Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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,COVER PLATE WITH REMOTELY CONTROLLABLE SWITCHING CIRCUIT
TECHNICAL FIELD
(0001) The present invention relates to a cover plate for access to the
thermostat of
an electric water heater and more particularly to a cover plate equipped with
a remotely
controllable switching circuit to control the operation of the electric
resistive heating
element associated with the thermostat. The cover plate with the switching
circuit is
further utilized as a retrofit to convert an existing water heater to an
intelligent water
heater.
BACKGROUND OF THE INVENTION.
(0002) Electrical water heaters of the domestic type comprise a tank in which
is
mounted two or sometimes three resistive heating elements disposed at
different levels
to heat water. The resistive heating elements are controlled by respective
thermostats
which have set point temperature values whereby to control the temperature of
the
water inside the tank at different levels. The thermostats have a control
portion and a
switching portion to switch the resistive heating elements on and off by
allowing and
cutting the power supply thereto depending on the temperature of the water in
relation
to the set point temperature of the thermostats. The power supply wiring is
usually
through a control box mounted on top of the water heater or through a port in
the outer
wall of the casing with the wiring extending along the tank wall to the
thermostats. The
wiring is usually held in place by the foam insulation which is injected
between the tank
and the outer casing mounted spaced about the tank. Foam dams prevent the
injected
insulating foam material from propagating into the space surrounding the
thermostats
and the resistive heating elements whereby to form an access space for
servicing and
adjustment of the set point temperature of the thermostat. The thermostat is
provided
with several terminals and the power supply wires are connected to specific
ones of
these. An access door is removably secured to the outer casing for access to
each
thermostat and resistive heating element.
(0003) With the advent of more intelligent water heaters it is necessary to
mount
electronic devices on such water heaters during fabrication and install
associated
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CA 02903507 2015-09-09
wiring to control the operation of the electric water heater. Although these
electronic
devices are mounted in housings it is necessary to provide access thereto for
trouble
'shooting and repair. Accordingly, because these housings are exteriorly
mounted they
are exposed to environmental conditions, such as dust, humidity, water
infiltration and
are succeptable to physical damage during installation of the water heater.
They are
also unsightly and occupy space.
(0004) Because intelligent water heaters are progressing quickly, new control
devices
are continuously being developed by various manufacturers, suppliers and
utility
providers and the benefit of such more intelligent water heaters can more
easily be
obtained by the purchasing of a new water heater. Accordingly, existing water
heaters
cannot benefit from this new technology unless these are modified on site to
adapt new
control devices thereto. Such modifications are very costly to the consumer or
the utility
and most will not bear such cost although there is a saving to them by
consuming less
electricity. Also, depending on the physical location of the water heater the
adaption of
new control hardware and wiring is often left to the installer to decide how
it will be
mounted and sometimes resulting in wiring exposed outside the water heating
unit and
controls being mounted on the outer casing at various locations and sometimes
on an
adjacent wall of the building structure.
SUMMARY OF THE INVENTION
(0005) It is desirable to overcome the above mentioned disadvantages of the
prior art
electric water heaters.
(0006) It is therefore a feature of the present invention to provide a novel
way of
mounting a switching circuit and control which is remotely controlled to
switch the
resistive heating elements on and off.
(0007) It is further feature of the present invention to provide a cover plate
for access
to the thermostat and resistive heating element and wherein the cover plate is
equipped
with a remotely controllable switching circuit to control the operation of the
electric
resistive heating element.
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(00) it is a further feature of the present invention to provide a cover plate
for
access to the thermostat associated with a resistive heating element and
wherein the
'cover plate has mounted, on an inner face thereof, a remotely controllable
switching
circuit provided with connection means for easy installation to the power
supply wiring of
the thermostat.
(0009) A further feature of the present invention is to provide a thermostat
cover plate
equipped with a remotely controllable switching circuit and which once
installed is not
visible to the eye as it is integrally mounted inside the access space to the
thermostat
and associated resistive heating element.
(0010) A still further feature of the present invention is to provide a
thermostat cover
plate provided with a remotely controllable switching circuit to retrofit an
existing electric
water heater to convert same to an intelligent water heater by being remotely
controlled
to regulate the consumption of electrical power.
(0011) Another feature of the present invention is to provide an inexpensive
means for
a utility or utility providers to convert existing electric water heaters to
remotely
controllable water heaters and wherein certification is not affected while
providing them
with a means to regulate power consumption and particularly in power failure
situations
or peak load sheading.
(0012) Another feature of the present invention is to provide the consumer of
an
inexpensive way to convert its existing electric water heater to an
intelligent water
heater to manage the operation of the water heater to thereby consume less
electricity
during a given time periods and wherein the installation thereof is foolproof
and easy.
