Patent Publication Number: US-2011067650-A1

Title: Water heater module having detachable heat exchanger

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a water heater, and more particularly to a water heater module equipped with a detachable heat exchanger in order to improve heat transfer efficiency. 
     2. Description of the Related Art 
       FIG. 1  shows a conventional water heater including a burning chamber  1 , a pipe assembly  2  above the burning chamber  1 , and a heat exchanger  3  between an inlet  2   a  and an outlet  2   b  of the pipe assembly  2 . It may heat cold water in the pipe assembly  2  with high temperature gas in the burning chamber  1  and the heated water flows out of the pipe assembly  2  via the outlet  2   b . Such water heater is very common. However, its heat transfer efficiency is only between 72% and 83%. It is because that some thermal will escape along with the gas from the water heater rather than be transferred into water. 
     In order to improve heat transfer efficiency, some water heaters are equipped with secondary pipe assembly and heat exchanger therein that there are two sets of pipe assemblies and heat exchangers for pre-heating and heating that may improve the heat transfer efficiency. However, such water heater still has some problems: 
     1. Both sets of pipe assemblies and heat exchangers are mounted in the water heater that such water heater usually has a greater size. It is inconvenient for delivery and assembling. 
     2. Besides, both sets of pipe assemblies and heat exchangers are undetectable that there are two types of water heaters, which are single set of pipe assembly and heat exchanger and double sets of pipe assemblies and heat exchangers in the market for consumers to choose. Although the double sets type water heater has better heat transfer efficiency, its massive size is inconvenient for consumers. 
     3. There are carbon dioxide and vapor in the high temperature gas. It causes the formation of acid water which adhere to surfaces of the pipe assemble. Moreover, most part of the pipe assemble is received in the water heater while the burning chamber is also received in the water heater that it is hard to wash the pipe assemble. Consequentially, acid water will eventually rust pipe assemble in the long run. 
     4. When the high temperature gas heats the pipe assemblies in sequence, it will decrease the heat transfer efficiency because the high temperature gas is gathered in the same space. 
     SUMMARY OF THE INVENTION 
     The primary objective of the present invention is to provide a water heater module, in which a heat exchanger can be detachably mounted in any type of water heater. The water heater of the present invention has a higher compatibility and better heat transfer efficiency when the secondary heat exchanger is mounted. 
     The secondary objective of the present invention is to provide a water heater module equipped with a detachable heat exchanger, whose pipe is easy to wash and consequently reduces the rust problem. 
     According to the objectives of the present invention, a water heater module of the present invention includes a water heater and an extra heat exchanger. The extra heat exchanger has a spiral pipe and is detachably connected to the water heater. The pipe is heated by high temperature gas from the water heater to pre-heat cold water in the pipe, and then the water is sent to the water heater for further heating. 
     In order to improve the heat transfer efficiency, the present invention further provides a first fin assembly having a plurality of fins and a second fin assembly also having a plurality of fins, wherein the first fin assembly is received in the water heater, and the second fin assembly is received in the extra heat exchanger. Furthermore, the first fin assembly has an exhaust cross section area, which is smaller than an exhaust cross section area of the second fin assembly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sketch diagram of the conventional water heater; 
         FIG. 2  is a perspective view of a first preferred embodiment of the present invention; 
         FIG. 3  is a sketch diagram of the first preferred embodiment of the present invention; 
         FIG. 4  is a sketch diagram of the heat exchanger without fins of the first preferred embodiment of the present invention; 
         FIG. 5  is a sketch diagram of the heat exchanger with fins of the first preferred embodiment of the present invention; 
         FIG. 6  is a sketch diagram of a second preferred embodiment of the present invention; and 
         FIG. 7  is a sketch diagram of the heat exchanger of the second preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As shown in  FIG. 2  and  FIG. 3 , a water heater module  100  of the first preferred embodiment of the present invention includes a water heater  10  and an extra heat exchanger  20 . In the present embodiment, the water heater  10  is the same as the conventional water heater including a first case  12 , in which a burning chamber  14 , a first pipe  16  and a first fin assembly  18  are provided. The burning chamber  14  may generate high temperature gas to heat the first pipe  16 . The first pipe  16  has a first connecting end  16   a  and an outlet  16   b . The case  12  is provided with a first opening  121  at a top thereof. The first fin assembly  18  includes a plurality of fins  181  arranged in a predetermined pattern. Intervals between the fins  181  are defined as S 1 . The first pipe  16  extends through the fins  181 . 
