US20120174878A1

US20120174878A1 - Gas-fired water heater with an exhaust assembly

Info

Publication number: US20120174878A1
Application number: US12/987,445
Authority: US
Inventors: Stephen T. English
Original assignee: AO Smith Corp
Current assignee: AO Smith Corp
Priority date: 2011-01-10
Filing date: 2011-01-10
Publication date: 2012-07-12
Also published as: CA2763382A1

Abstract

A gas-fired water heater including a storage tank, a combustion chamber, a burner for producing products of combustion, the burner positioned in the combustion chamber, a flue including a longitudinal axis, the flue extending from the combustion chamber through the storage tank, and an exhaust assembly positioned above the flue. The exhaust assembly includes a hood, a motor including a drive shaft, and a fan coupled to the drive shaft for rotation with the drive shaft about a rotational axis. The hood receives the products of combustion from the flue and directs the products of combustion at an acute angle toward the fan. The rotational axis is positioned at the acute angle relative to the longitudinal axis.

Description

BACKGROUND

The present invention relates to water heaters, and more particularly to gas-fired water heaters with exhaust assemblies.
Typical gas-fired water heaters produce exhaust gases or products of combustion that must be exhausted outside of the residence or other building in which the water heater is installed. An exhaust assembly, blower, or fan moves the exhaust gases generated by the water heater from the water heater to the atmosphere outside the building.

SUMMARY

The present invention provides, in one aspect, a gas-fired water heater including a storage tank, a combustion chamber, a burner for producing products of combustion, the burner positioned in the combustion chamber, a flue including a longitudinal axis, the flue extending from the combustion chamber through the storage tank, and an exhaust assembly positioned above the flue. The exhaust assembly includes a hood, a motor including a drive shaft, and a fan coupled to the drive shaft for rotation with the drive shaft about a rotational axis. The hood receives the products of combustion from the flue and directs the products of combustion at an acute angle toward the fan. The rotational axis is positioned at the acute angle relative to the longitudinal axis.
The present invention provides, in another aspect, an exhaust assembly for use with a gas-fired water heater including a flue having a longitudinal axis, the gas-fired water heater producing products of combustion. The exhaust assembly includes a hood, a motor including a drive shaft, and a fan coupled to the drive shaft for rotation with the drive shaft about a rotational axis. The hood receives the products of combustion from the flue and directs the products of combustion at an acute angle toward the fan. The rotational axis is positioned at the acute angle relative to the longitudinal axis.
Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is front view of a gas-fired water heater including an exhaust assembly.

FIG. 2 is a perspective view of the exhaust assembly of FIG. 1.

FIG. 3 is an exploded view of the exhaust assembly of FIG. 1.

FIG. 4 is a sectional view of the exhaust assembly of FIG. 1 along line 4-4.

Before any embodiments 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 and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

