Patent Publication Number: US-2017350620-A1

Title: Secondary flue restrainer for condensing water heater

Description:
FIELD OF INVENTION 
     The present invention relates to condensing water heaters and more specifically to a secondary flue restrainer for restraining the secondary flue conduit during manipulation of the condensing water heater prior to being placed in service. 
     BACKGROUND OF THE INVENTION 
     Domestic and commercial gas-fired water heaters have evolved for improving the efficiency thereof by capturing more of the hot combustion gases from its flue for heat exchange with the water contained in its water holding tank. This has been achieved by providing a secondary flue conduit which takes the hot flue gases from the exit end of the central flue and conducts them in a secondary flue conduit extending inside the water holding tank to create a second pass wherein to continue to extract heat from the flue gases by heat exchange with the water in the holding tank before being released into the atmosphere. As the flue gases cool condensation forms in the secondary flue conduit. A blower draws the flue gases through the primary flue and the secondary flue conduit. By doing so, the efficiency of the water heater is increased and the condensate from the cooling flue gas flows in a downward path through the secondary flue conduit which exits the water holding tank in a lower portion of its tank wall. The flue gases are released to the atmosphere at a reduced temperature and condensate is extracted at the lower end of the water heater outside the water holding tank. 
     Applicant&#39;s pending patent application Ser. No. 14/121,994 filed Nov. 13, 2014 illustrates the connection of a coiled secondary flue pipe supported about the central primary flue by dielectric pipe connectors. Other type of secondary flues and their securement are taught by the prior art. We have noted, that because the secondary flue is a long pipe or conduit extending substantially the length of the water holding tank, damage may occur to the connections of the secondary flue during manipulation of the tank after its leaves the factory where these condensing water heaters are fabricated. Because water heaters are long tubular devices it is easier to transport them at an inclination either on a dolly or by two people. Also, often these water heaters need to be installed in tight areas where the water heater is disposed horizontally or rolled inclined on its circular base. This manipulation of the condensing water heater prior to being placed in service can cause displacement of the secondary flue inside the tank and subject its connection to stress created by the weight of the secondary flue being displaced by the manipulation of the water heater. The stress imparted to the connections can damage the gasket, weld joints and other elements of the connection. 
     SUMMARY OF THE INVENTION 
     It is a feature of the present invention to overcome the above mentioned disadvantages of the prior art by a low cost solution comprised by a flue restrainer which is easy to install without the use of fasteners or welding. 
     Another feature of the present invention is to provide a restrainer which is fabricated has a single part from plastics material and which is easy to attach to the secondary flue without the use of fasteners or welding and which arrests the displacement of the secondary flue during transport and manipulation. 
     Another feature of the present invention is to provide a simple, low cost, method of restraining the secondary flue of a condensing water heater before it is placed in service. 
     According to the above features, from a broad aspect, the present invention provides a flue restrainer for condensing water heaters equipped with an internal secondary flue conduit disposed inside the water holding tank of the condensing water heater. The restrainer comprises a support member which has a flue tube engaging portion for restraining engagement with one or more portions of the secondary flue conduit. The support member has an abutment end for abutting engagement with a stationary internal surface of the water holding tank. 
