U.S. patent application number 09/757983 was filed with the patent office on 2001-11-08 for method and apparatus for cooling and expelling exhaust gases from a water heater.
Invention is credited to Stewart, Dale.
Application Number | 20010038794 09/757983 |
Document ID | / |
Family ID | 46257402 |
Filed Date | 2001-11-08 |
United States Patent
Application |
20010038794 |
Kind Code |
A1 |
Stewart, Dale |
November 8, 2001 |
Method and apparatus for cooling and expelling exhaust gases from a
water heater
Abstract
A blower unit is disclosed which seals atop a conventional water
heater. The unit utilizes a one-piece housing divided into two
chambers which are in fluid communication; the first chamber houses
the impeller, while the second chamber houses the exhaust flue of
the water heater. An inlet plate having an inlet opening is
disposed between the two chambers. The blower motor is separated
from the blower housing to prevent heated exhaust gases from
heating the motor. During operation, dilution air and exhaust gases
are drawn into the blower housing and mixed together to reduce the
temperature of the exhaust gases. The gas mixture is then expelled
from the unit via an exhaust outlet in the blower housing.
Inventors: |
Stewart, Dale; (Aurora,
MO) |
Correspondence
Address: |
Invensys plc Intellectual Property Department
Mail Stop BP52-1J
33 Commercial Street
Foxboro
MA
02035
US
|
Family ID: |
46257402 |
Appl. No.: |
09/757983 |
Filed: |
January 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09757983 |
Jan 10, 2001 |
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09398484 |
Sep 17, 1999 |
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6231311 |
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Current U.S.
Class: |
417/53 ;
417/201 |
Current CPC
Class: |
F23L 17/005 20130101;
F04D 29/5806 20130101; F04D 25/082 20130101 |
Class at
Publication: |
417/53 ;
417/201 |
International
Class: |
F04B 023/14; F04B
001/00 |
Claims
We claim:
1. A dilution air blower comprising: a blower housing; an inlet
plate having an opening; a first chamber; a second chamber, wherein
the second chamber is separated from the first chamber by the inlet
plate and is in fluid communication with the first chamber; a
housing vent, the housing vent allowing dilution air to enter the
second chamber; an exhaust outlet in fluid communication with the
first chamber; an external blower motor having a motor shaft, the
blower motor being attached to the blower housing; and an impeller
secured to the motor shaft and disposed in the first chamber.
2. The dilution air blower of claim 1, wherein the blower housing
further includes a sidewall defining an inlet shoulder for
receiving the inlet plate.
3. The dilution air blower of claim 1, further including a guide
vane attached to the inlet plate and extending into the
impeller.
4. The dilution air blower of claim 1, wherein the blower housing
has a first end having a first diameter and a second end having a
second diameter that is smaller than the first diameter.
5. The dilution air blower of claim 4, having a first skirt portion
extending from the first end and a second skirt portion extending
from the second end.
6. The dilution air blower of claim 5, wherein the first skirt
portion and the second skirt portion respectively includes a first
radially extended flange and a second radially extended flange.
7. The dilution air blower of claim 5, wherein the housing vent
consists of at least one slot placed in the second skirt.
8. A dilution air blower and water heater assembly comprising: a
water heater comprising a top surface, and an exhaust flue; and a
dilution air blower disposed at a surface of the water heater
comprising; a blower housing; an inlet plate having an opening; a
first chamber; a second chamber, wherein the second chamber is
separated from the first chamber by the inlet plate and is in fluid
communication with the first chamber; a housing vent, the housing
vent allowing dilution air to enter the second chamber; an exhaust
outlet in fluid communication with the first chamber; an external
blower motor having a motor shaft, the blower motor being attached
to the blower housing; and an impeller secured to the motor shaft
and disposed in the first chamber.
9. The dilution air blower and water heater assembly of claim 8,
further including a guide vane attached to the inlet plate and
extending into the impeller.
10. The dilution air blower and water heater assembly of claim 8,
wherein the blower housing further includes a sidewall defining an
inlet shoulder for receiving the inlet plate.
11. The dilution air blower and water heater assembly of claim 8,
wherein the water heater exhaust flue protrudes into the second
chamber, but does not protrude into the first chamber.
12. The dilution air blower and water heater assembly of claim 8,
wherein the blower housing has a first end having a first diameter
and a second end having a second diameter that is smaller than the
first diameter.
13. The dilution air blower and water heater assembly of claim 12,
wherein a first skirt portion extends from the first end and a
second skirt portion extends from the second end.
