fahrenheit 
                 6.64 
               
               
                   
                 Daily water heating energy consumption, Btu/day 
                 68,666.85 
               
               
                   
                 Adjusted daily water heating energy consumption, 
                 68,514.03 
               
               
                   
                 Btu/day 
               
               
                   
                 QHW - Energy used to heat water, Btu/day 
                 53,271.01 
               
               
                   
                 QHW77 - Energy used to heat water over 77 
                 47,649.68 
               
               
                   
                 degrees Fahrenheit rise, Btu/day 
               
               
                   
                 Modified daily water heating energy consumption, 
                 62,892.70 
               
               
                   
                 Btu/day 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                   
                   
                 Delivery: 
                 Inlet: 
               
               
                   
                   
               
               
                   
                 Average temperatures, Fahrenheit 
                 144.43 
                 58.53 
               
               
                   
                   
               
            
           
         
       
     
     On the other hand, when burner  114  is operating and combustion products are generated, such combustion products must be efficiently removed from the system. Therefore, the damper  200  provides a simple and efficient manner of allowing those combustion products to be removed, but still maintain the closed system when burner  114  is not operating. 
     Although specific structures and steps have been shown and described herein for purposes of illustration and exemplification, it is understood by those of ordinary skill in the art that the specific structures and steps shown and described may be substituted for a wide variety of alternative and/or equivalent implementations without departing from the scope of the appended claims. This disclosure is intended to cover any adaptations or variations of the structures and steps discussed herein.