     According to another broad aspect of the present invention there is provided a method of restraining a secondary flue conduit of a condensing water heater during manipulation of the condensing water heater before being placed into service. The method comprises positioning a flue restrainer for frictional attachment to the secondary flue conduit during fabrication of the condensing water heater to restrict the displacement of the secondary flue conduit during manipulation the condensing water heater. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       A preferred embodiment of the present invention will now be described with reference to examples thereof illustrated by the accompanying drawings in which: 
         FIG. 1  is a fragmented perspective view of a condensing water heater of the prior art equipped with a dielectrically insulated secondary tubular flue conduit having a helical tubular section and supported inside the water holding tank between a top dielectric connector and a bottom dielectric connector; 
         FIG. 2  is a fragmented side view illustrating the construction of the dielectric connector of  FIG. 1 ; 
         FIG. 3  is a fragmented side view of a first example of the construction of the flue restrainer of the present invention and showing it in frictional engagement with the coil windings of the secondary flue conduit of  FIG. 1 ; 
         FIG. 4  is a perspective view of the flue restrainer illustrated in  FIG. 3 ; 
         FIG. 5  is a fragmented top view of a condensing water heater illustrating a second example of the construction of the flue restrainer of the present invention in frictional and clamping engagement with a straight vertical secondary flue conduit disposed spaced from the primary flue of a condensing water heater; and 
         FIG. 6  is a perspective view of the flue restrainer illustrated in  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings there is illustrated at  FIG. 1  the construction of a condensing water heater  10  constructed in accordance with the invention describe in our earlier referred to U.S. patent application Ser. No. 14/121,994, which is herein incorporated by reference. As herein shown, the condensing water heater  10  is provided with a secondary flue conduit  11  consisting of a copper tube provided with a helical coil section  12  and a straight section  13  for positioning the helical coil section  12  in a lower portion of the water holding tank  14  where the water is cooler than the top section for better heat exchange of the flue gases passing through the helical coil section with the surrounding water in the tank  14 . The secondary flue conduit  11  is secured inside the water holding tank  14  by opposed dielectric tank connectors  15  and  15 ′. 
     As herein illustrated, the tank connectors  15  and  15 ′ are provided with a pressure flange  16  welded spaced from the threaded ends  17  of the secondary flue conduit  11  for pressing a gasket  18  once the connectors are firmly secured to the water holding tank walls by a compression nut  19  threaded on the threaded ends  17  extending out of the tank upper wall  20  and a lower portion of the side wall  21 . The connectors are identical at opposed ends of the secondary flue conduit  11  to firmly support the secondary flue conduit in position in the water holding tank. Hot gases  22 ′ exiting the top end of the central flue  22  are directed into the top end  23  of the secondary flue conduit  11  via an interconnecting channel member  9  and drawn through the secondary flue conduit  11  by a blower  24  mounted on the condensing water heater  10  and in communication with the exhaust flue pipe  25  connected to the exit end of the secondary flue conduit. Has can be seen, the majority of the weight of the secondary flue  11  is in the helical coil section  12  where there is a greater length of the copper tube of which the secondary flue conduit is constructed. Because these water heaters have to be manipulated for transport and installation, the secondary coil is subjected to vibrations, such as is generated during the displacement of transport vehicles, often being displaced on rough roads and for long distances, and to side angular displacement of the water heater when transported on dollies or when supported sideways or horizontally prior to installation. Because the weight is in a bundle-like area, the coil section, between the end connectors this weight applies a stressing force on the end connectors  15  and  15 ′ and this could result in damaging the seal  18  of the connectors and result in leakage and costly repairs has the water holding tanks  11  would have to be drained for replacing the lower gasket. 
     In order to prevent this stress on the connectors  15  and  15 ′ it is necessary to restrain the secondary flue from applying stress on its connectors during transport and manipulation of the condensing water heater  10 . This is accomplished by the flue restrainer  30  of the present invention as illustrated in  FIGS. 3 to 6 , wherein two examples of its construction is illustrated. The flue restrainer  30  of the present invention is a simple and inexpensive component which does not require any permanent connections to the secondary flue or any internal part of the water holding tank  14 . It is securable to the secondary flue by snap-fit or friction fit connection to the secondary flue. 