(0013) According to the above mentioned features, from a broad aspect, the
present
invention provides a removable cover plate secured to an outer jacket of an
electric
water heater for access to a thermostat connected to a resistive heating
element of an
electric water heater. The cover plated has an outer surface and an inner
surface and
wherein there is mounted on the inner surface switching circuit means having
input
electrical connection means for connection to power leads and output
electrical
connections for providing electrical connection to selected terminals to the
thermostat.
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The switching circuit means has a control circuit for operating a switch
interconnecting
the power leads connected to the input electrical connection means to the
output
'electrical connection means. The control circuit is operatively controlled by
a remote
controller to remotely control the operation of the switch to connect and
disconnect
power from the power leads to the selected terminals of the thermostat.
(0014) According to a further broad aspect of the present invention there is
provided a
retrofit cover plate for the replacement of an existing cover plate of an
electric water
heater for access to a thermostat connected to a resistive heating element of
the
electric water heater. The cover plate has an outer surface and an inner
surface and
wherein there is mounted on the inner surface switching circuit means. The
switching
circuit means has input electrical connection means for connection to power
leads
disconnected from selected terminals of the thermostat. Output electrical
connections
means provide electrical connection to the selected terminals. The switching
circuit
means has a control circuit for operating a switch interconnecting the power
leads
connected to the input electrical connection means to the output electrical
connection
means. The control circuit is operatively controlled by a remote controller to
remotely
control the operation of the switch to connect and disconnect the power from
the power
leads to the output connection means and thereby control the operation of the
resistive
heating element by connecting and disconnecting the power leads from the
selected
terminals of the thermostat.
DESCRIPTION OF THE DRAWINGS
(0015) A preferred embodiment of the present invention will now be described
with
reference to the accompanying drawings in which:
(0016) Figure 1 is a partly exploded view of a two element electric water
heater
showing the component parts of the resistive heating elements and associated
thermostat and cover plate illustrating the retrofit cover plate of the
present invention
provided with a remotely controllable switching circuit mounted on the back
face of the
retrofit cover plate;
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(0017) Figure 2 is a conventional wiring diagram of a thermostat and its
associated
resistive heating element;
(0018) Figure 3 is a wiring diagram similar to Figure 1, but illustrating the
switching
circuit of the cover plate connected to the thermostat of a top element of a
two element
electric water heater;
(0019) Figure 4 is a wiring diagram similar to Figure 3, but illustrating the
switching
circuit of the cover plate connected to the bottom thermostat of a two element
electric
water heater or the middle element of a three element electric water heater;
(0020) Figure 5 is a wiring diagram similar to Figure 3, but illustrating the
switching
circuit of the cover plate connected to the top resistive heating element
which is
connected in series with the bottom resistive heating element for controlling
the power
provided to both elements;
(0021) Figure 6A is a simplified electrical block diagram of a remotely
controllable
electronic switch;
(0022) Figure 6B is a block diagram of an electro-mechanical remotely
controllable
switch;
(0023) Figure 7 is a perspective rear view of the cover plate showing a
removably
mounted switching circuit, and
(0024) Figure 8 is a perspective front view of the cover plate showing various
modifications thereto.
DETAILED DESCRIPTION
(0025) Referring now to the drawings and more particularly to Figure 1, there
is shown
generally at 10 a two element electric water heater which is provided with a
inner casing
11, herein a steel tank, in which there is contained water to be heated by two
resistive
heating elements herein a top resistive heating element 12 and a bottom
resistive
heating element 13 having the same power ratings. Each resistive heating
element has
a mounting plate 14 provided with terminals 15 to which is connected wires
from an
associated thermostat 16 to receive power when the temperature of the water in
the
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tank in the area of the resistive heating elements falls below a set point
temperature as
set in the associated thermostat 16. A power supply entrance hole 21 is
provided in the
outer casing 19 adjacent one of the openings 17, or surrounding open area of
the
thermostat and resistive heating element, and is covered by a cover plate 18
removably
attached to the outer casing 19 by suitable fastening means such as a screw
20. As
herein illustrated, the top cover plate 18 is to be replaced by a modified
retrofit cover
plate 25 of the present invention.
(0026) Figure 2 illustrates the conventional wiring between the thermostat 15
and the
top resistive heating element 12 and the interconnection between both
resistive heating
elements 12 and 13. Power leads 26 and 27 are connected to power terminals 28
and
29 of the control portion 30 of the thermostat. The switching portion 31
contains a
switch, not shown but obvious to a person skilled in the art, which is
operated by the
control portion depending on the temperature of the water inside the casing
11. Of
course, the bottom resistive heating element 13 may be wired differently
wherein a
separate power cable may run from a control box usually mounted on top of the
water
heater, or from a power block conveniently mounted inside the tank next to the
top
thermostat.
