Abstract:
A hot water heater and method that includes power consumption reporting to enable consumers to better understand and control the energy usage and/or efficiency of the hot water heater. Monitoring energy consumption of an electric hot water heater having at least one electrical load that is selectively activated by a controller of the hot water heater includes sensing the amount of time the at least one electrical load is activated multiplying the amount of time by a known value corresponding to a power rating of the electrical load to determine energy consumed, and displaying on a display device an indicator corresponding to the energy consumed.

Description:
BACKGROUND OF THE DISCLOSURE 
     The following disclosure relates to energy management, and more particularly to energy management of household consumer appliances, as well as other energy consuming devices and/or systems found in the home. The present disclosure finds particular application to a hot water heater. 
     Basic hot water heaters generally include a water reservoir, a heating element such as a gas or electric burner, and a thermostat that controls the burner to maintain a set temperature of the water in the reservoir. In general, the temperature of the water is maintained at a relatively constant level corresponding to a set point of the thermostat, for example 140 degrees F, until it is needed. As hot water is dispensed from the reservoir, cold water is admitted thereby lowering the temperature of the water. Once the temperature drops below the set point of the thermostat, the heating element is activated to raise the temperature of the water. 
     Hot water heaters, and electric hot water heaters in particular, consume a significant amount of household electrical power. By way of example, in some instances a hot water heater consumes more energy than a several other appliances (e.g., washer, dishwasher, refrigerator, etc.) combined. Many consumers are not aware of the amount of energy a hot water heater consumes, or of the impact of the set point temperature on the efficiency and/or energy consumption of a hot water heater. 
     SUMMARY OF THE DISCLOSURE 
     A hot water heater is provided that includes power consumption reporting to enable consumers to better understand and control the energy usage and/or efficiency of the hot water heater. By providing the consumer with power consumption information, the consumer can make decisions regarding the set point temperature and/or other scheduling that can not only reduce energy consumption, but also save the consumer money. 
     According to one aspect, a method of monitoring energy consumption of an electric hot water heater, the hot water heater having at least one electrical load that is selectively activated by a controller of the hot water heater comprises sensing the amount of time the at least one electrical load is activated, multiplying the amount of time by a known value corresponding to a power rating of the electrical load to determine energy consumed, and displaying on a display device an indicator corresponding to the energy consumed. 
     The sensing can be performed by a microprocessor that senses when the controller activates the load. The hot water heater can have a plurality of electrical loads, and the sensing step can include sensing the amount of time each of the plurality of electrical loads is activated, and the multiplying step can include multiplying the amount of time sensed for each load by a corresponding power rating to determine energy consumed. The method can further comprise the step of summing energy consumed as computed for each load to determine total energy consumption of the hot water heater. The method can further include accessing a lookup table having values corresponding to the power ratings for the at least one load. The displaying step can include displaying at least one of total energy consumption, annual energy consumption, monthly energy consumption, weekly energy consumption, daily energy consumption, hourly energy consumption, and instantaneous energy consumption. The displaying step can include displaying an indicator on a display that is remote from the water heater. The displaying step can include displaying at least one of a numerical value, graphical representation, color, or shape corresponding to energy consumed. 
     In accordance with another aspect, an electric hot water heater for supplying hot water comprises a cold water inlet; a hot water outlet; an electric heat source for applying heat to a volume of water between the inlet and the outlet; a controller for selectively activating the heat source to heat the water, and a processor configured to: sense an amount of time the electric heat source is activated; and multiply the amount of time by a known value corresponding to a power rating of the electrical load to determine energy consumed by the electric heat source. 
     The water heater can further comprise a display for displaying an indicator corresponding to the energy consumed by the hot water heater. At least one of total energy consumption, annual energy consumption, monthly energy consumption, weekly energy consumption, daily energy consumption, hourly energy consumption, and instantaneous energy consumption can be displayed on the display. The display can be remote from the water heater. At least one of a numerical value, graphical representation, color, or shape corresponding to energy consumed can be displayed on the display. The hot water heater can have a plurality of electrical loads including the electric heat source, and the processor can be configured to sense the amount of time each of the plurality of electrical loads is activated and multiply the amount of time sensed for each load by a corresponding power rating to determine energy consumed, and further configured to sum the energy consumed as computed for each load to determine total energy consumption of the hot water heater. A lookup table stored in a memory associated with the processor can have at least one value corresponding to the power ratings of the electric heat source. The lookup table can further include power ratings for a plurality of electric loads of the hot water heater. 
