Note: Descriptions are shown in the official language in which they were submitted.
. .
WATER HEATER CONTROL USING EXTERNAL TEMPERATURE SENSOR
FIELD
[0002] The disclosure relates to electric water heaters and
more
particularly to a control system for controlling the capacity of an electric
water
heater for energy efficiency.
BACKGROUND
[0003] Electric water heaters are conventionally used in
residential and
commercial buildings to supply the occupants of the building with a reservoir
of
hot water. The water heater typically includes a tank that is fluidly coupled
to a
water supply of the building at an inlet and is fluidly coupled to building
fixtures
such as faucets, showers, and dishwashers at an outlet. The water heater tank
receives cold water from the building water supply at the inlet and heats the
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water to a set point temperature using lower and upper heating elements. The
lower and upper heating elements raise the temperature of the water disposed
within the water heater tank to the set point temperature by converting
current
from a building power supply into radiant heat. The heated water is stored
within
the tank and is held at the set point temperature by the heating elements so
that
a supply of hot water is constantly and consistently provided at a desired
temperature.
[0004]
Conventional electric water heaters typically include a control
system that monitors a temperature of water disposed within the water tank to
ensure that the water contained therein is maintained at a predetermined set
point temperature. The set point temperature is typically a consumer-selected
setting that allows the consumer to determine a temperature of the hot water
to
be produced by the water heater. The control system continuously monitors the
temperature of the water within the tank via a temperature sensor and compares
the sensed temperature to the set point temperature. The control system
generally includes an upper temperature sensor associated with the upper
heating element and a lower temperature sensor associated with the lower
heating element. The upper temperature sensor and lower temperature sensor
each provide information regarding the water temperature near the respective
elements. The respective sensors, in combination with the upper and lower
heating elements, allow the control system to selectively heat the water
disposed
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within the tank when the sensed temperature falls below the set point
temperature.
[0005] In operation, the upper heating element of a conventional
electric water heater is energized by the control system to heat a volume of
water
generally between the upper heating element and a top of the tank (i.e., an
upper
zone of the tank). Once the water in the upper zone of the tank is at the set
point
temperature, the control system de-energizes the upper heating element and
energizes the lower heating element. The lower heating element heats a volume
of water generally above the lower heating element and below the upper heating
element (i.e., a lower zone of the tank). The lower heating element remains
energized until the water within the lower zone of the tank is at the set
point
temperature.
[0006] Water, when heated, rises due to the physical properties (i.e.,
density) of heated water relative to the cooler water within the tank.
Therefore,
as the lower heating element heats water, the heated water rises within the
tank
and cold water descends toward the lower heating element. The descending
cold water mixes with the passing hot water and is heated by the lower heating
element. This process continues until the entire volume of water disposed
within
the lower zone of the tank reaches the set point temperature.
[0007] When a consumer draws hot water from the tank, the initial hot
water drawn from the tank outlet is disposed within the top zone of the tank,
near
the upper heating element and upper temperature sensor. When the hot water
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exits the tank, a fresh supply of cold water is introduced into the tank at an
inlet.
The inlet is generally disposed at a bottom of the tank, below the lower
heating
element. The incoming cold water eventually contacts the lower heating element
as the hot water is displaced (i.e., drawn from the tank at the outlet). At
this
point, the lower temperature sensor detects the influx of cold water and
relays
the information to the control system. The control system processes the
information from the lower temperature sensor and energizes the lower heating
element to heat the incoming cold water until the set point temperature is
achieved.
[0008] If the
consumer does not use all of the hot water available in the
tank, the lower heating element remains energized and continues to heat the
water (as described above) until the set point temperature is reached.
However,
there are instances when the consumer draws a sufficient volume of hot water
from the tank such that the volume of cold water entering the tank reaches the
upper heating element. Such an occurrence is known as a "deep draw" event. A
deep draw event is identified when the upper temperature sensor detects a
significant drop in temperature due to the incoming cold water. Upon detection
of
the incoming cold water, the control system de-energizes the lower heating
element and energizes the upper heating element in an effort to quickly heat
the
smaller volume of cold water above the upper element to the set point
temperature before the water exits the tank.
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[0009] When the
consumer stops using hot water, the influx of cold
water is similarly stopped. At this point, the upper heating element continues
to
heat water disposed in the upper zone of the tank until the upper temperature
sensor detects that the water disposed in the upper zone is at the set point
temperature. The control system then de-energizes the upper heating element
and energizes the lower heating element to heat the water disposed within the
lower zone of the tank. The lower heating element remains energized until the
lower temperature sensor detects that the temperature of the water disposed
within the lower zone is at the set point temperature. In this
manner,
conventional hot water heaters include a control system that responds to a
draw
of hot water from the tank by continually heating the entire volume of water
disposed within the tank to the set point temperature.
[0010] The
capacity of an electric water heater is conventionally
understood as the volume of water that the water heater is able to heat and
maintain at a set point temperature. For example, an eighty-gallon water
heater
can heat and store eighty gallons of water. In this regard, then, the capacity
of
the eighty-gallon water heater is eighty gallons.
[0011] The
effective capacity of the water heater that is realized by a
consumer, however, is greater than the simple volume capacity of the water
heater that was just described. This is so because a consumer does not
typically
use water at the set point temperature when a call for "hot water" at a
household
fixture is made. While the set point temperature for a water heater can vary,
it is
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not uncommon that the set point is at 120 F or higher. A consumer demand for
"hot water" at a fixture, however, generally is for water at a comfortable
temperature that is well below the set point temperature. Consequently, in
order
to produce the "hot water" that is used by the consumer, water drawn from the
water heater is mixed with cold water from the building water supply. Thus,
for
example, for every gallon of "hot water" that is used by the consumer, only a
half-
gallon of water is drawn from the water heater. This effectively increases the
amount of "hot water" that the electric water heater can provide to a
consumer.
[0012] As a
general proposition, the higher the set point temperature of
the water heater, the lower the volume of water that needs to be drawn from
the
water heater in order to produce "hot water" for the consumer. Similarly, the
lower the set point temperature of the water heater, the higher the volume of
water that needs to be drawn from the water heater in order to produce "hot
water" for the consumer. Thus, the effective capacity of the water heater can
be
adjusted by raising or lowering the set point temperature of the water heater.
For
example, a lower set point temperature would require more water from the water
heater to produce the desired "hot water." Thus, hot water from the water
heater
is used faster and the effective capacity of the system is reduced.
Conversely,
raising the set point temperature would require less water from the water
heater
to provide the same "hot water." Increasing the set point temperature,
therefore,
increases the capacity of the water heater.
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[0013] A conventional control system for an electric water heater
generally operates to maintain the entire volume of water in the tank at the
set
point temperature, as described above. These control systems operate
independent of the actual demands for hot water made by the consumer.
Therefore, even if the consumer's requirements for "hot water" were regularly
smaller than the effective capacity of the water heater, the water heater
would
nonetheless repeatedly heat all of the water to the set point temperature all
of the
time.
[0014] Therefore, it is desirable to provide a control system that can
continuously monitor and adjust the effective capacity of an electric water
heater
based on consumer demands in order to save energy associated with operation
of the electric water heater. Furthermore, it is also desirable to provide a
control
system that enables the electric water heater to satisfy government energy
standards, while simultaneously providing a consumer with an adequate "hot
water" capacity.
SUMMARY
[0015] A system for controlling a water heater that operates according
to a voltage supply includes a temperature sensor, mounted on at least one of
a
temperature and pressure (T&P) valve of the water heater and a hot water line
of
the water heater, that generates a temperature signal corresponding to a first
temperature of the at least one of the T&P valve and the hot water line. A
control
module mounted on the water heater includes a switching module that receives
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the voltage supply and outputs the voltage supply to the water heater. The
voltage supply passes at least one of through and adjacent to the control
module.
The control module determines a second temperature of water within the water
heater based on the temperature signal and selectively actuates the switching
module to turn on and turn off the voltage supply to the water heater based on
the second temperature.
[0016] A method for controlling a water heater that operates according
to a voltage supply includes mounting a temperature sensor on at least one of
a
temperature and pressure (T&P) valve of the water heater and a hot water line
of
the water heater, generating a temperature signal corresponding to a first
temperature of the at least one of the T&P valve and the hot water line, and
mounting a control module on the water heater, the control module including a
switching module that receives the voltage supply and outputs the voltage
supply
to the water heater. The voltage supply passes at least one of through and
adjacent to the control module. The method further includes, using the control
module, determining a second temperature of water within the water heater
based on the temperature signal and selectively actuating the switching module
to turn on and turn off the voltage supply to the water heater based on the
second temperature.
[0017] Further areas of applicability of the present disclosure will
become apparent from the detailed description, the claims and the drawings.
The
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detailed description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the disclosure.
DRAWINGS
[0018] The disclosure will become more fully understood from the
detailed description and the accompanying drawings, wherein:
[0019] FIG. 1 is a schematic representation of an electric water heater
that is operated in accordance with the principles of the present disclosure;
[0020] FIG. 2 is a schematic representation of a consumer interface
module of the electric water heater of FIG. 1;
[0021] FIG. 3A is a schematic representation of a control module
incorporating an electronic upper limit sensor for an electric water heater in
accordance with the principles of the present disclosure;
[0022] FIG. 3B is a schematic representation of a control module
incorporating a bimetal upper limit switch and electronic upper limit sensor
for an
electric water heat in accordance with the principles of the present
disclosure;
[0023] FIG. 4 is a flowchart that describes the operation of an energy
saver module for an electric water heater in accordance with the principles of
the
present disclosure;
[0024] FIG. 5 is a flowchart that describes the operation of an electric
water heater in accordance with the principles of the present disclosure;
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[0025] FIG. 6 is a flowchart that illustrates operation of a consumer
interface module for an electric water heater controller in accordance with
the
principles of the present disclosure;
[0026] FIG. 7 is a flowchart that describes the operation of a water
temperature differential module in accordance with the principles of the
disclosure;
[0027] FIG. 8 is a schematic representation of a control system for a
hot water heater according to the disclosure and incorporating a sensor
module,
a control algorithm, and a control module;
[0028] FIG. 9 is a schematic representation of a smart energy
controlled water heater system according to the principles of the present
disclosure;
[0029] FIGS. 10A, and 10B are schematic representations of smart
energy controlled water heaters according to the principles of the present
disclosure;
[0030] FIG. 11 is a schematic representation of a smart energy control
module according to the principles of the present disclosure;
[0031] FIG. 12 is a sensed current provided to a smart energy
controlled water heater according to the principles of the present disclosure;
[0032] FIG. 13 is a DC control module according to the principles of
the
present disclosure;
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[0033] FIG. 14 is a water heater including an electrical junction box
according to the principles of the present disclosure;
[0034] FIG. 15 is a water heater including a smart energy control
module mounted on the water heater according to the principles of the present
disclosure;
[0035] FIG. 16 shows an exemplary control module mounted on a
water heater according to the principles of the present disclosure;
[0036] FIG. 17 shows the exemplary control module mounted on the
water heater with an external temperature sensor according to the principles
of
the present disclosure; and
[0037] FIG. 18 illustrates an exemplary relationship between an actual
water temperature and a sensed temperature provided by the external
temperature sensor.
