Gas delivery system with pre-mix blower

Abstract

A gas delivery system for an appliance, such as a water heater, including a gas control valve and a blower housing assembly which are mounted to the water heater proximate one another. The blower housing assembly includes a motor for driving an impeller within the blower housing, and an outlet of the blower housing is connected to the gas burner assembly of the water heater. A gas supply conduit extends from the control valve into the blower housing, and the outlet of the gas supply conduit is disposed within the blower housing interior near the blower housing inlet and the central portion of the impeller. In operation, rotation of the impeller draws a flow of air through the blower housing. Concurrently, gas is supplied through the gas supply conduit to the interior of the blower housing near the impeller, and the gas is mixed with the flow of air to form an air/gas mixture which is supplied through the outlet of the blower housing to the gas burner for combustion. In this manner, the gas is pre-mixed with air within the blower housing before being supplied to the burner assembly, and wherein combustion of the air/gas mixture results in a cleaner combustion with reduced nitrous oxide emissions.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under Title 35, U.S.C. § 119(e) of U.S. Provisional Patent Application Ser. No. 60/545,340, entitled GAS DELIVERY SYSTEM WITH PRE-MIX BLOWER, filed on Feb. 17, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to gas delivery systems for gas-operated appliances, and in particular, relates to a gas delivery system for the gas burner assembly of a water heater.

2. Description of the Related Art

Gas water heaters are used in residential and commercial applications to heat cold water from a water source, and to store heated water for demand-based supply to one or more water taps or other appliances. Gas water heaters generally include an insulated holding tank having a cold water inlet, usually located near the top of the tank, which supplies cold water to the lower portion of the tank through a dip tube. A hot water outlet, also typically located near the top of the tank, supplies heated water from the upper portion of the tank to one or more use locations through suitable conduits.

A control valve, typically mounted near the lower outside portion of the tank of the water heater, is connected to a gas supply. The control valve includes a thermostat which detects the temperature of the water in the tank, and regulates gas delivery from the gas source to one or more gas burners which are located in a burner chamber beneath the tank. The burners are ignited by a pilot light or by a spark ignition system, for example. Gas is supplied by the control valve directly to the ignited burner for combustion in the presence of air, which generates heat for heating the water in the lower portion of the tank. The heated water generally rises to the upper portion of the tank, such that cold water supplied through the end of the dip tube is heated in the lower portion of the tank and thereafter rises to the upper portion of the tank.

A vent chimney vents exhaust gases from the burner chamber through suitable conduits to the atmosphere. Some water heaters also include a blower, usually located near the top portion of the tank, for assisting evacuation of the exhaust gases from the burner chamber through the chimney.

A problem with the foregoing gas delivery systems is that combustion of the gas by the burner, in which the gas is supplied directly to the burner, tends to produce a relatively large amount of nitrous oxide (NO_x) emissions.

What is needed is a gas delivery system for appliances, such as water heaters, which is effective to reduce nitrous oxide emissions.

SUMMARY OF THE INVENTION

The present invention provides a gas delivery system for an appliance, such as a water heater, including a gas control valve and a blower housing assembly which are mounted to the water heater proximate one another. The blower housing assembly includes a motor for driving an impeller within the blower housing, and an outlet of the blower housing is connected to the gas burner assembly of the water heater. A gas supply conduit extends from the control valve into the blower housing, and the outlet of the gas supply conduit is disposed within the blower housing interior near the blower housing inlet and the central portion of the impeller. In operation, rotation of the impeller draws a flow of air through the blower housing. Concurrently, gas is supplied through the gas supply conduit to the interior of the blower housing near the impeller, and the gas is mixed with the flow of air to form an air/gas mixture which is supplied through the outlet of the blower housing to the gas burner for combustion. In this manner, the gas is pre-mixed with air within the blower housing before being supplied to the burner assembly, and wherein combustion of the air/gas mixture results in a cleaner combustion with reduced nitrous oxide emissions.

Advantageously, the present inventors have found that supplying a mixture of air and gas to the burner for combustion, rather than supplying gas directly to the burner as in known gas burner systems currently used in water heaters, results in a cleaner combustion with reduced nitrous oxide emissions. Additionally, the present gas delivery system is easily assembled to the water heater, thus reducing the overall cost of the water heater.