     According to another aspect, a device for monitoring energy usage of an electric hot water heater comprises a processor for sensing an amount of time at least one electrical load of the hot water heater is activated and multiplying the amount of time sensed by a power rating to determine energy consumed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an exemplary hot water heater in accordance with the present disclosure. 
         FIG. 2  is a schematic diagram of another exemplary hot water heater in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings,  FIG. 1  illustrates an electric hot water heater  10  including a housing  12  in a which a reservoir  14  tank and a heat source  16  are enclosed. The heat source can be in the form of a resistive heating element, heat pump, or other electric heating device (or any combination thereof). The heat source  16  receives power from an electric power supply  18  and converts the power to thermal energy for heating the water in the tank  14 . Cold water is admitted to the reservoir  14  via cold water inlet  22 . Hot water is dispensed via a hot water outlet  24  for distribution to one or more hot water taps (not shown) or other hot water discharge (e.g., washing machine). 
     As will be appreciated a controller  30 , such as a thermostat, microprocessor or the like, controls the operation of the heat source. Such controller  30  typically operates to activate the heat source  16  to apply heat to a volume of water within the reservoir  14  to heat the water to a desired set point. The basic components and basic operation of the water heater  10 , as described to this point can be conventional, and further details of such conventional water heater are well-known and will not be described further. 
     In accordance with an aspect of the disclosure, a sensor unit  40  includes a processor  42 , a memory  44  and a sensor  46 . The sensor  46  is in communication with the controller  30  for sensing energy consumption by the heat source  16  and/or by other electrical loads of the hot water heater. Although the sensor unit  40  is shown in  FIG. 1  as a separate component, it will be appreciated that in practice the sensor unit  40  can be integrated with the controller  30 , and/or the controller itself can be adapted to perform the functions of the sensor unit as described herein. 
     As will be appreciated, the hot water heater  10  may have a plurality of electrical loads. For example, some hot water heaters may have a resistive heating element that can be operated at multiple output levels. In many hot water heaters, two or more resistive elements are employed (e.g., upper and lower heating elements). A hybrid electric water heater may include a heat pump and one or more resistive heating elements. The heat pump may typically include both a compressor and a fan, each constituting an electric load. Each of the resistive elements, compressor, fan etc., represent an electrical load. 
     In operation, the sensor  46  is configured to sense the amount of time each of the one or more electrical loads is activated. This can be done by detecting when the controller  30  activates/deactivates a respective load. That is, the sensor unit can be configured to assume a load is activated when commanded by the controller and likewise deactivated when commanded to deactivate by the controller. Thus, the sensor unit may be configured simply to receive a signal from the controller indicative of activation/deactivation of a given load. 
     In some embodiments, the sensor may include a device for measuring directly the power consumption of the water heater. Such device could be a submeter adapted to measure power flowing to the hot water heater via the electric power supply line  18 , for example. 
     Each of the electrical loads correspond to a respective power rating that may be stored in memory  44 . For example, activation of both resistive heating elements in a standard water heater may draw 5 kW of power, each resistive element drawing approximately 2.5 kW. In a hybrid electric water heater having a heat pump, the resistive heating elements may draw 4.5 kW, while the compressor draws 600 W and the fan 50 W. For a given water heater, the values corresponding to the power rating of each electrical load would be programmed or stored in the memory  44  of the sensor unit (e.g., a lookup table). 
     Once the sensor  46  has detected activation of one or more loads over time, energy consumption can be calculated by the processor by multiplying the power rating value by the amount of time a particular load is activated. Thus, if the compressor is running for 1.5 hours at a power rating of 600 W, the processor would determine that 900 Wh of energy was consumed by the compressor. By way of further example, consider the following table which illustrates the determination of power consumption by a hot water heater over a 24 hour period. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Time active  
                 Power  
                 Power  
               
