Patent Publication Number: US-6701069-B1

Title: Pre-heating contiguous in-line water heater

Description:
FIELD OF THE DISCLOSURE 
     The instant disclosure generally concerns water heaters. Specifically, the instant disclosure concerns pre-heating, in-line water heaters. 
     BACKGROUND 
     In-line water heaters (sometimes referred to as on-demand water heaters) are designed to heat a continuous supply of input water only when hot water is demanded by a user. This is in contrast to typical storage tank water heaters which keep, on the average, 30-70 gallons of water heated and ready for use 24 hours a day. Opening a hot water faucet triggers one or more heating units (typically, either electric or gas) to heat the water as it flows through the in-line water heater. The water takes a circuitous path through tubing in the in-line water heater so the heating units of the in-line heater have an opportunity to heat the water sufficiently. With in-line water heaters, there is never a shortage of hot water since there is never a tank to deplete. In addition, since there is no tank to heat continuously, there is a significant energy savings. 
     A conventional in-line water heater comprises a water input to allow water from the plumbing system to enter the water heater, a water output to distribute hot water for use, and a series of transit channels, or heating chambers, to direct the water through the in-line water heater. In many cases, these heating chambers are arranged in a baffle like arrangement which requires the water to travel an extended distance in the in-line water heater. Although the conventional in-line water heaters are more efficient than the storage tank water heaters, the conventional water heaters are not engineered to be as efficient as the in-line water heater described herein. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 shows a perspective view of one embodiment of the in-line water heater. 
     FIG. 2 shows a side view of one embodiment of the in-line water heater illustrated in FIG.  1 . 
     FIG. 3A shows a top view illustrating the internal arrangement of one embodiment of the in line-water heater illustrated in FIG.  1 . 
     FIG. 3B shows a top view illustrating the internal arrangement of an alternate embodiment of the in line-water heater illustrated in FIG.  1 . 
     FIG. 4 shows a top view illustrating the internal arrangement of an alternate embodiment of the in line-water heater. 
     FIG. 5 shows an alternate embodiment of the in-line water heater. 
     FIG. 6 shows an alternate embodiment of the in-line water heater where the input water is pre-heated by solar heating. 
     FIG. 7 shows a side view of an alternate embodiment of the in-line water heater illustrating a single, continuous transit channel. 
    
    
     SUMMARY 
     The present disclosure describes a pre-heating, contiguous in-line water heater. One goal of the present disclosure to provide such an in-line water heater that is more cost efficient in use than conventional water heaters. An alternate goal of the present disclosure is to provide an in-line water heater that utilizes passive heating to heat the input water before the water is exposed to active heating by the heating elements as described herein. Another goal of the present disclosure is to provide an in-line water heater with an expandable capacity. Another goal of the present disclosure is to provide an in-line water heater incorporating a control means that provides at least one of the following functions: 1) monitoring the temperature of the input water as it travels through the in-line water heater; 2) monitoring the heating elements to determine which elements are in use at a given time; 3) providing an input means to set the temperature of the input water to a desired level (referred to as the “set temperature”); 4) determining how many of the heating elements are required to heat the input water to the set temperature and controlling the activation of said heating elements to achieve such heating; 5) monitoring the heating elements to determine which elements are functioning properly; 6) monitoring the system for free water, such as may occur from leaks; 7) monitoring the flow of input water through the system and activating at least one heating element when a flow is detected; 8) alerting the user when the in-line water heater is not functioning within a first set of parameters; and 9) providing the user of a visual display of a second set of parameter, such as the set temperature, the presence of a leak, the status of each of the heating elements, the current temperature of the input and/or output water and whether the in-line water heater is currently being supplied with power. 
     DETAILED DESCRIPTION 
     The present disclosure describes a pre-heating, contiguous in-line water heater. As with conventional water heaters, cold water is fed into the system (input water) heated as it travels through the in-line water heater. The in-line water heater described herein has several embodiments. The in-line water heater is described as being used with water, however, it should be understood that the in-line water heater can be used with other liquids as well, if desired. The embodiments described below are given for the purpose of example only such that one of ordinary skill in the art may understand the scope and content of the disclosure and is not meant to preclude other embodiments from the scope of the disclosure. 
