Patent Application
20250109888
This disclosure relates to a system and method for water heater twinning.
Conventionally, water heaters may be combined in a configuration known as twinning where two or more water heaters are plumbed together. Nevertheless, there remain opportunities for improvements in water heater systems with twinned water heaters in terms of operation, efficiency, satisfaction of hot water demand, and/or ease of set up and operation.
The following description is directed, according to one aspect of the invention, to a water heater system including a first water heater including a first controller configured to transmit and receive a token; and a second water heater including a second controller configured to transmit and receive the token. The first water heater is plumbed to the second water heater in a twinned configuration, and the first controller is in communication with the second controller, the first controller being configured to control the first water heater to perform a first heating cycle while in possession of the token, and then transmit the token to the second controller, and the second controller being configured to control the second water heater to perform a second heating cycle while in possession of the token, and then transmit the token to the first controller.
According to another aspect of the invention, a method is provided for controlling a water heater system including a first water heater having a first controller and a second water heater having a second controller, where the first water heater is plumbed to the second water heater in a twinned configuration and the first controller of the first water heater is in communication with the second controller of the second water heater, the method comprising: controlling, by the first controller, the first water heater to perform a first heating cycle while in possession of a token; transmitting, by the first controller, the token to the second controller; controlling, by the second controller, the second water heater to perform a second heating cycle while in possession of the token; and transmitting, by the second controller, the token to the first controller.
According to still another aspect of the invention, a controller is provided for controlling a water heater configured to be twinned in a twinned configuration to an other water heater having an other controller, the controller of the water heater being configured for communication with the other controller of the other water heater, the controller comprising a processor configured to control the water heater to perform a first heating cycle while in possession of a token, and then transmit the token to the other controller, and receive the token from the other controller after the other water heater performs a second heating cycle while in possession of the token.
According to yet another aspect of the invention, a water heater is configured to be twinned with an other water heater, the water heater comprising plumbing connections configured to be plumbed to plumbing connections of the other water heater; and a controller configured to communicate with an other controller of the other water heater, control the water heater to perform a first heating cycle while in possession of a token, and then transmit the token to the other controller of the other water heater when the water heater is twinned with the other water heater, and receive the token from the other water heater after the other water heater performs a second heating cycle while in possession of the token.
According to another aspect of the invention, a method is provided for twinning a first water heater with a second water heater, the method comprising plumbing first plumbing connections of the first water heater to second plumbing connections of the second water heater; communicatively connecting a first controller of the first water heater to a second controller of the second water heater; and powering the first controller of the first water heater and the second controller of the second water heater to exchange possession of a token required for the first controller of the first water heater or the second controller of the second water heater to perform a heating cycle to ensure non-simultaneous operation of the first water heater and the second water heater when the first water heater is twinned with the second water heater.
The figures depict one or more implementations, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.
The twinning of water heaters has become more common in recent years to enable smaller sized tanks to be plumbed together in order to meet increased demand for hot water in both residential and commercial settings. Although in a twinning configuration the water heaters are plumbed together, they are typically controlled independently of one another. In other words, conventionally twinned water heaters perform heating cycles without regard to one another. This can, in some cases, lead to inefficiencies in meeting hot water demand.
In addition, electric water heaters are becoming more common in both residential and commercial installations. Electric water heaters generally include one or more resistive heating elements for heating water within the water heater tank. These heating elements draw large amounts of electrical current when they are powered (e.g. when the heating elements are powered ON). Therefore, electric water heaters are typically isolated to a respective electrical circuit (e.g. 240V/30 A). However, isolating each water heater to a separate electrical circuit can be costlier (e.g. additional wiring, additional circuit breakers, additional labor, etc.) and may not be possible in certain scenarios (e.g. a circuit breaker panel may not have additional open slots to support additional circuits).
Thus, there is a need to be able to coordinate heating cycles between two or more twinned electric water heaters to achieve various goals. Coordination of heating cycles not only addresses the goals of increased efficiency and performance in meeting hot water demand, but also provides a solution for two or more twinned electric water heaters to share a common electrical circuit without overloading the electrical circuit.
In general, the controller 108 can include devices, such as a microprocessor, memory devices, analog input/output (I/O), digital I/O, power regulation, etc. (not shown), which serve to perform various operations. For example, such operations may include actions related to transmission and receipt of a token to the two twinned water heaters, collecting and recording temperatures from sensors 118/119, and acting upon those temperatures to control the possession of the token based on those temperatures.