DETAILED DESCRIPTION
[0038] Example embodiments will now be described more fully with
reference to the accompanying drawings.
[0039] With reference to the figures, an electric water heater 10 is
provided and includes a control module 12. The control module 12 adjusts an
effective capacity of the electric water heater 10 by continuously monitoring
and
adjusting a set point temperature of the water heater 10 until an optimum
effective capacity of the electric water heater 10 is achieved. As used
herein, the
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term module refers to an application specific integrated circuit (ASIC), an
electronic circuit, a processor (shared, dedicated, or group), and memory that
execute one or more software or firmware programs, a combinational logic
circuit, and/or other suitable components that provide the described
functionality.
[0040] The set point temperature is a consumer-selected input and is
generally defined as the maximum temperature that the consumer selects for the
heated water that exits the water heater 10. The effective capacity of the
water
heater 10 is generally defined as the ability of the water heater 10 to
provide a
volume of water at a "delivered temperature." The delivered temperature is the
temperature of the water as used by the consumer at a fixture. The delivered
temperature of the water is generally lower than the set point temperature
because the delivered temperature is usually achieved by mixing water from the
water heater 10 at the set point temperature with cold water from the building
water supply.
[0041] The effective capacity of the water heater 10 is directly related
to the set point temperature as follows: the higher the set point temperature,
the
lower the volume of hot water that is necessary to be mixed with the cold
water to
produce the water at the fixture at the delivered temperature. Conversely, the
lower the set point temperature, the higher the volume of hot water that is
necessary to be mixed with the cold water to produce the water at the fixture
at
the delivered temperature. Therefore, there is a direct correlation between
the
set point temperature and the effective capacity of the water heater 10.
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[0042] The control module 12 monitors and controls the effective
capacity of the water heater 10 by selectively adjusting the consumer-selected
set point temperature. In so doing, the control module varies the effective
capacity of the water heater 10 to meet the specific needs of the consumer. By
adjusting the effective capacity of the water heater 10 to meet the demand of
the
consumer, the control module 12 is able to minimize energy consumption of the
water heater 10 while maintaining the ability to produce a satisfactory volume
of
hot water for the consumer.
[0043] With reference to FIG. 1, the electric water heater 10 is shown
to include a tank 14, an upper heating element 16, and a lower heating element
18. The tank 14 defines an interior 11 having a volume and includes an inlet
20
and an outlet 22, both fluidly coupled to the interior 11. The inlet 20 is
also fluidly
coupled to a water supply 24, while the outlet 22 is also fluidly connected to
the
hot water pipes leading to the building fixtures, such as faucets, showers,
dishwashers, and clothes washers, etc., which are schematically represented at
26. The inlet 20 receives a constant supply of cold water under pressure from
the building water supply 24 such that the interior 11 of the tank 14 is
always full
of water. Hot water only exits the tank 14 through the outlet 22 when a demand
for hot water is made at one of the fixtures 26 throughout the building. Cold
water, therefore, only enters the tank 14 when hot water exits the tank 14
through
the outlet 22.
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[0044] The upper heating element 16 and the lower heating element 18
each extend through a side wall 25 of the tank 14 and generally into the
interior
11. The upper heating element 16 is disposed near an upper wall 32 of the tank
14. The lower heating element 18 is disposed near a lower wall 34 of the tank
14. The lower heating element 18 is generally closer to the lower wall 34 of
the
tank 14 than the upper heating element 16 is to the upper wall 32.
[0045] The upper and lower heating elements 16, 18 receive current
from a power supply 30 via the control module 12. The control module 12
regulates each of the upper and lower heating elements 16, 18 between an ON
state and an OFF state.
[0046] The electric water heater 10 also includes a sensor module 35
(see, FIG. 8) in communication with the control module 12. The sensor module
35 comprises an upper temperature sensor 36 and a lower temperature sensor
38, each in communication with the control module 12. Outputs from the upper
and lower temperature sensors 36, 38 which correspond to their respective
temperature readings are monitored by the control module 12.
[0047] The upper temperature sensor 36 is disposed adjacent to the
upper heating element 16 to monitor a temperature of water within the tank 14
in
an upper zone (i.e., generally between the upper heating element 16 and the
upper wall 32). The lower temperature sensor 38 is disposed adjacent to the
lower heating element 18 to monitor a temperature of water within the tank 14
in
a middle zone (i.e., generally between the lower heating element 18 and the
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upper heating element 16). The temperature sensors 36, 38 are preferably
thermistors, such as NTC thermistors, but could be any suitable temperature
sensor that can accurately and reliably provide an output which is indicative
of
the temperature of the water residing within the tank 14 near the sensor.
[0048] In addition to the foregoing, the sensor module 35 could also
comprise two or more upper temperature sensors 36 disposed near the upper
heating element 16. Such an arrangement would provide redundant temperature
readings at the upper heating element 16. In a device having such an
arrangement, the control module 12 would monitor the output from the plurality
of
sensors 36 and the sensor output indicative of the highest measured
temperature
would be used to control the operation of the upper heating element 16. In
addition, the control module 12 can compare the respective outputs from the
sensors 36 for a self-diagnostic procedure. For example, if the difference
between the output of any two sensors 36 is above a predetermined threshold
value, the control module 12 could detect a sensor fault and require that the
water heater 10 be shut down for maintenance or repair.
[0049] Further, the sensor module 35 could also include a flow sensor
37 disposed at the inlet 20 or the outlet 22 of the tank 14. The flow sensor
37
could monitor a flow of water entering or exiting the tank 14. Therefore,
output
from the flow sensor 37 could be used by the control module 12 to control the
operation of the upper and lower heating elements 16, 18. The flow sensor 37
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could also be used to determine the volume of water that has been drawn from
the water heater 10 over a period of time.
[0050] Referring now to FIG. 2, the control module 12 includes a
consumer interface module 45 having a liquid crystal display (LCD) 40, a
series
of light-emitting devices (LEDs) 42, and a speaker 44, all contained within a
control module housing 46. The LCD 40 displays the operating parameters of
the electric water heater 10 such as the set point temperature (see bar graph
41
of FIG. 2), an energy savings level (e.g., 0, 1 or 2), actual energy savings
(e.g. in
energy or dollars saved), available hot water, and other useful information
such
as the date and time. In addition, the LCD 40 may be backlit to allow use of
the
control module 12 in a dark or dimly-lit basement. The LEDs 42 are positioned
adjacent to the LCD 40, but may also be incorporated into the LCD 40 to
visually
indicate operating parameters of the electric water heater 10. The speaker 44
allows the control module 12 to audibly alert a consumer of a particular
condition
of the water heater 10. In addition to the foregoing, the control module 12
also
includes at least user-input device 48 (e.g., a button) to enable the consumer
to
communicate with the consumer interface 45. The user-input devices 48 may
include, but are not limited to, set point control, programming, opt in/out,
and/or
vacation buttons.
[0051] Turning to FIG. 3A, the control module 12 also comprises a
microcontroller 50 in communication with the sensor module 35 and the
consumer interface module 45. The microcontroller 50 is powered by a power
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supply 52 disposed generally within the control module housing 46. The power
supply 52 receives power from line voltages L1, L2.
[0052] A limit control module 51 controls power to the heating elements
16, 18 based on readings from the upper and lower temperature sensors 36, 38.
The limit control module 51 of FIG. 3A is shown as an electronic limit control
module 53 and essentially acts as a backup device to the microcontroller 50.
For
example, if the microcontroller 50 fails to cut power to the upper and lower
heating elements 16, 18, the electronic limit control module 53 shuts down the
heating elements 16, 18 based on readings from the upper and lower
temperature sensors 36, 38. The limit control module 51 could also include a
bimetal snap disc thermostat 55, as shown in FIG. 3B. The bimetal snap disc
thermostat 55 receives line voltages L1, L2 and selectively prevents power
from
reaching the upper and lower heating elements 16, 18.
[0053] In either of the foregoing configurations, the limit control
module
51 is a separate circuit from the microcontroller 50 and selectively cuts
power to
the upper and lower heating elements 16, 18 based on readings from the upper
and lower temperature sensors 36, 38. The limit control module 51 only cuts
power to the upper and lower heating elements 16, 18 when the microcontroller
50 fails to do so based on readings from the upper and lower temperature
sensors 36, 38.
[0054] The microcontroller 50 is also in communication with a sensor
conditioning module 54 and a relay output and driver module 56. The sensor
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conditioning module 54 receives the output from the respective temperature
sensors 36, 38 and directs the output to the microcontroller 50 and electronic
limit control module 51. The relay output and driver module 56 receives event
messages from the microcontroller 50 based on input from the upper and lower
temperature sensors 36, 38 to toggle the upper and lower heating elements 16,
18 between the ON state and the OFF state by selectively allowing line voltage
L1, L2 to supply current to the respective heating elements 16, 18.
