U.S. patent application number 15/229664 was filed with the patent office on 2017-02-09 for air inlet damper.
The applicant listed for this patent is A. O. SMITH CORPORATION. Invention is credited to J. Eric Arnold, Janice Fitzgerald, George W. Kraus, II, Duane A. Lee, Robert Frederick Poehlman, Timothy Mitchel Smith, Chad Taylor Thompson.
Application Number | 20170038094 15/229664 |
Document ID | / |
Family ID | 57966270 |
Filed Date | 2017-02-09 |
United States Patent
Application |
20170038094 |
Kind Code |
A1 |
Poehlman; Robert Frederick ;
et al. |
February 9, 2017 |
AIR INLET DAMPER
Abstract
A fuel fired, atmospheric water heater has a burner positioned
inside a combustion chamber. All combustion air entering the
combustion chamber must pass through a damper. The damper is
operable to adjust the flow resistance to combustion air entering
the combustion chamber. The damper is biased to a closed position
such that during non-firing periods of the water heater, the damper
significantly reduces the flow rate of combustion air being
provided to the combustion chamber reducing standby heat loss. An
actuator is in fluid communication with a fuel supply line such
that when pressurized fuel is provided to the burner, the
pressurized fuel causes the actuator to move the damper to an open
position to permit operative combustion air delivery to the
combustion chamber during firing periods of the water heater.
Inventors: |
Poehlman; Robert Frederick;
(Cudahy, WI) ; Fitzgerald; Janice; (Mequon,
WI) ; Arnold; J. Eric; (Jonesborough, TN) ;
Smith; Timothy Mitchel; (Blountville, TN) ; Thompson;
Chad Taylor; (Dandridge, TN) ; Kraus, II; George
W.; (Johnson City, TN) ; Lee; Duane A.;
(Johnson City, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
A. O. SMITH CORPORATION |
Milwaukee |
WI |
US |
|
|
Family ID: |
57966270 |
Appl. No.: |
15/229664 |
Filed: |
August 5, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62202550 |
Aug 7, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F23L 3/00 20130101; F23N
3/007 20130101; F23N 2241/04 20200101; F24H 9/2035 20130101; F23N
1/027 20130101 |
International
Class: |
F24H 9/20 20060101
F24H009/20; F23N 3/00 20060101 F23N003/00 |
Claims
1. A water heater comprising: a combustion chamber; a burner
disposed in the combustion chamber; a fuel valve operable to adjust
a flow rate of fuel between a first flow rate and a second flow
rate greater than the first flow rate; a fuel supply line
communicating between the burner and the fuel valve for supply of
pressurized fuel from the fuel valve to the burner; an air inlet
assembly mounted to the combustion chamber and operable to permit
combustion air to enter the combustion chamber, the air inlet
assembly including: a damper movable between a first position
corresponding to a first resistance to air entering the combustion
chamber and a second position corresponding to a second resistance
to air entering the combustion chamber, wherein the first
resistance is greater than the second resistance; an actuator
operable to move the damper between the first position and the
second position; a conduit communicating between the actuator and
the fuel valve such that the actuator moves the damper to the first
position in response to the first flow rate and the actuator moves
the damper to the second position in response to the second flow
rate.
2. The water heater of claim 1, wherein the water heater is an
atmospheric water heater.
3. The water heater of claim 1, wherein the actuator has no
electrical components.
4. The water heater of claim 1, wherein the fuel valve is operable
to infinitely adjust the fuel flow rate.
5. The water heater of claim 4, wherein the damper resistance is
infinitely adjustable as a function of the fuel flow rate.
6. The water heater of claim 1, wherein the actuator includes a
diaphragm and a pin, such that the pin is coupled to a first side
of the diaphragm and a second side of the pin is in fluid
communication with the conduit.
7. The water heater of claim 1, further comprising an arm
functionally connecting the actuator and the damper.
8. The water heater of claim 1, further comprising a closure
mechanism to bias the damper to the first position.
9. The water heater of claim 8, wherein the closure mechanism is a
counterweight positioned on the damper.
10. The water heater of claim 8, wherein the closure mechanism is a
spring.
11. The water heater of claim 8, wherein the closure mechanism is
achieved by designing the damper so that its own weight biases it
to the closed position
12. The water heater of claim 1, wherein the damper translates
between the first position and the second position.
