U.S. patent application number 15/710795 was filed with the patent office on 2018-03-22 for warm air furnace with managed combustion air flow.
The applicant listed for this patent is United States Stove Company. Invention is credited to Brandon Lane Barry, Dustin Lee Mantooth.
Application Number | 20180080656 15/710795 |
Document ID | / |
Family ID | 61617973 |
Filed Date | 2018-03-22 |
United States Patent
Application |
20180080656 |
Kind Code |
A1 |
Barry; Brandon Lane ; et
al. |
March 22, 2018 |
WARM AIR FURNACE WITH MANAGED COMBUSTION AIR FLOW
Abstract
A warm air solid fuel furnace is disclosed that includes a
firebox defined by a floor, opposing sides, a top baffle, a front
door, and a rear wall, wherein the firebox floor is at least
partially lined with fire resistant material. A primary combustion
air flow path includes one or more holes through the front door. A
secondary air flow path receives air from a front of the furnace
and conducts received air along a first opposing side of the
firebox, up the rear wall of the firebox, and into at least one
tube having orifices, the tube located beneath the top baffle. A
rear pilot air flow path receives air from the front of the furnace
and conducts received air along a second opposing side of the
firebox, up the rear wall of the firebox, and into at least one
hole through the rear wall.
Inventors: |
Barry; Brandon Lane;
(Sewanee, TN) ; Mantooth; Dustin Lee; (South
Pittsburg, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
United States Stove Company |
South Pittsburg |
TN |
US |
|
|
Family ID: |
61617973 |
Appl. No.: |
15/710795 |
Filed: |
September 20, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62397081 |
Sep 20, 2016 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24B 5/026 20130101;
F24B 1/195 20130101; F24B 1/19 20130101 |
International
Class: |
F24B 1/19 20060101
F24B001/19; F24B 5/02 20060101 F24B005/02; F24B 1/195 20060101
F24B001/195 |
Claims
1. A warm air solid fuel furnace comprising: a firebox configured
to receive wood, said firebox defined by a floor, first and second
opposing sides, a top baffle, a front door, and a rear wall,
wherein the firebox floor is at least partially lined with fire
resistant material; a primary combustion air flow path, wherein the
primary air combustion flow path is one or more holes through the
front door; a secondary air flow path configured to receive air
from a front of the furnace and conduct the received air along the
first opposing side of the firebox, up the rear wall of the
firebox, and into at least one tube having orifices, wherein the at
least one tube is located at a top of the firebox beneath the top
baffle; and a rear pilot air flow path configured to receive air
from the front of the furnace and conduct the received air along
the second opposing side of the firebox, up the rear wall of the
firebox, and into at least one hole through the rear wall of the
firebox.
2. The furnace of claim 1, wherein: the firebox floor comprises a
section that is a grate that is not lined with fire resistant
material; and the furnace further comprises an ash tray mounted in
the furnace below the grate.
3. The furnace of claim 1, wherein a first inlet through the front
of the furnace to the secondary air flow path is separate from a
second inlet through the front of the furnace to the rear pilot air
flow path, and secondary air entering the first inlet does not mix
with rear pilot air entering the second inlet until the rear pilot
air and the secondary air enter the firebox.
4. The furnace of claim 1, wherein: the rear wall includes a rear
wall baffle in communication with the rear pilot air flow path; the
at least one hole in the rear wall is defined through the rear wall
baffle; and the rear wall baffle comprises a plurality of holes
therethrough, the plurality of holes providing increasing flow
capacity lower on the rear wall baffle than higher on the rear wall
baffle.
5. The furnace of claim 1, wherein: the rear wall includes a rear
wall baffle in communication with the rear pilot air flow path, the
at least one hole in the rear wall defined through the rear wall
baffle; and a top of the rear wall baffle is closer to the front of
the furnace than a bottom of the rear wall baffle such that the at
least one hole is oriented to direct rear pilot air toward the
floor of the firebox and toward the front of the furnace.
6. The furnace of claim 1, wherein the fire resistant material is
fire brick.
7. The furnace of claim 1, wherein a top of the top baffle is lined
with fire brick.
8. The furnace of claim 1, wherein the top baffle is higher at the
front of the furnace than at a rear of the furnace when the furnace
is in an upright position.