In one embodiment, the gas delivery system is assembled to a water heater as follows. First, the gas control valve is mounted to the water heater. Then, the blower housing assembly is mounted to the water heater near the gas control valve. The gas supply conduit is then extended from the blower housing for connection to a compression fitting at the outlet of the control valve. Thereafter, the compression fitting at the control valve outlet is tightened to secure the gas supply conduit to the gas control valve, followed by tightening a compression fitting at the gas inlet of the blower housing to secure the gas supply conduit to the blower housing.

In one form thereof, the present invention provides a gas supply assembly for supplying an air/gas mixture to the burner assembly of a water heater, including a blower housing assembly, including a blower housing having an inlet, and an outlet in fluid communication with the gas burner assembly; a motor having a rotatable output shaft; and an impeller coupled to the output shaft and disposed within the blower housing; and a gas supply conduit fluidly communicating a source of gas to the blower housing, whereby rotation of the impeller draws air into the blower housing through the inlet, and gas supplied through the gas supply conduit is mixed with the air within the blower housing to form an air/gas mixture which is supplied to the gas burner assembly through the blower housing outlet.

In another form thereof, the present invention provides a gas supply assembly for supplying an air/gas mixture to the burner assembly of a water heater, including a blower housing assembly, including a blower housing having an inlet, and an outlet in fluid communication with the gas burner assembly; a motor having a rotatable output shaft; and an impeller coupled to the output shaft and disposed within the blower housing; and a control valve fluidly communicating a source of gas to the blower housing, whereby rotation of the impeller draws air into the blower housing through the inlet, and gas supplied through the control valve is mixed with the air within the blower housing to form an air/gas mixture which is supplied to the gas burner assembly through the blower housing outlet.

In a further form thereof, the present invention provides a method of operating a gas supply assembly for a water heater, including the steps of rotating an impeller within a blower housing to induce an air flow through the blower housing; supplying gas from a gas source into the blower housing; mixing the gas with the air flow within the blower housing to form an air/gas mixture; and supplying the air/gas mixture to a burner assembly of the water heater.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of the lower portion of a water heater having a gas delivery system in accordance with the present invention, including a control valve, blower housing, and gas supply conduit;

FIG. 2 is a front view of the control valve, blower housing, and gas supply conduit of FIG. 1;

FIG. 3 is a section al view taken along line 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary view of a portion of FIG. 3, showing a compression fitting;

FIG. 5 is a perspective view of the blower housing assembly and gas supply conduit, viewed from above, in which the impeller is visible within the blower housing; and

FIG. 6 is a perspective view of the blower housing assembly and gas supply conduit, viewed from below, in which a portion of the impeller is visible within the blower housing.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention any manner.

DETAILED DESCRIPTION

Referring to FIG. 1, the lower portion of a water heater 20 is shown, which generally includes an insulated holding tank 22, and a gas burner assembly 24 disposed in the lower portion of water heater 20 generally beneath holding tank 22. Gas burner assembly 24 includes a gas manifold 26 and one or more burners (not shown) having spark or hot surface igniters, or example. Water heater 20 additionally includes other known features common to presently manufactured water heaters, such as those discussed above, which do not pertain to the present invention and therefore are not shown and described herein in detail.

Referring to FIGS. 1-3, 5, and 6, the gas delivery system or gas supply assembly 38 of the present invention includes a gas control valve 40 mounted to water heater 20 in a suitable manner, such as with screw fasteners, for example. Control valve 40 includes valve body 42 and, as shown in FIGS. 2 and 3, gas inlet 44 and gas outlet 46. Gas inlet 44 is connected to a gas supply in a conventional manner, such as to the gas supply in a residential home, for example. Control valve 40 further includes a thermostat with temperature control (not shown) for detecting the temperature of the water in tank 22 of water heater 20, and a control mechanism (not shown) for regulating the supply of gas to the gas burner assembly from the gas source. Control valve 40 may be a SV9560 or SV9570 or similar water heater control, available from Honeywell, Inc., Minneapolis, Minn., or a 2000 WIPER/WDER or similar gas heating control, available from RobertShaw Controls Company, Long Beach, Calif., for example.

Blower housing assembly 50 generally includes blower housing 52, electric motor 54, and impeller 56. Blower housing 52 may include features similar to the blower housings which are disclosed in U.S. patent application Ser. No. 10/934,004, entitled DRAFT INDUCER BLOWER WITH Z-AXIS VOLUTE, filed on Sep. 3, 2004; U.S. patent application Ser. No. 10/934,070, entitled LOBED JOINT DRAFT INDUCER BLOWER, filed on Sep. 3, 2004; and U.S. Pat. No. 5,954,476 to Stewart et al., each assigned to the assignee of the present invention, the disclosures of which are expressly incorporated therein by reference. Motor 54 may be, for example, any of a number of existing electric motors manufactured by Fasco, Inc. of Cassville, Mo.