13. The water heater of claim 1, wherein the damper rotates about
an axis from the first position to the second position.
14. The water heater of claim 1, wherein the damper includes a
front portion and a rear portion; and when the damper is in the
second position the front portion is lower than in the first
position and the rear portion is higher than in the first
position.
15. The water heater of claim 1, wherein a flame arrestor is
located between the combustion chamber and the air intake assembly
such that substantially all the combustion air passing through the
air intake assembly must pass through the flame arrestor before
arriving in the combustion chamber.
16. A control system for a flow of combustion air to a combustion
system of a water heater, the control comprising: a fuel valve for
supplying fuel to the combustion system at a selected flow rate;
and a damper restricting combustion airflow to a combustion chamber
as a function of the fuel flow rate.
17. A control system of claim 16, wherein the damper is movable
between a first position corresponding to a first resistance to
combustion air entering the combustion chamber and a second
position corresponding to a second resistance to combustion air
entering the combustion chamber, wherein the first resistance is
greater than the second resistance.
18. A control system of claim 16, wherein an actuator operably
moves the damper between a first position corresponding to a first
resistance to combustion air entering the combustion chamber and a
second position corresponding to a second resistance to combustion
air entering the combustion chamber, wherein the first resistance
is greater than the second resistance.
19. A control system of claim 16, wherein the actuator has no
electrical components.
20. A control system of claim 16, wherein the combustion air being
supplied to the combustion chamber is substantially at atmospheric
pressure.
21. A control system of claim 17 wherein the damper translates from
the first position to the second position.
22. A control system of claim 17, wherein the damper rotates about
an axis from the first position to the second position.
23. A control system of claim 17, wherein a closure mechanism
biases the damper to the first position.
24. A control system of claim 23, wherein the closure mechanism is
a spring.
25. A control system of claim 23, wherein the closure mechanism is
a counterweight.
26. The water heater of claim 23, wherein the closure mechanism is
achieved by designing the damper so that its own weight biases it
to the closed position
27. A method of controlling the flow of combustion air to a
combustion system of a water heater, the method comprising:
controlling a flow of fuel to the combustion system with a fuel
valve; and controlling a flow of combustion air to the combustion
system with a damper by setting a flow resistance of the damper as
a function of a flow rate of fuel from the fuel valve.
28. The method of claim 27, further comprising communicating the
fuel valve with the damper via a conduit; wherein controlling a
flow of combustion air includes actuating the damper in response to
pressure of fuel in the conduit.
29. The method of claim 27, further comprising providing an
actuator operable in response to pressure; exposing the actuator to
pressure of fuel supplied by the fuel valve; and wherein
controlling the flow of combustion air includes actuating the
damper with the actuator in response to pressure of the supplied
fuel.
30. The method of claim 29, wherein actuating the damper with the
actuator includes interconnecting the actuator with the damper by
way of an actuator arm.
Description
BACKGROUND
[0001] This application claims priority to U.S. Provisional Patent
Application No. 62/202,550 filed Aug. 7, 2015. The present
invention relates to an atmospheric water heater and more
specifically an atmospheric water heater with an air inlet
assembly.
SUMMARY
[0002] In one aspect, the invention provides a water heater
comprising a combustion chamber; a burner disposed in the
combustion chamber; a fuel valve operable to adjust a flow rate of
fuel between a first flow rate and a second flow rate greater than
the first flow rate; a fuel supply line communicating between the
burner and the fuel valve for supply of pressurized fuel from the
fuel valve to the burner; an air inlet assembly mounted to the
combustion chamber and operable to permit combustion air to enter
the combustion chamber, the air inlet assembly including: a damper
movable between a first position corresponding to a first
resistance to air entering the combustion chamber and a second
position corresponding to a second resistance to air entering the
combustion chamber, wherein the first resistance is greater than
the second resistance; an actuator operable to move the damper
between the first position and the second position; a conduit
communicating between the actuator and the fuel valve such that the
actuator moves the damper to the first position in response to the
first flow rate and the actuator moves the damper to the second
position in response to the second flow rate.
[0003] In another aspect, the water heater is an atmospheric water
heater. In another aspect, the actuator has no electrical
components. In another aspect, the fuel valve is operable to
infinitely adjust the fuel flow rate. In another aspect, the damper
resistance is infinitely adjustable as a function of the fuel flow.
