Improvements in Down Draft Stoves and Furnaces.
Year: 1899

page_text: Date of Application, 4th Feb., 1899-Accepted, 19th Aug., 1899
COMPLETE SPECIFICATION.
Improvements in Down Draft Stoves and Furnaces.
I, BENJAMIN JOSEPH BARNARD MILLS, of 23, Southampton Buildings, in the
County of London, Patent Agent, do hereby declare the nature of this invention
(a communication to me from William De Lancey Walbridge, of 393, West End
Avenue, in the City, County, and State of New York, one of the United States
of America, Gentleman), and in what manner the same is to be performed to be
particularly described and ascertained in and by the following statement:-
The invention has reference to improvements in down draft stoves and furnaces
adapted particularly for the consumption of bituminous or soft coals, and it
has for its object to materially improve the construction of stoves and furnaces
of that class arranged to burn coal of the character set forth, particularly when
self-fed, so that such coal will not become unduly coked and packed in the fire-
pot or magazine, while the downward feed and complete consumption of the fuel
will be insured.
To this end, the invention consists essentially in a down draft stove compris-
ing a fire pot or magazine having a lateral opening at, or near, its bottom com-
municating with a flue leading to the chimney, a fuel support at the bottom of
the fire pot, a plurality of air tubes extending downwardly from the top plate of
the fire pot or magazine from a point above the level of the fuel and adapted to
direct jets of air toward said fuel for the consumption of the same; combined
with means for conducting the air introduced through the fuel downwardly and
through the lateral opening at, or near, the bottom of the fire pot or magazine;
and the invention also applies to furnaces for heating dwellings or public build-
ings by either hot air or hot water or steam embodying the novel features
referred to in connection with the stove.
The nature of the invention will best be understood when described in con-
nection with the accompanying drawings, in which:-
Fig. 1 represents a sectional elevation of a cooking stove containing my
improvements.
Fig. 2 is a front elevation thereof.
Fig. 3 is a sectional elevation showing the stove provided with a detachable
fire pot or magazine.
Fig. 4 is a similar elevation showing the improvements applied to a heating
stove.
Fig. 5 is a front elevation of a hot air furnace provided with my improvements.
Fig. 6 is a vertical section on the line 6-6 Fig. 5.
Fig. 7 is a horizontal section on the line 7-7 Fig. 6.
Fig. 8 is a similar section on the line 8-8 Fig. 6.
Fig. 9 is a horizontal section on the line 9-9 Fig. 6.
Fig. 10 is a plan view of the lower portion of the furnace.
Fig. 11 is a plan or top view of the furnace.
Figures 12 and 13 are views of a detail part in plan and section respectively.
Fig. 14 is a vertical section of a steam heater embodying my invention.
Fig. 15 is a plan or top view of the same.

page_text: Fig. 16 is a section on the line 16-16, Fig. 14.
Fig. 17 is an elevation of a hot water heater embodying my invention.
Fig. 18 is a vertical section on the line 18-18 Fig. 17.
Fig. 19 is a horizontal section on the line 19-19 Fig. 18.
Fig. 20 is a similar section on the line 20-20, Fig. 18.
Similar letters and numerals of reference designate corresponding parts
throughout the several views of the drawings.
Referring at present to Figures 1 and 2 of the drawings, the letter A desig-
nates a stove or range adapted for cooking purposes and for heating water, the
same being of any approved form or construction.
The stove is provided with a fire pot or magazine 11, preferably located at, or
near, its front, which is closed by a suitable fuel support 10 located at, or near,
its bottom. A usual ash pit 12 is provided below the fuel support. The stove
may be provided, as usual, with an oven 13 and with a water back 30. The
fire pot or magazine 11 is formed with a rear wall 14, the lower end of which has
therein vertical slots forming lateral openings 15 for the passage of the products
or gases of combustion to an upwardly extending flue 16, which communicates
with a horizontal flue 17, passing over the oven and connecting with a smoke or
draft pipe 18 leading to the chimney. The top plate 19 of the fire pot or maga-
zine 11 is preferably arranged at a somewhat lower level than the top 20 of the
stove, and said top plate 19 is provided with a plurality of holes through which
is passed a number of downwardly extending air tubes 2, which lead and direct
jets of air against the surface of the fuel in the fire pot or magazine 11. These
tubes are preferably made conical, so as to form a converging jet of air under the
influence of the chimney, or other draft, and consequently, the action of each jet
is to supply air against a particular point of the fuel, and in view thereof, the
combustion of fuel gradually rises vertically along the path of the downward
current of air with the result that a vertical hole is formed in the coal along the
line of air supply. The coal adjacent to such openings formed by the air jets
naturally moves laterally, and, therefore, the body of the fuel is being continually
broken up or agitated, and coking or packing is positively prevented. The area
of the openings at the upper ends of the air tubes may be regulated by employ-
ing a damper or regulating plate 3 formed with openings corresponding to those
of the air tubes, which plate may be moved to increase or decrease the size of
the openings of said tubes, as may be found necessary for the proper regulation
of combustion. The air tubes may be arranged in a straight line, or they may
be staggered, or they may be arranged in any other preferred manner
depending largely on the general construction of the stove. The fire
pot or magazine 11 is preferably made separate from the stove, and
as shown in Figures 1 and 3, the front wall of the same may
be provided with perforations 9, so that the heated air between it and the
outer walls of the stove will be drawn through the fuel, and thus assist com-
bustion, while at the same time, the outer walls of the stove are protected from
the intense heat of the fire above the fuel support.
