U.S. patent number 3,662,735 [Application Number 05/055,378] was granted by the patent office on 1972-05-16 for wall-mounted fluid-fuel furnace.
This patent grant is currently assigned to Hydro Flame Corporation. Invention is credited to George W. Jackson.
United States Patent |
3,662,735 |
Jackson |
May 16, 1972 |
WALL-MOUNTED FLUID-FUEL FURNACE
Abstract
A gas or other fluid fired furnace for mounting in a wall,
especially of a recreational vehicle providing living
accommodations, such as so-called "campers," house trailers, and
the like, where space is at a premium and special problems of
vibration, proper venting, and reliability in operation are
presented. An elongate, specially fabricated, Venturi-tube burner
is mounted, along with a fuel feed control unit, on a removable
closure plate positioned across the lower end of a front pan-like
member of a shallow, rectangular, upstanding firebox. The firebox
provides a combustion chamber and heat exchanger for the furnace in
a compact heater unit housing and has an outwardly extending
peripheral fin through which a fuel supply extends at the bottom of
the firebox and is preferably canted forwardly along the top of the
firebox to direct air flow and increase efficiency. A special vent
unit, provided for mounting exteriorly of the spaced to be heated
flush with the exterior wall face and having a lower air inlet
separated from an upper gas outlet by baffles, is connected with
the heater unit by air or gas flow conduits which are thermally
isolated one from the other by special gasket and mounting
arrangements.
Inventors: |
Jackson; George W. (Salt Lake
City, UT) |
Assignee: |
Hydro Flame Corporation (Salt
Lake City, UT)
|
Family
ID: |
21997408 |
Appl.
No.: |
05/055,378 |
Filed: |
July 16, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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825189 |
May 16, 1969 |
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Current U.S.
Class: |
126/85B;
126/116B; 126/307R |
Current CPC
Class: |
F24C
15/002 (20130101); B60P 3/36 (20130101); F24C
3/004 (20130101) |
Current International
Class: |
F24C
15/00 (20060101); F24C 3/00 (20060101); B60P
3/32 (20060101); B60P 3/36 (20060101); F23l
001/00 (); F24h 003/02 () |
Field of
Search: |
;126/85,85B,90,110,11B,116,116B,307,314,315,317 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Myhre; Charles J.
Parent Case Text
RELATED APPLICATIONS
This application is a continuation-in-part of a copending original
application Ser. No. 825,189 filed by me May 16, 1969, now
abandoned.
Claims
I claim:
1. A fluid-fired furnace adapted to be mounted on a wall of a
structure to be heated, comprising a heater unit including a
substantially rectangular heat exchanger firebox having front and
rear broad panel walls and relatively narrow peripheral walls
defining an upstanding combustion chamber, said firebox being
formed by similar front and rear pan-like members having
outwardly-turned rims and being secured together in open face to
open face relationship to provide an intermediate peripheral fin
extending outwardly of such firebox to increase the heat exchange
surface area thereof; an elongate fluid fuel burner extending
substantially entirely across the lower end of said firebox to
direct flames upwardly in said combustion chamber across the width
thereof; conduit means communicating with the interior of the
firebox at a low level thereof through the rear panel wall for
supplying combustion-supporting air to said burner; conduit means
communicating with the interior of the firebox at an upper level
thereof for exhausting gaseous products of combustion from the
firebox; a housing having walls defining flow channels about the
exterior of said firebox for air to be heated and providing for
inflow of cool air and outflow of heated air; the lower end of the
front panel wall of the firebox and the adjacent bottom peripheral
wall portion of the corresponding pan-like member being provided
with an access opening leading to the interior of the firebox; a
closure plate for said opening provided with a depending flange
corresponding to the confronting portion of the rim of the rear
pan-like member, the burner being mounted on the inside face of
said closure plate; and a fluid fuel supply pipe leading into the
firebox from the exterior thereof and connected with said burner,
the rim of the rear pan-like member and the flange of the closure
plate being recessed for receiving and accommodating said pipe.
2. A furnace according to claim 1, additionally including a saddle
plate secured to the fuel supply pipe and to the inner face of the
depending flange of the closure plate.
3. A furnace according to claim 1, wherein a control unit for
feeding fluid fuel to the burner is connected to the supply pipe
below the firebox within the flow-channel-defining walls.
4. A furnace according to claim 1, wherein the broad panel walls of
the firebox in the areas thereof immediately above the burner and
between the low level and upper level conduits are transversely
corrugated, respectively, in mutually spaced relationship across
the interior of said firebox, said corrugations being in
approximately mating positional relationship with respect to the
placement of ridges and valleys to provide flame-diverting baffles
immediately above the burner.