In another aspect, the actuator includes a diaphragm and a pin,
such that the pin is coupled to a first side of the diaphragm and a
second side of the pin is in fluid communication with the conduit.
In another aspect, the water heater further comprises an arm
functionally connecting the actuator and the damper. In another
aspect, the water heater further comprises a closure mechanism to
bias the damper to the first position. In another aspect, the
closure mechanism is a counterweight positioned on the damper. In
another aspect, the closure mechanism is a spring. In another
aspect, the closure mechanism is achieved by designing the damper
so that its own weight biases it to the closed position. In another
aspect, the damper translates between the first position and the
second position. In another aspect, the damper rotates about an
axis from the first position to the second position. In another
aspect, the damper includes a front portion and a rear portion; and
when the damper is in the second position the front portion is
lower than in the first position and the rear portion is higher
than in the first position. In another aspect, a flame arrestor is
located between the combustion chamber and the air intake assembly
such that substantially all the combustion air passing through the
air intake assembly must pass through the flame arrestor before
arriving in the combustion chamber.
[0004] In another aspect, the invention provides a control system
for a flow of combustion air to a combustion system of a water
heater, the control comprising: a fuel valve for supplying fuel to
the combustion system at a selected flow rate; and a damper
restricting combustion airflow to a combustion chamber as a
function of the fuel flow rate.
[0005] In another aspect, the damper is movable between a first
position corresponding to a first resistance to combustion air
entering the combustion chamber and a second position corresponding
to a second resistance to combustion air entering the combustion
chamber, wherein the first resistance is greater than the second
resistance. In another aspect, an actuator operably moves the
damper between a first position corresponding to a first resistance
to combustion air entering the combustion chamber and a second
position corresponding to a second resistance to combustion air
entering the combustion chamber, wherein the first resistance is
greater than the second resistance. In another aspect, the actuator
has no electrical components. In another aspect, the combustion air
being supplied to the combustion chamber is substantially at
atmospheric pressure. In another aspect, the damper translates from
the first position to the second position. In another aspect, the
damper rotates about an axis from the first position to the second
position. In another aspect, a closure mechanism biases the damper
to the first position. In another aspect, the closure mechanism is
a spring. In another aspect, the closure mechanism is a
counterweight. In another aspect, the closure mechanism is achieved
by designing the damper so that its own weight biases it to the
closed position.
[0006] In another aspect, the invention provides a method of
controlling the flow of combustion air to a combustion system of a
water heater, the method comprising: controlling a flow of fuel to
the combustion system with a fuel valve; and controlling a flow of
combustion air to the combustion system with a damper by setting a
flow resistance of the damper as a function of a flow rate of fuel
from the fuel valve.
[0007] In another aspect, the method of controlling flow of
combustion air to a combustion system of a water heater further
comprises communicating the fuel valve with the damper via a
conduit; wherein controlling a flow of combustion air includes
actuating the damper in response to pressure of fuel in the
conduit.
[0008] In another aspect, the method of controlling flow of
combustion air to a combustion system of a water heater further
comprises providing an actuator operable in response to pressure;
exposing the actuator to pressure of fuel supplied by the fuel
valve; and wherein controlling the flow of combustion air includes
actuating the damper with the actuator in response to pressure of
the supplied fuel. In another aspect, actuating the damper with the
actuator includes interconnecting the actuator with the damper by
way of an actuator arm.
[0009] Other aspects of the invention will become apparent by
consideration of the detailed description and accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an isometric view of an atmospheric water heater
with a partial cutaway to illustrate internal components.
[0011] FIG. 2 is a bottom perspective view from line 2-2 of FIG. 1
illustrating an air inlet assembly of the atmospheric water heater
of FIG. 1 in a first position corresponding to a first airflow
rate.
[0012] FIG. 3 is a bottom perspective view from line 2-2 of FIG. 1
illustrating the air inlet assembly of the atmospheric water heater
of FIG. 1 in a second position corresponding to a second airflow
rate.
[0013] FIG. 4 is a cross-sectional view of the air inlet assembly
taken along line 4-4 of FIG. 3.
[0014] FIG. 5 is a top perspective view of the air inlet assembly
of FIG. 2.
[0015] FIG. 6 is a bottom perspective view of an air inlet assembly
including a flame arrestor.
[0016] FIG. 7 is a cross-sectional view of the air inlet assembly
including a flame arrestor of FIG. 6.