     FIG. 1 shows a perspective view of the in-line water heater of the present disclosure. The in-line water heater  1  comprises a body  2 , a top cap  4  and a bottom cap  6 . In one embodiment, the body  2  is generally cylindrical in form. However, the shape of the in-line water heater  1  may be varied as desired, with the cylindrical form being shown for exemplary purposes only. For example, FIG. 5 shows a body  2 A of generally rectangular form. Other forms may also be used as desired. The body  2  comprises an outer periphery that at least partially defines an interior  50 . The internal arrangement within interior  50  of body  2  may take on a number of forms. In its most basic form, the interior  50  of body  2  contains at least one transit channel to conduct input water from the cold water input  8  to the hot water output  10 . There may be multiple transit channels which are interconnected, or there may be a single transit channel within the interior  50 . All or less than all of the transit channels may contain a heating element to heat the input water as it travels through the in-line water heater  1 . The interior  50  may further comprise a passive heating means. The function of the passive heating means is to transfer a portion of the heat generated by the in-line water heater to other sections of the in-line water heater and/or to retain heat in the nature of a heat sink. The heat transferred may be generated by the heating elements, for example. The passive heating means may comprise a variety of materials, such as, but not limited to, insulating foam, Styrofoam, asbestos, glass fiber insulation, metal, stone and sand. The metal may be a variety of metals included but not limited to, copper, a copper alloy, aluminum, an aluminum alloy, tin or a tin alloy, brass or a brass alloy, or any other metal that is capable of conducting heat and/or to retain heat in the nature of a heat sink. The interior  50  may be hollow or the interior  50  may be solid. When the interior  50  is solid, the solid acts as the passive heating means and the at least one transit tube may be cast within the solid interior. When the interior  50  is hollow particulate matter (as described above) acts as the passive heating means and the transit tubes may be surrounded with the particulate matter. 
     So that one of ordinary skill in the art may understand the workings of in-line water heater  1 , reference is made to the specific embodiments illustrated in the figures. As shown in FIG. 1, the interior  50  of body  2  is cast from a solid material. In this embodiment, the solid interior  50  serves as the passive heating means. FIG. 1 shows 4 interconnected transit channels labeled  11 ,  12 ,  13  and  14 , which are cast in the solid interior  50 . However, fewer or greater number of transit tube may be used. For example, FIG. 5 shows an embodiment of the in-line water heater  1  comprising two transit channels,  11 A and  12 A and FIG. 7 shows an embodiment of the in line water heater  1  having a single, continuous transit channel  11 C. These transit channels are created in the casting process as hollow cavities within the solid interior  50 . The transit channels  11 - 14  are interconnected with one another (as shown in FIG.  3  and discussed below). Furthermore, at least one of the transit channels is connected to the cold water input  8  and at least one of the transit channels is connected to the hot water output  10 . The connections may be made by standard techniques known to one of ordinary skill in the art. In the embodiment illustrated in FIG. 1, transit pipe  11  is connected to cold water input  8  and transit pipe  14  is connected to hot water output  10 . 
     One or more of the transit channels may contain a heating element  18  as shown in FIG.  1 . FIG. 1 shows 3 heating elements  18 , but each of the transit channels  11 - 14  may contain a heating element (as illustrated in FIG. 5, where transit channels  11 A and  12 A each contain a heating element  18 ). The purpose of the heating element is to heat the input water as it flows through the transit channels. The transit channels  11 - 14  may not extend all the way to the top portion  44  of solid interior  50  and may terminate slightly below the top portion  44  to produce a recess  46  to receive the heating element  18 . The heating element  18  and the recess  46  may further comprise complementary male and female threads to removably secure the heating element  18  into the recess  46 . The recess  46  may also contain a sealing means, such as a gasket or O-ring. The heating element  18  is in communication with a control means as discussed below. Briefly, the control means receives input from various sensors positioned in the in-line water heater  1  and controls the activation of the individual heating elements  18 , among other things. 