9. The furnace of claim 1, wherein: the top baffle is higher at a
front of the furnace than at a rear of the furnace when the furnace
is in an upright position; the at least one tube is a series of
tubes each having orifices; the orifices in the series of tubes are
oriented to direct secondary air from the secondary air flow path
into the firebox toward at least one of the floor of the firebox
and the front of the furnace; and each tube of the series of tubes
is spaced equidistant from the baffle.
10. The furnace of claim 1, wherein the at least one hole in the
rear wall of the firebox is located no more than half way up the
rear wall.
11. The furnace of claim 1, wherein the firebox is configured to
preheat secondary air and rear pilot air as the secondary air and
rear pilot air move from the front of the furnace to a rear of the
furnace along the secondary air flow path and the rear pilot air
flow path respectively.
12. The furnace of claim 1, further comprising: an air plenum
positioned above the top baffle; and a gap between the top baffle
and a front of the furnace, the gap allowing exhaust gases to pass
from the firebox and into the air plenum.
13. The furnace of claim 12, further comprising a flue in
communication with the air plenum, said flue configured to receive
exhaust gases.
14. A warm air solid fuel furnace comprising: a firebox configured
to receive wood, said firebox defined by a floor, first and second
opposing sides, a top baffle, a front door, and a rear wall,
wherein a rear portion of the firebox floor is lined with fire
brick; a primary combustion air flow path, wherein the primary air
combustion flow path is defined by one or more holes through the
front door; a secondary air flow path configured to receive air
from a front of the furnace and conduct air along the first
opposing side of the firebox, up the rear wall of the firebox, and
into a series of tubes having orifices, wherein the tubes are
located at a top of the firebox and span laterally across the top
baffle, and the orifices are oriented at least partially towards
the firebox floor; and a rear pilot air flow path configured to
receive air from the front of the furnace and conduct air along the
second opposing side of the firebox, up the rear wall of the
firebox, and into a plurality of holes defined through the rear
wall of the firebox.
15. The furnace of claim 14, wherein: each of the tubes in the
series of tubes has a first and second end; and secondary air from
the secondary air flow path is directed into both ends of the
series of tubes.
16. The furnace of claim 14, wherein the secondary air flow path
and the rear pilot air flow path are separate and independent from
one another within the furnace until the respective air flow paths
reach the firebox such that a flow capacity of the primary air
path, a flow capacity of the secondary air path, and a flow
capacity of the rear pilot air flow path are independently
predetermined to maximize combustion of the wood and combustible
gases given off by the wood during combustion.
17. The furnace of claim 14, further comprising: an inner housing,
wherein the firebox, the secondary air flow path, and the rear
pilot air path are positioned within the inner housing; an outer
housing at least partially enclosing the inner housing, a forced
air passage formed between the inner housing and the outer housing;
an exit duct defined on the outer housing, the exit duct in fluid
communication with the forced air passage; and a blower unit
mounted to the outer housing, the blower unit configured to force
air through the forced air passage and out of the exit duct.
18. The furnace of claim 17, wherein the firebox is configured to
transmit heat to the air forced through the forced air passage by
the blower unit.
19. A warm air solid fuel furnace comprising: a firebox configured
to receive wood, said firebox defined by a floor, first and second
opposing sides, a top baffle, a front door, and a rear wall,
wherein a portion of the firebox floor is lined with fire brick; a
primary combustion air flow path defined by one or more holes
through the front door; a secondary air manifold configured to
receive air from a front of the furnace and conduct air along a
first opposing sides of the firebox, up the rear wall of the
firebox, and into a series of tubes having orifices, wherein the
tubes are located at a top of the firebox below the top baffle; and
a rear pilot air manifold configured to receive air from the front
of the furnace and conduct air along a second opposing side of the
firebox, up the rear wall of the firebox, and into at least one
hole defined through the rear wall of the firebox.
