Patent Publication Number: US-11047597-B2

Title: Electric hot water heater having a separated temperature sensor and heating element

Description:
FIELD OF THE INVENTION 
     The present subject matter relates generally to water heater appliances, and more particularly to water heater appliances having one or more electric heating elements or temperature sensors. 
     BACKGROUND OF THE INVENTION 
     Certain water heater appliances include a tank therein. Heating elements heat water within the tank during operation of such water heater appliances. In particular, the heating elements generally heat water within the tank to a predetermined temperature. The predetermined temperature is generally selected such that heated water within the tank is suitable for showering, hand washing, etc. 
     During operation, relatively cool water flows into the tank, and the heating elements operate to heat such water to the predetermined temperature. Thus, the volume of heated water available at the predetermined temperature is generally limited to the volume of the tank. Accordingly, water heater appliances are sold in various sizes to permit consumers to select a proper tank volume and provide sufficient heated water. 
     Common water heater appliances provide a heating element mounted together with an electromechanical temperature sensor in the bottom half of the tank. The electromechanical temperature sensor is generally positioned 1 to 3 inches above the heating element and activates or deactivates the heating element according to a predetermined temperature threshold. If the electromechanical temperature sensor detects a temperature below the predetermined temperature threshold, the heating element may be activated. If the electromechanical temperature sensor detects a temperature above the predetermined temperature threshold, the heating element may be deactivated. 
     Although the close proximity between the heating element and the electromechanical temperature sensor may facilitate easy installation of the heating element and electromechanical temperature sensor, the design also presents a number of drawbacks. For instance, the water heater appliance may be especially prone to temperature stacking within the tank. In other words, significant variations in temperature may be formed within the tank. Relatively small water draws, such as those caused by hand washing, may cause water adjacent to the electromechanical temperature sensor and heating element to fall below the predetermined temperature threshold, thereby leading to activation of the heating element, even though most of the water within the tank may be above the predetermined temperature threshold. Oftentimes, this causes the heating element to overheat the water above the desired temperature, especially if the heating element is a relatively high power heating element, which quickly heats water within the water heater tank. In turn, a slug of water near the top of the water tank may rise to a temperature well above predetermined temperature threshold. Having this hot water slug may then lead to high and variable hot water temperatures above the set temperature being supplied by the water heater appliance during a subsequent water draw. Along with affecting variation of hot water temperatures from the water heater appliance, this may increase cycling of the heating elements, which may in turn decrease the reliability and useful life of the heating element. 
     As a result, there is a need for improved water heater appliances. In particular, it would be useful and advantageous to provide a water heater appliance addressing one or more of the above identified issues. 
     BRIEF DESCRIPTION OF THE INVENTION 
     Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one exemplary aspect of the present disclosure, an electric water heater appliance is provided. The electric water heater appliance may include a tank, an electric heating element, and a temperature sensor. The tank may define an interior volume extending from a top portion to a bottom portion. The interior volume may define a volume height along a vertical direction between the bottom portion and the top portion. The electric heating element may be operable to heat water within the interior volume. The temperature sensor may be attached to the tank above the electric heating element. A sensor gap may be defined along the vertical direction between the electric heating element and the temperature sensor. A ratio of the sensor gap over the volume height may be equal to or greater than 0.1. 
     In another exemplary aspect of the present disclosure, an electric water heater appliance is provided. The electric water heater appliance may include a tank, a lower electric heating element, an upper electric heating element, a lower temperature sensor, and an upper temperature sensor. The tank may define an interior volume extending from a top portion to a bottom portion. The interior volume may define a volume height along the vertical direction between the bottom portion and the top portion. The lower electric heating element may be operable to heat water within the interior volume. The upper electric heating element may be positioned above the lower electric heating element and operable to heat water within the interior volume. The lower temperature sensor may be attached to the tank above the lower electric heating element and below the upper electric heating element. The upper temperature sensor may be attached to the tank above the upper electric heating element. A lower sensor gap may be defined along the vertical direction between the lower electric heating element and the lower temperature sensor. An upper sensor gap may be defined along the vertical direction between the upper electric heating element and the upper temperature sensor. The lower sensor gap may be greater than the upper sensor gap. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures. 
         FIG. 1  provides a perspective view of a water heater appliance according to exemplary embodiments of the present disclosure. 
