Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02901659 2015-08-25
DUAL/MULTI ENERGY GAS WATER HEATER
TECHNICAL FIELD
(0001) The present invention relates to a dual energy gas water heater
incorporating
therein a resistive heating element whereby the water heater can be operated
by a
selected one of the energy sources, gas or electricity, and remotely during
time periods
when one of such energies is readily available or operated alternatively with
both
energies during certain periods in a day when such energy is at its less
expensive rate
or favourable for use.
BACKGROUND OF THE INVENTION
(0002) The majority of water heaters in use are of the storage type and their
source of
energy is either gas or electricity. Such energy sources are available from
grids which
are often in peak demand. Accordingly, the utility or the energy provider in
extreme
demand situations are forced to cut the energy source to some of their
customers in
order to reduce and control the load. In certain heavily populated cities like
Los
Angeles, California, for example, during summer time when the climate is hot,
there is a
huge demand for electricity by air conditioning devices and water heaters and
the load
on the grid is often at its maximum and thus requiring the utility/provider to
do some
load shedding depriving service sectors of electricity. Because electric water
heaters
are also large consumers of electricity they are rendered inoperative during
load
shedding period which occur during high demand times. This is an inconvenience
to
the consumer. It would be desirable to overcome this problem by the use of gas
water
heaters which do not rely on the electric grid. However, during winter months
many
households rely on gas heating which also results in peak demand periods for
gas when
electricity is now in surplus. In an attempt to overcome such problems, such
utility
providers offer programs where they can remotely control certain high
consuming
devices, such as air conditioners, space heating devices and water heaters,
but such is
not popular and as not proven successful.
(0003) As mentioned above, most water heaters are of the storage type and
operated
by electricity or gas. These sources of energy are expensive and particularly
so during
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peak time periods. The loads created on the supply source is often too great
to manage
and the providers need to shed some of its load creating inconvenience to
their
customers. These storage type water heaters comprise a tank in which water
from the
supply line enters the tank at a temperature in the range of about 50 degrees
F, and this
varies depending on latitude and the seasons and the source of water, such as
city
supply or artesian well. A resistive heating element projecting in the tank or
a burner
disposed beneath the tank heats the water within the tank to a temperature
typically in
the range of from 105 to 120 degrees F. A resistive heating element which is
immersed
in water is substantially 100 percent efficient whereas gas water heater are
much less
efficient, usually in the range of from about 60 to 80 percent due to heat
loss. Also, gas
water heaters produce noise when the burner is operated as opposed to electric
water
heaters which do not produce noise when the elements are in use heating the
water.
Gas water heaters, however, heat water much more quickly than electric water
heaters.
It would be desirable to construct a water heater which overcomes the above
mentioned
disadvantages and which utilizes the advantages of both energy type water
heaters. It
would also be advantageous to utilise, in combination, a renewable energy
source to
reduce the demand on the electric grid or gas distribution network.
(0004) Electric utilities as well as gas utilities have a need to take control
of water
heaters to prevent excessive demand during peak hours and to use its
electricity or gas
when the demand and cost is low. Such control would create an equilibrium or a
mean
demand of electricity or gas. Control devices have been developed and continue
to be
developed to remotely control the demand for electricity or gas. It would
therefore be
desirable to construct a water heater which can be remotely controlled by a
utility to
shed load while at the same time does not deprive the consumer from having a
continuous supply of hot water.
SUMMARY OF THE INVENTION
(0005) It is a feature of the present invention to provide a dual energy gas
water
heater which substantially overcomes the above mentioned disadvantages and
which
provides the above mentioned needs.
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(0006) It is another feature of the present invention to provide a dual energy
gas water
heater which incorporates therein a resistive heating element to heat water
within the
tank of the water heater when necessary to do so and which is automatically
and/or
remotely controlled.
(0007) Another feature of the present invention is to provide a dual energy
gas water
heater which utilises one or more additional renewable energy sources to heat
water
within the tank of the water heater.
(0008) It is a still further feature of the present invention to provide a
method of
constructing a gas water heater as a dual energy source water heater
inexpensively.