14. The dilution air blower and water heater assembly of claim 13,
wherein the first skirt portion and the second skirt portion
respectively includes a first radially extended flange and a second
radially extended flange, both first and second radially extended
flanges acting to secure and seal the dilution air blower to the
water heater.
15. The dilution air blower and water heater assembly of claim 13,
wherein the housing vent consists of at least one slot placed in
the second skirt.
16. A method of providing dilution air to a dilution air blower and
water heater assembly comprising the steps of: providing a water
heater comprising a top surface, and an exhaust flue; providing a
dilution air blower disposed at a surface of the water heater
comprising; a blower housing; an inlet plate having an opening; a
first chamber; a second chamber, wherein the second chamber is
separated from the first chamber by the inlet plate and is in fluid
communication with the first chamber; a housing vent, the housing
vent allowing dilution air to enter the second chamber; an exhaust
outlet in fluid communication with the first chamber; an external
blower motor having a motor shaft, the blower motor being attached
to the blower housing; and an impeller secured to the motor shaft
and disposed in the first chamber; rotating the impeller to develop
negative air pressure in the first chamber to draw air from the
second chamber into the first chamber; generating negative air
pressure in the second chamber; drawing dilution air into the
second chamber via the housing vent; drawing exhaust gases through
the water heater flue and into the second chamber; cooling exhaust
gases flowing out of the exhaust flue with the dilution air
entering the second chamber via the housing vent to form a gas
mixture; drawing the gas mixture into the first chamber and
impeller via the opening in the inlet plate; expelling the gas
mixture from the dilution air blower via the exhaust outlet.
17. The method of claim 16, further comprising the steps of:
attaching a guide vane to the inlet plate and extending into the
impeller; recirculating the gas mixture inside the impeller via the
guide vane to generate additional pressure.
18. The method of claim 16, further comprising the step of
providing a blower housing having a first end having a first
diameter and a second end having a second diameter that is smaller
than the first diameter.
19. The method of claim 18, wherein a first skirt portion extends
from the first end and a second skirt portion extends from the
second end.
20. The method of claim 19, wherein the first skirt portion and the
second skirt portion respectively includes a first radially
extended flange and a second radially extended flange, both first
and second radially extended flanges acting to secure and seal the
dilution air blower to the water heater.
21. The method of claim 19, wherein the housing vent consists of at
least one slot placed in the second skirt.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is filed under 37 C.F.R. 1.53(b) and is a
continuation-in-part of application Ser. No. 09/398,484, filed Sep.
17, 1999.
TECHNICAL FIELD
[0002] This invention relates generally to draft inducers for hot
water heaters. More particularly, the present invention relates to
blower designs for cooling and expelling heated flue gases
emanating from conventional hot water heaters.
BACKGROUND ART
[0003] The water heater has 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 (flue
gases) that need to be drawn through the flue of the water heater
via the most rigorous path allowable in order to minimize heat
losses and maximize the overall efficiency of the water heater.
[0004] To move the gases through the water heater, centrifugal
blowers were engineered into the system. This 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. An
additional benefit of the use of a blower with a water heater was
that the temperatures of the exhaust gases exiting the flue were
reduced due to more efficient heat scrubbing. However, in naturally
aspirated water heaters, the gases exiting the water heater were
still extremely hot. This required the use of steel exhaust tubing,
which needed to be vented to the outside of the structure in a
nearly vertical manner for safety. By using a blower, the
temperatures of the exhaust gases were reduced to the point that a
wider array of materials became available for exhaust piping.
Specifically, this allowed for the safe use of PVC piping and
horizontal venting through the nearest wall to vent the exhaust
gases to the outside atmosphere.
[0005] However, the utilization of a blower in conjunction with a
water heater presented several challenges. The exhaust gases in the
flue, while much lower in temperature than normally aspirated water
heaters, were still above ideal temperatures for direct venting
through PVC piping. To achieve desirable temperature levels,
dilution (cooling) air at ambient temperature was introduced into
the system and mixed with the hot exhaust gases from the flue.
Hence, the complexity and expense of the blower assisted water
heater was introduced when exhaust gases were mixed with the
dilution air.
[0006] Attention is drawn to a solution for adding dilution air to
exhaust gases, which employed intricate plumbing layouts that
increased manufacturing costs and increased potential failure
sources through the myriad of connections. This solution involved
the use of a T-connection attached to the flue with dilution air
being drawn through the connection along with the hot exhaust
gases. The entire blower assembly required multiple tubes,
connections and other heat resistant components to direct the
exhaust gases and dilution air through and out of the water
heater/blower system.
[0007] An additional problem surrounding this solution 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.
