IMPROVEMENTS IN HOT AIR STOVES
Year: 1877

page_text: LETTERS PATENT to Caleb Wheeler Durham, of Chicago, United States of
America, but at present of No. 20, Southampton Buildings, in the County of
Middlesex, for the Invention of "IMPROVEMENTS IN HOT AIR STOVES."
Sealed the 28th February 1878, and dated the 29th December 1877.
PROVISIONAL SPECIFICATION left by the said Caleb Wheeler Durham at
the Office of the Commissioners of Patents on the 29th December 1877.
CALEB WHEELER DURHAM, of Chicago, United States of America, but at present
"IMPROVEMENTS
of No. 20, Southampton Buildings, in the County of Middlesex.
IN HOT AIR STOVES."
My Invention relates to that description of hot air stoves wherein the air to be
heated is brought in contact with ribs or plates projecting from a closed chamber
heated internally by a fire, hot water, or other heating medium, the heat from
which is radiated by the said plates and taken up by the air.
According to my present Invention I construct such stoves as follows:-I make
the central heating chamber by preference of rectangular shape on plan and of some
height, and to the sides thereof I fix a series of radiating plates one above the other
in inclined positions with narrow spaces intervening between them, and I connect
the upper and lower ends of these inclined plates on the one side of the heating
chamber respectively with the lower and upper ends of the plates of the contiguous
sides by means of horizontal plates, thus forming a series of continuous narrow
passages between the radiating plates all round the beating chamber, which passages
rise in an inclined position along the one side, then pass horizontally round the
corner, then rise again in an inclined position along the next side, and then pass
horizontally round the next corner, and so on, until they issue at the upper end;
thus the air admitted at the lower ends of these passages in travelling upwards in
them is brought into intimate and extensive contact with the surfaces of the
radiating plates so as to issue in a perfectly heated condition at the top of the
stove.

page_text: By constructing the heating chamber of a square section as deseribed, the currents
of air passing round are effectually broken up and mingled at the corners, thus
preventing the volume of air entering next the chamber at bottom from continuing
in contact therewith up to the top, whereby it would become heated to a greater
extent than the volume of air passing up at a greater distance from the heating
chamber. The latter might however be formed of a polygonal or even cylindrical
section, by retaining the above described peculiar arrangement of the radiating
plates with alternate inclined and horizontal portions, and the breaking up of the
currents might be effected by means of plates projecting into the passages.
The heating apparatus is enclosed by a casing fitting against the outer edges of
the radiating plates and having openings at bottom for the ingress of the air to be
heated and communicating at top with one or more flues for conducting the heated
air to wherever required.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Caleb Wheeler Durham in the Great Seal Patent Office on the
28th June 1878.
CALEB WHEELER DURHAM, of Chicago, United States of America, but at present of
No. 20, Southampton Buildings, in the County of Middlesex. "IMPROVEMENTS IN
HOT AIR STOVES."
My Invention relates to that descripton of hot air stoves wherein the air to be
heated is brought in contact with ribs or plates projecting from a closed chamber
heated internally by a fire, hot water, or other heating medium, the heat from
which is radiated by the said plates and taken up by the air.
According to my present Invention I construct such stoves as follows:-I make
the central heating chamber by preference of rectangular shape on plan, and of
some height, and to the sides thereof I fix a series of radiating plates, one above
the other in inclined positions with narrow spaces intervening between them, and
I connect the upper and lower ends of these inclined plates on the one side of the
heating chamber respectively with the lower and upper ends of the plates of the
contiguous sides by means of horizontal plates, thus forming a series of continuous
narrow passages between the radiating plates all round the heating chamber, which
passages rise in an inclined position along the one side, then pass horizontally
round the corner, then rise again in an inclined position along the next side, and
then pass horizontally round the next corner, and so on, until they issue at the upper
end; thus the air admitted at the lower ends of these passages in travelling upwards
in them is brought into intimate and extensive contact with the surfaces of the
radiating plates, so as to issue in a perfectly heated condition at the top of the
stove.
By constructing the heating chamber of a square section as described, the currrents
of air passing round are effectually broken up and mingled at the corners, thus