The memory of the controller 108 generally stores the programming for the controller 108. For example, the memory stores instructions that, when executed by the controller 108, cause the controller 108 to provide functionality related to temperature detection programming, coordinating the heating cycles between the two or more twinned water heaters, determining whether the twinned configuration is a series plumbing configuration or a parallel plumbing configuration of the two or more water heaters, etc. To facilitate these programs, the memory also stores various values, including but not limited to temperature values associated with the operation of the twinned water heaters; desired setpoint temperatures which can be set by the user; temperature records comprising the time, temperature, and the thermistors that recorded the corresponding temperature; and other information relevant to water heater control.
In operation, cold water inlet 102 receives cold water from cold-water feed 101. The cold water is introduced into the bottom of the tank via dip tube 106. Respective hubs 110/112 are mounted external to the tank, while electric heating elements 114/116 are mounted internal to the tank. The hubs include electrical terminals for providing the necessary power to actuate electric heating elements 114/116. During operation, the controller 108 generally monitors the temperatures in the upper/lower portions of the tank via upper/lower temperature sensors 118/119. The upper/lower temperature sensors 118/119 may be mounted on the outer surface of the tank wall such that they are thermally coupled to the tank wall 100. In general, the temperature of the outer tank wall correlates to the temperature of the water inside the tank. Thus, the upper temperature sensor 118 is able to detect the temperature of the water in the upper portion of the tank, while the lower temperature sensor 119 is able to detect the temperature of the water in the lower portion of the tank. The controller 108 uses these temperature readings to control the powering of the upper and lower heating elements 114/116 based on a setpoint temperature set by the user. Typically, the upper and lower heating elements 114/116 are actuated one at a time. For example, if the water in the lower portion of the tank drops below the setpoint temperature, then the controller 108 actuates the lower heating element 116. If the water in the upper portion of the tank drops below the setpoint temperature, then the controller 108 actuates the upper heating element 114.
The overall goal is to provide water (at the setpoint temperature) to the user via the hot water outlet 104 and hot water pipe 103. Generally, the upper portion of the tank takes precedent over the lower portion of the tank because the hot water is typically delivered from the upper portion of the tank. Thus, controller 108 may actuate upper heating element 114 if upper temperature sensor 118 indicates a heating demand even if lower temperature sensor 119 also indicates a heating demand. Heat demand is determined when the temperature sensor indicates that the water in the tank is below a desired setpoint temperature which is set by the user. Once the upper portion of the tank is recovered, the controller 108 is then able to actuate lower heating element 116 (if demand is needed) and recover the bottom portion of the tank. Of course, other control logic and priorities are contemplated as well, depending on the particular water heater configuration and other factors.
As mentioned above, some details are not shown in
As mentioned above, the water heater may include an optional heat pump 120 that may have various components that are not shown because they are known to one of skill in the art. These components include, but are not limited to, heat exchanger coils, a compressor, an expansion valve, and a fan. During operation, ambient air is sucked into an air heat exchanger coil in the top of the tank. The heat from the ambient air is absorbed into refrigerant flowing through the air heat exchanger. The refrigerant is then compressed, thereby increasing its temperature even further. This hot refrigerant then flows through a water heat exchanger inside the tank that is in contact with the water in the tank. The water in the tank absorbs the heat from the water heat exchanger and sends the cooled down refrigerant back to the air heat exchanger via an expansion valve. This process is triggered by controller 108 and is continuously repeated until the tank water reaches a setpoint temperature. The powering of the electric heating elements may also occur in conjunction with the heat pump if the heat pump alone cannot meet the heat demand due to high water usage and/or the low temperature of the incoming cold water.