20. The furnace of claim 1, further comprising: a first inlet
through the front of the furnace communicated with the secondary
air manifold; and a second inlet through the front of the furnace
communicated with the rear pilot air manifold; wherein secondary
air passing through the first inlet and the secondary manifold and
rear pilot air passing through the second inlet and the rear pilot
air manifold remain separated until the secondary air and the rear
pilot air enter the firebox.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a non-provisional of U.S. Patent
Application Ser. No. 62/397,081 filed Sep. 20, 2016 entitled "WARM
AIR FURNACE WITH MANAGED COMBUSTION AIR FLOW", the entire
disclosure of which is herein incorporated by reference in its
entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable
REFERENCE TO SEQUENCE LISTING OR COMPUTER PROGRAM LISTING
APPENDIX
[0003] Not Applicable
[0004] A portion of the disclosure of this patent document contains
material that is subject to copyright protection. The copyright
owner has no objection to the reproduction of the patent document
or the patent disclosure, as it appears in the U.S. Patent and
Trademark Office patent file or records, but otherwise reserves all
copyright rights whatsoever.
BACKGROUND OF THE INVENTION
[0005] The present invention relates generally to warm air solid
fuel furnaces. More particularly, the present invention relates to
solid wood fueled forced air furnaces.
[0006] Prior art solid fuel fired warm air furnaces include an
inner firebox, an outer cabinet, a flue, circulation blower(s), and
limit controls. The firebox is typically configured such that a
fire from solid fuel such as wood is built on a set of grates. A
baffle or series of baffles are positioned in the flow path of
gases produced as the solid fuel is combusted between the fire and
the flue of the appliance to slow combustion gases exiting the
appliance. These warm air solid fuel fired furnaces were previously
exempt from Environmental Protection Agency (EPA) emissions
requirements. However, conventional warm air solid fuel fired
furnaces produce significant amounts of particulate pollution
making these appliances noncompliant with current EPA emissions
requirements for Residential Wood Heaters. Warm air solid fuel
fired furnaces that are not compliant with EPA emissions
requirements can pose a serious health risk when used in a
residential setting.
BRIEF SUMMARY OF THE INVENTION
[0007] Aspects of the present disclosure provide a warm air solid
fuel fired furnace compliant with EPA emissions requirements for
Residential Wood Heaters. The furnace can include an improved
firebox design incorporating three managed airflows entering the
firebox. Primary air provides combustion air at the fuel. Preheated
secondary air burns off combustion gases where the secondary air
enters the firebox or combustion chamber just below a baffle in the
combustion air path. Preheated rear pilot air enters the firebox or
combustion chamber at the rear of the firebox or combustion chamber
to mix with the primary air and provide complete combustion of the
solid fuel.
[0008] One aspect of the present disclosure is a warm air solid
fuel furnace including a firebox configured to receive wood, said
firebox defined by a floor, first and second opposing sides, a top
baffle, a front door, and a rear wall, wherein the firebox floor is
at least partially lined with fire resistant material. The furnace
can include a primary combustion air flow path, wherein the primary
air combustion flow path is one or more holes through the front
door. A secondary air flow path can be configured to receive air
from a front of the furnace and conduct the received air along the
first opposing side of the firebox, up the rear wall of the
firebox, and into at least one tube having one or more orifices,
wherein the at least one tube is located at a top of the firebox
beneath the top baffle. A rear pilot air flow path can be
configured to receive air from the front of the furnace and conduct
the received air along the second opposing side of the firebox, up
the rear wall of the firebox, and into at least one hole through
the rear wall of the firebox.
[0009] In some embodiments, the fire resistant material can be fire
bricks, and the fire resistant material can line a rear portion of
the firebox floor. In some embodiments, the series of tubes can
span laterally across the top baffle, and the orifices can be
oriented towards the firebox floor and toward the front of the
furnace. In other embodiments, the tubes span distally across the
top baffle.
[0010] Another aspect of the present disclosure is a warm air solid
fuel furnace including a firebox configured to receive wood, said
firebox defined by a floor, first and second opposing sides, a top
baffle, a front door, and a rear wall, wherein a portion of the
firebox floor is lined with fire brick. A primary combustion air
flow path can be defined by one or more holes through the front
door. A secondary air manifold can be configured to receive air
from a front of the furnace and conduct air along a first opposing
side of the firebox, up the rear wall of the firebox, and into a
series of tubes having orifices, wherein the tubes are located at a
top of the firebox below the top baffle. A rear pilot air manifold
is configured to receive air from the front of the furnace and
conduct air along a second opposing side of the firebox, up the
rear wall of the firebox, and into at least one hole defined
through the rear wall of the firebox.