When stoves already constructed, or in use, are to be transformed into stoves
adapted to burn soft coal, the fire pot or magazine is made, as shown in Figure 3,
with a removable top plate 29 having the downwardly projecting air tubes 2,
so that the attachment may be readily applied to the stove.
The fuel may be supplied to the fire pot or magazine through a door 22 located
preferably near the top of the fire pot or magazine. In the present example, a
door is shown adapted to open vertically and located at the top of a feed chute or
spout 23 which latter conducts the fuel into the fire pot or magazine.
It is, of course, to be understood that the door could be placed directly at the
top of the fire pot or magazine.
When an ordinary grate 10 is used as a fuel support, such for instance as
shown in Figure 1, it is preferable to provide a lower set of grate bars 10% to
receive any unconsumed fuel which may pass through the first grate, while the

page_text: space between the two sets of bars forms a combustion chamber for the fuel.
When a solid grate 10, such as that shown in Figure 3, is used, the second
grate is not necessary, as the fuel is always maintained or held within the fire
pot or magazine.
In the modification shown in Figure 4, the improvements are applied to a heat-
ing stove B, wherein the self feeding coal fire pot or magazine 11 say of conical
tubular form, and with the lateral openings 15, is inserted into the stove upon
the usual horizontal grate-bars 10. The fire pot or magazine is provided with a
removable cover plate 29 carrying in a circular series the air tubes 2, a circularly
arranged damper or regulating plate 3 and a deflector 33. With this fire pot
or magazine, which is also preferably removable and thus independent of the
sides of the stove, is combined a short flue S having on its rear a vertical par-
tition 7 of say fire brick, an overhanging deflecting plate 6, and a lower or
damping plate 5. This flue 8 communicates with a main flue and thence with
the flue 18: The vertical partition 7 in use becomes more or less extremely hot,
and should any unconsumed carbon in the form of smoke pass from the burning
coal, it will be burned in striking said partition, and hence the escape of smoke
at the flue 18 be prevented. As more or less ashes may accumulate between the
vertical grate bars and the partition 7, the plate 5 is made a dumping plate, so
that the ashes may be dumped into the ash pit 12, or into the pan.
In the case of the stove in Fig. 4, the coal will be fed by removing the remov-
able cover plate 29, or a portion thereof, as may be deemed desirable.
In the construction shown in Fig. 1, wherein an open grate 10 is used, the
ash-pit door is arranged to substantially shut off the passage of air to the flue 16,
this being necessary to obtain a proper supply of air through the tubes 2 into
and through the mass of fuel. In the construction shown in Fig. 3, this is not
essential, as the fuel support 10 is made imperforate and prevents an upward
current of air.
In the construction shown in Fig. 4, the air tubes 2 are arranged contiguous
to the wall of the fire pot or magazine, so as to direct jets of air against the
fuel in close proximity to the wall of the said fire pot or magazine, thus form-
ing the holes previously referred to quite close to said wall, and thereby pre-
venting the formation of clinkers on the wall.
The top plate of the stove is preferably formed with an overhang provided
with curved deflecting plate or portion 23 extending over the air tubes 2, so
that the air will be deflected downwardly into the open ends of the air tubes
(see Figs. 1, 2 and 3).