         FIG. 2  provides a schematic view of certain components of the exemplary water heater appliance of  FIG. 1 . 
         FIG. 3  provides another schematic view of certain components of the exemplary water heater appliance of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
     The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). The terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. 
     Turning now to the figures,  FIG. 1  provides a perspective view of a water heater appliance  100  according to an exemplary embodiment of the present subject disclosure.  FIGS. 2 and 3  provide schematic views of certain components of water heater appliance  100 . As may be seen in  FIGS. 1 through 3 , water heater appliance  100  includes a casing  102  and a tank  112  mounted within casing  102 . Tank  112  defines an interior volume  114  for heating water therein. 
     Water heater appliance  100  also includes an inlet conduit  104  and an outlet conduit  106  that are both in fluid communication with tank  112  within casing  102 . As an example, cold water from a water source, such as a municipal water supply or a well, enters water heater appliance  100  through inlet conduit  104  (e.g., at an inlet  105  extending through an upper portion of tank  112 ). From inlet conduit  104 , such cold water enters interior volume  114  of tank  112  wherein the water is heated to generate heated water. Such heated water exits water heater appliance  100  at outlet conduit  106  (e.g., supplied through an outlet  107  at an upper portion of tank  112 ) and, for example, is supplied to a bath, shower, sink, or any other suitable feature. 
     As shown, interior volume  114  of tank  112  extends between a top portion  108  and a bottom portion  109  along a vertical direction V. Thus, water heater appliance  100  is generally vertically oriented. Water heater appliance  100  can be leveled (e.g., such that casing  102  is plumb in the vertical direction V) in order to facilitate proper operation of water heater appliance  100 . 
     In certain embodiments, a drain pan  110  is positioned at bottom portion  109  of water heater appliance  100  such that water heater appliance  100  sits on drain pan  110 . Drain pan  110  sits beneath water heater appliance  100  along the vertical direction V (e.g., to collect water that leaks from water heater appliance  100  or water that condenses on an evaporator  128  of water heater appliance  100 ). It should be understood that water heater appliance  100  is provided by way of example only and that the present subject matter may be used with any suitable water heater appliance. 
     Turning especially to  FIGS. 2 and 3 , water heater appliance  100  generally includes one or more electric heating elements, such as an upper heating element  118  or a lower heating element  119 , for heating water within interior volume  114  of tank  112 . Upper and lower heating elements  118  and  119  can be any suitable heating elements. For example, upper heating element  118  or lower heating element  119  may be an electric resistance element, an induction element, or any other suitable electric heating element or combination thereof. In optional embodiments, a sealed system  120  is further provided on or about tank  112  to heat water within interior volume  114 . 
     In certain embodiments, sealed system  120  includes a compressor  122 , a condenser  124 , a throttling device  126 , and an evaporator  128 . Condenser  124  is thermally coupled or assembled in a heat exchange relationship with tank  112  in order to heat water within interior volume  114  of tank  112  during operation of sealed system  120 . In particular, condenser  124  may be a conduit coiled around and mounted to tank  112 . During operation of sealed system  120 , refrigerant exits evaporator  128  as a fluid in the form of a superheated vapor or high quality liquid vapor mixture. Upon exiting evaporator  128 , the refrigerant enters compressor  122  wherein the pressure and temperature of the refrigerant are increased such that the refrigerant becomes a superheated vapor. The superheated vapor from compressor  122  enters condenser  124  wherein it transfers energy to the water within tank  112  and condenses into a saturated liquid or high quality liquid vapor mixture. This high quality/saturated liquid vapor mixture exits condenser  124  and travels through throttling device  126  that is configured for regulating a flow rate of refrigerant therethrough. Upon exiting throttling device  126 , the pressure and temperature of the refrigerant drop at which time the refrigerant enters evaporator  128  and the cycle repeats itself. In certain exemplary embodiments, throttling device  126  may be an electronic expansion valve (EEV). 