[0055] Operation of the electric water heater 10 and associated control
module 12 is best understood with reference to FIGS. 4-7. Generally speaking,
the control module 12 monitors the consumer's hot water usage over time and
provides an effective capacity for only the amount of hot water that is
actually
needed. The control module 12 can reduce the effective capacity by reducing a
consumer-selected set point temperature by a setback value and recommend a
reduction in the consumer-selected set point temperature if further reductions
to
the set point temperature are not possible. The control module 12 can increase
the effective capacity by recommending an increase in set point temperature.
In
this manner, the control module 12 is able to tailor the effective capacity of
the
water heater 10 to the actual hot water consumption of the consumer.
[0056] When the water heater 10 is initially installed, the tank 14 is
completely filled with cold water from the building water supply 24 via the
inlet 20.
At this point, all of the water within the tank 14 is substantially at the
same
temperature (i.e., cold). The consumer selects a set point temperature setting
at
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the consumer interface 45 by depressing one of the buttons 48. The set point
temperature represents the temperature of the water that the control module 12
seeks to achieve in the tank 14 within a tolerance. The tolerance recognizes
that
the actual water temperature within the tank may be different from the
measured
temperature provided by sensors 36, 38. The set point temperature can be set,
for example, to one of twenty temperature settings. The twenty settings are
exemplified by the bar graph of FIG. 2, though more or fewer temperature
settings could be used. The respective temperature settings provide the
control
module 12 adjusts the effective capacity of the water heater 10.
[0057] In addition to selecting the desired set point temperature, the
consumer is also able to select a desired energy savings setting, for example
0 ¨
No Energy Savings, 1 ¨ Moderate Energy Savings, or 2 ¨ Aggressive Energy
Savings. Selecting an energy level provides the control module 12 with the
ability to adjust the consumer set point temperature to tailor effective
capacity.
The energy savings levels are exemplified by levels 0, 1, 2 (FIG. 2) but could
include additional energy savings levels. The consumer selects the respective
energy savings setting at the consumer interface 45 by depressing one of the
buttons 48.
[0058] The first energy savings setting, 0 ¨ No Energy Savings, does
not allow the control module 12 to lower the consumer-selected set point
temperature. The second energy savings level, 1 ¨ Moderate, allows the control
module 12 to lower the consumer-selected set point temperature by an initial
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setback value. Thus, the temperature to which the water in the water heater 10
will be heated is the control set point temperature, Le., the consumer-
selected set
point temperature minus the initial setback value. As already described, a
lower
water temperature in the tank 14 reduces the effective capacity of the
electric
water heater 10. At the reduced set point temperature, the consumer draws
more hot water from the tank 14 in order to obtain water at a desired
temperature. Energy savings, though, is realized because the entire volume of
water in the tank 14 is heated to a lower temperature.
[0059] The third energy savings setting, 2 ¨ Aggressive, similarly
allows the consumer-selected set point temperature to be lowered by the
initial
setback value. In addition, the second energy savings setting allows the
control
module 12 to lower the set point temperature still further, by up to a maximum
setback value. With the maximum setback value, the control module 12 can
further reduce the effective capacity of the water heater 10 in an effort to
optimize
the energy efficiency of the water heater 10 based on consumer demand for hot
water.
[0060] Once the consumer selects a set point temperature and energy
savings setting, the control module 12 initially controls the water heater 10
based
on the respective consumer inputs (i.e., set point temperature and energy
savings setting).
[0061] In operation, the control module 12 first determines the control
set point temperature based on the initial setback value. Note that regardless
of
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which energy savings level is selected (i.e., 1 or 2), the control module 12
initially
sets the control set point temperature to a value equal to the consumer-
selected
set point temperature minus the initial setback value, unless the energy
savings
level chosen is 0 ¨ No Energy Savings. In so doing, the control module 12
generates a control set point temperature that is lower than the consumer-
selected set point temperature, reducing the effective capacity of the water
heater 10. With the control set point temperature determined, the control
module
12 then controls the function and operation of the electric water heater 10 as
previously described.
[0062] Once the water heater 10 is at the control set point temperature
the control module 12 monitors hot water consumption by the consumer. By
monitoring the upper heating element 16, the control module 12 is able to
react
to hot water usage and adjust effective capacity. As previously discussed, the
upper heating element 16 is only energized during a deep draw event when the
incoming cold water contacts the upper temperature sensor 36. Therefore, the
control module 12 is able to determine that the water heater 10 has excess
effective capacity when the upper heating element 16 has not been energized
for
a predetermined period. In addition, the control module 12 is able to
determine
that there is a need for additional effective capacity if the upper heating
element
16 has been energized for a predetermined period.
[0063] It should be noted that the predetermined amount of time is
generally referred to as a "cycle" and is usually at least one week in
duration to
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allow for a week's worth of household events that may give rise to a deep draw
event such as, for example, laundry day. The control module 12 may also
collect
usage data to generate historical usage data (i.e., water usage over time).
The
control module 12 may then utilize the collected historical data to develop
usage
patterns. The usage patterns may be used by the control module 12 in
anticipating setback temperatures for different times of day or days of the
week.
In this manner, the control module 12 may control the capacity of the water
heater 10 based on historical information to prepare for certain household
events.
[0064] For example, if laundry day falls on Thursday for three
consecutive weeks, the control module 12 may increase the effective capacity
of
the water heater 10 on Wednesday night in anticipation of laundry day.
Conversely, if a consumer is routinely away from home on Saturdays and
Sundays, the water heater 10 may reduce the effective capacity on Friday
night.
Therefore, the control module 12 may be used to tailor energy consumption
based on consumer water usage and may collect data to anticipate future water
usage.
[0065] If the control module 12 determines that there is excess
effective capacity in the water heater 10, the control module 12 will take one
of
two actions. First, if the energy savings setting is set to level 1, the
control
module 12 must continue to control the water heater at the consumer-selected
set point temperature minus the initial setback value. If conditions warrant a
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further decrease in effective capacity, however, the control module 12 alerts
the
consumer via consumer interface module 45 to change the energy savings
setting from level 1 to level 2. Second, if the energy savings setting is set
to level
2, the control module 12 lowers set point temperature by the maximum set back
value to further reduce the effective capacity of the water heater 10.
However,
the control module 12 is only permitted to reduce the set point temperature by
the maximum setback value.
[0066] Conversely, if the control module 12 determines that there is not
enough effective capacity in the water heater 10, the control module 12
increases
the effective capacity by raising the control set point temperature, but is
limited in
doing so by the consumer-selected set point temperature.
[0067] FIG. 4 details an exemplary savings module 58 for use by the
control module 12 for determining when an increase or a decrease in effective
capacity is warranted. The energy savings module 58 utilizes the control
module
12 and associated sensor module 35 to tailor the effective capacity of the
water
heater 10 to the specific needs of the individual consumer by continuously
monitoring the consumer's hot water usage. Initially, the control module 12
compares the consumer-selected set point temperature to a threshold cutoff
temperature, which is too low to allow operation of the energy savings module
58
(i.e., a setback from the consumer-selected set point temperature would result
in
a cold water condition). In one exemplary embodiment, the cutoff temperature
is
between 115 degrees Fahrenheit and 120 degrees Fahrenheit. Therefore when
23
CA 02831580 2016-08-04
the consumer-selected set point temperature is lower than the cutoff
temperature
(i.e., 115-120 degrees Fahrenheit), the energy savings module 58 sets the
control set point temperature at the consumer-selected set point temperature
at
62 as the control module 12 cannot setback the temperature lower than 115
degrees Fahrenheit. At this point, the control module 12 maintains the water
disposed within the tank 14 at the consumer-selected set point temperature by
selectively toggling the upper and lower heating elements 16, 18 between the
ON
and OFF states.
[0068] If the consumer-selected set point temperature is above the
cutoff temperature, the control module 12 reduces the consumer-selected set
point temperature by the initial setback amount to the control set point
temperature at 64. Once the control set point temperature is determined, the
control module 12 maintains the water within the tank 14 at the control set
point
temperature by selectively toggling the upper and lower heating elements 16,
18
between the ON and OFF states.
[0069] The control module 12 controls the water heater 10 at the
control set point temperature for one cycle (i.e., at least one week). The
control
module 12 monitors the sensor module 35 to determine if the upper heating
element 16 has been energized during the cycle at 66. If the upper heating
element 16 has been energized during the cycle, the control module 12
concludes that the water heater 10 has experienced a deep draw event and
requires additional effective capacity at 68. However, if the upper element 16
24
CA 02831580 2016-08-04
has not been energized during the cycle, the control module 12 references a
timer to determine whether the cycle has expired at 70. If the timer has
expired
(indicating that the cycle has ended), the control module 12 concludes that
the
water heater 10 has not experienced a deep draw event within the last cycle at
72. At this point, the control module 12 concludes that the set point
temperature
should be further reduced to decrease the effective capacity of the water
heater
10.
[0070] The control module 12 determines a float range for the setback
value based on whether the upper heating element 16 has been energized
during the last cycle at 74. The float range defines an amount the control
module
12 is allowed to either increase or decrease the set point temperature to
effectuate a change in effective capacity. The control module 12 is limited in
implementing the float range by the maximum setback value as the control
module 12 is not permitted to reduce the consumer-selected set point
temperature more than the maximum setback value at 76. In addition, the
control module 12 is limited by the cutoff temperature (i.e., 115-120 degrees
Fahrenheit).
[0071] If the control module 12 determines that additional energy
savings are possible because the upper heating element 16 has not cycled for a
predetermined time, or that the water heater 10 is not producing enough hot
water to keep up with demand (i.e., the upper heating element 16 is regularly
cycled ON), the control module 12 alerts the consumer. The control module 12
CA 02831580 2016-08-04
notifies the consumer that at least one of the set point temperature setting
or the
energy savings level should be adjusted to allow the control module 12 the
flexibility to optimize performance of the water heater 10. The control module
12
recommends such action through use of a performance monitoring module 78 to
rectify an over capacity or an under capacity situation.