DETAILED DESCRIPTION

FIG. 1 illustrates a gas-fired water heater 100. The water heater 100 includes a water storage tank 105 and a combustion chamber 110 positioned below the storage tank 105. A burner 115 is positioned in the combustion chamber 110. A flammable gas is provided to the burner 115 by a gas inlet or manifold 120 connected to a gas valve 125. The gas valve 125 is also connected to a gas supply. The combustion chamber 110 communicates with an air supply, for example, the atmosphere around the water heater 100. A jacket 130 including a cover 135 surrounds the storage tank 105 and combustion chamber 110. Foam insulation is provided between the storage tank 105 and jacket 130. A flue 140 extends from the combustion chamber 110, through the storage tank 105, and through the cover 135. The flue 140 includes a longitudinal axis 145. The products of combustion or exhaust gases created by the burner 115 flow through the flue 140 to heat the water stored in the storage tank 105. A cold water inlet pipe 150 is connected to a dip tube 155 to supply cold water to the storage tank 105. A hot water supply pipe 160 is connected to the storage tank 105 to supply hot water to an end-use location, for example, a faucet. An exhaust assembly 165 is coupled to the cover 135 and positioned above the flue 140. The exhaust assembly 165 receives the exhaust gas exiting the flue 140. The structure of the gas-fired water heater 100 other than the exhaust assembly 165 is typical of a storage or tank gas-fired water heater. The exhaust assembly 165 could also be used with other known gas-fired water heaters, including instantaneous or tankless water heaters or tank-tankless water heaters. Directional language refers to the exhaust assembly 165 as installed for normal, intended use with a gas-fired water heater 100.
As shown in FIGS. 2 and 3, the exhaust assembly 165 includes a hood 170, a blower housing 175, a fan, blower, or impeller 180, and a motor 185. The hood 170 includes a chamber 190 formed by multiple walls 195, including a rear wall 200. The chamber 190 includes an open bottom portion 205 that is positioned above the flue 140 to receive exhaust gas from the flue 140. The flue 140 includes a flue outlet 210. An air inlet 215 is connected to the chamber 190. At least a portion 220 of the rear wall 200 is angled toward the flue 140. An opening, hole, or aperture 225 is formed through the angled portion 220. A flow path axis 230 passes through the center of the opening 225, is perpendicular to the angled portion 220, and is positioned at an acute angle 232 relative to the longitudinal axis 145. An acute angle is greater than zero degrees and less than ninety degrees. Preferably, the acute angle 232 is forty-five degrees. A flow path 235 between the flue outlet 210 and the opening 225 is at least partially defined by the walls so that the hood 170 directs the exhaust gas toward the fan 180 at the acute angle 232 and through the opening 225 in a direction substantially parallel to the flow path axis 230. The direction of flow of the exhaust gas is shown by the arrows in FIG. 4.
The blower housing 175 includes a chamber 240 formed by a front wall 245, an outer wall 250, and a cover 255. The outer wall 250 is cylindrical and extends rearwardly from the front wall 245. The blower housing 175 is secured to the hood 170 so that the front wall 245 abuts the angled portion 220. In some embodiments, a gasket or seal is compressed between the front wall 245 and the angled portion 220 to create a substantially air-tight seal between the hood 170 and the blower housing 175. An opening, hole, or aperture 260 is formed through the front wall 245. The opening 260 is coaxial with the opening 225 and substantially the same size and shape as the opening 225. A blower outlet 265 extends vertically from the outer wall 250 along an outlet axis 270, with vertical being in the same direction as the longitudinal axis 145. The fan 180 is positioned within the chamber 240. The cover 255 is secured to the outer wall 250 at the distal end of the outer wall 250. The motor 185 is secured to the blower housing 175 by a motor housing 275. A drive shaft 280 extends through an opening in the cover 255 and is connected to the fan 180 so that that drive shaft 280 and the fan 180 both rotate about a rotational axis 285. The rotational axis 285 is parallel to or collinear with the flow path axis 230. Therefore, the rotational axis 285 is positioned at an acute angle 287 relative to the longitudinal axis 145. Preferably, the acute angle 232 is equal to the acute angle 287. The acute angle 287 is preferably forty-five degrees.
In use, exhaust gas exits the flue 140 through the flue outlet 210 in a flow direction generally parallel to the longitudinal axis 145. The exhaust gas is received within the chamber 190 and directed at the acute angle 232 toward the opening 225. Ambient dilution air is drawn through the air inlet 215 into the chamber 190. The dilution air mixes with the exhaust gas in the chamber 190, thereby reducing the concentration of undesirable chemicals formed during the combustion process and lowering the temperature of the exhaust gas before the mixture enters the blower housing 175. The mixture of exhaust gas and dilution air exits the hood 170 through the opening 225 in a flow direction generally parallel to the flow path axis 230. The mixture enters the chamber 240 through the opening 260. The rotating fan 180 moves the mixture through the chamber 240 to the blower outlet 265 where the mixture exits in a direction generally parallel to the outlet axis 270. The blower outlet 265 is connected to an exhaust duct that connects the exhaust assembly 165 to the atmosphere outside the building.
The rotational axis 285 acutely angled from vertical improves the efficiency of the exhaust assembly 165 over known horizontal or vertical exhaust assemblies. A vertical exhaust assembly includes a motor and fan oriented so that the rotational axis of the motor shaft and fan is parallel with the longitudinal axis 145. This causes the exhaust gas entering the vertical exhaust assembly to make a ninety degree turn when transitioning from the flue to the blower housing. A horizontal exhaust assembly includes a motor and a fan oriented so that the rotational axis of the motor shaft and fan is perpendicular to the longitudinal axis. This causes the exhaust gas entering the horizontal exhaust assembly to make a ninety degree turn when transitioning from the flue to the hood and a second ninety degree turn when transitioning from the hood to the blower housing. By acutely angling the rotational axis 285, the exhaust gas turns less than ninety degrees before entering the blower housing 175 so that the efficiency of the exhaust assembly 165 is improved and the power requirement for the motor 185 is reduced. The angled design of the exhaust assembly 165 also allows the exhaust assembly 165 to be positioned between the cold water inlet pipe 150 and the hot water supply pipe 160.
Various features of the invention are set forth in the following claims.

Claims

1. A gas-fired water heater, comprising:

a storage tank;

a combustion chamber;

a burner for producing products of combustion, the burner positioned in the combustion chamber;

a flue including a longitudinal axis, the flue extending from the combustion chamber through the storage tank; and

an exhaust assembly positioned above the flue, the exhaust assembly including a hood, a motor including a drive shaft, and a fan coupled to the drive shaft for rotation with the drive shaft about a rotational axis;

wherein the hood receives the products of combustion from the flue and directs the products of combustion at an acute angle toward the fan and the rotational axis is positioned at the acute angle relative to the longitudinal axis.

2. The gas-fired water heater of claim 1, wherein the acute angle is forty-five degrees.

3. The gas-fired water heater of claim 1 wherein the exhaust assembly further includes a blower housing coupled to the hood, the blower housing including a chamber and a blower outlet extending from the chamber along an outlet axis; and

wherein the fan is positioned within the chamber.

4. The gas-fired water heater of claim 3, wherein the outlet axis is parallel to the longitudinal axis.

5. The gas-fired water heater of claim 3, wherein the acute angle is forty-five degrees.

6. The gas-fired water heater of claim 4, wherein the acute angle is forty-five degrees.

7. An exhaust assembly for use with a gas-fired water heater including a flue having a longitudinal axis, the gas-fired water heater producing products of combustion, the exhaust assembly comprising:

a hood;

a motor including a drive shaft; and

a fan coupled to the drive shaft for rotation with the drive shaft about a rotational axis;

8. The exhaust assembly of claim 7, wherein the acute angle is forty-five degrees.

9. The exhaust assembly of claim 7 further comprising a blower housing coupled to the hood, the blower housing including a chamber and a blower outlet extending from the chamber along an outlet axis; and

wherein the fan is positioned within the chamber.

10. The exhaust assembly of claim 9, wherein the outlet axis is parallel to the longitudinal axis.

11. The exhaust assembly of claim 9, wherein the acute angle is forty-five degrees.

12. The exhaust assembly of claim 10, wherein the acute angle is forty-five degrees.