Additionally, exhaust gases contacting the motor were able to leak
into the ambient thereby creating various health risks due to the
toxicity of the exhaust fumes.
[0008] The instant invention solves many of the problems with the
plumbing and mixing of the hot exhaust gases with dilution air.
Additionally, the instant invention reduces production and
maintenance costs while increasing the overall safety, efficiency
and durability of the water heater blower assembly.
DISCLOSURE OF THE INVENTION
[0009] The present invention provides an improved motor blower
assembly as described herein. Said motor blower assembly, or
dilution air blower, includes a blower housing that mounts and
seals to a conventional hot water heater and is sized to fit
between the heater's inlet and outlet water pipes. Said blower
housing is vented in order to draw dilution air into the blower
unit to cool the flue gases expelled from the water heater.
[0010] 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 the
motor shaft. The blower housing has portions defining a first
chamber for receiving an impeller. The impeller is fixed to a motor
shaft attached to the rotor of a motor. Additionally, the housing
has portions which define an exhaust outlet that is in fluid
communication with the first chamber. The outlet provides egress
for exhaust gases emanating from a hot water heater to which the
blower is attached.
[0011] A blower housing cover or inlet plate is provided which is
attached to the blower housing at an intermediate location along
the sidewall of the blower housing. The inlet plate has an inlet
opening to allow dilution air and exhaust gases from a hot water
heater to enter the first chamber.
[0012] The sidewall of the blower housing extends beyond the inlet
plate and forms a first and second skirt. The blower housing is
vented through the provision of at least one vent opening or slot
disposed within the second skirt. Both the first and second skirt
have portions defining a flange adapted for securing the blower
housing to the top of a hot water heater. The combination of the
lower portion of the housing sidewall, the first and second skirt,
the inlet plate, and the top of the water heater form a second
chamber within which a flue pipe of the hot water heater is
confined. The second chamber is in fluid communication with the
first chamber via the inlet aperture of the inlet plate.
[0013] When the impeller is rotated, a negative pressure is created
in the first chamber. This negative pressure draws dilution air
through the at least one vent slot or opening in the skirt section
of the housing, and draws exhaust gases from the hot water heater.
The dilution air mixes with the hot exhaust gases in the second
chamber, which significantly reduces the temperature of the gases
to an acceptable level for expulsion. The gas/air mixture is then
drawn into the first chamber where it is forced through the outlet
portion of the blower housing.
BRIEF DESCRIPTION OF DRAWINGS
[0014] Reference is made to the accompanying drawing in which is
shown an illustrative embodiment of the invention from which its
novel features will be apparent.
[0015] In the drawing:
[0016] FIG. 1 shows a side view of the dilution air blower in
accordance with the invention;
[0017] FIG. 2 shows a side cut-away view of the dilution air blower
in accordance with the invention;
[0018] FIG. 3 shows a side view of the dilution air blower mounted
atop a conventional water heater in accordance with the
invention;
[0019] FIG. 4 shows a bottom view of the dilution air blower in
accordance with the invention;
[0020] FIG. 5 shows a top view of the dilution air blower housing
in accordance with the invention;
[0021] FIG. 6 shows a bottom view of the inlet plate in accordance
with the invention.
MODE FOR CARRYING OUT THE INVENTION
[0022] At the outset, the invention is described in its broadest
overall aspects with a more detailed description following.
Accordingly, a conventional hot water heater includes a combustion
air inlet, a combustion air chamber, a heat recovery section, a
draft inducer and a combustion gas exhaust. When the water heater
is in operation, the draft inducer or water heater blower creates a
negative pressure or induces a draft in the water heater so air for
combustion is drawn into the air inlet and then into the combustion
chamber. Once in the combustion chamber, the air is mixed with fuel
such as natural gas for combustion or burning (i.e., the heat
energy source). The heat energy of the combustion process is then
extracted from the combustion or exhaust gases (flue gases) in the
heat recovery section, which also results in the reduction in the
temperature of said gases.
[0023] After passing through the heat recovery section of the water
heater, the relatively cooler combustion gases are drawn into the
water heater blower by the rotation of the impeller or rotating
blades within said blower. The rotation of the impeller or rotating
blades generates the draft (negative pressure) which draws the air
for combustion into and through the hot water heater and its heat
recovery sections. The combustion gases are then expelled via the
water heater blower through an exhaust pipe out to the
atmosphere.
[0024] To provide an even, efficient flow of gases, it is important
that the housing for the blower be adequately sealed so that gases
are drawn into the blower at an inlet and exhausted at an outlet.