     With reference to  FIGS. 3 and 4 , there is illustrated a first example of the construction of the flue restrainer  30 . As herein illustrated, the flue restrainer  30  is constituted by a flat support plate  31  formed of plastics material, which plastics material has properties suitable for maintain its rigid shape in the hottest water to be contained in the water holding tank  14 , typically 120 degree F. to 150 degrees F. It can also be used in domestic or commercial water heaters or boilers. The plate has a thickness of about half inch to assure its rigidity and is molded in one piece from polypropylene or polysulphite or from other equivalent suitable plastics. As herein shown, the support plate  31  has a flue tube engaging portion  32  formed with flue tube engaging jaw formations  33  spaced apart a distance equivalent to the distance between the coil windings  12 ′ of the helical section  12 . The jaw formations  33  are u-shaped formations defining a throat section shaped for receiving a transverse portion of a respective tube of the coil windings  12 ′ and in close fit therein for clamping engagement or friction fit engagement. A pair of clamping fingers  34  at the mouth of the throat section embrace the transverse portion of the coil in friction fit to prevent the jaw formation  33  from detachment after its engagement with the coils. 
     The support plate  31  of the flue restrainer  30  defines a support plate extension brace arm which is shaped for restraining abutment in a lower surrounding through  36  defined between the outer periphery of the top wall  37  of the combustion chamber  38  of the water holding tank  14  and the surrounding side wall  14 ′ of the tank  14 . The flue restrainer  30  is clamped onto the helical section  12  after the secondary flue conduit  11  has been secured inside the water holding tank from the open bottom end of the tank. Thereafter, the top wall  14 ′ of the combustion chamber, which constitutes the bottom wall of the tank  14 , is fitted into position and welded about the tank side wall  14 ′ as indicated by weld  39 . The flue restrainer  30  extends substantially vertically within the tank with the free end  35 ′ of the extension arm section  35  in abutment against an internal surface of the water holding tank. 
     With reference now to  FIGS. 5 and 6  there is shown another example of the construction of the flue restrainer, herein flue restrainer  40 . It is also a molded part formed of plastics material and it is adapted to restrain a vertical secondary flue conduit  41  which extends into the water holding tank  14  and spaced substantially parallel to the primary flue  42 . As herein shown, the flue restrainer  40  also defines a jaw formation  43  of u-shaped profile defined between a pair of clamping fingers  44 . The clamping fingers define a throat opening  45  between them and dimensioned to receive there between a transverse section of the secondary flue conduit  41  for frictional and clamping engagement of the secondary flue conduit in the jaw formation  43 . 
     The flue restrainer  40  also defines an extension brace arm  46  of predetermined length formed integral with the jaw formation  33  and extending rearwards thereof in a common plane. The length of the extension brace arm  46  spans the distance between the outer surface of the secondary flue conduit  41  and the inner surface  14 ″ of the water holding tank  14 . The free end  47  of the extension brace arm has a slightly convex face for smooth contact with the inner face  14 ″ of the water holding tank side wall  14 ′ which is usually coated with a glass liner. In order to firmly arrest the secondary flue conduit  41  in position within the tank, one of the clamping fingers  44  may be provided with an extension free end dimensioned for abutment against the primary flue  42  wherein the secondary flue conduit  41  is retained captive between the rigid primary flue  42  and the inner surface  14 ″ of the side wall  14 ′ of the water holding tank  14 . If desired two or more of these flue restrainers  40  may be attached to the secondary flue without affecting the performance of the condensing water heater. If the secondary flue consists of two or more conduits disposed with the water holding tank and projecting from a manifold combustion gas distributor, then a flue restrainer can be attached to all of the conduits or at least a few of them 
     Concluding, the present invention provides a novel and inexpensive method of restraining a secondary flue conduit of a condensing water heater to prevent damage to the secondary flue attachments during manipulation and transport of the water heater prior to being placed in service. The flue restrainer  30  and  40  is inexpensive to produce, easy and quick to install as it is snap or friction fitted onto the secondary flue conduit(s) eliminating any permanent connections to the secondary flue conduit as well as to internal parts of the water holding tank, such as by welding or the use of fasteners. 
     It is within the ambit of the present invention to cover other modified configurations of the flue restrainer depending on the secondary flue conduit construction, provided such modifications fall within the scope of the appended claims.