Blower housing 52 is mounted to water heater 20 with suitable fasteners which extend through mounting bosses 57 (FIG. 2) into water heater 20 or a suitable bracket (not shown) attached to water heater 20. Blower housing 52 may be made of stamped and/or formed sheet metal components, or alternatively, may be formed of molded plastic components, and generally includes first housing section 58 connected to second housing section 60 in a suitable manner, such as via a tongue-and-groove snap fit connection of the type disclosed in the above-incorporated U.S. Pat. No. 5,954,476 to Stewart et al. First housing section 58 is disposed adjacent water heater 20, and includes a circular inlet opening 62. Motor 54 is mounted to second housing section 60, and includes output shaft 64 extending through a hole in second housing section 60. Motor 54 is electrically connected to control valve 40, and the operation of motor 54 is controlled by control valve 40.

Impeller 56 is mounted to the end of output shaft 64, and is rotatably driven by motor 54 within blower housing 52 to draw air into blower housing 52 through inlet opening 62 and to discharge the air through outlet 66 of blower housing 52. Outlet 66 of blower housing 52 is connected to manifold 26 of gas burner assembly 24 beneath tank 22 of water heater 20, and gas burner assembly 24 includes one or more gas burners (not shown) for burning an air/gas mixture which is supplied to the gas burner assembly in the manner described below.

Referring additionally to FIG. 4, first housing section 58 of blower housing 52 additionally includes gas inlet 68 including threaded interior bore 70. Gas supply conduit 72 includes inlet end 74 connected to gas outlet 46 of control valve 40, and also includes outlet end 76. In particular, gas supply conduit 72 is connected to gas outlet 46 of control valve 40 and to blower housing 52 by first and second compression fittings 78 and 80. Referring to FIG. 4, each compression fitting 78 and 80 is identical, and includes nut 82 with external threads 83 for engagement with the internal threads 85 of gas outlet 46 of control valve 40 and threaded bore 70 of gas inlet 68 of blower housing 52. Compression fittings 78 and 80 each additionally include annular ferrule 84, which is deformably and sealingly compressed about the external surface of gas supply conduit 72 upon tightening of nut 82.

The gas delivery system 38 may be assembled to water heater 20 in the following manner, although variations in the procedure described below will be apparent to those skilled in the art. First, control valve 40 is mounted to water heater 20 in a suitable manner. Blower housing assembly 50 is mounted to water heater 20 below gas valve 40 in a suitable manner, and outlet 66 of blower housing 52 is connected to the gas burner assembly of water heater 20. During installation of blower housing assembly 50, gas supply conduit 72 may be slidably fitted within inlet 68 of blower housing 52 in a downwardly or inwardly-shifted position, in which gas supply conduit 72 is translated toward the interior of blower housing 52.

Following mounting of blower housing assembly 50 to water heater 20, gas supply conduit 72 is translated upwardly or outwardly of blower housing 52 to engage inlet end 74 thereof with gas outlet 46 of control valve 40. Thereafter, nut 82 of first compression fitting 78 is tightened to secure inlet end 74 of gas supply valve 40 to gas outlet 46 of control valve 40. Then, nut 82 of second compression fitting 80 is tightened to secure gas supply conduit 70 to blower housing 52.

As shown in FIGS. 3 and 6, after gas supply conduit 72 has been thus secured, outlet end 76 of gas supply conduit 72 is disposed closely adjacent the central portion of impeller 56 and at substantially a 90° relationship to the direction of air flow through inlet opening 62 of blower housing 52. Thus, outlet end 76 of gas supply conduit 72 is connected to blower housing 52 adjacent inlet opening 62 of blower housing 52 in the manner described herein. Advantageously, upon rotation of impeller 56, air is drawn into blower housing 52 through inlet opening 62, forming a low pressure area at inlet opening 62. Thus, when impeller 56 is rotating, gas supplied through gas supply conduit 72 is readily and immediately drawn into inlet opening 62. Alternatively, in other embodiments, control valve 40 may be mounted directly to blower housing 52, wherein the length of gas supply conduit 72 may be reduced, or gas supply conduit 72 may be unnecessary.