[0011] In some embodiments, a first inlet through the front of the
furnace can be communicated with the secondary air manifold, and a
second inlet through the front of the furnace can be communicated
with the rear pilot air manifold, wherein secondary air passing
through the first inlet and the secondary air manifold and rear
pilot air passing through the second inlet and the rear pilot air
manifold remain separated until the secondary air and the rear
pilot air enter the firebox.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0012] FIG. 1 is a front view of an embodiment of a warm air solid
fuel furnace of the present disclosure.
[0013] FIG. 2 is a front cutaway view of the warm air solid fuel
furnace of FIG. 1 showing a forced air flow path of the
furnace.
[0014] FIG. 3 is a side cutaway view at a right side of a firebox
of the warm air solid fuel furnace of FIG. 1 showing various air
flow paths of the furnace.
[0015] FIG. 4 is a top cutaway view of the warm air solid fuel
furnace of FIG. 1 showing the various air flow paths of the
furnace.
[0016] FIG. 5 is a rear cutaway view of the warm air solid fuel
furnace of FIG. 1 showing the secondary air flow path and the rear
pilot air flow path of the furnace.
[0017] FIG. 6 is a detailed cutaway view of an embodiment of a rear
wall baffle receiving rear pilot air from the rear pilot air flow
path.
[0018] Reference will now be made in detail to optional embodiments
of the invention, examples of which are illustrated in accompanying
drawings. Whenever possible, the same reference numbers are used in
the drawing and in the description referring to the same or like
parts.
DETAILED DESCRIPTION OF THE INVENTION
[0019] While the making and using of various embodiments of the
present invention are discussed in detail below, it should be
appreciated that the present invention provides many applicable
inventive concepts that can be embodied in a wide variety of
specific contexts. The specific embodiments discussed herein are
merely illustrative of specific ways to make and use the invention
and do not delimit the scope of the invention.
[0020] To facilitate the understanding of the embodiments described
herein, a number of terms are defined below. The terms defined
herein have meanings as commonly understood by a person of ordinary
skill in the areas relevant to the present invention. Terms such as
"a," "an," and "the" are not intended to refer to only a singular
entity, but rather include the general class of which a specific
example may be used for illustration. The terminology herein is
used to describe specific embodiments of the invention, but their
usage does not delimit the invention, except as set forth in the
claims.
[0021] As described herein, an upright position is considered to be
the position of apparatus components while in proper operation or
in a natural resting position as described herein. Vertical,
horizontal, above, below, side, top, bottom, and other orientation
terms are described with respect to this upright position during
operation unless otherwise specified. The term "when" is used to
specify orientation for relative positions of components, not as a
temporal limitation of the claims or apparatus described and
claimed herein unless otherwise specified. The terms "above",
"below", "over", and "under" mean "having an elevation or vertical
height greater or lesser than" and are not intended to imply that
one object or component is directly over or under another object or
component.
[0022] The phrase "in one embodiment," as used herein does not
necessarily refer to the same embodiment, although it may.
Conditional language used herein, such as, among others, "can,"
"might," "may," "e.g.," and the like, unless specifically stated
otherwise, or otherwise understood within the context as used, is
generally intended to convey that certain embodiments include,
while other embodiments do not include, certain features, elements,
and/or states. Thus, such conditional language is not generally
intended to imply that features, elements and/or states are in any
way required for one or more embodiments or that one or more
embodiments necessarily include logic for deciding, with or without
author input or prompting, whether these features, elements and/or
states are included or are to be performed in any particular
embodiment.
[0023] Referring to FIGS. 1-6, a warm air solid fuel furnace 10
according to one embodiment of the invention utilizes three managed
airflows entering a firebox 12. The firebox 12 can be configured
for receiving solid fuel such as wood, wood chips, coal, etc. In
one embodiment, the fuel is cut wood (such as would be used in a
fireplace). As shown in FIGS. 2-3, the firebox 12 can be defined by
a floor 14, two opposing sides 16 and 18, a top baffle 20, a front
door 22, and a rear wall 24. In one embodiment, the firebox floor
14 can be at least partially lined with fire resistant material 17
(e.g., fire brick or ceramic fire board). The firebox floor 14 can
also include a grate 15 that is not lined with fire resistant
material. The firebox front door 22 can be selectively opened to
serve as the fuel loading point for the firebox 12.