5. A furnace according to claim 1, wherein the peripheral fin of
the firebox is canted forwardly along the top of the firebox to
direct air flow.
6. A furnace according to claim 1, additionally including a vent
unit for drawing in combustion-supporting air from, and for
exhausting combustion gases to, the atmosphere while the structure
to be heated is traveling along a highway, said vent unit having
baffle means separating a gas-exhaust area from an air-intake area,
the low level conduit means communicating with said air-intake area
and the upper level conduit means comprising an exhaust flue
communicating with said gas-exhaust area and passing through a wall
of the flow-channel-providing housing; and a fluid-tight, heat
resistant seal supporting said flue in its passage through the
housing wall, said seal including a recessed retainer frame secured
to said wall and holding a sheet of stiffly flexible, heat
resistant, sealing material with freedom for lateral movement, said
flue passing snugly through said sheet of sealing material and
through said wall in spaced relationship with said wall and said
retainer frame.
7. A furnace according to claim 6, wherein the exhaust flue extends
to interconnection with the vent unit through a radiation
protective conduit supported at one end by brackets affixed to the
retainer plate of the seal and at the opposite end by brackets
affixed to the vent unit.
8. A furnace according to claim 7, wherein the vent unit includes a
housing adapted to be mounted in the wall of the space to be
heated, and the baffle means includes an exhaust vent pan having a
baffle thereon defining exhaust openings near the top and being
open at the bottom for the inflow of atmospheric air, said vent pan
being secured to the exhaust flue and removably secured to the vent
unit housing.
9. A furnace according to claim 8, wherein the vent pan is
removably secured to the vent unit housing by means of tongues at
opposite sides of the vent pan frictionally fitted into receiving
recesses of mounting brackets secured to the vent unit housing.
10. A furnace according to claim 1, wherein the burner is
fabricated from two recessed metal stampings having outwardly
extending peripheral rims and welded together in open face to open
face relationship to provide an intermediate peripheral fin, there
being a series of burner openings extending longitudinally of each
of said metal stampings to one side of said fin and canted
outwardly toward the broad panel walls of the firebox.
11. A furnace according to claim 1, wherein the housing defining
flow channels about the exterior of the firebox includes top,
bottom, side and rear walls, an internal first heat radiation
shield attached to the firebox and defining flow channels
therearound, a second heat radiation shield defining flow channels
around the said first shield, and a third heat radiation shield
interposed between said first and said second shields, the said top
wall being cut and bent upwardly as a flap to form another heat
radiation shield extending along the width of the housing.
12. A furnace according to claim 11, wherein the first and second
radiation shields and said second radiation shield and the flap of
the top wall of the housing are connected by dimpled portions of
said second radiation shield.
13. In a fluid-fired furnace adapted to be mounted on a wall of a
structure to be heated and comprising a heater unit, provided with
a heat exchanger firebox having front and rear broad panel walls
and with a housing having walls defining flow channels about the
exterior of said firebox, a vent unit for exhausting combustion
gases to the atmosphere from said firebox, and an exhaust flue
interconnecting said firebox and said vent unit and passing through
a wall of said housing, the provision of a fluid-tight, heat
resistant seal supporting said flue in its passage through the
housing wall, said seal including a retainer frame secured to said
wall; and a sheet of stiffly flexible, heat resistant, gasket
material held by said frame with freedom of movement within said
frame as an entire sheet and peripherally thereof substantially
without distortion, said flue passing snugly through said sheet and
through said wall in spaced relationship with said wall and said
retainer frame.
Description
BACKGROUND OF THE INVENTION
1. Field
The invention is in the general field of small fluid-fired furnaces
having compact heater units for space heating and having vent units
for both drawing in combustion air and discharging combustion gases
exteriorly of the space to be heated, especially in a vehicle.
State of the Art
Popularity of mobile homes and of recreational vehicles, such as
"campers" carried in the beds of conventional pick-up trucks, house
trailers, and specially built automobiles of various types
providing living space therein, has prompted the development of
small, wall-mounted furnaces fired by gas supplied from so-called
"LPG," liquified petroleum gas, cylinders. A typical furnace of
this type is shown in U.S. Pat. No. 3,168,091 granted Feb. 2, 1965.
Although furnaces of this design and construction have been
generally satisfactory, it has been recognized that improvements in
efficiency, reliability, and durability would be desirable.
Objectives
This invention was made to improve the performance of wall furnaces
of this type, without increasing size, and to minimize breakdowns
due to the inevitable jolting and vibration resulting even from
travel over smooth roads.