     The number of heating elements  18  and or transit channels used will depend on the volume of water to be heated by the in-line water heater  1 . Referring to the embodiment illustrated in FIG. 1, for a typical residential setting, three heating elements  18  and 4 transit channels  11 - 14  will generally provide sufficient quantities of hot water for use. When less than all of the transit channels  11 - 14  contain a heating element  18 , it is preferred that the transit tube connected to the cold water input  8  not contain a heating element (transit tube  11  in this example). Once the heating elements  18  are activated by the control means as discussed below, the heating elements  18  will rapidly heat the solid interior  50  of the in-line water heater  1  via transduction of heat by the passive heating means. This will create conditions where the water flowing through transit tube  11  will be heated by the interior  50  of the in-line water heater  1  (referred to as “passive heating”). The use of passive heating allows additional heating of the water flowing through the in-line water heater  1  without the expenditure of additional energy and contributes to the efficiency of the unit. In initial studies the water is heated an average of 4-6 degrees Fahrenheit (F.) as it travels up transit pipe  11  (from an input temperature of 56 degrees F. to 60-62 degrees F.). This passive heating of the water occurs at no added energy expense to the system. In addition, the passive heating allows the water to be heated to the set temperature in a shorter time. In essence, the energy efficient design of the instant in-line water heater  1  allows a head start on the heating process at no added energy expense. 
     In commercial applications, each of the transit channels  11 - 14  may contain a heating element  18 . Other factors that may influence the number of heating elements and/or transit channels to be incorporated include the climate of the area where the in-line water heater  1  is used. In temperate climates, three or fewer heating elements may be incorporated into the in-line water heater for use in a residential setting. In colder climates, four heating elements may be required to provide sufficient quantities of hot water. In addition, more transit channels could be incorporated into the in-line water heater  1  and used with or without heating elements  18 . The size of the structure may also influence the number of heating elements used and/or the number of transit channels used. For larger structures, more heating elements and/or transit channels may be used as discussed above. Furthermore, the desired output temperature of the water may also influence the number of heating elements and transit channels used. Alternatively, more than one in-line water heater may be used to generate additional quantities of hot water. 
     FIGS. 2 and 3 illustrate an example of the flow of water through the in-line water heater  1 . Input water (as normally supplied by standard systems) enters the in-line water heater  1  through the cold water input  8 . The water travels up transit pipe  11 . During the movement up transit pipe  11 , the water is heated either passively as discussed above or via a heating element  18  which is in communication with the input water. The water reaches the top of transit pipe  11  and passes through connecting pipe  30 A and travels down transit pipe  12  where it flows through connecting pipe  30 B into transit pipe  13 . The water flows up transit pipe  13 , through connecting pipe  30 C into transit pipe  14 . The water flows down transit pipe  14  and out of the in-line water heater  1  through hot water output  10 . The hot water is then distributed for use via standard feed pipes. As the water flows through transit channels  12 - 14  the water may be heated by heating elements 18 , which are in communication with the water when present. In addition, the water undergoes additional passive heating as described. 
     An alternate embodiment of the in-line water heater  1  is shown in FIG.  4 . In this embodiment, there are 4 transit channels and the cold water input and hot water output extend into the interior  50  of the in-line water heater  1 . In this embodiment, the cold water input and hot water output extend to just below the top portion  44 . The cold water enters through transit pipe  110  which is connected to the cold water input (not shown). The water travels up transit tube  110  through connecting tube  112 A into transit tube  102 . The water travels down transit tube  102 , through connecting tube  112 B and up transit tube  104 , through connecting tube  112 C, down transit tube  106 , through connecting tube  112 D, up transit tube  108 , through connecting tube  112 E and down transit tube  114 . The water exits transit tube  114  through the hot water output (not shown). In this embodiment, the transit channels  110  and  114  do not contain heating elements  118 , although in an alternate embodiment heating elements could be used (as might be the case if it was desired to increase heating capacity). Instead, the water flowing through transit channels  110  and  114  is passively heated by the proximity to transit channels containing heating elements and via heat conducted by the passive heating means (in this embodiment solid interior  50 ). In an alternate embodiment, the passive heating means could be any one of the materials described above. 
     Referring to FIGS. 1 and 3, the body  2  has an outer covering  40  covering the solid interior  50 . The outer covering  40  is optional, and functions to allow a user to handle the in-line water heater  1  when the unit is in operation. The outer covering  40  may be constructed of a variety of materials, including, but not limited to, various polymers (such as PVC), various plastics or metals (such as stainless steel). There may also be a layer of insulation between the outer covering  40  and the solid interior  50  (shown as  42  in FIGS. 1,  3  and  4 ). 
