METHODS FOR OPERATING HEAT PUMP WATER HEATER APPLIANCES

Abstract

Heat pump water heater appliances and operational methods therefor are provided. A method includes receiving a peak generation signal, and activating a secondary heating element of the heat pump water heater appliance when the peak generation signal is received. The method further includes activating a sealed system of the heat pump water heater appliance when the peak generation signal is received, and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

Description

FIELD OF THE INVENTION

The present subject matter relates generally to heat pump water heater appliances and methods for operating the same, and more particularly to cost and energy efficient heating of water within heat pump water heater appliances.

BACKGROUND OF THE INVENTION

Water heater appliances generally operate to heat water within the water heater appliance's tank to a set temperature. The set temperature is generally selected such that heated water within the tank is at least hot enough for showering, washing hands, etc. Heat pump water heaters are gaining broader acceptance as a more economic and ecologically-friendly alternative to electric and gas water heaters. Heat pump water heaters include a sealed system for heating water to the set temperature.

One issue with use of a sealed system is that, when the system is activated, a warm-up period is typically required before normal operation of the system commences. For example, an expansion valve of the system may cycle for a period of time (in some cases 2-3 minutes) to balance the various pressures within the system before compressor operation commences. Accordingly, slight delays in heating are incurred when typical sealed systems are utilized.

Heat pump water heater appliances generally receive power from a utility, and in exemplary embodiments an electrical utility. Power, such as electricity, is supplied by the utility to a structure, such as a residential or commercial building. Additionally, utilities have recently begun charging different prices for power at different times depending on the amount of power that is being required from the utility. At peak load times, when demand by consumers is in excess of the amount of power being generated, a higher price can be required of consumers by the utility. At peak generation times, when the amount of power being generated by the utility is in excess of the demand by consumers, a lower price can be required of consumers by the utility.

It would be generally desirable to take advantage of lower costs during peak generation periods by operating the heat pump water heater at these times. However, in some cases, periods of peak generation and peak load can occur in relatively short lengths of time, such as between 4 seconds and 10 minutes. Further, in some cases, it can take between 1 minute and 5 minutes for the sealed system to warm-up. Accordingly, a peak generation period may have expired by the time that the sealed system is operational to heat the water within the appliance.

Accordingly, improved heat pump water heater appliances and methods for operating the same are desired. In particular, cost and energy efficient heat pump water heater appliance operations which take advantage of peak generation periods would be advantageous.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one embodiment, a method for operating a heat pump water heater appliance is provided. The method includes receiving a peak generation signal, and activating a secondary heating element of the heat pump water heater appliance when the peak generation signal is received. The method further includes activating a sealed system of the heat pump water heater appliance when the peak generation signal is received, and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

In accordance with another embodiment, a heat pump water heater appliance is provided. The heat pump water heater appliance includes a tank defining a chamber, the tank further defining an inlet aperture and an outlet aperture. The heat pump water heater appliance further includes a hot water conduit extending through the outlet aperture and in fluid communication with the chamber of the tank, the hot water conduit configured for directing a flow of water out of the chamber of the tank, and a cold water conduit extending through the inlet aperture and in fluid communication with the chamber of the tank, the cold water conduit configured for directing a flow of water into the chamber of the tank. The heat pump water heater appliance further includes a sealed system configured to heat water within the chamber of the tank, and a secondary heating element configured to heat water within the chamber of the tank. The heat pump water heater appliance further includes a controller in communication with the sealed system and the secondary heating element. The controller is configured for receiving a peak generation signal, and activating the secondary heating element when the peak generation signal is received. The controller is further configured for activating the sealed system when the peak generation signal is received, and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

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 an exemplary embodiment of the present subject matter.

FIG. 2 provides a schematic view of certain components of the exemplary water heater appliance of FIG. 1.

FIG. 3 illustrates a method for operating a water heater appliance according to an exemplary embodiment of the present subject matter.

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.

FIG. 1 provides a perspective view of a water heater appliance 100 according to an exemplary embodiment of the present subject matter. FIG. 2 provides a schematic view of certain components of water heater appliance 100. As may be seen in FIGS. 1 and 2, 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 may include similar components, be constructed in a similar manner to and/or operate in the manner described in U.S. Pat. No. 8,422,870 of Nelson et al., which is hereby incorporated by reference in its entirety.

Water heater appliance 100 also includes a cold water conduit 104 and a hot water conduit 106 that are both in fluid communication with tank 112 within casing 102. As an example, cold water from a water source, e.g., a municipal water supply or a well, enters water heater appliance 100 through cold water conduit 104. From cold water 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 hot water conduit 106 and, e.g., is supplied to a bath, shower, sink, or any other suitable feature.