(0009) According to the above features, from a broad aspect, the present
invention
provides a dual energy gas water heater which is comprised of a tank for
containment of
water to be heated. A water inlet is secured to the tank for receiving water
to be heated
from a domestic water supply line. A water outlet is provided in a top portion
of the tank
for feeding hot water to a hot water supply line. A combustion chamber is
provided in a
lower portion of the tank and a gas burner is mounted in the chamber. A gas
supply line
is connected to the gas burner through a gas shut-off valve. A flue tube is
sealingly
secured to a top wall of the combustion chamber and extends vertically
throughout the
tank for heat exchange with water in the tank together with the top wall of
the
combustion chamber. A resistive heating element is secured in a lower portion
of the
tank above the combustion chamber. A resistive heating element is secured in a
lower
portion of the tank above the combustion chamber. The resistive heating
element is a
curved resistive heating element having a length greater than the distance
between the
wall of the tank to the flue tube and is curved to extend spaced about a
portion of the
flue tube. The curved resistive heating element has a density in the range of
20 to 80
watts/sq. inches and a length sufficient to heat water within the tank to a
desired
temperature. A thermostat is secured to the resistive heating element. A
switch is
secured between the thermostat and a voltage supply line. A controller is
provided to
selectively operate the switch and the gas valve to disconnect the voltage
supply line
from the thermostat and/or shut off the gas shut-off valve secured to the gas
supply line.
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(0010) According to a further broad aspect of the present invention there is
provided
a method of constructing a gas water heater as a dual energy source water
heater. The
method comprises securing a curved resistive heating element to a wall of a
tank of the
gas water heater at a location spaced above a top wall of a combustion chamber
of the
gas water heater in a lower portion the tank. The curved resistive heating
element has
a length greater than the distance between the wall of the tank to a flue tube
extending
centrally and vertically from the top wall of the combustion chamber. The
curved
resistive heating element extends in a curved portion thereof spaced from the
flue tube.
The curved resistive heating element is a low density, long life, resistive
heating
element having a density in the range of from about 20 to 80 watts/sq. inches
and a
length sufficient to heat water within the tank to a desired temperature.
DESCRIPTION OF THE DRAWINGS
(0011) A preferred embodiment of the present invention will now be described
with
reference to the accompanying drawings in which:
(0012) Figure 1 is a simplified fragmented section view of a gas water heater
constructed as a dual energy gas water heater wherein a resistive heating
element is
secured above the top wall of the combustion chamber and operated by a
controller;
(0013) Figure 2 is a transverse cross-section view of the tank showing the
position of
the curved resistive heating element relative to the flue tube and the tank
sidewall;
(0014) Figure 3 is a plan view of the square flange mount of the resistive
heating
element and a schematic diagram of a thermostat and remote control switch
connection
thereto;
(0015) Figure 4 is an exploded perspective view illustrating the mounting of
the curved
resistive heating element to a lower portion of the tank wall above the
combustion
chamber, and
(0016) Figure 5 is a simplified block diagram illustrating different renewable
energy
sources connected to a supplemental heating element secured to the tank wall
and
extending into the tank to heat water therein.
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DESCRIPTION OF THE PREFERRED EMBODIMENT
(0017) Referring now to the drawings and more particularly to Figures 1 and 2,
there is
shown generally a 10 a gas-fired water heater constructed in accordance with
the
present invention and wherein a resistive heating element 11 is secured to the
sidewall
13 of the tank 12 of the water heater above the top wall 14 of the combustion
chamber
15 located at the bottom of the tank 12. The tank 12 is filled with water 16
to be heated
from an inlet pipe 17 connected to the domestic water supply line 18. Water to
be
heated is released at the bottom of the tank via a dip tube 17'. A water
outlet 19 is
secured to the tank in a top portion thereof, herein the top wall 20 of the
tank 12 and
connected to a hot water supply line 19'. A gas burner 21 is supported in the
combustion chamber 15 and a gas supply line 22 is connected thereto via a gas
shut-off
valve 23. A flue tube 24 is sealingly secured in a central portion of the top
wall 14 of the
combustion chamber 15 and extends centrally and vertically throughout the tank
for
heat exchange with the water 16 together with the top wall 14 of the
combustion
chamber. A flue baffle 24' is usually secured in the flue tube 24 to retard
hot flue gases
from the combustion chamber to provide a more efficient heat exchange with the
water
16 within the tank 12. A sacrificial anode 26 extends within the tank to
protect exposed
steel within the tank from corrosion. The tank has an outer casing 27 secured
spaced
from the tank and an insulation 28 is disposed between the outer casing and
the tank to
provide thermal insulation.