[0072] With particular reference to FIG. 5, operation of the performance
monitoring module 78 is described. The performance monitoring module 78
generates a recommendation to the consumer to save energy by selecting a
lower set point temperature or generates a recommendation to the consumer to
increase the set point temperature based on hot water demand history. For
example, if the setback value is equal to the maximum setback value, the
control
module 12 cannot further reduce the consumer-selected set point temperature
even if there is excess effective capacity in the water heater 10. Therefore,
the
only way for the control module 12 to reduce the effective capacity of the
water
heater 10 is to start at a lower consumer-selected set point temperature.
Therefore, the control module 12 must alert the consumer that the consumer-
selected set point temperature should be adjusted.
[0073] The control module 12 first determines if the setback value
equals the maximum setback value at 80. If the setback value equals the
maximum setback value, and the upper heating element 16 has not cycled ON
for a predetermined period of time, the control module 12 recommends to the
consumer via the LCD 40, LED 42, and/or speaker 44 that the consumer-
26
CA 02831580 2016-08-04
selected set point temperature should be reduced to realize further energy
savings at 82. If the consumer reduces the set point temperature, the control
module 12 is able to further reduce the effective capacity of the water heater
10
by calculating the control set point temperature from a lower consumer-
selected
set point temperature. Such a reduction in effective capacity ultimately saves
the
consumer energy as excess water is not needlessly heated. In this manner,
even though the control module is restricted from reducing the consumer-
selected set point temperature by the maximum setback value, the control
module 12 can still further reduce the effective capacity of the water heater
10.
[0074] If the setback amount is zero, and the upper heating element 16
has been cycled ON during a previous period, the control module 12 determines
that an increase in effective capacity is necessary at 84. At this point, the
control
module 12 alerts the consumer of the need for additional effective capacity at
86
and recommends increasing the consumer-selected set point temperature via the
LCD 40, LED 42, and/or speaker 44. If the control module 12 is able to
properly
control the effective capacity of the water heater 10 based on hot water
demand
and consumer-selected input, the control module 12 displays that the system is
functioning within its limits and is able to sufficiently optimize the
effective
capacity of the water heater 10 at 88.
[0075] In each of the foregoing situations, the control module 12 must
alert the consumer to either raise or lower the consumer-selected set point if
the
27
CA 02831580 2016-08-04
maximum setback is achieved. The control module 12 makes such
recommendations through a consumer interface display module 90.
[0076] The consumer interface display module 90 for use with the
above-described performance monitoring module 78 is shown in FIG. 6. The
consumer interface display module 90 determines whether the LCD 40
recommends an increase in the consumer-selected set point temperature and
whether the consumer has acted on the recommendation 92. If the consumer
has acted on the recommendation, the recommendation is removed and the
display 40 notes that the system is functioning within limits. At this point,
the
control module 12 sets the setback value to be generally equal to the initial
setback value plus the amount that the consumer-selected set point temperature
was increased 96.
[0077] Similarly, the consumer interface display module 90 determines
whether the LCD 40 recommends a decrease in the consumer-selected set point
temperature and whether the consumer has acted on the recommendation 98. If
the consumer has acted on the recommendation, the recommendation is
removed and the display 40 that the system is functioning within limits and is
able
to sufficiently optimize the effective capacity of the water heater 10 at 100.
At
this point, the control module 12 sets the setback value to be generally equal
to
the initial setback value minus the amount that the consumer-selected set
point
temperature was decreased 102.
28
CA 02831580 2016-08-04
[0078] It should be noted that for the consumer interface display
module 90, the consumer's acting on the recommendation (Le., to raise or lower
the set point temperature range) does not immediately change the temperature
of the water disposed within the tank 14. Following the recommendation simply
shifts the control module's 12 operational limits so that the control module
12 has
greater flexibility to further adjust the effective capacity of the water
heater 10
when necessary in view of hot water demand history, thereby realizing greater
energy efficiency.
[0079] The control module 12, by optimizing effective capacity of the
water heater 10, allows more hot water to be available at lower set point
temperatures, as demonstrated by the differential module 104 of FIG. 7.
[0080] During periods of non-use, the temperature of water within the
tank 14 will fall due to heat escaping through tank walls. Therefore,
maintaining
the tank 14 at a lower temperature reduces energy loss. At lower set point
temperatures, the water within the tank 14 is only allowed to vary from the
set
point temperature a small amount to increase the average temperature of the
tank 14. Reducing the operating range of the tank 14 at lower set point
temperatures ensures that there is enough hot water within the tank 14 to
deliver
water at a comfortable temperature (i.e., the delivered temperature).
[0081] For higher set point temperatures, the differential module 104
allows a wider temperature differential (i.e., 12 F) between the set point
temperature and the temperature of the water at which the heating elements 16,
29
CA 02831580 2016-08-04
18 are energized. For lower temperatures, the differential module 104 allows a
narrower temperature differential (i.e., 7 F). This relationship allows more
hot
water to be available at lower set point temperatures. For example, a set
point
temperature of 145 F requires a differential of 12 F, thereby allowing the
water to
range between 133 F and 157 F. A set point temperature of 105 F requires a
differential of 7 F, thereby allowing the water to range between 98 F and 112
F.
[0082] Each degree lost by the water heater 10 during non-use has a
greater impact in reducing effective capacity at lower set point temperatures
than
at higher set point temperatures. Maintaining the temperature of the water
close
to the set point temperature allows more hot water to be available.
[0083] Therefore, by controlling the effective capacity of the water
heater 10 to a state that minimizes the set point temperature (i.e., by
reducing
the consumer-selected set point temperature by the setback value), more hot
water is available at lower set point temperatures and energy is saved.
[0084] FIG. 8 schematically represents the relationship between the
control module 12, sensor module 35, energy savings module 58, performance
monitoring module 78, user interface module 90, and differential module 104.
Each of the modules 35, 58, 78, 90, 104 communicate with the control module 12
to aid the control module 12 in continuously adjusting the set point
temperature
of the water heater 10 until the effective capacity and energy use are
optimized.
[0085] Referring now to FIG. 9, a smart energy controlled water heater
system 200 is shown schematically to include an electric water heater 202
CA 02831580 2016-08-04
(including a control module 204), a service panel 206 (that includes, for
example,
a circuit breaker panel), and a smart energy meter 208. The electric water
heater
202 receives electrical power from a power grid 210 via the service panel 206.
The smart energy meter 208 measures the amount of electrical energy
consumed by the electric water heater 202 and other household devices (not
shown).
[0086] The smart energy meter 208 communicates electrical energy
consumption data to a smart energy network 212. The smart energy network
212 monitors the electrical energy consumption of the household for billing
purposes. Further, the smart energy network 212 monitors total electrical
energy
consumption of the power grid 210 for various smart energy applications,
including, but not limited to, peak usage information, load shedding,
availability of
renewable energy, and/or pricing. The smart energy meter 208 communicates
with the smart energy network 212 via a wired or wireless communication
network. Similarly, the smart energy meter 208 may communicate with the
control module 204 via wired or wireless communication. For example only, the
smart energy meter 208 and/or the control module 204 may wirelessly
communicate according to the ZigBee communication protocol specification,
which is based on the IEEE 802.145.4-2003 standard, or any other suitable
wireless home area network (WHAN) or wireless personal area network (WPAN)
protocol (e.g. Bluetooth). The system 200 may also include other connections
214 for providing communication between the control module 204 and the smart
31
CA 02831580 2016-08-04
energy network 212. For example, the other connections 214 may include, but
are not limited to, a home area network (HAN) to wide area network (WAN)
gateway (e.g., a WiFi connection), a cellular to cloud connection, and/or a
UHF
connection.
[0087] More
specifically, the control module 204 of the present
disclosure may include a communication module 206 that communicates with the
smart energy meter 208. As shown, the control module 204 is located on an
upper portion of the water heater 202 to facilitate both communication with
the
smart energy meter 208 and control of power delivered to the water heater 202
from the service panel 206, though other arrangements of the control module
204
are anticipated. The communication module 206 may monitor and record usage
information of the water heater 202 to determine both hot water and electrical
power consumption associated with the water heater 202. For example, the
communication module 206 may determine which times correspond to peak
usage of the water heater 202 and which times correspond to little or no usage
of
the water heater 202. Although
the control module 204 and/or the
communication module 206 are described as monitoring and recording the usage
information, any other suitable component may provide these functions. For
example only, the smart energy meter 208 or another component of the system
200 may monitor and record the usage or other information.
[0088] Further,
the communication module 206 communicates with the
smart energy meter 208 to receive energy information associated with the power
32
CA 02831580 2016-08-04
grid 210 from the smart energy network 212. For example, the smart energy
meter 208 may transmit power grid usage (e.g. the peak usage information and
other alerts associated with power grid usage), load shedding, availability of
renewable energy, and/or pricing information to the communication module. The
control module 204 optimizes operation of the water heater 202 based on the
usage information of the water heater 202 and the energy information received
from the smart energy meter 208. For example, the control module 204 may
power the water heater 202 on and off according to the energy information
received from the smart energy meter 208.
[0089] Referring now to FIGS. 10A and 10B, the electric water heater
202 and the control module 204 are shown. The control module 204 may include
and implement any of the features described with respect to the control module
12 (as shown in FIG. 2), as well the corresponding description for FIGS. 1-8.
The control module 12 further includes the communication module 206.
[0090] The control module 204 receives line voltages L1, L2 and
controls power supply and operation of the electric water heater 202. The
electric water heater 202 includes an upper heating element 220 and a lower
heating element 222. For example, the upper heating element 220 and the lower
heating element 222 may be selectively energized to heat the water in the
electric water heater 202 according to principles of the present disclosure
described in FIGS. 1-8. The control module 204 selectively provides current
from
the line voltages L1, L2 to the upper heating element 220 via a switching
module
33
CA 02831580 2016-08-04
(e.g. relay 224) and a thermostat 226. For example, when the relay 224 is
closed and the thermostat 226 is in a first position, the upper heating
element
220 is energized. Conversely, when the relay 224 is open or the thermostat 226
is in a second position, the upper heating element 220 is de-energized.