[0024] An ash tray 26 can be mounted below the grate 15, such that
ash can be swept into the ash tray 26 through the grate 15 between
uses of the furnace 10. In some embodiments, a rear portion 14a of
the firebox floor 14 can be lined with fire resistant material. The
grate 15 can be positioned on a front portion 14b of the firebox
floor 14, such that ash can be raked forward and into the ash tray
26 below the firebox 12. In some embodiments, an ash tray access
door 28 can be positioned on the front of the furnace 10 beneath
the front door 22 of the firebox 12. The ash tray access door 28
can be selectively opened to provide access to the ash tray 26 for
removal and emptying of the ash tray 26 as needed. In other
embodiments, the grate 15 can be positioned on the rear portion 14a
of the firebox floor 14 and the front portion 14b of the firebox
floor 14 can be lined with fire resistant material, with the ash
tray access door 28 located on a rear side of the furnace 10. In
some embodiments, the firebox floor 14 can include an open area
positioned above an ash tray 26 without a grate such that ash can
be swept directly into the ash tray 26 without passing over a
grate.
[0025] During use of the furnace, a solid fuel fire can be built on
the portion of the firebox floor 14 lined with fire resistant
material 17. Primary air 30 is introduced into the firebox 12
through the main firebox door 22. A primary air combustion air flow
path 32 can be defined by one or more holes 34 defined through the
front door 22 of the firebox 12. Primary air 30 can provide an
initial source of air for combusting the solid fuel positioned on
the firebox floor 14.
[0026] Top baffle 20 is positioned at the top of the firebox 12 and
can be positioned above a fire built within the firebox 12. An air
plenum 21 can be defined above the top baffle 20, and a flue 23 can
be in fluid communication with the air plenum 21. Top baffle 20 can
extend from a rear wall 24 of the firebox 12 toward the front of
the furnace 10. A gap 25 can be formed between the top baffle 20
and the front of the furnace 10. Air gap 25 can be relatively small
in comparison to the length of the firebox 12 and the length of the
top baffle 20, such that the top baffle 20 forms a substantial
barrier between the firebox 12 and the air plenum 21 above the top
baffle 20. The top baffle 20 thus encourages exhaust gas and smoke
produced from the combustion of the solid fuel within the firebox
12 to remain in the firebox 12 to produce a more complete
combustion of the solid fuel, including further combustion of
particulate matter in the smoke or gas produced from the solid
fuel. In one embodiment, the top baffle 20 is insulated or lined on
a top side of the baffle with fire resistant material (e.g., fire
brick or ceramic fiber board) to help retain heat within firebox
12. Exhaust gases and smoke can slowly be emitted from the firebox
12 through the air gap 25 into the air plenum 21, where the flue
can receive the exhaust gases and the exhaust gases and smoke can
be emitted from the furnace 10 through the flue 23. The flue 23 in
some embodiments can be extended or routed through an exterior wall
or roof of a residential dwelling such that smoke being emitted
from the furnace 10 can escape to an exterior of the residence.
[0027] As shown in FIGS. 3-5, secondary air 36 enters the furnace
10 at the front of the furnace 10 and travels through a secondary
air manifold 38 from the front of the furnace 10 to the back of the
furnace 10, the secondary air manifold 38 positioned on the first
opposing side 16 of the firebox 12. In one embodiment, the first
opposing side 16 and the secondary air manifold 38 of the firebox
12 are integral with one another.
[0028] The secondary air manifold 38 can extend around and up the
rear wall 24 of the firebox 12. The secondary air manifold 38 can
thus conduct secondary air 36 up the rear wall 24 of the firebox 12
and between the rear wall 24 of the firebox 12 and the secondary
air manifold 38. The secondary air 36 can then travel back toward
the front of the firebox 10 and into at least one tube 46 including
orifices 48, the tube 46 positioned beneath the top baffle 20.
Secondary air 36 can be directed into the at least one tube 46 and
out the orifices 48. In some embodiments, the secondary air 36 can
travel through first and second upper side passages 42 and 44
positioned on opposing sides of top baffle 20, as shown in FIGS.