     As shown, water heater appliance  100  includes one or more tank temperature sensors, such as a first temperature sensor  130  (e.g., lower temperature sensor) and a second temperature sensor  132  (e.g., upper temperature sensor). Generally, tank temperature sensors  130 ,  132  are configured for measuring a temperature of water within interior volume  114  of tank  112  and can be any suitable temperature sensing device (e.g., in operative communication with the controller  150 ). For example, one or more tank temperature sensors  130 ,  132  may be provided as a thermocouple, thermistor, or electromechanical temperature-dependent switch (e.g., bimetal switch). When assembled, one or more tank temperature sensors  130 ,  132  may be positioned within interior volume  114  of tank  112  or may be mounted to tank  112  outside of interior volume  114  of tank  112 . When mounted to tank  112  outside of interior volume  114  of tank  112 , a tank temperature sensor (e.g., first temperature sensor  130  or second temperature sensor  132 ) can be configured for indirectly measuring the temperature of water within interior volume  114  of tank  112 . For example, tank temperature sensors  130 ,  132  can measure the temperature of tank  112  and correlate the temperature of tank  112  to the temperature of water within interior volume  114  of tank  112 . 
     Water heater appliance  100  further includes a power source or controller  150  that is configured for regulating operation of water heater appliance  100  (e.g., by selectively directing electrical power energy from a connected power grid). Controller  150  is in, for example, operative communication (e.g., electrical communication through one or more conductive wires/busses) with upper heating element  118 , lower heating element  119 , compressor  122 , or tank temperature sensors  130 ,  132 . Thus, controller  150  may selectively activate upper and lower heating element  118  and  119  or compressor  122  in order to heat water within interior volume  114  of tank  112 . As an example, controller  150  may activate/deactivate heating elements  118 ,  119  directly in response to signals from temperature sensors  130 ,  132 . As another example, controller  150  may activate/deactivate heating elements  118 ,  119  indirectly by supplying an electrical current separately to heating elements  118 ,  119  through respective temperature sensors  130 ,  132 ; the temperature sensors  130 ,  132  being configured to open or close the electrical path therethrough (i.e., restrict or permit electrical current to the respective heating element  118  or  119 ) in response to a detected temperature. 
     In some embodiments, controller  150  includes memory (e.g., non-transitive media) and one or more processing devices such as microprocessors, CPUs or the like, such as general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with operation of water heater appliance  100 . The memory can represent random access memory such as DRAM, or read only memory such as ROM or FLASH. The processor executes programming instructions stored in the memory. The memory can be a separate component from the processor or can be included onboard within the processor. Alternatively, controller  150  may be constructed without using a microprocessor (e.g., using a combination of discrete analog or digital logic circuitry; such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software. 
     Controller  150  may operate upper heating element  118 , lower heating element  119 , or compressor  122  in order to heat water within interior volume  114  of tank  112 . As an example, a user may select or establish a predetermined set temperature, t s , for water within interior volume  114  of tank  112 , or the set temperature t s  for water within interior volume  114  of tank  112  may be a default value (e.g., selected during design or assembly of water heater appliance  100 ). Based upon the set temperature t s  for water within interior volume  114  of tank  112 , controller  150  may selectively activate upper heating element  118 , lower heating element  119 , or compressor  122  in order to heat water within interior volume  114  of tank  112  to the set temperature t s  for water within interior volume  114  of tank  112 . 
     In certain embodiments, detection of a temperature at first temperature sensor  130  that is below the set temperature t s  prompts activation of lower heating element  119  (e.g., by closing a temperature-dependent switch at first temperature sensor  130  such that an electrical current is permitted to lower heating element  119 ). Detection of a temperature that is above the set temperature t s  prompts restriction of lower heating element  119  (e.g., by opening a temperature-dependent switch at first temperature sensor  130  such that electricity is withheld from lower heating element  119 ). In additional or alternative embodiments, detection of a temperature at the second temperature sensor  132  that is below the set temperature t s  prompts activation of upper heating element  118  (e.g., by closing a temperature-dependent switch at second temperature sensor  132  such that an electrical current is permitted to upper heating element  118 ). Detection of a temperature that is above the set temperature t s  prompts restriction of upper heating element  118  (e.g., by opening a temperature-dependent switch at second temperature sensor  132  such that an electrical current is withheld from upper heating element  118 ). 
     The set temperature t s  for water within interior volume  114  of tank  112  may be any suitable temperature. For example, the set temperature t s  for water within interior volume  114  of tank  112  may be between about one hundred degrees Fahrenheit and about one hundred and eighty-degrees Fahrenheit. As used herein with regards to temperature approximations, the term “about” means within ten degrees of the stated temperature. 