[0091] The control
module 204 selectively provides the current from the
line voltages L1, L2 to the lower heating element 222 via the relay 224 and a
thermostat 228 (as shown in FIG. 10A) or via the relay 224 (as shown in FIG.
10B). For example, as shown in FIG. 10A, when the relay 224 and the
thermostat 228 are closed and the thermostat 226 is in the second position,
the
lower heating element 222 is energized. When either the relay 224 or the
thermostat 228 is open or the thermostat 226 is in the first position, the
lower
heating element 222 is de-energized. As shown in FIG. 10B, when the relay 224
is closed and the thermostat 226 is in the second position, the lower heating
element 222 is energized. When the relay 224 is open or the thermostat 226 is
in the first position, the lower heating element 222 is de-energized.
[0092] The water heater 202 as shown in FIG. 10A may be a pre-
existing water heater that is modified to include the control module 204
according
to the present disclosure. In other words, the water heater 202 may be
manufactured and installed in a home and configured to operate according to
the
thermostats 226 and 228. Subsequently, the water heater 202 may be modified
to include the control module 204. The modified water heater 202 is configured
to operate according to the control module 204 and the relay 224 in addition
to
34
CA 02831580 2016-08-04
the thermostats 226 and 228. For example only, the control module 204 is
installed on an upper portion of the water heater 202 to facilitate connection
to
the line voltages L1, L2.
[0093] Conversely, the water heater 202 as shown in FIG. 10B may be
manufactured to include the control module 204 and a sensor 230 (e.g. a
thermistor). The control module 204 communicates with the sensor 230 to
determine a water temperature in a lower portion of the water heater 202. The
control module 204 controls energizing and de-energizing of the lower heating
element 222 based on the sensor 230. The sensor 230 may be arranged within
a tank of the water heater 202. Conversely, when the water heater 202 is
modified to include the control module 204 after manufacture, the sensor 230
may be arranged on an outer surface of the water heater 202.
[0094] Further, the water heater 202 as shown in FIG. 10B may include
a single thermostat 226 that transitions between the upper heating element 220
and the lower heating element 222. For example, when the thermostat 226 is
connected to the lower heating element 222, the lower heating element 222 is
energized. Conversely, when the thermostat 226 is connected to the upper
heating element 220, the upper heating element 220 is energized.
[0095] As shown in each of FIGS. 10A and 10B, the control module
204 includes the relay 224 to control energizing and de-energizing of both the
upper heating element 220 and the lower heating element 222 further based on:
i) usage information of the water heater 202 collected by the control module
204;
CA 02831580 2016-08-04
and ii) energy information associated with the power grid 210 received from
the
smart energy meter 208. More specifically, the control module 204 may
selectively de-energize both the upper heating element 220 and the lower
heating element 222 of the water heater 202 using the relay 224, independently
of the operation of the thermostats 226 and 228.
[0096] The water heater 202 as shown in each of FIGS. 10A and 10B
may include an electrical cut-off (ECO) switch 232 in communication with the
upper heating element 220 and the lower heating element 222. The ECO switch
232 may disconnect the upper heating element 220 and the lower heating
element 222 from the line voltages L1, L2 under certain conditions. For
example,
the ECO switch 232 may be configured to disconnect the upper heating element
220 and the lower heating element 222 when the water temperature reaches or
exceeds a high temperature threshold.
[0097] The water heater 202 may include one or more other sensors
that monitor operating characteristics of the water heater 202. The one or
more
other sensors include, but are not limited to, a water leak sensor 234.
Although
the water leak sensor 234 is shown located within the water heater 202, the
water leak sensor 234 may be arranged in any suitable location in or near the
water heater 202. For example, the water leak sensor 234 may be located on a
flooring surface external to the water heater 202, and may be any suitable
type of
sensor. The control module 204 communicates with the water leak sensor 234 to
determine whether the water heater 202 is leaking. For example, the water leak
36
CA 02831580 2016-08-04
sensor 234 may be a separate device that is configured to operate with the
control module 204 and connect to the control module 204 using a wired and/or
wireless interface. For example only, the water leak sensor 234 may be plugged
in to the control module 204 by a user. If a leak is detected using the water
leak
sensor 234, the control module 204 may notify the user via electronic
messaging
or any other known remote communication method.
[0098] Referring
now to FIG. 11, the control module 204 is shown to
include the communication module 206, the relay 224, a power supply 300, a
relay driver 302, a microcontroller 304, and a user interface 306.
Additionally,
the control module 204 may include any of the elements described in FIGS. 3A
and 3B.
[0099] The power supply 300 communicates with the line voltages L1,
L2 to provide power to the water heater 202 via the relay 224 (e.g. a 30 amp
single pole, double throw relay) at a desired level. The relay may utilize
normally
closed contacts to ensure the load is on when power is removed. For example
only, the power supply 300 is a 3 volt power supply. The relay driver 302
receives control inputs from the microcontroller 304 to selectively energize
and
de-energize the relay 224 according to desired on/off times for the water
heater
202. For example only, the relay driver 302 may be a zero cross, direct drive,
charge pump, or other suitable type of driver. The microcontroller 304
receives
user inputs from the user interface 306 as described in, for example, FIGS. 3A
and 3B, and from the communication module 206.
37
CA 02831580 2016-08-04
[0100] The microcontroller 304 receives energy information from the
smart energy meter 208 via the communication module 206 as described above
with respect to FIGS. 10A and 10B. The microcontroller 304 controls the relay
driver 302 to actuate the relay 224 based in part on the energy information
received from the smart energy meter 208. The microcontroller 304 may store
the energy information for the power grid 210 (e.g. peak usage times,
available
renewable energy, pricing, etc) and usage information for the water heater 202
to
optimize operation of the water heater 202 for both cost and energy savings.
[0101] For example, the microcontroller 304 may open and close the
relay 224 based on a comparison between the energy information and the usage
information for the water heater 202. More specifically, the microcontroller
304
may open the relay 224 to de-energize the upper heating element 220 and the
lower heating element 222 during peak usage times of the power grid 210, low
availability of renewable energy on the power grid 210, low usage times of the
water heater 202, times associated with a higher pricing tier, and any
combination thereof. For example, it is typically beneficial to utilize
renewable
resources when they are available. If a certain time corresponds to both a low
availability of renewable energy on the power grid 210 and a low usage time of
the water heater 202, the microcontroller 304 may open the relay 224 until
there
is renewable energy available on the power grid 210, at which time the
microcontroller 304 may close the relay 224. Further, the microcontroller 304
may open the relay 224 only if there is sufficient hot water in the water
heater
38
CA 02831580 2016-08-04
202 to satisfy anticipated demand during the upcoming low availability of
renewable energy.
[0102] In
addition, when the microcontroller 304 receives renewable
energy information from the smart energy meter 208 via the communication
module 206, the microcontroller 304 can estimate energy required to heat the
water to the setpoint temperature by using temperature sensor 234, usage
information of the water heater 202, or any combination thereof. The
microcontroller 304 may then send this estimated energy to the smart energy
network 212 via the communication module 206 and smart energy meter 208.
[0103] The
microcontroller 304 may further be responsive to inputs
received from the user interface 306. For example, a user may force the
microcontroller 304 to one of open and close the relay 224 in response to
information displayed by the user interface 306. In other words, a user may
opt
to close the relay 224 during times corresponding to higher pricing tiers
and/or
peak usage in view of anticipated high usage times of the water heater 202.
Conversely, a user may opt to open the relay 224 during times corresponding to
higher pricing tiers and/or peak usage despite anticipated high usage times of
the
water heater 202.
[0104]
Communication between the user and the microcontroller 304 is
not limited to the user interface 306. For example, the user may provide
inputs to
the microcontroller 304 using electronic messaging via a home area network or
a
thermostat. Conversely, information can be communicated to the user using a
39
CA 02831580 2016-08-04
local or home display located elsewhere (e.g., the display of a thermostat
control), using mailed documentation, and/or using electronic messaging such
as
e-mail, sms, or a smart phone interface.
[0105] In a water heater that is modified to include the control module
204 (e.g., the control module 204 is attached to the water heater 202 after
the
water heater 202 is installed), the control module 204 may itself monitor,
store,
and/or determine usage information for the water heater 202. For example, in
some implementations, a water heater may already include structure (such as
the control module 12 as described in FIGS. 2-8) for determining usage
information. Accordingly, in some implementations, the control module 204 may
receive the usage information from the control module 12. For example, the
control module 12 may include a communication port for communicating, either
wirelessly or via a wired connection, with the control module 204.
[0106] Conversely, if the control module 204 is installed in a system
including a water heater that does not include the control module 12, or if
the
control module 12 is not configured to communicate the usage information to
the
control module 204, the control module 204 according to the principles of the
present disclosure may monitor various operating characteristics of the water
heater 202 to determine the usage information. For example, the control module
204 may include a usage monitoring module 320. The usage monitoring module
320 receives one or more signals from the system 200 to allow the control
module 204 to monitor and determine the usage information. Accordingly, the
CA 02831580 2016-08-04
control module 204 may determine the usage information independently of the
control module 12.
[0107] For example, the usage monitoring module 320 may receive
one or more signals from sensors such as a current sensor 322. The current
sensor 322 may sense a current through one of the lines L1 or L2. The current
may be indicative of energization of a lower heating element (e.g., the lower
heating element 222 as shown in FIGS. 10A and 10B) and/or an upper heating
element (e.g., the upper heating element 220 as shown in FIGS. 10A and 10B).
More specifically, the current may be indicative of a transition from the
lower
heating element 222 to the upper heating element 220. The usage monitoring
module 320 may provide information (e.g., information indicative of time and
duration of each energization of the upper heating element 220) to the
communication module 206 and/or the microcontroller 304. Accordingly, the
usage monitoring module 320 may determine usage information by measuring
operating characteristics of the system 200 external to the water heater 202
and/or the control module 12.