[0017] FIG. 8 is a bottom perspective partial view of a water
heater including a protective bottom according to a first
construction.
[0018] FIG. 9 is a bottom perspective partial view of a water
heater including a protective bottom according to a second
construction.
[0019] FIG. 10 is a bottom perspective partial view of a water
heater including a protective bottom according to a third
construction.
[0020] FIG. 11 is a bottom perspective view of an air inlet
assembly including a mechanical linkage.
[0021] FIG. 12 is a cross-sectional view of the air inlet assembly
including the linkage of FIG. 11.
[0022] FIG. 13 is a bottom perspective view of an air inlet
assembly according to another construction.
[0023] FIG. 14 is a bottom perspective view of an air inlet
assembly according to another construction.
[0024] FIG. 15 is a top view of the air inlet assembly of FIG.
14.
[0025] FIG. 16 is a side view of the air inlet assembly of FIG.
14.
[0026] FIG. 17 is a bottom perspective view of an air inlet
assembly according to another construction.
[0027] FIG. 18 is a bottom perspective view of an air inlet
assembly according to another construction.
[0028] FIG. 19 is a perspective view of another water heater
construction according to the invention.
[0029] FIG. 20 is a perspective view of the bottom portion of the
water heater of FIG. 19 with a manifold door and a bottom cover
removed.
[0030] FIG. 21 is a side cross section view of the damper mechanism
of the water heater in FIG. 19 in a first position.
[0031] FIG. 22 is a side cross section view of the damper mechanism
of the water heater in FIG. 19 in a second position.
[0032] FIG. 23 is an enlarged view of a portion of the damper
mechanism in the first position.
[0033] FIG. 24 is an enlarged view of a portion of the damper
mechanism in the second position.
DETAILED DESCRIPTION
[0034] Before any constructions of the invention are explained in
detail, it is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the following drawings. The invention is capable of other
embodiments or constructions and of being practiced or of being
carried out in various ways.
[0035] With reference to FIG. 1, a fuel-fired atmospheric water
heater 10 is illustrated with portions removed for illustrative
purposes. More specifically, the water heater 10 includes a tank 14
to hold water to be heated and a jacket 18 surrounding the tank 14.
The tank 14 and the jacket 18 are supported on a skirt 22 including
a plurality of openings 26. The skirt 22 raises the tank 14 and the
jacket 18 up off the ground and the plurality of openings 26 allows
for air to flow underneath the tank 14, as will be described in
greater detail below. In alternative constructions, the tank 14 and
the jacket 18 are raised up off the ground by legs instead of by a
skirt (see, for example, legs 146 of FIG. 6). A combustion chamber
30 is positioned underneath the tank 14 and a main burner 34 is
positioned within the combustion chamber 30. The burner 34 and
combustion chamber 30, when used together, may also be referred to
as a combustion system. A flue 38 extends through the tank 14 from
the combustion chamber 30 to an exhaust vent 42 positioned at a top
end 46 of the water heater 10. The water heater 10 is an
atmospheric water heater that does not include any powered blowers
or fans to create airflow, but rather relies upon the natural
convection of air and combustion exhaust through the water heater
10.
[0036] With reference to FIGS. 1-3, an air inlet assembly 50 is
positioned beneath the combustion chamber 30. The air inlet
assembly 50 includes a damper 54 rotatably mounted to a housing 58.
The housing 58 includes a plurality of flanges 62 in order to mount
the air inlet assembly 50 to the bottom of the combustion chamber
30, and the housing 58 further defines an air inlet opening 66
(FIG. 3) at atmospheric pressure. In other words, the air inlet
assembly 50 provides an air intake at atmospheric pressure to the
combustion chamber 30.
[0037] In the illustrated construction, the damper 54 is rotatable
about a horizontal axis 70 between a first position (FIG. 2)
corresponding to a first resistance to air entering the combustion
chamber and a second position (FIG. 3) corresponding to a second
resistance to air entering the combustion chamber. In alternative
constructions, the damper 54 is configured to translate relative to
the housing 58 between a first and a second position. The first
resistance to air entering the combustion chamber is greater than
the second resistance to air entering the combustion chamber. Air
at atmospheric pressure enters the combustion chamber corresponding
to a first airflow rate at the first resistance, and at a second
airflow rate corresponding to the second resistance. The airflow
rate is the amount of air entering the combustion chamber 30 as a
function of time. The second airflow rate supports full combustion
at the burner 34 (e.g., between approximately 5 CFM and
approximately 13 CFM), and the first airflow rate is only enough to
support combustion at a standing pilot burner (not shown) (e.g.,
between approximately 0.03 CFM and approximately 0.15 CFM). In this
regard, the damper 54 adjusts the restriction of airflow into the
combustion chamber 30.