     The top cap  4  may contain connecting means for standard electrical connections for use with residential housing and commercial structures and a control means. In one embodiment, the top cap  4  may be divided into two sections, one containing the electrical connections and one containing the control means. The control means comprises electronics monitoring and regulating components. The electrical connections are those that are commonly used in the field and are well know to those of skill in the art. The control means also comprises standard components, the operation and arrangement of which are well known to those of skill in the art. The control means is in communication with the various sensors and regulators described below and is also in communication with the heating elements. The control means may contain a processing unit with sufficient memory and capacity to execute the functions described. The control means is capable of performing a number of self-monitoring and self-regulating functions regarding the in-line water heater. These functions include, but are not limited to: 1) monitoring the temperature of the input water as it travels through the in-line water heater; 2) monitoring the heating elements to determine which elements are in use at a given time; 3) providing an input means to set the temperature of the input water to a desired level (referred to as the “set temperature”); 4) determining how many of the heating elements are required to heat the input water to the set temperature and controlling the activation of said heating elements to achieve such heating; 5) monitoring the heating elements to determine which elements are functioning properly; 6) monitoring the system for free water, such as may occur from leaks; 7) monitoring the flow of input water through the system and activating at least one heating element when a flow is detected; 8) alerting the user when the in-line water heater is not functioning within a first set of parameters; and 9) providing the user of a visual display of a second set of parameter, such as the set temperature, the presence of a leak, the status of each of the heating elements, the current temperature of the input and/or output water and whether the in-line water heater is currently being supplied with power. Other functions that are used in water heaters as are currently known in the art may also be incorporated into the control means. 
     The visual display may be any means to visually inform the user of a desired aspect of the in-line water heater. For example, the visual display may be a LED display. The LED display may give the information in any convenient format. For example, the LED display may give the set temperature in a numeric readout and inform the user regarding the status of the heating elements through the use of individual display elements representing each heating element in the in-line water heater. If a heating element was in operation, a display element may be illuminated, or illuminated in a first color. If the heating element is not operating correctly, the display element may be illuminated in a second color. Such display element may simply be a circular LED, or may be graphical in nature. 
     In addition to a visual display, the in-line water heater may comprise an alarm to alert the user when the in-line water heater is not functioning within established parameters, such as when a leak is detected, when a heating element is not functioning properly, when a block is detected in the transit channels or when the heating elements in operation cannot supply input water at the set temperature for sustained periods of time. For example, if the in-line water heater is not able to generate water meeting the set temperature requirement, an alarm may be generated. In addition, an alarm may be generated when one of the heating elements fails to function properly. Any aspect of the functioning of the control means may be linked to an alarm. The methods for linking such functions to an alarm are known to those of skill in the art. The alarm may be an audible alarm, a visual alarm or a combination of a audible alarm or a visual alarm. 
     The control means may receive signals from a flow detection means. The flow detecting means is in fluid communication with the water input into the in-line water heater. The flow detection means may be a flow detector (illustrated as  16  in FIG.  1 ). The operation and integration of flow detectors as described is within the ordinary skill in the art. The flow detection means would signal the control means when water was flowing thought the in-line water heater. The signal would cause the control means to activate a sufficient number of heating elements in order to heat the input water to the set temperature. In some cases all of the heating elements may be activated and in some cases less than all of the heating elements may be activated. Location of the flow detecting means may be any position where the flow detecting means has access to determine the flow of water through the system. In one embodiment, the flow detecting means is located in conjunction with cold water input  8 . In an alternate embodiment, the flow detecting means is located in conjunction with hot water output pipe  10 . In other embodiments, the flow detecting means may be placed in conjunction with transfer tubes (such as transfer tubes  11 - 14  in FIG.  1 ). 
     In addition to monitoring the flow of water through the system, the in-line water heater described can also monitor the temperature of the input and output water through the use of temperature detecting means. The temperature detecting means is in fluid communication with the water input into the in-line water heater. Alternatively, the temperature detecting means may be in communication with the exterior of the transit channels and be calibrated to determine the temperature of the water from the temperature of the transit channels. The temperature detecting means may be temperature sensors as are common in the field. The operation and integration of temperature detecting means as described is within the ordinary skill in the art. As with the flow detecting means, the temperature detecting means may be positioned at any position where the temperature detecting means has access to the water flowing through the system. In one embodiment the temperature detecting means are located in conjunction with hot water outlet pipe  10 . 