Electric water heaters such as the one shown in
Regardless of the twinning configuration (series or parallel) of the electric water heaters, the controllers 108A/108B of the electric water heaters are coupled (wired or wirelessly) together via communication channel 202 to provide communication and coordination of operation (e.g., coordination of actuation). Such coordination of operation is beneficial for ensuring performance (e.g., adequately meeting hot water demand by the user) and ensuring efficiency (e.g., not heating more water than is needed). Such coordination of operation can also be beneficial for managing temperature recovery. For example, in a parallel twinning configuration, it may not be desirable to heat the water in one of the tanks of the two electric water heaters before heating the water in the other tank because if the water in one of the tanks is completely cold and the water in the other tank is completely hot, then the parallel twinning configuration would deliver warm water, and not hot water, as desired. Heating the water in both tanks to increase the water temperature in both tanks at the same time or heating first the water in the top portions of both tanks and after that heating the water in the bottom portion of the two tanks would be preferable. To achieve these objectives, possession of the token can be divided between the two electric water heaters for a specific range of temperature. For example, one of the electric water heaters can have possession of the token for the next 10 F degrees of temperature recovery while the other electric water heater can have possession of the token for the next temperature range or in a load leveling. Similarly, in a series twinning configuration, it may be desirable to heat the water in one of the tanks of the two electric water heaters (e.g., the lead tank) first, such that the lead tank can provide hot water in response to future demand of hot water over the follower tank. In addition, coordination of operation provides a solution that allows two or more electric water heaters to share the same electric circuit without overloading the circuit. This is primarily accomplished by coordinating operation such that the electric water heaters do not actuate (e.g., power up) their respective heating elements simultaneously.
As mentioned above, the twinned electric water heaters shown in
As mentioned above, during operation, the user sets a setpoint temperature via the user I/O (e.g., rotatable knob and the like) for both tanks. This setpoint, as well as the sensed temperatures, are used by the controllers 402A/402B to control actuation of the respective heating elements. In addition, the tank controllers 402A/402B pass what is referred to as a “token” back and forth to coordinate heating cycles. In general, possession of the token authorizes the respective controller 402A/402B to be able to actuate its heating elements if/as needed (i.e., heat demand determined based on the setpoints and sensed temperatures), while non-possession of the token prevents the respective controller 402A/402B from actuating its heating elements regardless of heat demand. Essentially, the token is a permission that ensures non-simultaneous firing of the tanks. In practice, the token may be a piece of digital information (e.g., a known code, flag, etc.) that is passed between the tank controllers 402A/402B to coordinate firing of heating elements.
In one example, the token can be an all-or-nothing token as described above, where the controller in possession of the token is able to actuate its heating elements, while the controller not in possession of the token is prevented from actuating its heating elements. In another example, the token may allow both water heaters to actuate at the same time as long as their combined power consumption is less than the circuit capacity. For example, in a scenario where each water heater element is actuated at the same time, the token may be split up into pieces such that a tank can actuate its heating elements at a rate that correlates to the amount (e.g., percentage) of token in its possession. In a typical situation, a token can represent the maximum current draw allowed. This value may be set according to a particular water heater model. For example, some water heaters are designed for use with 50 amp breakers, 30 amp breakers, 25 amp breakers, or other current draws. The heating elements (and perhaps a compressor in the case of a heat pump water heater) are typically sized and controlled to not over-draw the maximum current rating as maximum wattage draw for a given voltage.
If, for example, two heat pump water heaters are twinned, it may not be desirable to repeatedly cycle a compressor on/off as a token (as permission to use power from the electrical circuit) is passed back and forth between the water heaters. In this case, a lead controller may subtract a portion of the token before passing it to a follower controller. For example, the lead controller may be using no power, so it passes the full token to the follower controller. The follower controller may then use up to the full amount of power indicated by the token. But if the lead controller is using compressor heat, the lead controller may pass a reduced value token to the follower controller. In this case, the follower may only use power up to the value of the token passed to it.
If the lead controller passes the full token to a follower controller and the follower controller calls for a portion of the token for compressor heat, the follower controller may return a reduced value token back to the lead controller after a predetermined time or event expires. The follower controller would do this if the need for compressor heat was not satisfied. In this case, the lead controller has the option of accepting the reduced value token or demanding the full token back from the follower controller. If the full token is demanded, the follower controller will drop all use of power and return the full value of the token back to the lead controller.
For example, if a Tank 1 controller holds 100% of the token and the Tank 2 controller holds 0% of the token, the Tank 1 controller can actuate its heating elements at 100% capacity, while a Tank 2 controller can actuate its heating elements at 0% (i.e., cannot actuate at all) capacity. However, in another example, if the Tank 1 controller holds 60% of the token and the Tank 2 controller holds 40% of the token, the Tank 1 controller can actuate its heating elements at 60% capacity, while the Tank 2 controller can actuate its heating elements at 40% capacity.