[0038] The damper 54 includes a front portion 74 and a rear portion
78. When the damper 54 is in the second position, the front portion
74 of the damper 54 is lower (i.e., closer to the ground) than the
rear portion 78. When the damper 54 is in the first position, the
front portion 74 of the damper 54 is adjusted to create a larger
inlet area that substantially all the combustion air entering the
combustion chamber 30 must pass through, allowing a higher airflow
rate. The resistance to combustion air entering the combustion
chamber 30 is inversely related to the size of the inlet area such
that when the air inlet area is at its maximum the resistance to
air entering the combustion chamber is at a minimum. The damper 54
further includes a sealing gasket 80 to create an air-tight seal.
The sealing gasket 80 is positioned on the bottom of the rear
portion 78 and on the top of the front portion 74. In the
illustrated construction, the damper 54 includes an air opening 82
formed therein. The air opening 82 is sized and specifically
engineered to calibrate the first airflow rate when the damper 54
is in the first position such that it is only enough to support
combustion of a standing pilot. In some constructions, a spacer is
positioned between the housing 58 and the damper 54 to create an
opening that sets the first airflow rate when the damper 54 is in
the first position. In further alternatives, the damper 54 is
undersized to create an air gap between the damper 54 and the
housing 58 sufficient to set the first airflow rate.
[0039] With reference to FIG. 4, the air inlet assembly 50 further
includes an actuator 86 positioned outside of the housing 58 and is
coupled to an exterior 90 of the housing 58 by a bracket 94. The
actuator 86 includes a linearly-actuated pin 98 (FIG. 4) extending
from an actuator housing 102. The pin 98 is operably connected to
the damper 54 such that linear actuation of the pin 98 causes the
damper 54 to move between the first position and the second
position. An arm 106 extends between the damper 54 and the pin 98,
and the arm 106 acts as a force transfer member that converts
linear translation of the pin 98 into rotational motion of the
damper 54 about the axis 70. In the illustrated construction, the
arm 106 is secured to the front portion 74 of the damper 54. In
alternative constructions, the arm 106 is formed integrally with
the damper 54. The actuator 86 includes a diaphragm 110 and the pin
98 is coupled to a first side 114 of the diaphragm 110. A second
side 118 of the diaphragm 110 is selectively exposed to a
pressurized gas, as explained further below. In alternative
constructions, the pin 98 moves the damper 54 between the first and
second positions through direct contact. Alternatively, cylinder
style actuators or any type of actuator that utilizes a pressurized
fluid to motivate movement can be used in place of the diaphragm
actuator disclosed above.
[0040] With reference to FIGS. 1-3, the water heater 10 further
includes a fuel valve 122 that receives a fuel supply and is
coupled to a spud projection from the tank 14. The fuel supply may
be provided from a utility or other source of gas at an elevated
pressure (e.g., above atmospheric pressure) which may be referred
to as pressurized gas. The gas may alternatively be referred to as
"fuel" for the purposes of this disclosure.
[0041] A first conduit 126 is in fluid communication between the
fuel valve 122 and the burner 34, and a second conduit 130 is in
fluid communication between the first conduit 126 and the actuator
86. The first conduit 126 may alternatively be referred to as the
fuel supply line and the second conduit 130 may alternatively be
referred to as the pressure signal line. In the illustrated
configuration, the second conduit 130 is connected to a tee 134
formed in the first conduit 126. As an alternative configuration,
the second conduit 130 may communicate directly between the fuel
valve 122 and the actuator 86 parallel to the first conduit 126, as
distinguished from the series-parallel configuration of the first
and second conduits 126, 130 illustrated in FIG. 1-3. For example,
the second conduit 130 may tap into the fuel valve 122 through an
existing port such as a pressure test port of the fuel valve 122.
Alternatively, a fuel valve 122 could be designed with a port
specifically dedicated to the purpose of providing a pressure
signal to the actuator 86 through the second conduit 130. An
opposite end of the second conduit 130 is connected to a
pressurized gas inlet 132 formed in the actuator housing 102.