SUMMARY OF THE INVENTION
In the accomplishment of the objectives of this invention, a
Venturi-type burner of unique design is combined in a unique manner
with a special firebox that provides a combustion chamber and heat
exchanger for the furnace. The firebox is formed as a fluid-tight
rectangular housing having opposite broad panel walls and
relatively narrow peripheral walls and provided with conduits for
drawing in combustion-supporting air and for exhausting gaseous
products of combustion by way of a special vent unit open to the
atmosphere exteriorly of the space to be heated.
The burner utilizes standard controls for supplying the gas and is
constructed for compactness by turning a Venturi fuel-air mixing
portion back under the burner proper. A unique feature of the
burner is its fabrication from a pair of metal stampings, each
provided with a longitudinally extending series of circular gas jet
orifices of varying sizes and the pair being secured together in
face-to-face, fluid-tight relationship. The burner and controls
therefor are advantageously mounted on the inside face of a plate
that fits over a front access opening at the bottom of the
firebox.
The firebox is constructed of a pair of shallow, pan-like metal
stampings with outwardly extending rims and preferably having
transverse corrugations pressed into their broad panel walls, the
corrugations of one panel wall being located in mating relationship
with those of the opposite panel wall immediately above the burner
for increasing rigidity as well as for flame-baffling purposes.
These pan-like members are placed in open-face to open-face
relationship and are sealed together at and along their rims, as by
seam welding, so as to form a combustion chamber with the
flame-baffling corrugations located with respect to each other as
indicated above. The access opening is provided along the lower end
of the front pan-like member and is closed by the plate that
carries the burner and controls. A fuel supply pipe for the burner
is accommodated by receiving recesses found in confronting portions
of the rims of the front and rear pan-like members. The firebox as
so formed is mounted within a louvered housing to form a heater
unit that provides for the inflow of cool air to be heated and for
the outflow of such air after passing over the heat-exchanger walls
of the firebox. The peripheral fins of the firebox provided by the
outwardly extending rims of the pan-like members is preferably
canted forwardly along the top of the firebox to direct air flow
and increase efficiency.
Inlet conduits for combustion supporting air and for exhaust of
combustion gases are connected to the rear panel wall of the
firebox and pass through both the heater unit housing and the wall
of the structure in which the furnace is mounted. Passage of the
exhaust conduit through the wall of the heater unit housing is
supported and sealed by a special gasket arrangement. A special
vent unit for the control of inflow of combustion air and for the
outflow of gases of combustion is connected to such conduits at the
opposite set of ends thereof so as to be located exteriorly of the
structure in which the furnace is placed, flush with an exterior
wall face.
THE DRAWINGS
There is shown in the accompanying drawings a gas furnace
construction that is presently contemplated as the best mode of
applying the invention in actual practice.
In the drawings:
FIG. 1 is a view in front elevation of the furnace as adapted for
installation in a wall of living space in a vehicle, much of the
decorative and protective louver at the front of the heater unit
being broken away to reveal interior parts;
FIG. 2, a top plan view, intermediate parts of the conduits between
heater unit and vent unit being broken out for convenience of
illustration;
FIG. 3, a longitudinal vertical section taken along the line 3--3
of FIGS. 1 and 2 and drawn to a somewhat larger scale;
FIG. 3A, a fragmentary vertical section taken along the line 3A--3A
of FIG. 3;
FIG. 4, a transverse horizontal section taken along the line 4--4
of FIG. 1 and drawn to a somewhat larger scale;
FIG. 5, a fragmentary vertical section taken along the line 5--5 of
FIG. 3 to show the Venturi burner in front elevation;
FIG. 6, a fragmentary horizontal section taken along the line 6--6
of FIG. 3 to show the Venturi burner in top plan;
FIG. 7, a fragmentary horizontal section taken along the line 7--7
of FIG. 5 and drawn to a larger scale;
FIG. 8, a vertical section taken along the line 8--8 of FIG. 3 to
show the interior of the vent unit in elevation; and
FIG. 8A, an end elevation of the heater unit and its
rearwardly-extending conduit sections as viewed from the line
8A--8A FIG. 3.
DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENT
In the specific construction illustrated, the furnace is adapted to
be mounted in and through a wall of the living space to be heated
in a recreational vehicle or mobile dwelling. As shown in FIGS. 2
and 3, a heater unit 10 is connected with a vent unit 11 by means
of an assembly 12 of flow conduits.