     In optional embodiments water heater appliance  100  also includes a mixing valve  160  and a mixed water outlet conduit  162 . Mixing valve  160  may be in fluid communication with inlet conduit  104  via a bypass conduit  161 , tank  112 , and mixed water outlet conduit  162 . As would be understood, mixing valve  160  may be configured for selectively directing water from inlet conduit  104  and tank  112  into mixed water outlet conduit  162  in order to regulate a temperature of water within mixed water outlet conduit  162 . Mixing valve  160  may be positioned or disposed within casing  102  of water heater appliance  100  (e.g., such that mixing valve  160  is integrated within water heater appliance  100 ). 
     Turning especially to  FIG. 3 , the vertical positions of one or more of the electric heating elements (e.g., upper heating element  118  or lower heating element  119 ) or one or more of the temperature sensors  130 ,  132  (e.g., first temperature sensor  130  second temperature sensor  132 ) may be preset along tank  112  for advantageous operation of water heater appliance  100 . In particular, heating elements  118 ,  119  and temperature sensors  130 ,  132  may be provided at predetermined locations along the volume height  170  of interior volume  114 , which is defined along the vertical direction V between bottom portion  109  and top portion  108 . 
     In certain embodiments, first temperature sensor  130  is attached to tank  112  at a location above lower heating element  119 . Lower heating element  119  may thus define a lower element height  172  (e.g., vertical distance between lower heating element  119  and bottom portion  109 ) that is less than a first sensor height  174  defined by first temperature sensor  130  (e.g., vertically between first temperature sensor  130  and bottom portion  109 ). Moreover, a sensor gap  176  (e.g., lower sensor gap) may be defined along the vertical direction V between lower heating element  119  and first temperature sensor  130 . As shown, sensor gap  176  may further define a vertical distance within which no other electrical heating element is provided. Thus, the region of interior volume  114  through which sensor gap  176  is defined may be free of any electrical heating elements—even so, sensor gap  176  may span a portion of a condenser  124  along tank  112  between lower heating element  119  and temperature sensor  130 , as illustrated in  FIG. 2 . 
     Sensor gap  176  may be defined according to a predetermined ratio of relative vertical heights. As an example, a gap ratio of the sensor gap  176  over the volume height  170  [i.e., ( 176 )/( 170 )] may be predetermined as a value greater than or equal to 0.1. Additionally or alternatively, the gap ratio of the sensor gap  176  over the volume height  170  may be defined as a value greater than or equal to 0.2. Optionally, the gap ratio of the sensor gap  176  over the volume height  170  may be defined as a value between 0.2 and 0.5. Advantageously, the described gap ratios may ensure an even heat distribution within interior volume  114  and prevent excessive cycling of lower heating element  119 . 
     As shown, upper heating element  118  and second temperature sensor  132  may both define vertical heights above first temperature sensor  130 . In certain embodiments, upper heating element  118  defines an upper element height  182  (e.g., vertical distance between upper heating element  118  and bottom portion  109 ) that is less than a second sensor height  184  defined by second temperature sensor  132  (e.g., vertically between second temperature sensor  132  and bottom portion  109 ). Optionally, an upper sensor gap may be defined along the vertical direction V between the upper heating element  118  and the second temperature sensor  132  (e.g., as the difference between second sensor height  184  and upper element height  182 ) as a value less than sensor gap  176  (i.e., the lower sensor gap). In other words, the lower sensor gap  176  may be greater than the upper sensor gap between upper heating element  118  and the second temperature sensor  132 . Additionally or alternatively, a separation ratio of the first sensor height  174  over the upper element height  182  [i.e., ( 174 )/( 182 )] may be defined as a value between 0.3 and 0.8. Advantageously, the positioning of second temperature sensor  132  may ensure temperature detection of first temperature sensor  130  is not undesirably affected by heat generated at upper heating element  118 . 
     In exemplary embodiments, a base height ratio of the lower element height  172  over the volume height  170  [i.e., ( 172 )/( 170 )] may be predetermined as a value less than or equal to 0.2. Additionally or alternatively, the base height ratio may be defined as a value less than or equal to 0.1. Optionally, the base height ratio may be defined as a value between 0.2 and 0. Advantageously, the base height ratios may ensure lower heating element  119  is positioned proximate to bottom portion  109  and prevents any cold-water slug from forming therebelow. Moreover, the above-described embodiments may ensure water heater appliance  100  is able to meet various required energy usage standards (e.g. mandated by the United States government) while heating water in, for example, substantially all of interior volume  114 . 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.