As may be seen in FIG. 1, water heater appliance 100 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.

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 now to FIG. 2, water heater appliance 100 includes an upper heating element 118, a lower heating element 119 and a sealed system 120 for heating water within interior volume 114 of tank 112. Thus, water heater appliance 100 is commonly referred to as a “heat pump water heater appliance.” Upper and lower heating elements 118 and 119 can be any suitable heating elements. For example, upper heating element 118 and/or lower heating element 119 may be an electric resistance element, a microwave element, an induction element, or any other suitable heating element or combination thereof. Lower heating element 119 may also be a gas burner, and water heater appliance 100 need not include upper heating element 118 when lower heating element 119 is a gas burner.

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 and/or high quality 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 and/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).

Water heater appliance 100 also includes a tank temperature sensor 130. Tank temperature sensor 130 is configured for measuring a temperature of water within interior volume 114 of tank 112. Tank temperature sensor 130 can be positioned at any suitable location within or on water heater appliance 100. For example, tank temperature sensor 130 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, tank temperature sensor 130 can be configured for indirectly measuring the temperature of water within interior volume 114 of tank 112. For example, tank temperature sensor 130 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. Tank temperature sensor 130 may also be positioned at or adjacent top portion 108 of water heater appliance 100, e.g., at or adjacent an inlet of hot water conduit 106.

Tank temperature sensor 130 can be any suitable temperature sensor. For example, tank temperature sensor 130 may be a thermocouple or a thermistor. As may be seen in FIG. 2, tank temperature sensor 130 may be the only temperature sensor positioned at or on tank 112 that is configured for measuring the temperature of water within interior volume 114 of tank 112 in certain exemplary embodiments. In alternative exemplary embodiments, additional temperature sensors may be positioned at or on tank 112 to assist tank temperature sensor 130 with measuring the temperature of water within interior volume 114 of tank 112, e.g., at other locations within interior volume 114 of tank 112.

Water heater appliance 100 further includes a controller 150 that is configured for regulating operation of water heater appliance 100. Controller 150 is in, e.g., operative, communication with upper heating element 118, lower heating element 119, compressor 122 (and thus sealed system 120 generally), and tank temperature sensor 130. Thus, controller 150 may selectively activate upper and lower heating elements 118 and 119 and/or compressor 122 in order to heat water within interior volume 114 of tank 112, e.g., in response to signals from tank temperature sensor 130 and other signals as discussed herein

It should be understood that controller 150 may be integrated within water heater appliance 100, in certain exemplary embodiments. However, in alternative exemplary embodiments, controller 150 may be separate from other components of water heater appliance 100 and be positioned outside of casing 102. Thus, controller 150 may be positioned remotely relative to casing 102, e.g., within a building housing water heater appliance 100. In such exemplary embodiments, controller 150 may wirelessly communicate with other components of water heater appliance 100.

Controller 150 includes memory 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 and/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 and/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 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. 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 and/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. 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.

Controller 150 also includes a network interface (not shown). The controller 150 of water heater appliance 100 may include any suitable components for interfacing with one more networks, such as a network 160. For example, the network interface may include transmitters, receivers, ports, controllers, antennas, or other suitable components for interfacing with network 160. The network interface may establish communication with network 160 via a connection 152. Connection 152 may be any suitable medium, e.g., wired or wireless.

Network 160 may be any type of communications network, such as a local area network (e.g. intranet), wide area network (e.g. Internet), or some combination thereof. In general, communication between controller 150 and network 160 may be carried via associated network interfaces using any type of connection, using a variety of communication protocols (e.g. TCP/IP, HTTP), encodings or formats (e.g. HTML, XML), and/or protection schemes (e.g. VPN, secure HTTP, SSL). In particular, network 160 may be a wireless local area network (WLAN) configured to conform to IEEE 802.11.

As may be seen in FIG. 2, controller 150 may receive data or information from various sources via network 160. For example, controller 150 may be in communication with a utility 162 that is providing power to the appliance 100. In exemplary embodiments, the utility may be an electrical utility which is providing electrical power to the appliance 100. The utility 162 may send signals to the controller 150, in some cases via a network 160, to control operation of the appliance 100. For example, utility 162 may send signals regarding the demand status of the utility 162, i.e. whether the demand status is operating at peak load, peak generation, or normal operation (between peak load and peak generation). For example, utility 162 may send peak load signals and peak generation signals (as well as normal operation signals). In exemplary embodiments, the peak load and peak generation signals may correspond to different line frequencies; i.e. the frequency of oscillations of alternating current being transmitted from the utility to the end user and thus to the appliance 100. For example, in some embodiments, a peak generation signal may be a line frequency of greater than a normal line frequency, i.e. 50 Hertz or 60 Hertz. A peak load signal may be a line frequency of less than a normal line frequency, i.e. 50 Hertz or 60 Hertz. Accordingly, a non-peak generation signal may be a signal that corresponds to normal operation or peak load operation, and may thus in some embodiments be considered to be a normal line frequency or a frequency of less than a normal line frequency, i.e. at or below 50 Hertz or at or below 60 Hertz. In other embodiments, the peak load and peak generation signals may be electronic signals received (either wirelessly or via a wired connection) by the controller 150, such as from the utility 100. In general, a peak load signal indicates that demand on the utility 162 is in excess of the amount of power being generated, and may be associated with a relatively higher power price. In general, a peak generation signal indicates that the amount of power being generated by the utility is in excess of the demand, and may be associated with a relatively lower power price.