2-3. In some embodiments, the tube 46 can extend laterally across
the top baffle 20 between the first and second side passages 42 and
44. In other embodiments, the at least one tube 46 can extend
distally across the top baffle 20. In some embodiments, the at
least one tube 46 is a series of tubes 46, each tube 46 including a
plurality of orifices 48. In some embodiments, each of the tubes 46
can be spaced equidistantly from the top baffle 20.
[0029] In some embodiments, secondary air 36 from the secondary air
manifold 38 and side passages 42 and 44 can travel into the series
of tubes 46 and out of the orifices 48 into the firebox 12. Each
tube 46 can have a first tube end 46a communicated with the first
side passage 42, and a second tubed end 46b communicated with the
second side passage 44, such that secondary air 36 from the
secondary manifold 38 can be directed into both ends of the tubes
46. In other embodiments, a single side passage can be defined on
the furnace 10 and secondary air 36 can be directed into the tubes
46 and out of the orifices 48 from only one end of the tubes 46.
The orifices 48 can be generally oriented to direct secondary air
36 toward the firebox floor 14. The secondary air 36 can thus
direct smoke from the solid fuel back toward the fire and the
bottom of the firebox 12 for further combustion.
[0030] The tubes 46 can be positioned beneath the top baffle 20 and
spaced equidistantly beneath the top baffle 20. In some
embodiments, the tubes 46 can be directly mounted to the top baffle
20. In other embodiments, the tubes 46 can be suspended beneath the
top baffle 20 between first and second side passages 42 and 44. In
one embodiment, the top baffle 20 is higher at the front of the
furnace 10 than at the rear of the furnace 10, and the orifices 48
on the tubes 46 can be oriented in a downward direction toward the
firebox floor 14 and toward the front of the furnace 10.
[0031] Thus, as shown in FIGS. 2-5, a secondary air flow path 40
can be defined on the furnace 10 and can be configured to receive
air from the front of the furnace 10 and conduct air along the
first opposing side 16 of the firebox 12, up the rear wall 24 of
the firebox 12, and into a series of tubes 46 having orifices 48,
wherein the tubes 46 are located beneath the top baffle 20. In some
embodiments, the tubes 46 can span laterally across the top baffle
20 between first and second side passages 42 and 44, and the
orifices 48 can be oriented to direct air toward the firebox floor
14 and toward the front of the furnace 10.
[0032] Tertiary or rear pilot air 50 enters the furnace 10 through
the front of the furnace 10 and travels to the back of the firebox
12 through a rear pilot air manifold 52 on the second opposing side
18 of the firebox 12 and opposite the secondary air 36. In one
embodiment, the second opposing side 18 of the firebox 12 and the
rear pilot air manifold 52 are integral with one another.
[0033] The rear pilot air manifold 52 can extend around and up the
rear wall 24 of the firebox 12. The rear wall 24 can include at
least one hole 54 defined through the rear wall 24 of the firebox
12, the at least one hole 54 being communicated with the rear pilot
air manifold 52 such that rear pilot air 50 can be directed from
the rear pilot air manifold 52 through the at least one hole 54 in
the rear wall 24 and into the firebox 12. The at least one hole 54
can be located no more than half way up the rear wall 24 of the
firebox 12 in some embodiments such that the rear pilot air 50 can
be directed into the firebox 12 from the rear pilot air manifold 52
approximately halfway up the rear wall 24 of the firebox 12 through
a series of holes in the rear wall 24, as shown in FIG. 2. In some
embodiments, the rear wall 24 can be a substantially flat and
vertical wall such that rear pilot air 50 can be directed into the
firebox 12 in a direction generally toward the front of the furnace
10.
[0034] Referring to FIGS. 2-3 and 6, in some embodiments, the rear
wall 24 can include a rear wall baffle 56, the rear wall baffle 56
forming a part of the rear pilot air manifold 52. The rear wall
baffle 56 can be substantially sealed against the rear wall 24 of
the firebox 12. The rear wall baffle 56 can be oriented with a top
of the rear wall baffle 56 closer to the front of the furnace 10
than a bottom of the rear wall baffle 56 when the furnace is in an
upright position. The at least one hole 54 in the rear wall 24 can
be located in the rear wall baffle 56 such that the rear wall
baffle 56 is angled with the holes 54 in the rear wall baffle 56
oriented to direct rear pilot air 50 toward at least one of the
bottom of the firebox 12 or the firebox floor 14 and the front of
the firebox 12. The rear pilot air 50 in some embodiments can
further direct smoke from the solid fuel back toward the fire and
the bottom of the firebox 12 for further combustion. As shown in
FIG. 2, in some embodiments, the rear wall baffle 56 can include a
plurality of holes 54 therethrough, the plurality of holes 54
providing increasing flow capacity lower on the rear wall baffle 56
than higher on the rear wall baffle 56. Rear wall baffle 56 is
shown in FIG. 2 having an upper and lower row of holes 54, with the
lower row of holes including a greater number of holes than the
upper row of holes to achieve an increasing flow capacity lower on
the rear wall baffle 56.