[0042] Regardless of the configuration of the first and second
conduits 126, 130, when gas is supplied to the burner 34 through
the first conduit 126, gas is also supplied to the actuator 86
through the second conduit 130. The pressurized gas in the second
conduit 130 bears against and acts on the second side 118 of the
diaphragm 110, causing the diaphragm 110 to elastically deflect and
linearly actuate the pin 98. The un-deflected state of the
diaphragm 110 and pin 98 is shown with dashed lines in FIG. 4.
[0043] With reference to FIGS. 4-5, the air inlet assembly 50
further includes a closure mechanism (described in more detail
below) that biases the damper 54 to the first position (FIG. 2)
quickly after operation of the burner 34 has stopped due to closing
of the fuel valve 122 (i.e., after the pressure signal to the
actuator 86 via the second conduit 130 has been turned off). While
moving to the first position, the damper 54 pushes on the diaphragm
110 via the pin 98 and moves the diaphragm to its un-deflected
state (see dashed lines in FIG. 4). Such rapid movement of the
diaphragm 110 to the un-deflected state causes back-pressure in the
second conduit 130. Because the first conduit 126 communicates with
the second conduit 130 either directly (in the illustrated
series-parallel configuration) or indirectly (through the fuel
valve 122 in the alternative parallel configuration described
above), the back-pressure in the second conduit 130 pushes gas out
of the first and second conduits 126, 130 to the burner 34. Thus,
the closure mechanism can be said to purge or partially purge gas
from the first and second conduits 126, 130 following cessation of
burner 34 operation. Rapidly purging or partially purging gas from
the conduits 126, 130 can help reduce the extent of soot buildup in
the combustion chamber 30 and flue 38 arising from a slow,
fuel-rich burn of the residual fuel in the conduits 126, 130
following normal burner 34 operation (this is commonly referred to
in the industry as "candling") with the damper 54 in the first
position.
[0044] Referring to FIGS. 4-5, one construction of the closure
mechanism may include a counterweight 138 mounted on the rear
portion 78 of the damper 54. The counterweight 138 may take the
form of, for example, a hem formed from bending the end of the
damper 54 over onto itself The hem itself may form the
counterweight 138 or it may be folded around additional dense
material to add to the counterweight 138. With reference to FIGS.
2-4, another construction of the closer mechanism may include
torsional springs 142 mounted about the axis 70. In further
alternatives, the closure mechanism may include a damper with a
center-of-gravity positioned in the rear portion to effectively
provide its own counterweight. In further alternatives, the closure
mechanism may include a spring mounted around the pin 98 inside of
the actuator 86 between the diaphragm 110 and an interior wall of
the actuator housing 102. One or more of the described closure
mechanisms may be utilized in combination.
[0045] During operation, when heating of the water held in the tank
14 is desired, gas is supplied to the burner 34 from the fuel valve
122 through the first conduit 126 and gas is simultaneously
supplied to the actuator 86 through the second conduit 130 (in
series-parallel or in parallel, as discussed above). The gas to the
burner 34 provides fuel for combustion, and the gas to the actuator
86 provides a pressure signal for moving the damper 54 to the
second position. When the damper 54 is in the second position, the
damper 54 opens the opening 66 to permit sufficient airflow into
the combustion chamber 30 to support complete combustion at the
burner 34. The products of combustion are then used to heat the
water held in the tank 14 as the products of combustion move from
the combustion chamber 30 through the flue 38 and out the exhaust
vent 42. Once heating is no longer desired, the fuel valve 122
stops the flow of gas to the burner 34 through the first conduit
126, which also automatically cuts off the gas pressure signal to
the actuator 86 through the second conduit 130. As described above,
once the flow of gas is stopped, the counterweight 138, torsion
springs 142, or other closure mechanism or mechanisms act to
quickly move the damper 54 into the first position. Quickly closing
the damper 54 drives or purges excess gas from the conduits 126,
130. Once the damper 54 is in the first position, the airflow rate
is reduce to an amount for supporting a standing pilot only and
significantly reduces heat loss from excess air moving through the
combustion chamber 30 and the flue 38 when combustion at the burner
34 is not occurring.