Referring now to Figs. 5 to 13 for a description of hot air furnace embody-
ing my invention, numerals 2 designate the air tubes which are fitted to the
top D of the furnace and which extend downwardly into the combustion
chamber G. The supply of air through the tubes 2 is regulated by means of a
suitable plate 3, similar to that described in connection with Fig. 4, which plate
is provided with a suitable handle a and indicating device b so that the plate can
be easily turned from the front of the furnace and its position indicated. By
means of this regulating plate or damper 3, the entire combustion of the furnace
is regulated. 10 is a curved fuel support closing the bottom of the fire pot or
magazine 11, which grate may be made imperforate so as to substantially close
off access of air from below, or it may be made perforate as shown, in which
latter case, however, the ash pit door I must be tightly fitted to the casing B
of the furnace. The fuel support 10 is mounted in the usual manner, so that it
can be turned over or oscillated to clear the fire put or magazine of obstructions.
Near the bottom of the fire pot or magazine are formed lateral openings 15 which
connect with the flues L leading to the chimney flue 18. These openings form
passages for the products of combustion generated in the fire-pot or magazine.
The air
The parts of the furnace exposed to fire are lined in the usual manner.
to be heated enters at c in the usual manner, and after circulating around the
Blues Lis conducted away at the top through the usual flues leading to the several

page_text: apartments or rooms. Fuel is introduced through the feed door 22 near the top
of the furnace.
In practice, the air tubes 2 are arranged to alternate in a horizontal plane with
the lateral openings 15 at the bottom of the fire pot or magazine 11, that is to
say, they are so arranged that each vertical jet of air is directed between two
openings 15, and consequently, the burning out of the brick or lining at the
bottom of the fire-pot or magazine is retarded and the jets of air are diverted
from the perpendicular. The lateral openings 15 at the bottom of the fire pot or
magazine 11 communicate with a common head d, so as to conduct the products
of combustion to the several flues L in the usual manner. The bottoni of this
head d is provided with openings e opposite the fire flues L, which openings are
closed by doors f hinged to the base of the casing and adapted to be opened and
closed by the device shown in detail in Figs. 12 and 13. This device consists of
a segment provided with a series of teeth h corresponding in number to the
doors f. These teeth are adapted to engage with the doors, or with suitable pro-
jections thereon, so that when the segment is turned in one direction by means
of the handle i, the doors are closed tightly, in view of the inclined faces of the
teeth h. When the segment is turned in the reverse direction, the doors open
by their own weight and discharge the ashes which may have accumulated,
through the funnel-shaped portion of the segment g.
In Figs. 14 to 16 I have shown the principle of the invention applied to a
boiler adapted for heating purposes. The construction is substantially the same
as that described in connection with Figs. 5 to 13, with the exception that water
is introduced into the space instead of air, and that the usual arrangement of
tubes is used in place of the flues L for conducting the products of combustion
from the head to the chimney flue 18.
In Figs. 17 to 20, I have shown a hot water heater embodying the improve-
ments which, in the main, are the same as those previously described in con-
nection with Figs. 5 to 16 but I have shown an improved construction for the
water space. This I build up of superimposed sections m and n of different
diameter arranged alternately at equal distances apart and communicating with
each other through nipples o preferably cast on the respective sections and enter-
ing sockets 2' in the adjoining sections. The several sections are held together
water and steam tight by means of bolts s extending through said sections and
through the connecting nipples.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
1. In a down draft stove or furnace, the combination of a fire pot or magazine
having a lateral opening at or near its bottom communicating with a flue lead-
ing to the chimney, a fuel support at the bottom of the fire pot or magazine,
and a plurality of air tubes extending downwardly from the top plate of the fire
pot from a plane above the level of the fuel and adapted to direct jets of air
towards the fuel for its combustion; all constructed for the purpose of conduct-
ing the air and the products of combustion downwardly through the fuel and
through the lateral opening in the fire pot or magazine under the influence of
the draft, substantially as described.
2. In a down draft stove or furnace, the combination of a fire pot or magazine
having a lateral opening at or near its bottom communicating with a flue lead-
ing to the chimney, a fuel support at the bottom of the fire pot or magazine, and
a plurality of air tubes arranged contiguous to the wall of the fire pot or maga-
zine and extending downwardly from the top of the fire pot or magazine to direct
jets of air into the fuel in close proximity to the walls of the said fire pot or
magazine for the combustion of said fuel; all constructed for the purpose of
conducting the air and the products of combustion downwardly through the fuel
and through the lateral opening in the fire pot or magazine under the influence

page_text: of the draft and to prevent the formation of clinkers on the walls of the fire pot
or magazine, substantially as described.
