US20170038094A1

US20170038094A1 - Air inlet damper

Info

Publication number: US20170038094A1
Application number: US15/229,664
Authority: US
Inventors: Robert Frederick Poehlman; Janice Fitzgerald; J. Eric Arnold; Timothy Mitchel Smith; Chad Taylor Thompson; II George W. Kraus; Duane A. Lee
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 2015-08-07
Filing date: 2016-08-05
Publication date: 2017-02-09
Also published as: CA2938260A1

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.

Description

BACKGROUND

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

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.
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.
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.
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.
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.
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.
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.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an atmospheric water heater with a partial cutaway to illustrate internal components.

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.

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.

FIG. 4 is a cross-sectional view of the air inlet assembly taken along line 4-4 of FIG. 3.

FIG. 5 is a top perspective view of the air inlet assembly of FIG. 2.

FIG. 6 is a bottom perspective view of an air inlet assembly including a flame arrestor.

FIG. 7 is a cross-sectional view of the air inlet assembly including a flame arrestor of FIG. 6.

FIG. 8 is a bottom perspective partial view of a water heater including a protective bottom according to a first construction.

FIG. 9 is a bottom perspective partial view of a water heater including a protective bottom according to a second construction.

FIG. 10 is a bottom perspective partial view of a water heater including a protective bottom according to a third construction.

FIG. 11 is a bottom perspective view of an air inlet assembly including a mechanical linkage.

FIG. 12 is a cross-sectional view of the air inlet assembly including the linkage of FIG. 11.

FIG. 13 is a bottom perspective view of an air inlet assembly according to another construction.

FIG. 14 is a bottom perspective view of an air inlet assembly according to another construction.

FIG. 15 is a top view of the air inlet assembly of FIG. 14.

FIG. 16 is a side view of the air inlet assembly of FIG. 14.

FIG. 17 is a bottom perspective view of an air inlet assembly according to another construction.

FIG. 18 is a bottom perspective view of an air inlet assembly according to another construction.

FIG. 19 is a perspective view of another water heater construction according to the invention.

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.

FIG. 21 is a side cross section view of the damper mechanism of the water heater in FIG. 19 in a first position.

FIG. 22 is a side cross section view of the damper mechanism of the water heater in FIG. 19 in a second position.

FIG. 23 is an enlarged view of a portion of the damper mechanism in the first position.

FIG. 24 is an enlarged view of a portion of the damper mechanism in the second position.

DETAILED DESCRIPTION

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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.

Claims

What is claimed is:

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.