     There may be multiple temperature detecting means to monitor the temperature of the water at various stage of transit through the in-line water heater. In one embodiment, the control means compares the temperature of the output water to the set temperature and determines the difference between the two. If this difference is large, then the control means activates all available heating elements. This may occur when the flow detecting means first detects a flow of water through the system. As the difference becomes smaller, then the control means may inactivate one or more heating elements. The control means can be set to respond as desired to a range of differences between the temperature of the output water and the set temperature. In one embodiment where three heating elements are present, when the difference is at least 25 degrees F., all three heating elements are activated. When the difference is between 24 and 10 degrees F., then two heating elements are activated. When the difference is between 9 and 1 degrees F., then only one heating element is activated. Finally, when the temperature of the output water is equal to or greater than the set temperature, no heating elements are activated. Other temperature parameters may be selected with the above parameters being exemplary only. 
     The in-line water heater may also contain a leak detection means. The leak detection means may be a sensor capable of sensing the presence of free water in the system. The operation and integration of the leak detecting means as described is within the ordinary skill in the art. The leak detection means may be located at any desired location, but in one embodiment the leak detection (illustrated as  22  in FIG. 1) is located near the drain  24  in bottom cap  6 . If the leak detection means senses free water, then the leak detection means may signal the control means to sound an audible alarm and/or a visual alert to the user. 
     The bottom cap  6  functions to cover the bottom of the in-line water heater  1 . The bottom cap  6  has openings therein to receive the cold water input  8  and the hot water output  10 . In addition, the bottom cap  6  comprises a drain  24 . The bottom of bottom cap  6  may be concave to allow the collection and drainage of water that may escape from the in-line water heater  1 . As discussed above, the leak detecting means may be placed near the drain  24 . 
     The top cap  4  and bottom cap  6  are adapted with an engagement means to securely and reversible engage the body  2 . The engagement means may employ a snap/friction fit, one or more hinges, the use of complementary male and female threads on the top cap  4  and/or bottom cap  6  and the body  2 , a combination of the above, or other commonly used means. In addition, there may be a gasket or other sealing means to separate the contents of the top cap  4  from the body  2 . Since the top  4  and bottom  6  caps are removable, the system may be easily accessed for maintenance and repair. For example, if the control means indicated that a heating element is not functioning properly (either by a visual alarm, an audible alarm or both as discussed above), the top cap  4  may be removed. The LED display would indicate which heating element was not functioning correctly. The suspect heating element could then be removed by simply unscrewing the heating element and replacing the heating element with a new one if required. 
     It should be noted that the in-line water heater described herein incorporates certain standard features that are common on both in-line water heaters and/or storage tank water heaters. These features and their applicability to the in-line water heater described herein are within the ordinary skill in the art in the plumbing field and are not discussed in detail. Such features include those described above such as electrical connections, flow detecting means, temperature detecting means, leak detecting means, but also include features such as, but not limited to, relief valves and standard connecting elements and couplings. 
     The water heater describe is energy efficient in use for a number of reasons. First, the heating elements of the in-line water heater are only in use when water is flowing through the system. When the flow detection means does not detect a flow of water through the in-line water heater, the heating elements are maintained in an inactive state. Second, the in-line water heater is constructed from materials that retain the heat produced by the heating elements and the heated water. As a result, the body of the in-line water heater serves to passively heat the water flowing through the system. In addition, the water that is contained in the in-line water heater will retain its heat for a longer period of time. Third, the control means of the in-line water heater monitors the temperature of the output water and compares that temperature to the set temperature to determine how many of the heating elements are required to be in operation in order to maintain the temperature of the output water at the set temperature. If there is a large gap between the temperature of the output water and the set temperature, the control means activates all available heating elements. As the gap becomes smaller fewer that all the heating elements are activated by the control means. 
     An additional alternate embodiment of the in-line water heater  1  is described below and illustrated in FIG.  6 . The basic concepts of the operation of the in-line water heater  1  remain the same as described above. In this embodiment, the input water for the in-line water heater is not drawn directly from the water normally supplied to the structure. Instead, the water is drawn from an intermediary holding tank  60 . The water in the intermediary holding tank may be heated before being delivered to the in-line water heater  1 . The heating may be by any means, such as gas or electric. Alternatively, the tank may not be directly heated, but may be heated by solar energy (illustrated in FIG. 6 as solar panel  62  being irradiated by solar rays  64 ) or other means. The temperature of the intermediary holding tank will ideally be above that of the water that would otherwise be supplied to the in-line water heater  1 . 
     The features of the new in-line water heater described herein are not meant to be an exhaustive listing of features, but only to provide a general idea of the operation of the system. Other features may be apparent to those of ordinary skill in the art.