Any leaks in the housing will inevitably lead to the inefficiency
and incomplete removal of combustion gases. Additionally, it is
imperative that the combustion gases are not allowed to escape into
the ambient, as these gases are toxic.
[0025] Equally important is a means to cool the blower motor during
operation. To provide effective cooling while preventing hot
exhaust gases from entering into the motor housing (i.e., to
prevent the exhaust gases from heating the motor), the blower motor
housing is separated from the blower housing such that the pressure
at the point where the blower motor shaft enters the blower housing
is maintained at a slight vacuum. Furthermore, a cooling fan housed
in a vented mounting plate for the motor is attached to the motor
shaft to draw air through the motor assembly.
[0026] To accomplish all of these functions as well as others, a
new dilution air blower has been devised. The blower incorporates a
one-piece housing that seals on the full circumference of its
mounting base atop a conventional water heater or any other device
requiring exhaust expulsion. The housing is designed to form a
vented skirt, which extends beyond the housing sidewall so that two
chambers are formed which are in fluid communication with one
another. A first chamber located in the upper portion of the
housing encompasses the impeller, while a second chamber located in
the lower portion of the housing, houses the water heater flue.
Separating the chambers is an inlet plate having portions defining
an opening or inlet to allow the flue gas/dilution air mixture to
pass from the second chamber to the first chamber.
[0027] Referring to FIGS. 1-2 and 5, a dilution air blower 1 is
shown which provides a blower motor assembly and blower housing
that attaches directly to a hot water heater (not shown).
[0028] Said dilution air lower 1 comprises a blower housing 2
adapted to receive a conventional blower motor 3. Motor mounting
bores 23 are provided on the top surface of the motor housing 2 for
receiving mechanical fasteners (not shown) to secure said blower
motor 3 to said blower housing 2. Additionally, the top surface of
the blower housing 2 defines an aperture 24 for receiving a motor
shaft. The blower motor 3 is positioned on the outside of the
blower housing 2 prevent heated exhaust gases emanating from the
water heater from making contact with the blower motor 3 to keep
the blower motor 3 from overheating.
[0029] The blower Motor 3 has a motor shaft 4 for receiving a
cooling fan 5 and an impeller 6. At the base of said motor is a
vented shroud 7 configured to enclose a cooling fan 5. Directly
attached to the motor shaft 4 is the cooling fan 5, which is freely
rotatable within the vented shroud 7 to cool the motor during
operation. Also attached to the motor shaft 4 is an impeller 6,
which is freely rotatable within dilution air blower 1. The
impeller 6 is fitted with an optional non-vented backplate 17 to
provide structural integrity.
[0030] Said blower housing 2 has a blower housing sidewall 8 within
which the impeller 6 is situated. Side wall 8 preferably has an
inner surface 9 that is scroll shaped (as shown in FIG. 4) to
maximize the efficient flow of exhaust gases into an exhaust outlet
10 formed in blower housing 2. Exhaust outlet 10 preferably has a
shoulder 31 which is provided as a seat to an exhaust pipe (not
shown) used to channel the exhaust gases out of an enclosed
structure such as a house basement.
[0031] Referring now to FIGS. 1 and 5, a blower housing 2 is shown
which is adapted to fit about the infeed and outfeed water lines of
a hot water heater. In this embodiment, the blower housing 2 is
shaped such that a first or larger end 11 and a second or smaller
end 12 are formed. The exhaust outlet 10 is situated near the
second end 12, while the blower motor 3 is positioned towards the
first end 11. First end 11 has portions defining a first skirt 14.
Second end 12 has portions defining a second skirt 15. The blower
housing 2 is vented by the provision of at least one vent opening
or slot 16 disposed in the second skirt 15, which can be modified
to enable the dilution air blower to fit different makes and models
of water heaters. The at least one vent opening or slot 16 allows
dilution air to flow into the blower housing.
[0032] A first flange 18 extends radially from the first skirt 14
and a second flange 19 extends radially from the second skirt
15.
[0033] Flange bores 20 are provided in said flanges 18,19 for
securing and sealing the blower housing 2 to the water heater 30
with any variety of mechanical fasteners such as hex bolts 40, as
shown in FIG. 3. By design, the blower housing 2 of the dilution
air blower is secured directly to the water heater, particularly to
the top surface, and forms a seal around the full circumference of
its mounting base. The housing 2 is positioned such that an exhaust
flue (not shown) of the water heater is biased towards the second
skirt 15. Furthermore, the housing 2 is configured such that the
water heater exhaust flue protrudes into a lower chamber or second
chamber 39 (FIG. 2) of the blower housing 2, but does not protrude
into an upper or first chamber 38 (FIG. 2) of the blower housing 2
(the upper and lower chambers will be described in more detail
below), which is critical to the operation of the dilution air
blower 1.