Possession of the token (or a percentage of the token) essentially represents the maximum current draw allowed to a heating element, while also considering the maximum allowed power capacity of the circuit. As in the example provided above, in which water heaters can be built for 50 A circuit breakers, 30 A circuit breakers, 25 A circuit breakers, etc.), the heating elements of the water heater (which may include a compressor in the case when the water heater uses a heat pump) are sized and controlled to not overdraw the maximum current rating indicated on the rating plate of the heating element as the maximum wattage draw (e.g., 1000 W, 2000 W, etc.) for a given voltage. When the system includes compressors, which are considered as separate elements, using both heating elements when the compressors operate can cause overheating of the system.
The twinning can therefore be used to share loads back and forth between the heating elements. In certain circumstances, the heating elements can both operate during a certain percentage of time, with a rest period, to avoid damage due to overheating to the system. The heating elements can both operate during a certain percentage of time, so long as they are not operating in the same time slot and at a capacity that will overload the system. It is important to know the type of the heating elements in order to establish a time-sharing arrangement. In the case when two heat pump water heaters are twinned, it is not desirable to keep cycling on/off the compressor(s) as the token (e.g., permission to use power from the electrical circuit) is passed back and forth as noted above. In this case, the leader controller may subtract a portion of the token before passing the token to the follower controller. For example, if the water heater is using compressor heat, the leader controller may pass a reduced value token to the follower controller. In this case, the follower controller may only use power up to the value of the token that is passed to it. If the leader controller passes the full token to the follower controller, and the follower controller uses a portion of the token for compressor heat, the follower controller may return a reduced value token back to the leader controller after the predetermined time or event expires. In this case, the leader controller has the option of accepting the reduced value token or demanding the full token back from the follower controller. If the full token is demanded, the follower controller will have to stop all use of power and return the full value of the token back to the leader controller.
In other words, the token can ensure that no more than 100% of the total predetermined circuit capacity can be used at once, whether that be solely used by one tank or used in a shared manner by both tanks. It is noted that the heating element capacity is the maximum wattage (e.g., 1000 W, 2000 W, etc.) consumed by a heating element when connected to the power supply. It is also noted that an actuation rate percentage of 100% is achieved by continuously connecting the heating element to the power supply (e.g., holding the TRIAC ON), while an actuation rate percentage of <100% (e.g., 50%) is achieved by periodically connecting the heating element to the power supply (e.g., periodically turning the TRIAC ON/OFF). For example, the controller may control the TRIAC (e.g., power switch) to turn ON/OFF according to a pulse width modulation scheme or the like. This allows the controller to actuate the electric heating elements from 0%-100% capacity.
The twinned electric water heaters with the coupled controllers described above provide a means for intelligent control of heating cycles utilizing a token-based (e.g., permission-based) solution. The details of this token-based solution will now be described with respect to
When water heaters are twinned by a plumbing professional, they are plumbed together and their controllers are connected together (either wired or wirelessly). However, the controllers do not initially know whether they are parallel or series plumbed.
Generally speaking, parallel or series plumbing configurations can be determined by monitoring water temperature in response to or otherwise associated with a water draw from the twinned water heater system. In other words, when water is being drawn from the water heater system, the plumbing configuration can be determined or established. More specifically, series and parallel configurations can be detected by monitoring temperatures, how temperatures are changing, and/or the rate of temperature change when hot water is withdrawn from the twinned water heaters. Because standby loss is typically a slow loss of heat from the tanks of both water heaters, a draw causes a more rapid change, especially in the temperature in the lower portion of the tanks.
Accordingly, as described in greater detail below, when the temperatures in the lower portions of the tanks of both water heaters indicate a draw or change in such a way as to indicate a draw, and especially when the rate of temperature change indicates a draw or is similar in both water heaters, then parallel plumbing of both water heaters is recognized.
Alternatively, as described in greater detail below, during a water draw from a series-plumbed water heater system, cold water may enter the bottom of the tank of the upstream water heater (e.g., the tank that is fed a cold-water supply) and hot water may enter the bottom of the tank of the downstream water heater (e.g., the tank that is feeding hot water to a household plumbing system). In such a series-plumbed water heater system, it would be expected that the temperature sensor in the bottom of the tank of the upstream water heater would drop and the temperature sensor in the bottom of the tank of the downstream water heater would drop to a lesser degree or perhaps even rise.