[0046] As such, the air inlet assembly 50 is an energy saving
device that is designed to limit the amount of air allowed to enter
the combustion chamber 30 when the burner 34 is not operational to
avoid losing heat to the environment through the flue 38. The air
inlet assembly 50 has two distinct functional positions (i.e., a
high airflow rate position permitting sufficient airflow for burner
operation and a low airflow rate position permitting sufficient
airflow for pilot burner operation). Alternatively, the air inlet
assembly may be designed for any of an infinite range of positions
corresponding to an infinite number of flow resistances (e.g., for
use with a modulating burner). When the burner 34 is not
operational, the air inlet assembly 50 is in the low airflow rate
position to minimize inefficiencies.
[0047] With reference to FIGS. 6 and 7, the air inlet assembly 50
is utilized in combination with a thermal cut-out switch, the fuel
valve 122, and a flame arrestor 150. The flame arrestor 150 reduces
the risk of combustion escaping the combustion chamber 30 via the
air inlet assembly 50 by absorbing the heat from a flame front,
thus lowering the temperature of the burning fuel/air mixture below
its auto-ignition temperature. The heat is absorbed through small
passages built into the flame arrestor 150. The thermal cut-out
switch is activated when there is an over-temperature arising, for
example, when the flue 38 is blocked, when there is a flammable
vapor event, or another occurrence of elevated heat in the
combustion chamber 30. The thermal cut-out switch stops the flow of
gas to the burner 34 through the first conduit 126 and the pressure
signal to the actuator 86 through the second conduit 130. As
described above, when the thermal cut-out switch is activated, the
system responds to return the damper 54 to the first position. If
the elevated temperature is due to a flammable vapor event, any
combustion in the combustion chamber is starved of oxygen due to
the damper 54 being in the first position, and the combustion will
eventually be extinguished.
[0048] With reference to FIGS. 8-10 the air inlet assembly 50 may
include shipping protection to protect the air inlet assembly 50
from damage when traveling between the manufacturing plant and
installation, for example. The shipping protection may be left on
the water heater 10 during operation of the water heater. FIG. 8
illustrates a sheet metal plate 154 permanently fixed to the bottom
of the legs 146. Rubber pads 158 are positioned on the underside of
the protective sheet metal plate 154. A manifold door 162 is also
provided to protect the first and second conduits 126, 130
including the gas line 130 supplying the actuator 86 with
pressurized gas. As an alternative, FIG. 9 illustrates a sheet
metal plate 166 permanently fixed to the base ring 170. As a
further alternative, FIG. 10 illustrates a base pan 174 to
completely encase and protect the air inlet assembly 50. The base
pan 174 includes a central opening 178 and side-opening
perforations 182 formed in the jacket 18 to allow air to flow into
the air inlet assembly 50. Rubber pads 186 are also included on the
bottom of the base pan 174 to raise the base pan 174 slightly off
the ground.
[0049] With reference to FIGS. 11 and 12, in alternative
constructions, a mechanical linkage 190 is used to connect the
actuator 86 to the damper 54. In particular, the actuator 86 is
coupled to the bottom of the combustion chamber 30, or to the outer
jacket 18, and the pin 98 is drivingly connected to a first end 194
of the linkage 190. A second end 198 of the linkage 190 is coupled
to a rod 202 that extends to an arm 206 fixed to the rear portion
78 of the damper 54. The linkage 190 is supported on a bracket 210
and is operable to pivot about an axis 214. When the pin 98 is
actuated, the linkage 190 rotates, causing the second end 198 to
rise up (i.e., move closer to the air inlet assembly 50). As the
second end 198 of the linkage 190 rotates upwards, the rear portion
78 of the damper 54 also rotates upwards via the mechanical
connection through the rod 202 and the arm 206. When the pin 98 is
retracted, the linkage 190 and damper 54 are biased to return to
the first position. By utilizing the mechanical linkage 190, the
length of the gas line 130 to the actuator 86 is minimized.
[0050] With reference to FIG. 13, an air inlet assembly 50A
according to another construction is illustrated in an open
position. The air inlet assembly 50A includes similar components as
the air inlet assembly 50, and similar components are referenced
similarly with an "A" suffix. The air inlet assembly 50A differs
from the air inlet assembly 50 in that the damper 54A rotates to
open along a long edge 72A of the damper 54A. The long edge 72A is
longer than a short edge 76A of the damper 54A.