[0034] Turning to FIGS. 2, 4 and 5, a side view, bottom view and
top view of the blower housing 2 are respectively shown. An inlet
shoulder 34 is formed and is preferably scroll-shaped to allow for
the efficient flow of exhaust gases towards the exhaust outlet 10.
An inlet plate 36 (shown in FIG. 6), which is sized and shaped to
fit within the blower housing 2 is secured to the inlet shoulder 34
with any of a variety of attachment methods such as clips,
self-tapping screws, adhesives, mating locking surfaces, etc. The
method to secure the inlet plate 36 to the blower housing 2 is not
particularly important so long as the seal between the blower
housing 2 and the inlet plate 36 is tight. A first chamber 38 (FIG.
2) for housing the impeller 6 is formed by the combination of the
upper section of the blower housing sidewall 8, the top section of
the blower housing 2 and the inlet plate 36. A second chamber 39
(FIG. 2) for housing the water heater flue, is formed by the
combination of the lower section of the blower housing sidewall 8,
the first and second skirt 14,15, the surface of the water heater
to which the blower unit is directly attached (not shown), and the
inlet plate 36. The inlet plate 36 separates the first and second
chambers of the blower housing and has portions defining an inlet
opening 40 that keeps the first chamber and second chamber in fluid
communication.
[0035] Attached to the inlet plate 36 is a guide vane 42, which
extends into the inlet portion of the impeller 6. Said guide vane,
available under the trade name "Swirlator" and described in U.S.
Pat. No. 4,549,848, guides the incoming flue gas and dilution air
mix into the inlet of the impeller 6 and re-circulates the gas/air
mixture in the impeller to increase the pressure level achieved by
the rotating impeller.
[0036] Attached to the blower housing 2 is an over temperature
protector transducer 44. Said transducer acts to shut down the
dilution air blower in the event that the blower motor fails, or
the dilution vents in the second skirt and/or the exhaust section
of the blower housing become blocked. Additionally, an optional
auxiliary box 46 for housing the water heater and dilution air
blower controls is affixed to the blower housing opposite the
exhaust outlet 10, while an optional vacuum port 48 (FIG. 2) is
positioned in the blower housing sidewall 8 to work with the water
heater if necessary.
[0037] Having described the components of dilution air blower 1,
attention will now be drawn its operation. Operation of the blower
motor 3 causes the rotation of the impeller 6 and the motor cooling
fan 5. Rotation of the impeller 6 generates negative air pressure
in the first chamber 38, which causes air and combustion gases to
be drawn into the first chamber 38 from the second chamber 39.
Additionally, rotation of the impeller 6 creates a slight vacuum at
the point where the motor shaft 4 passes into the blower housing 2
thus preventing heated exhaust gases from coming in contact with
the blower motor 3. The drawing of air and combustion gases from
the second chamber 39 causes the development of negative air
pressure in the second chamber 39. This negative air pressure
causes dilution air to pass through the at least one housing vent
opening or slot 16 in the second skirt 15.
[0038] The dilution air passing into the second chamber 39 mixes
with exhaust gases flowing out of the rigorous water heater flue
path resulting in a desirable reduction in temperature of the
exhaust gases. The mixed dilution air and exhaust gases are then
drawn into the first chamber 38 through the inlet opening 40 of the
inlet plate 36 and guided into the opening of the impeller via the
guide vane 42. Said guide vane 42 re-circulates the mixed gases,
which increases the overall amount of pressure generated by the
rotating impeller 6. Finally, the rotation of the impeller 6 drives
the mixed gases into the exhaust outlet 10 for final expulsion from
the hot water heater system.
[0039] To control the flow of dilution air from the second chamber
39, the size, shape and number of vent openings or slots 16 in the
second skirt 15 can be modified. Any reduction in the number of
second skirt vent openings or slots 16 will lesson the amount of
dilution air entering the blower. Conversely, an increase in the
number of vent openings or slots will increase the amount of
dilution air entering the dilution air blower unit 1. It is to be
cautioned that too many vent slots will cause an undesirable
reduction in negative air pressure development, which will render
the system inefficient. On the other hand, even one skirt vent slot
could be used to accomplish the cooling tasks.
[0040] It is to be understood that the present invention is by no
means limited to the particular constructions herein disclosed
and/or shown in the drawings, but also comprises any modifications
or equivalents within the scope of the claims.
* * * * *