               
                   
                 Load Name 
                 over last 24 h 
                 Rating 
                 Consumption 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Res. Heat element 1 
                 1.2 hour 
                 2.5  
                 kW 
                 4.5  
                 kWh 
               
               
                   
                 Compressor 
                 4.6 hour 
                 600 
                 W 
                 2.76  
                 kWh 
               
               
                   
                 Fan 
                 4.2 hour 
                 50 
                 W 
                 210  
                 Wh 
               
             
          
           
               
                   
                 TOTAL 
                   
                   
                 7.47  
                 kWh 
               
               
                   
                   
               
             
          
         
       
     
     In the table above, the sensor detects activation of the one or more loads over a 24 hour period. As will be appreciated, each load may be activated/deactivated multiple times over the 24 hour period, and the second column displays the total time activated for each load over the 24 hour period. Then the processor  42 , for each load, multiplies the time active by the power rating (column 3) for the respective load. The power consumption for each load is then provided in the fourth column. To calculate the total energy consumption of the hot water heater over the 24 hour period, the power consumption of each load (column 4) is then summed, resulting in 7.47 kWh of energy consumed over the 24 hour period. 
     It will be appreciated that the processor  42  can provide power consumption data over any period of time, for example, total energy consumption (lifetime of unit), annual energy consumption, monthly energy consumption, weekly energy consumption, daily energy consumption, hourly energy consumption, as well as instantaneous power consumption. 
     This energy consumption data is then displayed on the display  50  for viewing by a consumer. The display may be provided as part of the hot water heater, such as part of a control panel or the like, and may optionally display other information in addition to the energy consumption data. For example, the display could be used for programming operation of the hot water heater, such as setting a set point, or turning off the unit. In this regard, the display  50  could be a touchscreen display for allowing a user to input data to the system. 
     The display  50  can be configured to display a wide variety of data relating to energy consumption. Raw energy consumption data can be displayed, such as the total kWh consumed etc. Some consumers, however, may not find such raw data useful. Accordingly, the display  50  can be configured to display graphical representations of energy consumption. Such graphical representations can include, charts, graphs, colors, shapes, etc. that correspond to energy consumption. 
     By way of example, when the hot water heater is consuming a small amount of energy, a green image may be displayed to indicate low power operation. As energy consumption increases, the green image can be transitioned to, or replaced by, a red image. Alternatively, a graph showing energy consumption of the hot water heater over time may be displayed, or a chart illustrating energy usage over the past week, month, year, etc. Of course, other types of graphical display can be employed as desired. 
     Turning to  FIG. 2 , another exemplary hot water heater  60  is illustrated as part of a home energy management system  62 . Home energy management (HEM) systems are becoming a key to reducing energy consumption in homes and buildings, in a consumer friendly manner. Existing HEMs are commonly in the form of a special custom configured computer with an integrated display, which communicates to devices in the home and stores data, and also has simple algorithms to enable energy reduction. 
     Key functions of a HEM include:
         Creates a network of energy consuming devices within the home,   Measures the consumption of the whole home/building or individual devices,   Records and stores energy consumption information in a database, and   Enables consumer interface with all energy consuming devices in a home to:
           view consumption data of individual devices   set preferences for operation of energy consuming devices at different times during the day or at different energy pricing levels   control/program energy consuming devices.   
               

     Returning to  FIG. 2 , the hot water heater includes a reservoir  64  and a heat source  66  connected to an electric power supply  68 . A cold water inlet  72  admits water to the reservoir  64 , while hot water flows from the reservoir  64  via hot water outlet  74 . As will be understood, a controller  80  controls the heat source  56  in a conventional manner to heat the water in the reservoir  54 . 
     A sensor  96  is provided for sensing the activation of one or more loads of the hot water heater  60 , as previously described. In this embodiment, however, the sensor  96  is a separate unit that includes a communication interface  98  for communicating with a home energy manager (HEM) unit  100  that includes a processor  102  and a memory  104 . A display  106  is connected to the HEM  100  for displaying information related to energy consumption of the hot water heater  60  to a consumer. 
     The sensor  96  can be installed on the water heater  60  and can communicate data sensed to the HEM for use by the HEM  100 . In this regard, the communication interface  98  can be any suitable wired or wireless interface such as WIFI, Bluetooth, Zigbee, Ethernet, etc. 
     As will be appreciated, the sensor  96  operates in the same manner as the previously described sensor to detect activation of one or more electrical loads of the hot water heater  60  by the controller  80 . The sensor  96  then relays such information to the HEM  100  via the communication interface  98 , and the processor  102  calculates the energy consumption of the hot water heater  60  in the manner set forth previously. As with the embodiment of  FIG. 1 , it will be appreciated that the sensor  96  can be integrated with the controller  80  and/or the controller  80  can be configured to perform the functions of the sensor  96 . 
     By providing the information to the HEM unit  100 , the energy usage of the hot water heater  60  can be calculated and displayed to a consumer in the same manner as described in connection with  FIG. 1 . This can provide a more convenient interface for a consumer since, unlike a water heater that is often installed in a basement or closet (or otherwise out-of-sight), the display  106  associated with the HEM unit  100  is more likely installed in a readily accessible location. For example, a HEM unit  100  may be installed in a kitchen or laundry room. Accordingly, display of energy consumption information is more likely to be seen by a consumer in such configuration. 
     Moreover, the energy consumption data can be utilized by the HEM unit  100  in its functions to actively manage energy use within the household. For example, given that the HEM unit  100  is uniquely aware of energy consumption of other devices in a household that consume hot water, such as a dishwasher, clothes washer, etc., the HEM unit  100  can utilize such information in combination with the energy consumption data relating to the water heater to usage to customize control of the water heater. For example, starting the dishwasher could be delayed until late in the evening after evening showers are taken. In a home having a hybrid electric water heater, delaying operation of the dishwasher can represent more efficient operation since it may be possible to utilize only the more efficient heat pump rather than the resistive heating elements. Other uses of the energy consumption data are also possible. 
     As will be appreciated, the processor  102  and memory  104  of the present embodiment are housed within the home energy management unit  100 , separate from the sensor  96 . However, it will be understood that the sensor  96 , communication interface,  98 , processor  102  and memory  104  could all be provided as a separate sensor unit, similar to the sensor unit  40  of  FIG. 1 . Further, such sensor unit could be integrated with the controller  80  and/or the controller  80  can be configured to perform the various functions of the sensor/sensor unit as described above. 
     The disclosure has been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the disclosure be construed as including all such modifications and alterations.