3. In a down draft stove or furnace, the combination of a removable fire pot or
magazine having a lateral opening at or near its bottom communicating with a
flue leading to the chimney, a fuel support at the bottom of the fire pot or
magazine, and a plurality of air tubes extending downwardly from the top plate
of the fire pot from a plane above the level of the fuel and adapted to direct jets
of air toward the fuel for its combustion; all constructed for the purpose of con-
ducting the air and the product of combustion downwardly through the fuel and
through the lateral opening in the fire pot or magazine under the influence of
the draft, substantially as described.
4. In a down draft stove or furnace, the combination of a fire pot or magazine.
having a lateral opening at or near its bottom communicating with a flue leading
to the chimney, a fuel support at the bottom of the fire pot or magazine, a
plurality of air tubes extending downwardly from the top plate of the fire pot
from a plane above the level of the fuel and adapted to direct jets of air toward
the fuel for its combustion, and an uptake 16 contiguous to the walls of the fire
pot or magazine; all constructed for the purpose of conducting the air and the
products of combustion downwardly through the fuel and through the lateral
opening in the fire pot or magazine under the influence of the draft substan-
tially as described.
5. In a down draft stove or furnace, the combination of a fire pot or magazine
having a lateral opening at or near its bottom communicating with a flue leading
to the chimney, a fuel support at the bottom of the fire pot or magazine, a plurality
of air tubes extending downwardly from the top of the fire pot or magazine to
direct jets of air into the fuel, and an ash pit normally closed off from the
external air to prevent an upward draft; all constructed for the purpose of con-
ducting the air and the products of combustion downwardly through the fuel and
through the lateral opening in the fire pot or magazine under the influence of
the draft, substantially as described.
6. In a down draft stove or furnace, the combination of a fire pot or magazine
having a lateral opening at or near its bottom communicating with a flue lead-
ing to the chimney, an imperforate fuel support adapted to close the bottom of
the fire pot substantially against the admission of air, and a plurality of air
tubes extending downwardly from the top of the fire pot & adapted to direct
jets of air against and into the fuel for its combustion; all constructed for the
purpose of conducting the air and the products of combustion exclusively down-
ward through the fuel and through the lateral opening in the fire pot or maga-
zine under the influence of the chimney draft, substantially as described.
7. In a down draft stove or furnace, the combination of a fire pot or magazine
having a lateral opening at or near its bottom communicating with a flue lead-
ing to the chimney, an imperforate fuel support adapted to close the bottom of
the fire pot or magazine substantially against the admission of air a plurality
of air tubes extending downwardly from the top of the fire pot or magazine &
adapted to direct jets of air against and into the fuel for its combustion; all
constructed for the purpose of conducting the air and the products of combustion
exclusively downward through the fuel & through the lateral opening in the fire
pot or magazine under the influence of the chimney draft, a draft chamber in
communication with the upper ends of said air tubes, and a regulator controlling
the supply of air to all said tubes simultaneously substantially as described.
8. In a down draft stove or furnace, the combination of a fire pot or magazine
having lateral openings at or near its bottom communicating with flues leading
upwardly to the chimney, an imperforate fuel support adapted to close the bottom
of the fire pot or magazine substantially against the admission of air, a plurality
of air tubes extending downwardly from the top of the fire pot or magazine and
adapted to direct jets of air against and into the fuel for its combustion; all
constructed for the purpose of conducting the air and the products of combus-

page_text: tion downward through the fuel and through the lateral openings in the fire pot
or magazine under the influence of the draft, and means for discharging the ash
or refuse from the flues leading to the chimney, substantially as described.
9. In a down draft stove or furnace, a fire pot or magazine having lateral open-
ings at or near its bottom communicating with horizontal flues leading to the
chimney, an imperforate base or plate closing the bottom of the fire pot or
magazine, a plurality of downwardly extending air tubes alternating in a hori-
zontal plane with the lateral openings at the bottom of the fire pot or magazine,
and heating flues arranged contiguous to the fire pot or magazine and to the
draft flues for the purpose of heating air or other media for distributing heat,
substantially as described.
10. In a down draft stove, the combination of a fire pot or magazine, a fuel
support at the bottom of the fire pot or magazine, and a plurality of air tubes
extending downwardly from the top of the fire pot or magazine to direct jets of
air into the fuel for its combustion; all constructed for the purpose of conducting
the air and products of combustion downwardly through the fuel under the influ-
ence of the draft, substantially as described.
Dated this 4th day of February 1899
HARRIS & MILLS,
23, Southampton Buildings, London, W.C., Agents.