page_text: preventing the volume of air entering next the chamber at bottom from continuing
in contact therewith up to the top, whereby it would become heated to a greater
extent than the volume of air passing up at a greater distance from the heating
chamber. The latter might however be formed of a polygonal section, while
retaining the above described peculiar arrangement of the radiating plates with
alternate inclined and horizontal portions, and the breaking up of the currents
might be effected by means of plates projecting into the passages.
The heating apparatus is enclosed by a casing fitting against the outer edges of
the radiating plates and having openings at bottom for the ingress of the air to be
heated and communicating at top with one or more flues for conducting the heated
air to wherever required.
DESCRIPTION OF THE DRAWINGS.
Fig. 1 is a vertical section through the centre of the furnace; Fig. 2, a horizontal
section on line a, b; Fig. 3, a vertical section on line e, f; Fig. 4, a horizontal
section on line c, d; Fig. 5, an isometrical view of the evaporating pan: Fig. 6, an
elevation of an unobstructed side of the radiator shewing arrangement of radiating
plates; and Fig. 7, an isometrical view of a portion of the stove, shewing more
clearly the arrangement of the radiating plates and one method of attaching them
to the stove.
In the Drawings R is a wrought-iron radiator or stove which contains the fire-
place F, the ash-pit P, and the indirect draught chamber H. The feed passage A is
also of wrought iron, rivetted to the heating chamber, as are also short sections of
the smoke pipes S and B.
It is intended that all the various parts of the heating chamber before-mentioned
shall be rivetted together steam tight, so that there shall not be any joint by which
any of the products of combustion shall be able to pass into the warm air chamber
surrounding the radiator under any conditions. The radiating surface is increased
by attaching to the heating chamber R, in the manner shewn in Figs. 6 and 7,
flanged metallic plates C, rising at any angle desired, and as near together as may
be found most effective. These plates C starting from the bottom or near the
bottom run continuously around it, except when interrupted by the feed passage A,
until the top is reached. These plates are of various widths in heaters of different
capacity, that being a matter for calculation. The flange can be formed on the
plates and bolted to the heating chamber; or the plates can be bolted to pieces of
angle iron rivetted to the heating chamber or by any method securing close contact,
so that they will be effectually warmed from the same. The heating chamber
being square or rectangular, and the inclined plates being connected at each corner
necessarily by a horizontal plate, there occurs a double change in the direction of
the current of air flowing between two plates, by which the current is broken up
and the outside portion of the current takes the place of the inside stratum, thus
heating the current of air equally throughout. The warm air chamber is enclosed
by a casing T, formed of sheet metal (preferably) with a bright reflecting surface,
or by walls of brick masonry, with a covering of the same supported by T bars.
Indirect draught is secured by the use of cast-iron linings L for the fire-place of the
general form shewn in Figs. 2, 3, and 4, by which arrangement (after the fire burns
briskly) by turning the damper D in the direct smoke pipe B the hot draught is
carried down the sides of the heating chamber and underneath the false bottom of
the ash-pit P to the smoke pipe S. The heating chamber being raised several
inches from the foundations by feet or supports, its bottom is also available as a
radiating surface; and it would be a good arrangement to bring the fresh air from
outside so that it would enter the warm air chamber underneath the heating
chamber instead of at one side as is usual. The air so entering would be distributed
more evenly to the several passages. The dust or ashes deposited in the indirect
draught chamber H can be removed with a scraper by taking off the fan plate I
underneath the ash-pit door N. The sinoke pipe S can be cleaned by removing the
cap K. The evaporating pan E containing water is supported from the top of the

page_text: radiator or from the walls of the warm air chamber; it is made as in Fig. 5, for
the purpose of withdrawal if necessary; it should be placed so far above the heating
chamber that the water will not be warmed except by the ascending warm air.
For the protection of the wrought-iron heating chamber at the point where the
indirect draught would cause a stream of hot air to constantly impinge on its surface
in curving over the top of the fire-place linings, I provide cast-iron reinforcing
plates Z, which hang to the top of the linings, as shewn in Fig. 3, also I suspend a
circular concave casting J over the fire to protect the wrought-iron top of the
heating chamber.
Having thus described the nature of my said Invention and in what manner the
same is to be performed, I claim:-The before described improved construction of
hot air stoves in which a heating chamber has projecting from its sides radiating
plates passing in an inclined direction along the sides of the chamber with hori-
zontal portions at the corners connecting the inclined portions, substantially as and
for the purposes herein described.
In witness whereof, I, the said Caleb Wheeler Durham, have hereunto set
my hand and seal, this Eighth day of June, in the year of our Lord One
thousand eight hundred and seventy-eight.
C. WHEELER DURHAM. (L.S.)