[0035] As shown in FIGS. 2-5, a rear pilot air flow path 60 can
thus be defined on the furnace 10, the rear pilot air flow path 60
configured to receive air from a front of the furnace 10 and
conduct air along a second opposing side of the firebox 12, up the
rear wall 24, and into at least one hole 54 through the rear wall
24 of the firebox 12 to provide rear pilot air 50 to the firebox
12.
[0036] A first inlet 62 can be defined through the front of the
furnace 10, and a second inlet 64 can be defined through a front of
the furnace 10. The first inlet 62 can be communicated with the
secondary air manifold 38 and the secondary air flow path 40 and
the second inlet 64 can be communicated with the rear pilot air
manifold 52 and the rear pilot air flow path 60. Secondary air 36
passing through the first inlet 62 and the secondary air manifold
38 and rear pilot air 50 passing through the second inlet 64 and
the rear pilot air manifold 52 remain separated until the secondary
air 36 and the rear pilot air 50 enter the firebox 12. In other
words, the secondary air flow path 40 and the rear pilot air flow
path 60 remain separate and independent of one another until the
respective air flow paths reach the firebox 12, such that secondary
air 36 entering the first inlet 62 does not mix with the rear pilot
air 50 entering the second inlet 64 until the secondary air 36 and
the rear pilot air 50 enter the firebox 12.
[0037] Keeping the manifolds 38 and 52 and the air flow paths 40
and 60 separate from one another, as well as separate from the
primary air path, can help prevent the air flow paths 32, 40 and 60
from negatively interfering with one another and affecting the
intake rates of air coming into the respective air flow paths and
manifolds during use of the furnace 10. By keeping the air flow
paths separate, a flow capacity of the primary air path, a flow
capacity of the secondary air path, and a flow capacity of the rear
pilot air flow path are independently predetermined to maximize
combustion of the wood and combustible gases given off by the wood
during combustion.
[0038] Secondary air manifold 38 can generally be a passage or
network of passages oriented to direct secondary air 36 from the
first inlet 62 to the tubes 46 below the top baffle 20, and rear
pilot manifold 52 can generally be a passage or network of passages
oriented to direct rear pilot air 50 from the second inlet 64 to
the at least one hole 54 in the rear wall 24. In some embodiments,
each of the secondary air manifold 38 and the rear pilot air
manifold 52 can be a single unitary duct, pipe, or chamber
extending from the respective inlet to the respective entrance
point into the firebox 12. In other embodiments, each manifold can
include a combination of multiple ducts, pipes, chambers, etc.
extending between and defining an air path from the respective
inlet to the respective entrance point into the firebox 12.
[0039] The secondary air 36 and the rear pilot air 36 can be heated
as the air sources travels through the secondary air manifold 38
and the rear pilot air manifold 52 and along the secondary air flow
path 40 and the rear pilot air flowpath 60, respectively, from the
front of the furnace 10 to the rear of the furnace 10. In some
embodiments, at least a portion of the sides 16 and 18 of the
firebox 12 along which the secondary air 36 and rear pilot air 50
respectively travel are not insulated, such as by fire brick or
ceramic fire board, from the firebox 12. In other embodiments, the
secondary air manifold 38 and the rear pilot manifold 52 can be
positioned directly within the firebox 12. In some embodiments, a
portion of the sides 16 and 18 of the firebox 12 are lined with
fire resistant materials such as fire bricks such that heat
transfer from the firebox 12 can primarily occur in the areas of
the sides 16 and 18 where the secondary air manifold 38 and the
rear pilot air manifold 52 are located, thus helping optimize heat
transfer into the secondary air 36 and rear pilot air 50 passing
through the furnace 10.