[0051] With reference to FIGS. 14-16, an air inlet assembly 50B
according to another construction is illustrated in an open
position. The air inlet assembly 50B includes similar components as
the air inlet assembly 50 and similar components are referenced
similarly with a "B" suffix. The air inlet assembly 50B differs
from the air inlet assembly 50 in that the damper 54B is coupled to
a vertical side 60B of the housing 58B such that one or more
openings 66B are formed on one or more sides of the air inlet
assembly 50B. The actuator 86B is mounted within the housing 58B
and the pin 98B of the actuator 86B extends through an aperture 64B
formed in the vertical side 60B. When pressurized gas is present in
the line 130B, the pin 98B extends through the aperture 64B,
causing the damper 54B to move into an opened position. When the
pressurized gas is no longer present in the line 130B, the pin 98B
retracts and the damper 54B returns to the closed position. In the
illustrated construction, the damper 54B still allows some air to
flow (i.e., enough to support a pilot flame) through the air inlet
assembly 50B when the damper 54B is in the closed position by
virtue of a non-air-tight seal between the damper 54A and the
housing 58B.
[0052] With reference to FIG. 17, an air inlet assembly 50C
according to another construction is illustrated in an open
position. The air inlet assembly 50C includes similar components as
the air inlet assembly 50, 50B, and similar components are
referenced similarly with a "C" suffix. The air inlet assembly 50C
differs from the air inlet assembly 50B in that the housing 58C is
square-shaped, whereas the housing 58B of the air inlet assembly
50B is rectangular-shaped. In particular, a bottom surface 59C of
the housing 58B is square-shaped.
[0053] With reference to FIG. 18, an air inlet assembly 50D
according to another construction is illustrated in an open
position. The air inlet assembly 50D includes similar components as
the air inlet assembly 50, 50B, 50C, and similar components are
referenced similarly with a "D" suffix. The air inlet assembly 50D
differs from the air inlet assembly 50B in that the housing 58D is
trapezoid-shaped, whereas the housing 58B of the air inlet assembly
50B is rectangular-shaped. The trapezoidal shape of the housing 58D
maximizes the size of the inlet openings 66D, allowing the maximum
amount of air through the air inlet assembly 50D. In particular, a
front edge 75D of the housing 58D is longer than a rear edge
77D.
[0054] FIGS. 19-24 illustrate another construction of the damper
assembly previously described. Similar components are referenced
with the suffix "E". The fuel valve 122E, air inlet assembly 50E,
and the actuator 86E are covered with a manifold door 162E having a
louvered opening 220.
[0055] The fuel valve 122E includes a pressure testing port or
dedicated port 224 for communicating with one end of the second
conduit 130E. The opposite end of the second conduit 130E
communicates with the actuator 86E via a pressurized gas inlet
132E. The second conduit 130E is configured in parallel with the
first conduit 126E because they both communicate directly with the
fuel valve 122E.
[0056] The actuator 86E is supported by a bracket 228 that extends
from the combustion chamber housing or combustion or chamber door.
The actuator 86 is mounted inside the bracket 228 such that the
actuator 86E is between the bracket and the water heater 10E, such
that the bracket provides some protection for the actuator 86E. The
actuator 86E in this construction is possibly more serviceable than
previously-discussed constructions since it is mounted on an
exterior surface of the water heater 10E and is more readily
accessible by a service technician than an actuator 86 mounted
under the water heater 10.
[0057] The actuator 86E is similar to the previously-described
actuators 86 which include a diaphragm 110E and a pin 98E for
converting the gas pressure signal from the second conduit 130E
into linear motion. Because the actuator 86E is mounted on the side
of the water heater 10E with the diaphragm 110E essentially
vertical and the pin 98E essentially horizontal, the actuator 86E
is relatively far away from the air inlet assembly 50E. The
configuration includes a push rod 232 that extends vertically down
and horizontally through the base ring 170E to connect with the arm
106E that is used to move the damper 54E to the second
position.
[0058] A joint 236 between the push rod 232 and the arm 106E
accommodates essentially horizontal movement of the push rod 232
with respect to the pivoting arm 106E (which is pivoting about the
axis 70E of the damper 54E). The joint 236 includes a necked-down
segment 240 of the push rod 232 within a circular hole 244 in the
arm 106E. The necked-down segment 240 is of smaller diameter than
the hole 244, such there is room for the necked-down segment within
the hole 244 as the arm 106E pivots about the axis 70E.
* * * * *