[0108] The current sensed by the current sensor 322 is indicative of
the
current provided to the heating elements 220 and 222. As described above,
typically the lower heating element 222 is energized to heat the water in the
water heater 202. However, during deep draw events, the upper heating element
220 is energized and the lower heating element 222 may be de-energized.
Accordingly, for the water heater 202 as shown in FIG. 10B, the thermostat 226
41
CA 02831580 2016-08-04
may first be connected to energize the lower heating element 222 during or
after
a draw event. Subsequently, the thermostat 226 may be connected to the upper
heating element 220 to energize the upper heating element 220 during a deep
draw event. Consequently, characteristics of the current sensed by the current
sensor 322 may be affected. More specifically, the transition of the
thermostat
226 from the lower heating element 222 to the upper heating element 220 may
result in a detectable event in the sensed current.
[0109] Referring now to FIG. 12, a current 400 sensed by the current
sensor 322 is shown. For example, the current 400 is an alternating current
having a low peak 402 and a high peak 404. When the lower heating element
222 is energized, the current 400 varies periodically between the low peak 402
and the high peak 404. When the thermostat 226 transitions from the lower
heating element 222 to the upper heating element 220, a detectable event may
occur as shown at 406. Specifically, the current 400 may include a transient
surge at 406. The surge may also occur when the thermostat 226 transitions
from the upper heating element 220 to the lower heating element 222.
[0110] The current sensor 322 senses the surges indicating the
transition from the lower heating element 222 to the upper heating element 220
and the transition from the upper heating element 220 to the lower heating
element 222. Accordingly, the signals from the current sensor 322 are
indicative
of usage information such as a time and duration of deep draws. Further, if
the
current 400 is provided to the water heater 202 without a surge being
detected,
42
CA 02831580 2016-08-04
then the current 400 indicates a time and duration of a short draw. The usage
monitoring module 320 determines the usage information from the signals
received from the current sensor 322. For example only, the usage monitoring
module 320 (or another component of the control module 204) may include a real
time clock or other timing device to determine usage patterns associated with
the
usage information.
[0111] The control
module 204 may be configured to determine various
other characteristics of the water heater 202. For example, the control module
204 may determine a capacity of the water heater 202 based on the usage
information and one or more other measured characteristics, including, but not
limited to, inlet water temperature (e.g., as measured by a temperature sensor
mounted on a cold water supply line), outlet water temperature (e.g., as
measured by a temperature sensor mounted on a hot water supply line), wattage
(using the measured current and an input voltage to the system 200), and on
and
off times of the heating elements 220 and 222. The control module 204 may
calculate the volume of water drawn from the water heater 202 based on these
characteristics. Accordingly, the control module 204 may estimate a capacity
of
the water heater 202 that is actually used over a given period.
[0112] In some implementations, the control module 204 may
determine whether temperature sensors are mounted properly on the cold water
supply line and the hot water supply line. For example, if the temperature
sensors are reversed (i.e., each of the temperature sensors are mounted on the
43
CA 02831580 2016-08-04
wrong supply line), the corresponding measured temperatures will be outside of
an expected range. Specifically, the temperature sensor mounted on the cold
water supply line (instead of the hot water supply line) will indicate a
temperature
that is significantly less than a hot water temperature threshold, and the
temperature sensor mounted on the hot water supply line (instead of the cold
water supply line) will indicate a temperature that is significantly greater
than a
cold water temperature threshold. Further, if the cold water supply line does
not
increase in temperature when the heating elements 220 and 222 are off, or if
the
hot water supply line does not decrease when the heating elements 220 and 222
are off, then the control module 204 may determine that the temperature
sensors
are installed improperly. The control module 204 may provide an indication
(e.g.,
via a fault message) that the temperature sensors are installed improperly.
[0113] The control
module 204 may divide each day into a plurality of
periods (e.g., four periods) and assign each of the periods to a usage amount
category (e.g., none, low, medium, and high usage categories). The assigned
categories correspond to the usage information (including the other measured
characteristics, capacity of the water heater, etc.) for each respective
period.
The control module 204 may further apply a confidence value for each period
and the corresponding category. For example, the control module 204 may
increase the confidence value if the usage information for a particular period
is
consistently the same, or decrease the confidence value if the usage
information
varies by more than a threshold from day-to-day or week-to-week. The control
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CA 02831580 2016-08-04
module 204 may operate the relay 224 during a particular period further based
on the assigned categories and confidence values.
[0114] Referring now to FIG. 13, the control module 204 may include a
direct current (DC) control module 500. For example, the usage monitoring
module 320 or another component of the control module 204 may include the DC
control module 500, or the DC control module 500 may be independent of other
components of the control module 204. When the relay 224 is open, power
provided to the water heater 202 may be interrupted. Accordingly, the DC
control
module 500 may include a power source to provide power for certain operations
while the relay 224 is open.
[0115] Further, when the relay 224 is open, the DC control module 500
allows the control module 204 to continue to determine whether additional hot
water is need. For example, the DC control module 500 may continue to monitor
transitions of the thermostat 226 even when the relay 224 is open.
Accordingly,
if the transitions of the thermostat 226 indicate that hot water is needed,
the
control module 204 can close the relay 224 to resume normal operation of the
upper heating element 220 and the lower heating element 222.
[0116] The DC control module 500 includes a simplified example
detection circuit 502. The detection circuit 502 communicates with the line
voltages L1 and L2 and the relay 224. When the relay 224 is open, a DC voltage
is generated across capacitor 504, and resistors 506 and 508 limit a current
provided to the water heater 202 (e.g., to approximately 2-3 mA).
CA 02831580 2016-08-04
[0117] A voltage across the resistor 508 may be indicative of a
transition between the lower heating element 222 and the upper heating element
220. For example, when the thermostat 226 is connected to the lower heating
element 222, a small voltage across the resistor 508 may be measured.
Conversely, during the transition from the lower heating element 222 to the
upper
heating element 220, the voltage across the resistor 508 may momentarily
decrease (e.g., to zero or close to zero). Accordingly, the control module 204
and/or the usage monitoring module 320 may measure the voltage across the
resistor 508 when the relay 224 is open to determine usage information.
[0118] In other implementations, the control module 204 may
implement other methods to determine whether hot water is needed. For
example, a temperature sensor may be provided on an outside surface of the
water heater 202 near an upper portion of the water heater 202, or mounted on
a
hot water line of the water heater 202. The control module 204 may determine
that hot water is needed if a sensed temperature at the upper portion of the
water
heater or the hot water line decreases below a threshold, and close the relay
224
accordingly.
[0119] Referring now to FIG. 14, a water heater 600 may be initially
installed without a control module as described in FIGS. 9-13, but may include
an
original manufacturer control module 602. Water (e.g., cold water) is supplied
to
the water heater 600 via a water supply line 604. Conversely, hot water is
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CA 02831580 2016-08-04
provided via a hot water line 606. Service wiring 608 provides AC power to the
water heater 600.
[0120] For example, the water heater 600 may include a junction box
including a junction box cover 610, mounted within the water heater 600. The
junction box cover 610 may include first and second plates 612 and 614. The
first plate 612 may provide connection for the wiring 608. The second plate
614
may be removable and provide access to wiring within the water heater 600. For
example only, when installed the first plate 612 may include a perforated
portion
that is removed to form an opening 616 for connecting the wiring 608 within
the
water heater 600.
[0121] Referring now to FIG. 15, the control module 204 according to
the present disclosure may be mounted to the water heater 600 at any time
during or after installation. Specifically, the water heater 600 may be
modified to
accommodate connection to the control module 204. For example, the control
module 204 may be mounted on the first plate 612. The service wiring 608
passes through the control module 204, and the service wiring 608 may be
modified to connect to internal circuitry of the control module 204 as shown
in
FIGS. 10 and 11. Accordingly, a remaining portion of the service wiring 620
may
remain connected to internal wiring of the water heater 600 through the second
plate 614. In other words, the service wiring 608 external to the water heater
600
may be modified to interface with the control module 204 without disconnecting
the wiring 620 from the internal wiring of the water heater 600. For example,
an
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CA 02831580 2016-08-04
opening 622 may be formed in the second plate 614 to receive the wiring 620.
Or, the wiring 620 may pass through the bottom of the control module 204
through the first plate 612. The originally provided first plate 612 and the
second
plate 614 may be modified to connect to the control module 204 and the wiring
620, and/or additional plates that are already configured to connect to the
control
module 204 may be provided with the control module 204.
[0122] In other implementations, the control module 204 may not
connect to either of the plates 612 and 614. Instead, one or both of the
plates
612 and 614 may be removed and the control module 204 can be connected
directly to the water heater 600 (or, for example, via an optional adaptor).
For
example, the first plate 612 (i.e., a plate that receives the service wiring
608) may
be removed. A bottom side of the control module 204 may be configured to
cover the opening left by the removal of the first plate 612. For example
only, a
bottom footprint of the control module 204 may be configured to be the same
size
and shape as the first plate 612. Or, the control module 204 may include an
integrated bottom plate that is sized to fit the opening. In other words, the
integrated bottom plate may have a different footprint than the control module
204.
[0123] In other implementations, the control module 204 may be
positioned in a location other than the top of the water heater 600. For
example,
the control module 204 may be mounted on a wall near or adjacent to the water
heater 600. Accordingly, the control module 204 may interface with the service
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CA 02831580 2016-08-04
wiring 208 in a location other than at the junction box of the water heater
600.
For example, the service wiring 208 may pass through or near the control
module
204 mounted on the wall, and then into an opening of the first plate 612.
[0124] In any of the implementations described in FIG. 15, the control
module interfaces with the service wiring 208 prior to the service wiring 208
entering the water heater 600. More specifically, the relay 224 is connected
to
interface with the service wiring 208 (e.g., is arranged in series with the
service
wiring 208) both external to the water heater 600 and either internal to or
adjacent to the control module 204. Similarly, the current sensor 322 is
arranged
to communicate with the service wiring either internal to or adjacent to the
control
module 204.
[0125] Accordingly, the control module 204 can be arranged to
selectively control current provided to the water heater 600, as well as
monitor
usage of the water heater 600, without modifying or accessing either internal
circuitry of the water heater or the control module 602.