     The extra heat exchanger  20  includes a second case  22  having a plurality of detachable fasteners  23  to secure the first case  12  of the water heater  10 . The second case  22  includes a bottom plate  24  having a second opening  241  communicated with the first opening  121  of the first case  12 . In other words, the high temperature gas generated by the burning chamber  14  of the water heater  10  flows into the second case  22  through the first opening  121  and the second opening  241  in sequence. 
     The extra heat exchanger  20  further includes a second pipe  26  and a second fin assembly  28 , as shown in  FIG. 4  and  FIG. 5 . The second pipe  26  is a spiral pipe formed with a plurality of annular sections  261  from top down. The second pipe  26  has an inlet  26   a  and a connecting end  26   b . Cold water flows into the second pipe  26  via the inlet  26   a , and the connecting end  26   b  of the second pipe  26  is connected to the connecting end  16   a  of the first pipe  16  of the water heater  10 . The bottom plate  24  of the second case  22  is provided with a collecting slot  242  with a curved bottom beside the second opening  241  and a weephole  243  on the bottom of the collecting slot  242 . The second case  22  further has a detachable panel  25 . The second fin assembly  28  has a plurality of fins  281 , and the second pipe  26  extends through the fins  281 . Intervals between the fins  281  are defined as S 2 . 
     Above is the structure of the water heater module  100  of the first preferred embodiment of the present invention. In practice, the first case  12  is filled with the high temperature gas generated by the burning chamber  14  of the water heater  10 , and the second case  22  is filled with the high temperature gas also to pre-heat water in the second pipe  26  that the water flows into the first pipe  16  from the second pipe  26  is warm. At the same time, the burning chamber  14  will also heat up the water in the first pipe  16  directly that the temperature of the water in the first pipe  16  will be raised within a short time. 
     The first fin assembly  18  has an exhaust cross section area which is smaller than that of the second fin assembly  28 . The exhaust cross section area is the total cross section area of the high temperature gas generated by the burning chamber  14  of the water heater  10  passing through the fin assembly. Such structure will generate a stack effect with heat convection in the water heater  10  and the extra heat exchanger  20 . It may help the high temperature gas going up to improve the heat transfer efficiency. 
     Choosing a suitable number of fins  181  and  281  of the first and second fin assembles  18  and  28  may also help to achieve aforesaid stack effect. A number of the fins  181  of the first fin assemble  18  (shown in  FIG. 3 ) is greater than the fins  281  of the second fin assemble  28  (shown in  FIG. 5 ) that the intervals S 1  of the fins  181  of the first fin assemble  18  is smaller than the intervals S 2  of the fins  281  of the second fin assemble  28 . Such pattern may generate aforesaid stack effect also. Besides the number of the fins, thickness of the fins may affect the stack effect also. For example, when the numbers of the fins  181  and  281  of the first and second fin assembles  18  and  28  are the same and the fins  181  of the first fin assemble  18  are thicker, it may cause the exhaust cross section area of the first fin assembly  18  to become smaller than the second fin assembly  28 . 
     The characters and advantages of the present invention are: 
     1. The extra heat exchanger  20  is an independent item which has a high compatibility to be incorporated with any type of water heater. It may improve the heat transfer efficiency, and furthermore, consumers don&#39;t need to buy water heater with double pipes of other types to combine their water heater with the extra heat exchanger. 
     2. Acid water on the second pipe  26  will drop into the collecting slot  242  on the bottom plate  24  of the second case  22  and flows out through the weephole  243 . It may reduce the rust problem of the second case  22  and the second pipe  26 . 
     3. When the panel  25  of the second case  22  is disassembled, the second pipe  26  is exposed for washing and the burning chamber  14  will not interfere with washing. 
     4. A predetermined design of the first and second fin assembles  18  and  28  may achieve the stack effect. It may improve the heat transfer efficiency and reduce the production of waste gas for safety. 
     The water heater and the extra heat exchanger of the water heater of the present invention may be adjusted in its assembling way to become applicable to a different work place.  FIG. 6  shows a water heater module  200  of the second preferred embodiment of the present invention, which has a water heater  30  and an extra heat exchanger  50  to be connected with a pipe  40 . The extra heat exchanger  50  has a second pipe  52  therein which is a spiral pipe with several annular sections  521 . It may help the acid water dropping when the spiral second pipe  52  is clockwise from a top thereof. A second case  54  of the extra heat exchanger  50  has a bottom plate  55  with a weephole thereon to drain the acid water. The bottom plate  55  may be concave or tilted to collect acid water. 
     The description above is a few preferred embodiments of the present invention and the equivalence of the present invention is still in the scope of the claim of the present invention.