(0018) With additional reference to Figures 3 and 4 there will now be
described the
resistive heating element 11 and its mounting to the tank wall 13. The
resistive heating
element 11 is a curved resistive heating element having a length greater than
the
distance between the inner surface 13' of the tank wall 13 and the flue pipe
24, namely
the distance "d", herein indicated. As shown, the curved resistive heating
element 11
extends into the tank about a portion of the flue tube 24 and spaced between
the flue
tube and the inner surface 13' of the side wall 13 of the tank. The curved
resistive
heating element is a low density, long life, resistive heating element having
a density in
the range of 20 to 80 watts/sq. inches and length sufficient to heat the water
16 within
the tank to a desired temperature. A thermostat 30 operates the resistive
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element through a switch 30' incorporated in a switching section thereof to
maintain the
water within the tank to a desired preset temperature by switching the power
to the
resistive heating element on and off. In the present embodiment, an additional
switch
29 is provided to supply power to the thermostat 30 and accordingly to the
resistive
heating element 11 when there is a need to heat water with electricity as
opposed to
gas. This switch 29 is controlled by a controller 31 which may be programmed
to
operate both the gas valve 23 and the switch 29 or the controller 31 may be
controlled
remotely by a utility or utility provider 32 through a wireless network
communication link
33 or a wired link 34.
(0019) As shown in Figures 3 and 4, the curved resistive heating element 11
has a
power rating of between 3000 to 4500 watts which is sufficient to heat the
water in the
tank up to at least 120 degrees F and is formed as a loop defined by a curved
end 35
and a parallel extension 36 terminating a short distance from its square
flange mounting
plate 37. The resistive heating element has a length of between 15 to 35
inches
depending on its power rating. The square flange mounting plate 37 is secured
to the
tank wall by four bolts 39 and sealed by an electrically insulated seal
assembly 38.
When mounted, the resistive heating element 11 has a first curved section 11'
which
projects inside the tank between the dip tube 17' and the flue tube 24 and a
second
curved section 11" which is shaped to extend spaced about the flue tube 24
along a
curve and disposed substantially central between the curved outer surface of
the flue
tube 24 and curved inner surface 13' of the tank side wall 13.
(0020) As shown in Figure 1, in one of its applications, the dual energy gas
water
heater is controlled by a utility or provider 32 which can switch the
operation of the
water heater from a gas supply source to an electrical supply source.
Accordingly, in
seasons when there is an excessive demand for electricity, the water heater
operates
as a gas water heater and when electricity is not in high demand the water
heater
operates as an electric water heater, of course, taking cost into
consideration and
resulting in a benefit to both the customer and the utility. In another
application, both
sources of energy can be used simultaneously or in an alternative fashion. For
example, the resistive heating element can be a stand-by resistive heating
element to
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maintain the water temperature in the tank at a set temperature value during
stand-by-
periods of the water heater to prevent the gas burner from cycling on and off
thereby
resulting in gas saving and eliminating noise generated by the burner during
night time
when electricity costs are at their minimum, thus improving the efficiency of
the water
heater.
(0021) With reference now to Figure 5 the dual energy water heater 10 is shown
as
being provided with a further electrical heating element 40 supported from the
tank wall
13 and extending within the tank at a predetermined location, herein in a
central portion
of the tank. A renewable energy source , such as a roof top mounted solar
panel 41
provides an additional source of electrical current to operate the element 40
and heat
water in the tank. The solar panel has a voltage regulator 42 which is
connected to a
normally closed switch 43 which is operated by the controller 31 to switch the
element
40 on and off in response to temperature signals received from a temperature
probe 44
connected to the tank wall 13. Normally, the switch would be operated to
maintain a
threshold temperature of about 120 degrees F in the upper portion of the tank.
The
renewable energy source can also be from a wind generator 45 of a wind or gas
turbine
46. Accordingly, the dual energy gas water heater can operate as a multi-
energy gas
water heater controlled by the controller 31 and/or remotely by the utility
32. The control
circuit 31 can be programmed to switch to different sources of energy, as
required
depending on water temperature or availability of energy and costs.
(0022) Summarizing, there is also provided a method of constructing a gas
water
heater as a dual energy source water heater by securing a curved resistive
heating
element 11 to a wall of the tank 13 of the water heater at a location spaced
above a the
top wall 14 of the combustion chamber 15. The curved resistive heating element
11 has
the characteristics and specification as described herein. The resistive
heating element
11 is connected to a switch or switching circuit 29 operated by a controller
31 to connect
and disconnect a voltage supply therefrom to provide for an alternative source
of energy
to heat water within the tank. When gas is in short supply or when electricity
is less
costly than gas, the water is heated by the resistive heating element. When
electricity is
in short supply the water heater operates with gas. Both sources can also be
used at
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the same time as described above. The dual energy gas water heater can be
operated
by a programmed controller or remotely by the utility/provider.
(0023) It is within the ambit of the present invention to cover any
modification of the
preferred embodiment described herein, provided such modifications fall within
the
scope of the appended claims.
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