[0126] In some implementations, a balance valve 630 may be
provided. The balance (i.e., mixing) valve 630 is connected between the water
supply line 604 and the hot water line 606. The control module 204 may control
the balance valve 630 to mix a selected amount of cold water from the water
supply line 604 with the hot water line 606. For example, the balance valve
630
may be controlled to provide an amount of cold water to achieve the setpoint
temperature. Conversely, an internal setpoint of the water heater 600 (e.g.,
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CA 02831580 2016-08-04
corresponding to any internal thermostats of the water heater 600) may be set
to
a maximum setting (e.g., 160 degrees Fahrenheit). Accordingly, the temperature
of the water supplied by the hot water line 606 is moderated by the balance
valve
630.
[0127] In this manner, the water in the water heater 600 itself is
maintained at the maximum temperature. With respect to hot water capacity, a
water heater maintained at this maximum temperature is significantly larger
than
a water heater maintained at a lower temperature (e.g., 120 degrees
Fahrenheit),
increasing both capacity and efficiency. For example, the water heater 600 may
be operated to heat the water to the maximum temperature during lowest pricing
tier hours (e.g., between 10:00 pm and 10:00 am). Consequently, operation
during higher pricing tier hours (e.g., between 10:00 am and 10:00 pm) can be
reduced significantly.
[0128] In other implementations including the balance valve 630, a
system described above in Figure 10A may be controlled according to the usage
information if the water heater 202 or energy information from the smart
energy
meter 208 via the communication module 206. For example, the microcontroller
304 may close the relay 224 to energize the upper heating element 220 and the
lower heating element 222 during non-peak usage times of the power grid 210,
high availability of renewable energy on the power grid 210, high usage times
of
the water heater 202, times associated with a low pricing tier, and any
combination thereof to transfer energy usage from a less beneficial time to a
CA 02831580 2016-08-04
more beneficial time. More
specifically, it is typically beneficial to utilize
renewable resources when they are available. If a certain time corresponds to
a high availability of renewable energy on the power grid 210, the
microcontroller
304 may close the relay 224 for as long as there is renewable energy available
on the power grid 210 or until the maximum temperature is reached, whichever
comes first. This allows energy used by the hot water heater to be transferred
from non-renewable energy sources to renewable energy sources. Further, the
microcontroller 304 may open the relay 224 only if there is sufficient hot
water in
the water heater 202 to satisfy anticipated demand during the upcoming low
availability of renewable energy.
[0129] In
addition, when the microcontroller 304 receives renewable
energy information from the smart energy meter 208 via the communication
module 206, the microcontroller 304 can estimate energy required to heat the
water to the setpoint temperature by using temperature sensor 234, usage
information of the water heater 202, or any combination thereof. The
microcontroller 304 may then send this estimated energy to the smart energy
network 212 via the communication module 206 and smart energy meter 208.
[0130] Referring
now to FIG. 16, an example control module 700 may
be mounted on a water heater 704. For example only, the water heater 704 may
include an upper surface 708 and an electrical junction box 712 arranged
adjacent to the upper surface 708. The upper surface 708 may include one or
more plates 716 and 720, which may be removable. For example, the plate 716
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CA 02831580 2016-08-04
may be removable to provide access to an interior of the electrical junction
box
712 for inspection and/or service. The plate 720 may be integral to the water
heater 704, or may be removable. The control module 700 may be mounted on
the plate 720. Or, the plate 720 may be removed and a bottom surface of the
control module 700 may replace the plate 720.
[0131] Service wiring 724 (e.g., wiring providing electrical power to
the
water heater 704 from a circuit breaker service panel or another suitable
power
source) may be inserted into the control module 700 through an opening 728
(e.g., a knock-out hole). Conversely, internal wiring 732 (e.g., internal hook-
up
wires configured to electrically communicate with the service wiring 724) of
the
water heater 704 may pass through an opening 736 in the plate 720 (and/or in
the bottom surface of the control module 700) into the control module 700. For
example only, the opening 736 may correspond to a knock-out hole in the plate
720 and/or a knock-out hole in the control module 700. For example only, the
opening may include a threaded conduit 740 configured to interface with a
threaded connection member 744 of the control module 700 for attachment of the
control module 700 to the water heater 704.
[0132] The service wiring 724 may be connected to the internal wiring
732 within the control module 700. For example only, the control module 700
may include a control circuitry portion 748 and an electrical connection
portion
752. The control circuitry portion 748 includes, for example, a current sensor
756
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CA 02831580 2016-08-04
(shown, for example only, as an inductor), a relay 760, and other components
as
described in FIGS. 9-15.
[0133] The
electrical connection portion 752 includes wire connection
terminals 764-1, 764-2, 764-3, and 764-4, referred to collectively as wire
connection terminals 764. For example, the wire connection terminals 764
include, but are not limited to, electrical lugs, twist-on wire connectors,
and/or any
other type of terminal for providing a connection interface between the
service
wiring 724 and the internal wiring 732. In this manner, the service wiring 724
may be disconnected from the internal wiring 732 (e.g., if the service wiring
724
is connected to the internal wiring 732 within the electrical junction box
712) and
reconnected to the internal wiring 732 within the electrical connection
portion 752
of the control module 700. Accordingly, no additional wiring needs to be
provided to connect the service wiring 724 to the internal wiring 732, and no
modifications (e.g., splicing or cutting) need to be made to the service
wiring 724
or the internal wiring 732. Instead, the internal wiring 732 may be passed
through the opening 736 into the electrical connection portion 752 and
connected
to the service wiring 724 within the control module 700.
[0134] For example
only, the control module 700 may include a
partition 768 that separates the electrical connection portion 752 from the
control
circuitry portion 748. The
partition 768 may be electrically insulative to
electrically isolate the control circuitry portion 748 from the service wiring
724 and
the internal wiring 732.
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CA 02831580 2016-08-04
[0135] Referring now to FIG. 17, the water heater 600 may include an
externally mounted temperature sensor 780. The temperature sensor 780 is
preferably mounted on a temperature and pressure (T&P) valve 784, but may be
mounted on the hot water line 606 (e.g., as indicated by 780') or any other
suitable location of the water heater 600. For example, the T&P valve 784 has
characteristics of a thermal conductor to conduct heat from the hot water
inside
the water heater 600, which is in fluid communication with the T&P valve 784.
Accordingly, the temperature of the T&P valve 784 varies with the temperature
of
the water inside the water heater 600. For example only, the temperature
sensor
780 may include a thermocouple, a thermistor sensor, or any other suitable
temperature sensor. The temperature sensor 780 senses a temperature of the
valve 784 and provides the sensed temperature to the control module 204. The
sensed temperature of the valve 784 closely corresponds to the temperature of
the water in the water heater 600.
[0136] Referring now to FIG. 18, an exemplary relationship 800
between an actual water temperature 804 and a sensed temperature 808
provided by the temperature sensor 780 mounted on the T&P valve 784 is
illustrated. As shown, the sensed temperature 808 closely corresponds to the
actual water temperature 804. However, the sensed temperature 808 differs
from the actual water temperature 804 by a temperature offset 812. Although
the
offset 812 may vary according to factors including, but not limited to,
ambient
temperature, draw events, and recovery periods (i.e., a period of reheating
the
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CA 02831580 2016-08-04
water after a draw event), the offset 812 is relatively constant. Accordingly,
the
sensed temperature 808 is indicative of the actual water temperature 804.
[0137] The control module 204 monitors the sensed temperature 808
to determine the actual water temperature 804 and to control the water heater
600 accordingly (e.g., monitor and store usage history, open and close the
switch
760, etc.). The control module 204 may first monitor the sensed temperature
808
to determine the actual water temperature 804. For example, the control module
204 may monitor the sensed temperature 808 to determine various setpoint
temperatures, maximum temperatures, and/or trigger temperatures (e.g.,
temperatures that trigger recovery events) of the water heater 600.
[0138] For example
only, the control module 204 may monitor the
sensed temperature 808 for a predetermined period (e.g., 24 hours) to
determine
a maximum temperature of the sensed temperature 808 during the
predetermined period. The maximum temperature of the sensed temperature 808
during predetermined period corresponds to a maximum temperature of the
actual water temperature 804 during the same predetermined period. Typically,
a
maximum temperature of the actual water temperature 804 corresponds to a
temperature setpoint. Accordingly, the control module 204 can determine that
the
maximum temperature of the sensed temperature 808 corresponds to the
temperature setpoint of the water heater 600. Alternatively, the control
module
204 may determine that a temperature peak of the sensed temperature 808
immediately following a recovery event corresponds to the temperature
setpoint.
CA 02831580 2016-08-04
For example, during a recovery event, heating elements of the water heater 600
may be energized until the actual water temperature 804 reaches the
temperature setpoint.
[0139] The control module 204 estimates the offset 812 between the
actual water temperature 804 and the sensed temperature 808 based on the
maximum temperature of the sensed temperature 808. For example, if the
temperature setpoint of the water heater 600 is known, then the control module
204 simply determines the offset 812 based on a difference between the
maximum temperature of the sensed temperature 808 (e.g., an average
difference, median difference, etc. over a predetermined period) and a known
temperature setpoint associated with the water heater 600. For example only, a
user may input or select a temperature setpoint using an interface of the
control
module 204.
[0140] Alternatively, if the temperature setpoint of the water heater
600
is not known, then the control module 204 may determine the offset 812 based
on a difference between the maximum temperature of the sensed temperature
808 and an estimated temperature setpoint of the water heater 600. For
example, the estimated temperature setpoint may be based on a typical and/or
default maximum temperature setpoint (e.g., 130 degrees) associated with the
water heater 600.
[0141] Further, it can be seen that the control module 204 may
determine other temperatures of the actual water temperature 804 that trigger
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CA 02831580 2016-08-04
water heater events, such as recovery events. For example, as shown in FIG.
18,
the sensed temperature 808 is also indicative of draw events and temperature
drops that trigger recovery events.