Notably, while in some embodiments controller 150 is configured, via a wired or wireless connection, to receive electronic signals as discussed, in other embodiments, controller 150 may simply be configured to receive line frequencies from the utility 162. In either case, controller 150 may receive signals in accordance with the present disclosure.

Signals as discussed above may be received by the controller 150. The controller 150 may advantageously utilize the received signals to control operation of the appliance 100. For example, the controller 150 through measurement of the voltage oscillations may analyze the line frequency, and may thus be instructed via the utility 162 demand response signal. Such instruction may include, as discussed herein, deactivating particular heat sources when the line frequency shows signs of sagging, indicating high demand, and is thus considered a peak load signal. Such instruction may further include, as discussed herein, activating particular heat sources when the line frequency shows signs of surging, indicating low demand, and is thus considered a peak generation signal. Such features of water heater appliance 100 are discussed in greater detail below in the context of FIG. 3.

FIG. 3 illustrates a method 300 for operating a water heater appliance in accordance with one embodiment of the present disclosure. Method 300 may be used to operate any suitable heat pump water heater appliance. For example, method 300 may be used to operate water heater appliance 100. Thus, method 300 is discussed in greater detail below in the context of water heater appliance 100. In exemplary embodiments, controller 150 may be configured or programmed to implement various steps of method 300. Operation of an appliance 100 as discussed herein may advantageously be relatively cost and energy efficient by taking advantage of peak generation periods to heat water within the appliance 100.

Method 300 may include, for example, the step 310 of receiving a peak generation signal, such as from utility 162 as discussed above. Method 300 may further include, for example, the step 320 of activating one or more secondary heating element 118, 119 when the peak generation signal is received. Such activation may be performed upon receipt of the peak generation signal and in response to the peak generation signal. Such activation may cause heating of water within tank 112 by the secondary heating elements 118, 119. In exemplary embodiments, the secondary heating elements 118, 119 may be electrical resistance elements, although alternatively, other suitable secondary heating elements 118, 119 as discussed herein may be utilized. Such activation may advantageously facilitate heating of water within the tank 112 during peak generation times, and thus in many cases at relatively lower cost to the consumer.

Method 300 may further include, for example, the step 315 of increasing a set temperature t_s when the peak generation signal is received. For example, the set temperature t_s may be increased to a temperature value above a predetermined value, i.e. a value set by the user or a default value, as discussed above. In some embodiments, for example, the set temperature t_s may be increased to a maximum set temperature value, i.e. a maximum value at which the set temperature t_s can be set. Step 315 in exemplary embodiments may occur before step 320. Further, in some embodiments, step 320 may occur at least partially as a result of the occurance of step 315. In other words, because the set temperature t_s is increased, one or more secondary heating elements may be activated.

Method 300 may further include, for example, the step 330 of activating the sealed system 120 when the peak generation signal is received. Such activation may be performed upon receipt of the peak generation signal and in response to the peak generation signal. Notably, activation of the sealed system 120 may in some embodiments cause the sealed system 120 to function in a “warm-up” state, rather than in an operational state. When the sealed system 120 is operational, the system 120 is performing active heating operations as discussed herein. When the sealed system 120 is warming up, the system 120 is preparing to perform active heating operations, and for example, the throttling device 126 is cycling between open and closed positions to equalize pressures within the system 120. Notably, the compressor 122, may operate when the sealed system 120 is operational, but may not operate when the sealed system 120 is warming up.

Method 300 may further include, for example, the step 340 of deactivating the one or more secondary heating elements 118, 119 when the sealed system 120 is operational after activation or when a non-peak generation signal is received, such as from the utility 162, subsequent to receipt of the peak generation signal. For example, in some cases, the sealed system 120 may become operational (after warming up) before the peak generation period has ended. In these cases, the secondary heating elements 118, 119 may be deactivated, and the sealed system 120 allowed to actively heat the water within the tank 112. Such deactivation may occur, for example, upon initiation of operation of the sealed system 120. In other cases, the peak generation period may end before the sealed system 120 becomes operational. In these cases, the secondary heating elements 118, 119 may be deactivated to cease power consumption thereby. In exemplary embodiments, whichever case occurs first after step 320 and 330 may cause the one or more secondary heating elements 118, 119 to be deactivated.

