Liquid heaters and vaporizers – Miscellaneous
Reexamination Certificate
2001-11-29
2003-03-11
Lu, Jiping (Department: 3745)
Liquid heaters and vaporizers
Miscellaneous
C417S360000
Reexamination Certificate
active
06530346
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to draft inducers for hot water heaters. More particularly, the present invention relates to a blower design for expelling flue gases emanating from conventional hot water heaters.
Water heaters have been around for many years to provide a supply of heated water for both commercial and consumer usage. To generate the requisite thermal energy needed to increase the temperature of the water therein, a gas or oil fired burner is commonly employed. The burner produces hot combustion gases or flue gases, which need to be expelled from the water heater.
To minimize heat losses and maximize the overall efficiency of the water heater, it is desirable to have the heated flue gases flow through the water heater via the most rigorous path possible. Essentially, the more rigorous the path is, the more heat (energy) can be recovered from the flue gases and transferred to the water.
Presently, the vast majority of commercial water heaters rely on the chimney effect to draw flue gases up the center flue and out the chimney. Because the chimney effect relies on natural ventilation, water heaters must be designed to incorporate a less rigorous path through the flue, which sacrifices efficiency.
In some instances, centrifigal blowers have been engineered into the hot water heating system to move the gases through the water heater. The use of a blower allowed the most rigorous path possible for the flue, which in turn increased the amount of heat transferred from the flue gases to the water. However, the addition of a centrifugal blower significantly increased the overall cost and complexity of the water heating system through the use of intricate plumbing layouts and multiple piece blower housings. Furthermore, these blowers introduced dilution air into the system, which required a more powerful motor, thereby reducing the overall savings realized by recovering more heat from the flue gases.
Another problem with these blower/water heater systems was that exhaust fumes could potentially make contact with the blower motor, thereby causing the blower motor to overheat, which affected the longevity of the motor and overall efficiency of the blower unit. Also, exhaust gases contacting the motor were able to leak into the ambient environment, thereby creating various health risks due to the toxicity of the exhaust fumes.
The present invention solves many of the problems regarding the plumbing of the hot exhaust gases inside of and outside of the water heater. Additionally, the instant invention reduces production and maintenance costs while increasing the overall safety, efficiency and durability of the water heater heating system.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a water heater blower unit that is cost effective to manufacture, assemble and maintain.
An additional object of the present invention is to increase the overall efficiency of a conventional hot water heater by allowing for the implementation of a more rigorous flue path to maximize the amount of heat that can be recovered from the heated gases traveling therein.
A further object of the present invention is to provide a blower motor assembly that seals on the full circumference of its mounting base and easily mounts atop a conventional hot water heater to facilitate and maximize the potential to draw exhaust gases through and away from the water heater while minimizing the amount of motor power required to drive the system.
Still yet another object of the present invention is to keep exhaust gases from making contact with the blower motor and leaking into the surrounding atmosphere.
The present invention achieves the objectives set forth above by providing an improved motor blower assembly as described herein. The motor blower assembly of the present invention includes a scroll-shaped blower housing that mounts and seals atop a conventional hot water heater and is sized to fit between the heater's inlet and outlet water pipes. The blower housing is not vented, in order to maximize the amount of negative pressure needed to draw flue gases out of the water heater.
The one-piece blower housing has three apertures on its top surface to receive bolts to secure a conventional motor to the blower housing, and one radially centered aperture to receive a motor shaft. The blower housing has portions defining an upper chamber for receiving an impeller. The impeller is fixed to a motor shaft attached to the rotor of the motor. Additionally, the housing has portions which define a vertical outlet that is in fluid communication with the upper chamber. The outlet provides egress for exhaust gases emanating from a hot water heater to which the blower is designed to be attached.
A blower inlet plate is provided which is positioned internal within the blower housing at an intermediate location along a sidewall of the housing. The inlet plate includes an inlet aperture that creates a vertical inlet through which exhaust gases exiting the hot water heater enter the upper chamber. The combination of the inlet plate, the lower sidewall of the blower housing and the top of the water heater form a lower chamber within which a flue pipe of the hot water heater is confined. The lower chamber is in fluid communication with the upper chamber of the blower housing via the inlet aperture of the blower inlet plate.
When the impeller is rotated, a negative pressure is created in the upper chamber of the blower housing. This negative pressure draws exhaust gases through and out of the hot water heater and into the lower chamber. The gases are then drawn into the upper chamber through the inlet aperture of the inlet plate, where they are forced through the vertical outlet of the blower housing.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.
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Coones Lyn D.
Gatley William S.
Andrus Sceales Starke & Sawall LLP
Fasco Industries, Inc.
Lu Jiping
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