[0142] The control module 204 may recalculate the offset 812 to
compensate for any variations in the difference between the actual water
temperature 804 and the sensed temperature 808. For example only, the control
module 204 may recalculate the offset 812 periodically, after a reset event,
in
response to temperature changes (e.g., ambient temperature changes or
changes in the sensed temperature 808) greater than or equal to a
predetermined threshold, and/or in response to a user input.
[0143] In some implementations, the water heater 600 may have
adjustable temperature setpoints and/or a plurality of predetermined
temperature
setpoints. For example, the predetermined temperature setpoints may include
low (110 F), medium (120 F), and high (130 F) temperature setpoints.
Accordingly, the control module 204 may determine which of the predetermined
temperature setpoints is selected and determine the sensed temperature 808
accordingly. For example, the control module 204 may determine the maximum
sensed temperature over a predetermined period and determine whether the
maximum sensed temperature varies as compared to previous predetermined
periods.
[0144] For example only, the control module 204 may initially
determine that the maximum sensed temperature corresponds to a default
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CA 02831580 2016-08-04
temperature setpoint (e.g., the medium temperature setpoint). Subsequently, if
the maximum sensed temperature in a later predetermined period is greater than
the initial maximum sensed temperature, the control module 204 may determine
that the new maximum sensed temperature corresponds to a higher temperature
setpoint (e.g., the high temperature setpoint). Conversely, if the maximum
sensed temperature in a later predetermined period is less than the initial
maximum sensed temperature, the control module 204 may determine that the
new maximum sensed temperature corresponds to a lower temperature setpoint
(e.g., the low temperature setpoint).
[0145] As described above, the control module 204 monitors the
sensed temperature 808 and determines usage patterns of the water heater 600
and selectively opens and closes the relay 224 accordingly. For example, as
described above with respect to FIGS. 9-16, an original manufacturer control
module 602 maintains the actual water temperature 804 at the temperature
setpoint (e.g., regardless of usage patterns/history). In other words, the
control
module 602 selectively energizes the heating elements of the water heater 600
to
maintain the actual water temperature 804 as closely as possible to the
temperature setpoint. For example only, the control module 602 may energize
the heating elements until the actual water temperature 804 reaches the
temperature setpoint and then de-energize the heating elements. Subsequently,
the control module 602 may re-energize the heating elements when the actual
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CA 02831580 2016-08-04
water temperature 804 decreases below a threshold (e.g., an offset of several
degrees less than the temperature setpoint).
[0146] Conversely, while the control module 602 operates to energize
the heating elements regardless of usage patterns/history, the control module
204 selectively opens the relay 224 to interrupt energization of the heating
elements by the control module 602 as described above with respect to FIGS. 9-
17. Further, the control module 204 can accurately estimate the actual water
temperature 804 using the sensed temperature 808 and control the relay 224
accordingly. For example, as described above, the control module 204 may open
the relay 224 to prevent energization of the heating elements by the control
module 602 if certain criteria are met (e.g., usage patterns/history indicate
that
hot water is not presently needed, to conserve energy, to delay energization
until
energy costs are more economical, etc.).
[0147] For example, the control module 204 may close the relay 224 to
ensure that the actual water temperature 804 does not decrease below a
predetermined minimum temperature. Or, the control module 204 may close the
relay 224 a predetermined time before a predicted hot water draw. For example
only, the predetermined time may be based on an estimate of how long it takes
to increase the actual water temperature 804 from the predetermined minimum
temperature to the temperature setpoint. Accordingly, if the control module
204
predicts a draw event at a time T (e.g., 6:00 AM or another time associated
with
household occupants waking up and using hot water), then the control module
59
CA 02831580 2016-08-04
204 may close the relay 224 at, for example only, a time Y (e.g., where Y = T
¨ X
and X corresponds to the length of time to heat the actual water temperature
804
to the temperature setpoint. Alternatively, the control module 204 may
continuously calculate X based on a current actual water temperature 804. In
other words, X may vary as the actual water temperature 804 decreases from the
temperature setpoint to the predetermined minimum temperature.
[0148] Further,
the control module 204 may adjust the predetermined
minimum temperature and/or the predetermined time to close the relay 224
before an anticipated hot water draw according to previous observed results.
For
example, the control module 204 may monitor the actual water temperature 804
over time to determine whether the actual water temperature 804 typically
reaches the setpoint temperature prior to the beginning of an anticipated hot
water draw. If the control module 204 determines that the actual water
temperature 804 does not reach the setpoint temperature in time for the hot
water draw, the control module 204 may increase the predetermined minimum
temperature and/or increase the predetermined time prior to the anticipated
hot
water draw to close the relay 224. For example only, the control module 204
may
record a number of times over a predetermined period that the actual water
temperature 804 does not reach the setpoint temperature prior to an
anticipated
hot water draw, and adjust the predetermined minimum temperature and/or the
predetermined time prior to the anticipated hot water draw if the number of
times
exceeds a predetermined threshold.
CA 02831580 2016-08-04
[0149] In other words, as described above, although the control module
204 generally opens and closes the relay 224 based on criteria such as usage
patterns/history, energy costs (e.g., in peak times vs. off-peak times), etc.,
the
control module 204 also controls the relay 224 according to the predetermined
minimum temperature. Accordingly, the predetermined minimum temperature
may supersede other criteria. Further, the predetermined minimum temperature
may vary as described above.
[0150] In some implementations, the control module 204 controls the
relay 224 based on usage patterns/history, the predetermined minimum
temperature, and load shedding information as shown below in Table 1. For
example only, the control module 204 communicates with the power grid 210
(e.g., via the smart energy meter 208) to receive the load shedding
information.
Table 1
Usage 1 2 3 4
High On On Off (110 min) Off
Medium On Off (110 min) Off (105
min) Off
Low Off (110' min) Off (105 min) Off (105 min) Off
None Off (110 min) Off (105 min) Off (105 min) Off
[0151] As shown in Table 1, the control module 204 (and/or the power
grid 210, the smart energy meter 208, or another device) may store information
indicative of a user's usage amount in a given period. The given period may
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CA 02831580 2016-08-04
correspond to one of a plurality of periods (e.g., six 4-hour periods)
throughout a
day. For example, the control module 204 may determine the usage amount
based on the usage patterns/history. Further, the Table 1 may correspond to a
plurality of water heaters in communication with the power grid 210.
[0152] The usage amount may include usage levels such as high,
medium, low, and none (i.e., no usage during a given period). Each usage level
corresponds to a different load shedding control for each load shedding
category
(1, 2, 3, or 4). For example, the load shedding categories correspond to a
desired load shedding operation for water heaters associated power grid 210.
Load shedding category 1 may correspond to a lowest level of load shedding
while load shedding category 4 corresponds to a highest level of load
shedding.
For example only, if the power grid 210 is in (or, requests) the load shedding
category 1 (based on, for example, a low load time of day), water heaters
associated with high or medium usage levels during that period are on. In
other
words, the associated control module 204 closes the relay 224. However, water
heaters associated with low or no usage levels during that period are off,
unless
the actual water temperature 804 drops to a predetermined minimum
temperature (e.g., 110 F). In other words, the control module 204 opens the
relay 224 until the actual water temperature 804 drops to the predetermined
minimum temperature, and then closes the relay 224.
[0153] Similarly, if the power grid 210 is in the load shedding category
2, water heaters associated with a high usage level during that period are on.
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CA 02831580 2016-08-04
Water heaters associated with medium, low, or no usage levels during that
period are off, unless the actual water temperature 804 drops to a
predetermined
minimum temperature. As shown in Table 1, the predetermined minimum
temperatures may vary based on usage level. For example, the predetermined
minimum temperature for water heaters associated with a medium usage level
may be 110 F while the predetermined minimum temperature for water heaters
associated with low or no usage levels may be 105 F. In the load shedding
category 3, water heaters associated with all usage levels during that period
are
off unless the actual water temperature 804 drops to a predetermined minimum
temperature, which may vary by usage level.
[0154] The load shedding category 4 may correspond to a "critical"
load shedding situation where load shedding has a maximum priority for the
power grid 210. For example, the load shedding category 4 may correspond to a
situation where load shedding must be performed to avoid power interruption
(e.g., brownouts or other emergency operations). In the load shedding category
4, water heaters in all usage levels are off.
[0155] In some implementations, the control module 204 may control
the relay 224 during recovery periods according to a duty cycle limit. For
example, during a recovery period, the control module 204 may limit the amount
of time that the relay 224 is closed in a given period (e.g., an hour). The
amount
of time may be predetermined, variable, and/or randomized. Further, the amount
of time may be continuous within the given period, or separated (e.g.,
randomly)
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CA 02831580 2016-08-04
into different periods within the given period. For example only, a plurality
of the
control modules 204 associated with a plurality of respective water heaters
may
have different randomized times during the given period. In this manner,
respective recovery periods may have a longer duration but reduce overall
load.
[0156] Further, although the control module 204 is described in various
implementations as including, for example, a communication module 206 for
communication with the power grid 210 (e.g., via the smart energy meter 208),
the control module 204 is configured to control the relay 224 as described
above
without communication with the power grid 210 and/or the smart energy meter
208. For example, the control module 204 may include a real time clock (not
shown) to accurately determine a day, date, time of day, etc. The control
module
204 may be programmed to include additional information including, but not
limited to, peak and off peak timing information, grid load information,
and/or
other information related to cost and energy savings. Accordingly, the control
module 204 controls the relay 224 as described above notwithstanding the
ability
to communicate with the power grid 210 and/or the smart energy meter 208.
[0157] The foregoing description of the embodiments has been
provided for purposes of illustration and description. It is not intended to
be
exhaustive or to limit the disclosure. Individual elements or features of a
particular embodiment are generally not limited to that particular embodiment,
but, where applicable, are interchangeable and can be used in a selected
embodiment, even if not specifically shown or described. The same may also be
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CA 02831580 2016-08-04
varied in many ways. Such variations are not to be regarded as a departure
from
the disclosure, and all such modifications are intended to be included within
the
scope of the disclosure.