(0027) With reference now to the additional Figures, there is described the
present
invention of the modified cover plate 25. As shown in Figures 7 and 8, the
cover plate
25 is fabricated from non-electrically conductive material such as plastic,
fibreglass, etc.
to permit wireless communication with the control circuit. The cover plate has
an outer
surface 25' and an inner surface 25". The inner surface 25" is provided witch
a
switching circuit means mounted in a housing 32 secured thereto. The housing
32
could also be detachably mounted by clamps 33 for ease of replacement. On the
outer
surface 25' there is herein illustrated an antenna module 34 mounted thereon
or
moulded therein. In the case where the cover plate is a metal plate, then the
antenna
would be exteriorly mounted on the cover plate or on top of the water heater
with the
wiring disposed between the tank 11 and the outer casing 19 in a tube (not
shown)
disposed in place before injection to the foam insulation. A USB port 35
provides for
connection to the circuitry of the switching circuit or other circuitry to
extract information
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or download information in associated circuits. A pilot lamp 36 may also be
provided to
indicate that the resistive heating element is active or dormant. An LED
screen 37 may
also be mounted on the front face 25' to provide various information
associated with the
switching circuit and its controls. As illustrated, the bottom edge of the
cover plate 25 is
provided with legs 24 which are shaped to be retained captive behind notches
23 cut in
the lower edge of the opening 17. Alternatively, the bottom edge of the cover
plate 25
could be fitted with a hinge to hingedly attach the cover plate adjacent the
lower edge of
the opening 17. Still further, the cover plate 25 could have a tether lead or
wire
connected thereto for attachment to the outer casing 19 whereby the retrofit
cover plate
is attached to the outer casing of the water heater for security purposes.
(0028) With reference to Figures 3 to 5, there is illustrated various wiring
arrangement for controlling the operation of the top or bottom resistive
heating element
12 and 13. In a three element electric water heater the bottom element 13 can
be
considered as a middle element and the third bottom element could also be
fitted with
the cover plate of the present invention with its control circuit to also
control the
operation of the bottom resistive heating element. The switching circuit means
is
generally indicated by reference numeral 40 and may consist of different types
of
switching arrangements and associated circuitry, a few of which are generally
depicted
by Figures 6A and 6B, which illustrates an electronic switch and electro-
mechanical
switch, respectively.
(0029) As shown in Figure 3, the switching circuit 40 is provided input
electrical
connection means in the form of terminals 41 for receiving power leads
directly from the
power cable entering hole 21 in the outer casing of the water heater or power
leads
disconnected from the power terminals 28 and 29 of the control portion 30 of
the
thermostat 16. The switching circuit 40 also has output electrical connection
means in
the form of terminals 42 for providing electrical connection through wires to
selected
terminals of a selected one of the thermostat depending if it is controlling
to top or
bottom resistive heating element or both simultaneously. The selected
terminals are
from the control portion 30 and the switching portion 31 of the thermostat
depending on
which of the two resistive heating elements is being controlled. In Figure 3
the wiring is
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for control of the top electrical resistive heating element 12 only, whereas
in Figure 4 the
wiring illustrates the connection for operating the bottom resistive heating
element only.
Figure 5 shows the 220 volts entrance power cable connected directly to the
input
terminals 41 of the switching circuit 40 and the output terminals 42 are
connected to the
power terminals 28 and 29 of the thermostat control portion of the top
resistive heating
element 12. Of course, instead of screw terminals 41 and 42 these may be
constituted
by leads to which the connection are made when considering that the switching
circuit
could be encapsulated in electrically insulating molded material.
(0030) Figure 6A is a simplified block diagram of an electronic switch, herein
in the
form of a triac 45, operated by a driver circuit 46 which is placed into
operation by a
control circuit 47. An AC/DC converter circuit 50 provides the necessary 24
vdc to the
circuitry of the control circuit 47 and the driver circuit 46. The control
circuit 47 is
remotely controlled, in a wireless manner, by signals received from its
antenna 48 from
a satellite and emanating from a utility 49 or utility provider. The control
circuit 47 may
also be controlled by wired connection from an Ethernet network topography or
an
Internet connectivity or any other communication circuit arrangement obvious
to a
person skilled in the art.
(0031) Figure 6B is a further simplified block diagram of an electro-
mechanical switch,
herein a relay switch 51 having an energizing circuit 52 controlled by a
controller circuit
53. An AC/DC converter 54 provides the necessary 24 vdc to the circuits. The
220 vac
is connected to the terminal 56 of the switch arm 57 which is operated by
energizing its
coil 58. The coil 58 is energized by its energizing circuit connection 59
controlled by the
control circuit 53 which is itself remotely controlled by the utility or
utility provider 49 or
other remote controller device.
(0032) It is within the ambit of the present invention to cover any obvious
modifications of the embodiments described herein provided such modifications
fall
within the scope of the appended claims.
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