[0040] Such configurations allow for the secondary air 36 and rear
pilot air 50 to be preheated by the firebox 12 as they pass through
their respective manifolds 38 and 52. Heating of the secondary air
36 and rear pilot air 50 can help burn leftover fuel and
particulate matter in the smoke being emitted from the primary
combustion of the fuel resting on a floor 14 of the firebox 12 as
the secondary and rear pilot air 36 and 50 interact with the smoke
within the firebox 12. Fire bricks in the floor 14 of the firebox
12 can replace traditional open grates to form a solid bottom or
floor 14 for the fuel to sit on. This reduces overall turbulence
around the wood (i.e., fuel) during combustion which allows for a
more metered air introduction.
[0041] The primary, secondary, and rear pilot airstreams, in
addition to the fire brick floor 14 for the fuel to rest on
(instead of the traditional all grate firebox floor) allow for a
combustion air flow balance in the system so that optimal
combustion can occur within the firebox 12. This results in reduced
overall particulate matter emissions and improved efficiency over
traditional warm air furnaces (i.e., more heat delivered to an area
to be warmed by the furnace 10 for a given amount of wood burned
within the furnace firebox 12).
[0042] Referring to FIG. 2, in some embodiments, the furnace 10 can
include an inner housing 70. The firebox 12, the secondary air
manifold 38, and the rear pilot air manifold 52 can be positioned
within the inner housing 70, with smoke and other biproduct from
the combusted solid fuel being contained and emitted from the inner
housing 70. In some embodiments, one or more of the firebox 12
components, the secondary air manifold 38, or the rear pilot air
manifold 52 can form a part of the inner housing 64. In other
embodiments, the inner housing 70 can be an entirely separate
housing, with the firebox 12, secondary air manifold 38, and the
rear pilot air manifold 52 positioned entirely within the inner
housing 70.
[0043] The furnace 10 can include an outer housing 72 at least
partially enclosing the inner housing 70. The outer housing 72 can
be spaced from the inner housing to form a forced air passage 76
between the inner housing 70 and the outer housing 72. One or more
blower units 74 can be mounted to the outer housing unit 72 and be
operable to force air through the forced air passage 76. An exit
duct 78 can be communicated with the forced air passage 76, such
that the blower unit 74 can force air through the forced air
passage and out of the exit duct 78. During use of the furnace 10,
as air is forced through the forced air passage 76, the air can be
heated by the firebox 12, such that heated air can be emitted from
the exit duct 78. In a residential setting, the heated air can exit
the duct into a single room, or the heated air can be directed to
various rooms within the residence by way of a duct system to
condition multiple rooms within the residence.
[0044] This written description uses examples to disclose the
invention and also to enable any person skilled in the art to
practice the invention, including making and using any devices or
systems and performing any incorporated methods. The patentable
scope of the invention is defined by the claims, and may include
other examples that occur to those skilled in the art. Such other
examples are intended to be within the scope of the claims if they
have structural elements that do not differ from the literal
language of the claims, or if they include equivalent structural
elements with insubstantial differences from the literal languages
of the claims.
[0045] It will be understood that the particular embodiments
described herein are shown by way of illustration and not as
limitations of the invention. The principal features of this
invention may be employed in various embodiments without departing
from the scope of the invention. Those of ordinary skill in the art
will recognize numerous equivalents to the specific procedures
described herein. Such equivalents are considered to be within the
scope of this invention and are covered by the claims.
[0046] All of the compositions and/or methods disclosed and claimed
herein may be made and/or executed without undue experimentation in
light of the present disclosure. While the compositions and methods
of this invention have been described in terms of the embodiments
included herein, it will be apparent to those of ordinary skill in
the art that variations may be applied to the compositions and/or
methods and in the steps or in the sequence of steps of the method
described herein without departing from the concept, spirit, and
scope of the invention. All such similar substitutes and
modifications apparent to those skilled in the art are deemed to be
within the spirit, scope, and concept of the invention as defined
by the appended claims.
[0047] Thus, although there have been described particular
embodiments of the present invention of a new and useful "WARM AIR
FURNACE WITH MANAGED COMBUSTION AIR FLOW" it is not intended that
such references be construed as limitations upon the scope of this
invention except as set forth in the following claims.
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