Method 300 may further include, for example, the step 350 of deactivating the sealed system 120 when a non-peak generation signal is received, such as from the utility 162, subsequent to receipt of the peak generation signal (i.e. subsequent to step 310). Such deactivation may occur whether the sealed system 120 is operational or warming up, and may occur to cease power consumption thereby.

Method 300 may further include, for example, the step 335 of decreasing the set temperature t_s when a non-peak generation signal is received. For example, the set temperature t_s may be decreased to a temperature value below the value to which the set temperature t_s was previous increased (i.e. in step 315). In some embodiments, the set temperature t_s may be decreased to a predetermined value, i.e. a value set by the user or a default value, as discussed above. Step 335 in exemplary embodiments may occur before step 340 (when step 340 occurs due to receipt of a non-peak generation signal) and/or step 350. Further, in some embodiments, step 340 (when step 340 occurs due to receipt of a non-peak generation signal) and/or step 350 may occur at least partially as a result of the occurance of step 335. In other words, because the set temperature t_s is decreased, the one or more secondary heating elements and/or sealed system 120 may be deactivated.

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.

Claims

1. A method for operating a heat pump water heater appliance, the method comprising:

receiving a peak generation signal;

activating a secondary heating element of the heat pump water heater appliance when the peak generation signal is received;

activating a sealed system of the heat pump water heater appliance when the peak generation signal is received; and

deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

2. The method of claim 1, further comprising deactivating the sealed system when the non-peak generation signal is received subsequent to receipt of the peak generation signal.

3. The method of claim 1, wherein the secondary heating element is an electrical resistance heating element.

4. The method of claim 1, wherein the peak generation signal is a line frequency of above 60 Hertz.

5. The method of claim 1, wherein the non-peak generation signal is a line frequency of at or below 60 Hertz.

6. The method of claim 1, further comprising increasing a set temperature for the heat pump water heater appliance when the peak generation signal is received.

7. The method of claim 6, wherein the set temperature is increased to a maximum set temperature value.

8. The method of claim 1, further comprising decreasing the set temperature for the heat pump water heater appliance when the non-peak generation signal is received.

9. The method of claim 8, wherein the set temperature is decreased to a predetermined set temperature value.

10. A heat pump water heater appliance, the heat pump water heater appliance comprising:

a tank defining a chamber, the tank further defining an inlet aperture and an outlet aperture;

a hot water conduit extending through the outlet aperture and in fluid communication with the chamber of the tank, the hot water conduit configured for directing a flow of water out of the chamber of the tank;

a cold water conduit extending through the inlet aperture and in fluid communication with the chamber of the tank, the cold water conduit configured for directing a flow of water into the chamber of the tank;

a sealed system configured to heat water within the chamber of the tank;

a secondary heating element configured to heat water within the chamber of the tank;

a controller in communication with the sealed system and the secondary heating element, the controller configured for: receiving a peak generation signal; activating the secondary heating element when the peak generation signal is received; activating the sealed system when the peak generation signal is received; and deactivating the secondary heating element when the sealed system is operational after activation or when a non-peak generation signal is received subsequent to receipt of the peak generation signal.

11. The heat pump water heater appliance of claim 10, wherein the controller is further configured for deactivating the sealed system when the non-peak generation signal is received subsequent to receipt of the peak generation signal.

12. The heat pump water heater appliance of claim 10, wherein the secondary heating element is an electrical resistance heating element.

13. The heat pump water heater appliance of claim 10, wherein the peak generation signal is a line frequency of above 60 Hertz.

14. The heat pump water heater appliance of claim 10, wherein the non-peak generation signal is a line frequency of at or below 60 Hertz.

15. The heat pump water heater appliance of claim 10, wherein the controller is further configured for increasing a set temperature for the heat pump water heater appliance when the peak generation signal is received.

16. The heat pump water heater appliance of claim 15, wherein the set temperature is increased to a maximum set temperature value.

17. The heat pump water heater appliance of claim 10, wherein the controller is further configured for decreasing the set temperature for the heat pump water heater appliance when the non-peak generation signal is received.

18. The heat pump water heater appliance of claim 17, wherein the set temperature is decreased to a predetermined set temperature value.

19. The heat pump water heater appliance of claim 10, wherein the controller is in communication with a network, the network in communication with a utility.

20. The heat pump water heater appliance of claim 19, wherein the controller is in wireless communication with the network.