The heater unit 10 includes a gas-tight firebox 13 of rectangular
formation having opposite broad panel walls 13a and relatively
narrow peripheral walls 13b. The firebox is fabricated from two
similar, shallow, pan-like metal stampings 14 with out-turned rims
14a and transverse mating corrugations 14b. Such stampings are
placed together in open-face to open-face relationship with the
corrugations 14b in mating placement immediately above the burner,
as shown, for flame-baffling purposes, and are sealed, fluid-tight,
about their rims as by means of seam welding. The rims and
resulting peripheral fins are canted forwardly, as at 14a, FIG. 3
(also FIG. 4), along the top of the firebox to direct air flow and
increase efficiency, thereby contributing significantly to the
compactness of the furnace.
An access opening 15, FIG. 6, leading into the interior of firebox
13 is provided in the front panel wall 13a at the lower end thereof
and is normally closed tightly by a plate 16, that is held in place
by screws (not shown). Such plate 16 has a dependent flange 16a
corresponding to the rims 14a. A gas burner 17 is mounted on the
inside face of such closure plate 16, as is also a conventional
pilot light burner 18. A gas supply pipe 19 projects downwardly
from connection with the burner 17 and passes through a receiving
opening in the bottom of the firebox formed by corresponding
recesses 14c and 16b in the rim and flange 16a, respectively, see
FIGS. 3 and 5, to connection with a conventional gas-feed control
unit 20. A saddle plate 21 welded to pipe 19, secures such pipe to
the flange 16a of closure plate 16 at recess 16b, such saddle plate
being welded to flange 16a.
The burner 17 is elongate, and has a gas-air mixing, Venturi
portion 17a turned back under an elongate, burner proper 17b. Pipe
19 connects to the burner at the end of such turned-back portion
17a, and a fine jet of fuel is discharged from a jet nozzle 22,
FIG. 7, through an air gap 23, where it entrains air, and into the
throat of Venturi tube 24. The gas-air fuel mixture rounds bend 17c
of the burner and flows along the length of the burner proper 17b,
emerging through orifices 25. These preferably vary in size along
the length of such burner proper to provide for substantially
uniform distribution of the fuel mixture. Size variations are
empirically determined for any particular furnace design by
observation of the burning characteristics and altering the size of
any given hole or holes when yellow flames are observed rather than
the more desirable smoke-free blue flames. An additional orifice
25a near the pilot light aids in igniting the burner.
Burner 17 is fabricated from a pair of metal stampings, indicated
by 17b and 17c in FIG. 6, which have out-turned rims 17d and are
welded together, fluid-tight, in face-to-face relationship. The gas
jet orifices are stamped out in double rows in the respective
stampings at opposite sides of the rims 17d and directed upwardly
and outwardly toward the walls of the firebox, see FIG. 3.
Back of burner 17 in the back panel wall of the firebox, a pair of
air-flow tubes 26 carry air from a plenum chamber 27, FIG. 3, into
the interior of the firebox at the level of burner 17. A baffle
plate 28 across the upper portion of such tubes insures delivery of
air below the level of the burner orifices.
An exhaust conduit or flue 29 communicates with the interior of the
firebox through the back panel wall 13a thereof above corrugations,
i.e. baffles, 14b, and extends backwardly through plenum chamber 27
to connection with vent unit 11. It should be noted that the
corrugations or baffles 14b preferably occupy the entire panel wall
expanse between low level conduits 26 and upper level conduit or
flue 29.
Firebox 13 and control unit 20 are mounted within a housing 30,
which defines flow channels 31, FIG. 3, about the heat exchanger
walls of such firebox for air to be heated. A louvered front 32 for
the housing is attached to sheet metal bottom wall 30a, as by screw
33, and, by means of a tongue and groove arrangement 32a, to a
radiation flap 30c cut from top wall 30d. A first radiation shield
34, FIG. 1, is attached to firebox 13, as by means of mounting
brackets 34a, and a second radiation shield 35 is riveted to the
first at dimples 35a. A third radiation shield 35-1 is interposed
between the first two. These radiation shields and the walls of
housing 30 define an air-flow passage 36. Rear wall 30e of the
housing, it should be noted, forms the front wall of plenum chamber
27.
A small electric fan and controls therefore 37, FIG. 1, are mounted
in the lower part of housing 30 next to gas control 20. The lower
part 32b, FIG. 3, of louvered front 32 may be formed as a
conveniently removable door to provide access to the controls.
The fan draws cool air in through louvers 32b and forces it to flow
upwardly about the heat exchanger walls of firebox 13 and through
air-flow channels 36 and 31 and out louvers 32 along the upper part
of housing 30. Radiant heat passes through louvers 32 from front
panel wall 13a.