In operation, when control valve 40 detects via its thermostat that water in tank 22 of water heater 20 needs to be heated, control valve 40 actuates motor 54 to rotate impeller 56 within blower housing 52 to draw inlet air through inlet opening 62 of blower housing 52, and to discharge the air through outlet 66 of blower housing 52 to the gas burner assembly of water heater 20. After a flow of air is established through blower housing 52, control valve 40 supplies gas through gas supply conduit 72, such that the gas exits the gas supply conduit 72 at outlet end 76. The gas is then immediately drawn into the air stream and is intimately mixed with the intake air within blower housing 52 to form an air/gas mixture which is then supplied through outlet 66 of blower housing 52 to gas burner assembly 24 of water heater 20. Control valve 40 may control both the speed of rotation motor 54 and impeller 56, as well as amount of gas which is supplied through gas supply conduit 72 to portion the air/gas mixture as desired.

In this manner, blower housing 52 and impeller 54 act similar to the carburetor of an engine to intimately and thoroughly mix the gas with a supply of intake air to form an air/gas mixture which is supplied to gas burner assembly of water heater 20 for combustion. Combustion of the gas/air mixture results in a cleaner combustion, which reduces nitrous oxide emissions over the higher emissions observed when gas is supplied directly to the burners for combustion, as in the burners of known water heaters.

While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Claims

1. A gas supply assembly for supplying an air/gas mixture to the burner assembly of a water heater, comprising:

a blower housing assembly, comprising: a blower housing having an inlet, and an outlet in fluid communication with the gas burner assembly; a motor having a rotatable output shaft; and an impeller coupled to said output shaft and disposed within said blower housing; and

a gas supply conduit fluidly communicating a source of gas to said blower housing, whereby rotation of said impeller draws air into said blower housing through said inlet, and gas supplied through said gas supply conduit is mixed with the air within said blower housing to form an air/gas mixture which is supplied to the gas burner assembly through said blower housing outlet.

2. The gas supply assembly of claim 1, wherein said gas supply conduit includes an outlet end disposed adjacent said inlet of said blower housing.

3. The gas supply assembly of claim 1, wherein said gas supply conduit includes an outlet end aligned substantially 90° with respect to a direction of air flow into said blower housing inlet.

4. The gas supply assembly of claim 1, wherein said blower housing includes a bore, at least a portion of said gas supply conduit received within said bore.

5. The gas supply assembly of claim 1, further comprising a control valve in fluid communication with the gas source, said control valve selectively controlling gas flow from the gas source through said gas supply conduit.

6. The gas supply assembly of claim 5, wherein said gas supply conduit comprises:

an inlet end connected to said control valve; and

an outlet end connected to said blower housing.

7. The gas supply assembly of claim 6, wherein at least one of said inlet and said outlet ends of said gas supply conduit is connected to said control valve and said blower housing via a compression fitting.

8. A gas supply assembly for supplying an air/gas mixture to the burner assembly of a water heater, comprising:

a blower housing assembly, comprising: a blower housing having an inlet, and an outlet in fluid communication with the gas burner assembly; a motor having a rotatable output shaft; and an impeller coupled to said output shaft and disposed within said blower housing; and

a control valve fluidly communicating a source of gas to said blower housing, whereby rotation of said impeller draws air into said blower housing through said inlet, and gas supplied through said control valve is mixed with the air within said blower housing to form an air/gas mixture which is supplied to the gas burner assembly through said blower housing outlet.

9. The gas supply assembly of claim 8, further comprising a gas supply conduit connecting said control valve and said blower housing.

10. The gas supply assembly of claim 9, wherein said gas supply conduit includes an outlet end disposed adjacent said inlet of said blower housing.

11. The gas supply assembly of claim 9, wherein said gas supply conduit includes an outlet end aligned substantially 90° with respect to a direction of air flow into said blower housing inlet.

12. The gas supply assembly of claim 9, wherein at least one of an inlet and an outlet end of said gas supply conduit is connected to said control valve and said blower housing via a compression fitting.

13. A method of operating a gas supply assembly for a water heater, comprising the steps of:

rotating an impeller within a blower housing to induce an air flow through the blower housing;

supplying gas from a gas source into the blower housing;

mixing the gas with the air flow within the blower housing to form an air/gas mixture; and

supplying the air/gas mixture to a burner assembly of the water heater.

14. The method of claim 13, wherein said supplying step further comprises supplying gas from a gas source into the blower housing through a gas supply conduit fluidly connecting the gas source to the blower housing.

15. The method of claim 13, wherein said supplying step further comprises supplying gas from a gas source into the blower housing through a control valve.

16. The method of claim 13, wherein said supplying step further comprises supplying gas from a gas source into the blower housing at a location adjacent an inlet of the blower housing.