Turning now to
If it is determined that the tanks are plumbed in series, the controllers 402A/402B then perform additional steps to determine the identity of the upstream tank and the downstream tank (e.g., which tank is connected to the cold-water supply and which tank is connected to the hot water outlet to the user). For example, in step 514, the controllers 402A/402B determine if Temp 1 is decreasing at the draw rate. If Temp 1 is decreasing at the draw rate, then it is determined in step 516 that Tank 1 is the upstream tank and Tank 2 is the downstream tank (i.e., Tank 1 is receiving the cold water from the supply). If, however, Temp 1 is not decreasing at the draw rate (i.e., Temp 2 is decreasing at the draw rate), then it is determined in step 518 that Tank 1 is the downstream tank and Tank 2 is the upstream tank (i.e., Tank 2 is receiving the cold water from the supply).
Once the plumbing configuration is determined, the controllers 402A/402B can then proceed to coordinate heating cycles using the token. A generic example of heating cycle coordination and a more specific example of heating cycle coordination are described with respect to
If the tanks are determined to be parallel plumbed, the controllers 402A/402B agree on one of controller 402A or 402B to initially hold the token. In step 604, for example, controller 402B of Tank 1 may initially hold the token and perform a heating cycle. In step 606, if a predetermined time elapses or a predetermined event occurs (e.g., a predetermined temperature value is detected by controller 402B via sensors 410B), controller 402B of Tank 1 stops the heating cycle and passes the token to controller 402A of Tank 2 in step 608. In step 610, controller 402A of Tank 2 holds the token and performs a heating cycle. In step 612, if a predetermined time elapses or a predetermined event occurs (e.g., a predetermined temperature value is detected by controller 402A via sensors 410A), controller 402A of Tank 2 stops the heating cycle and passes the token back to controller 402B of Tank 1 in step 614. This overall control sequence is repeated such that the token is passed back and forth between the water heater controllers, thereby allowing the controllers to perform heating cycles to reach their respective setpoints while avoiding or reducing any simultaneous operation.
If, however, in step 602, it is determined that the tanks are not parallel plumbed, but instead are series plumbed (step 616), the controllers seek to determine the identity of the downstream tank in step 618. In step 618, if Tank 1 is determined to be downstream tank, then the control proceeds to step 604 as described above where controller 402B Tank 1 initially holds the token and begins the heating cycle. If, however, in step 618, the controller determines that Tank 2 is the downstream tank, the control proceeds to step 608 where Tank 1 sends the token to Tank 2 which begins the heating cycle. In other words, the downstream tank takes possession of the token first. This is primarily due to the system configuration in which the downstream tank may be supplying the hot water to the user.
For example, in step 700, when both controllers 402A/402B are connected, the controllers detect the user set modes of both tanks. In step 702, if controller 402B of Tank 1 is in setpoint mode and controller 402A of Tank 2 is in vacation mode, then controller 402B of Tank 1 is designated as the leader and controller 402A of Tank 2 is designated as the follower in step 704. In step 706, if controller 402B of Tank 1 is in vacation mode and controller 402A of Tank 2 is in setpoint mode, then controller 402B of Tank 1 is designated as the follower and controller 402A of Tank 2 is designated as the leader in step 708.
In step 710, the controllers determine if they are parallel plumbed. If the tanks are determined to be parallel plumbed (see algorithm in
If, however, the tanks are determined to be series plumbed (see algorithm in
It is noted that although
It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. For example, the term “coupled” as used herein refers to any logical, optical, physical or electrical connection, link or the like by which signals or light produced or supplied by one system element are imparted to another coupled element. Unless described otherwise, coupled elements or devices are not necessarily directly coupled or connected to one another and may be separated by intermediate components, elements or communication media that may modify, manipulate or carry the signals. Also, the term “coupled” can refer to direct or indirect mechanical or thermal connectedness. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “includes,” “including,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises or includes a list of elements or steps does not include only those elements or steps but may include other elements or steps not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
Unless otherwise stated, any and all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. Such amounts are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain. For example, unless expressly stated otherwise, a parameter value or the like may vary by as much as ±10% from the stated amount. The term “substantially” as used herein means the parameter value or the like.
In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various examples for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed examples require more features than are expressly recited in each claim. Rather, as the following claims reflect, the subject matter to be protected lies in less than all features of any single disclosed example. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
In the above detailed description, numerous specific details were set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings.
While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that they may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all modifications and variations that fall within the true scope of the present concepts.
This application claims priority to U.S. Provisional Patent Application No. 63/541,089, filed on Sep. 28, 2023, titled “SYSTEM AND METHOD FOR WATER HEATER TWINNING,” the entirety of which is incorporated by reference herein for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63541089 | Sep 2023 | US |