Exhaust conduit or flue 29 runs through protective tubes 38 and
38a, and the conduit 39 discharge into plenum chamber 27.
Vent unit 11 is formed as a rectangular, pan-like housing 40 with a
louvered front 40a. Flue 29, tube 38a, and conduit 39 communicate
with the interior of housing 40 through its back wall 40b. An
exhaust vent pan 41 is carried within housing 40 by the discharge
end of flue 29. It has side walls 41a, upwardly sloping top wall
41b, a partial front wall 41c immediately behind louvered front
40a, an open bottom 41d, and a back wall 41e. Front wall 41c leaves
an upper, discharge opening 42 extending across the width of such
exhaust pan. Behind such discharge opening and extending below the
upper end of front wall 41c is an exhaust baffle 43.
Exhaust vent pan 41 and baffle 43 are advantageously constructed as
a unit attached to the end of the adjacent section of exhaust flue
29, so that all of these parts are easily assembled by merely
pushing them into place as such flue section is telescoped into the
other flue section, see FIG. 3. The position of such unit relative
to housing 40 is securely fixed by tongues 41f pushed into
receiving recesses of respective mounting brackets 41g, FIG. 8.
Flue gases discharge from the upper part of exhaust vent pan 41 and
through exhaust baffle 43 and out to the atmosphere through the
upper part of louver 40a. Combustion air enters housing 40 and
conduit 39 through the lower part of louver 40a. An entry passage
44 for air to flow into the space between exhaust flue 29 and tube
38a is provided opposite the louvered lower open front of the vent
unit. A rectangular heat shield 40d is provided as a part of
housing 40 for direct installation in an exterior wall of the
structure to be heated by the furnace, so that the flanges 40c of
housing 40 will be substantially flush with the exterior face of
such wall.
It is important that there be a minimum, if any, transfer of heat
from exhaust flue 29 to its surrounding air-flow conduits and to
housing 30. To this end, a specially fabricated, flue-supporting
seal 45 is provided between exhaust flue 29 and rear wall 30e of
heater housing 30. By use of this seal, it is possible to increase
heat output per unit time without altering compactness of the
furnace and without causing a fire hazard.
The seal 45, see especially FIG. 3A, comprises a recessed retainer
frame 46, advantageously in the form of a metal stamping,
positioned against and secured tightly to the back face of heater
housing rear wall 30e as by means of welding. Within recessed
portion 46a of frame 46 is a sheet or plate of stiffly flexible,
heat-resistant gasket material 47 having a central receiving
opening for flue 29, whose diameter is somewhat less than the
outside diameter of such flue so as to make a fluid-tight
connection when the flue is pressed through the receiving opening.
Frame 46 has a central opening 46b whose diameter is sufficiently
larger than the outside diameter of the flue to insure that there
is no contact between flue and plate when the former is installed
in the seal 45. Heater housing rear wall 30e is correspondingly
apertured at 48, FIG. 3, for the same purpose.
Support for radiation protective tube 38 is provided at seal 45 by
brackets 49, FIG. 3A, which are advantageously stamped out of the
metal blank from which retainer frame 46 is stamped. The joinder
between the end of tube 38 and its interconnected tube 38a
preferably has considerable tolerance, as indicated at 50, to
simplify assembly of vent unit 11 with heater unit 10. Support for
the tube 38a near its interconnection with tube 38 is provided by
brackets 51, FIG. 8A, and support for the opposite end of tube 38a
is provided by brackets 52, FIG. 8, secured to such tube 38a and to
housing 40.
Gasket 47 is smaller in extent than is the recess of recessed
portion 46a (see the dotted line representation in FIG. 3A) to
afford leeway for lateral expansion and contraction under changing
thermal conditions. Such gasket is preferably made by cutting or
stamping to required configuration a steel-wire-reinforced, pressed
asbestos board obtainable on the open market.
It should be noted that the unique arrangement of pan-like members
14 and closure plate 16, with burner 17, control unit 20, and fuel
supply pipe 19 carried by such closure plate, not only makes for
ease and economy of fabrication during the manufacturing stages but
enables important operating parts of the furnace to be conveniently
removed as a single entity for repair purposes if and when
required. All that is necessary for this is to unscrew the
attachment screws holding closure plate 16 in place and to
disconnect control unit 20 at 20a from the gas line (not
shown).
Although the specific construction illustrated is presently
preferred and is contemplated as being the best mode of applying
the invention in practice, there are various ways in which the
broader inventive concepts taught here can be carried out.
* * * * *