IMPROVEMENTS IN HOT AIR STOVES
Year: 1879

page_text: LETTERS PATENT to August Kohlhofer, of Munich, in the Kingdom of Bavaria,
but at present of No. 28, Southampton Buildings, in the County of Middlesex,
for the Invention of "IMPROVEMENTS IN HOT AIR STOVES."
PROVISIONAL SPECIFICATION left by the said August Kohlhofer at the
Office of the Commissioners of Patents on the 8th November 1879.
AUGUST KOHLHOFER, of Munich, in the Kingdom of Bavaria, but at present of
No. 28, Southampton Buildings, in the County of Middlesex. "IMPROVEMENTS IN
HOT AIR STOVES."
According to my present Invention I construct hot air stoves as follows:-Within
a casing, which may be of any suitable material, is a closed fuel chamber, by pre-
ference of rectangular shape, and constructed of flat cast iron plates secured to angle
irons at the corners, and divided by a vertical partition into two separate compart-
ments, each of which is provided with a grate and fire door, so that either both
compartments may be in action at the same time, or only one may be in use, according
to the degree of heat required. These compartments are filled with fuel through an
opening at top which is closed by a removeable cover fitting with a lip in a sand
trough, so as to make an air tight joint. The combustion is maintained by the
entrance of regulated quantities of air through air valves in the fire or ash pit door,
and the gaseous products of combustion are carried off through a side opening near
the top into a vertical pipe which communicates with both fuel chambers, and which
at a certain height branches into two separate bend pipes, so that the hot gases are
made to divide and pass off through each bend. These bends each communicate
with the upper end of a vertical pipe situated at opposite sides of the fuel chamber,
which pipes are each connected at bottom by bends to a series of other vertical
pipes so arranged and connected that the hot gases have to pass alternately up one
pipe, then down the next, and so on, the last pipe of each series being made to com-
municate with a chimney flue. By this arrangement a very extended heating
surface is afforded by the pipes, so that the air to be heated, in being brought in
[Duink

page_text: contact therewith, will effectually take up the heat therefrom, and the gases will
consequently leave the stove in a comparatively cool state.
For the purpose of readily gaining access to the interior of the heating tubes, for
clearing them of carbonaceous deposits, the bends connecting the upper and lower
ends have openings which are hermetically closed by a cover secured by a bridge
piece and screw.
The casing of the stove, which encloses both the fuel chambers and the heating
pipes, has at its lower end a number of openings, each provided with a regulating
valve, through which a regulated quantity of air can enter, and it also has a corre-
sponding number of apertures provided with regulating valves at top, so that the
air entering at bottom, after passing up in the casing in close contact with the
surfaces of the fuel chambers and heating pipes, so as to become effectually and
uniformly heated, thereby passes out again through the upper openings of the casing.
If the stove is situated in the locality which is to be heated thereby the hot air
simply issues from the top openings into the surrounding space, but if the stove is
required also to heat one or more other localities situated at a greater or less distance
therefrom, then a corresponding number of both the upper and lower openings of
the casing are made to communicate respectively with such localities by pipes or
flues, so that the cold air will pass from each such locality to one or more of the
lower openings of the stove, and after becoming heated on its passage through the
stove will ascend from one or more of the upper openings to the same locality; or
the cold air may, if desired, be taken directly from the external atmosphere, instead
of from the locality to be heated.
The casing of the stove has a sufficiently large door to enable access to be readily
gained to the fuel chambers for filling them, and for clearing the grates and ashpits
when required.
As the fuel chambers contain a column of fuel of some height, which gradually
sinks down as it is consumed, they only require attention and refilling after com-
paratively long intervals of time. As the burning fuel is entirely enclosed in the
fuel chambers, and these are again enclosed by the casing, it will be seen that this
construction of stove offers great security against fire, rendering it specially applicable
for prisons, schools, hospitals, railway stations, and the like; while its great heating
surface in proportion to its size, and the facility with which the heated air may be
conveyed from it to a distance, make it also applicable for heating railway trains or
other localities where a number of separate chambers require to be heated by one
and the same stove.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said August Kohlhofer in the Great Seal Patent Office on the 5th May
1880.
AUGUST KOHLHOFER, of Munich, in the Kingdom of Bavaria, but at present of
No. 28, Southampton Buildings, in the County of Middlesex. "IMPROVEMENTS IN
HOT AIR STOVES."
According to my present Invention I construct hot air stoves as follows:-
Within a casing, which may be of any suitable material, is a closed fuel chamber,
by preference of rectangular shape, and constructed of flat cast iron plates secured
to angle irons at the corners, and divided by a vertical partition into two separate
compartments, each of which is provided with a grate and fire door, so that either
both compartments may be in action at the same time, or only one may be in use,
according to the degree of heat required. These compartments are filled with fuel
through an opening at top which is closed by a removeable cover fitting with a lip
in a sand trough, so as to make an airtight joint. The combustion is maintained
by the entrance of regulated quantities of air through air valves in the fire or ash
pit door, and the gaseous products of combustion are carried off through a side
opening near the top into a vertical pipe which communicates with both fuel
chambers, and which at a certain height branches into two separate bent pipes, so
that the hot gases are made to divide and pass off through each bend. These bends
each communicate with the upper end of a vertical pipe situated at opposite sides
of the fuel chamber, which pipes are each connected at bottom by bends to a series
of other vertical pipes so arranged and connected that the hot gases have to pass
alternately up one pipe, then down the next, and so on, the last pipe of each series
being made to communicate with a chimney flue. By this arrangement a very
extended heating surface is afforded by the pipes, so that the air to be heated, in
being brought in contact therewith, will effectually take up the heat therefrom, and
the gases will consequently leave the stove in a comparatively cool state.
For the purpose of readily gaining access to the interior of the heating tubes, for
clearing them of carbonaceous deposits, the bends connecting the upper and lower
ends have openings which are hermetically closed by a cover secured by a bridge
piece and screw.
corre-
The casing of the stove, which encloses both the fuel chambers and the heating
pipes, has at its lower end a number of openings, each provided with a regulating
valve, through which a regulated quantity of air can enter, and it also has
sponding number of apertures provided with regulating valves at top, so that the
air entering at bottom, after passing up in the casing in close contact with the
surfaces of the fuel chambers and heating pipes, so as to become effectually and
uniformly heated thereby, passes out again through the upper opening of the casing.
If the stove is situated in the locality which is to be heated thereby the hot air
simply issues from the top openings into the surrounding space, but if the stove is
required also to heat one or more other localities situated at a greater or less distance
therefrom, then a corresponding number of both the upper and lower openings of
the casing are made to communicate respectively with such localities by pipes or
flues, so that the cold air will pass from each such locality to one or more of the
lower openings of the stove, and after becoming heated on its passage through the
stove will ascend from one or more of the upper openings to the same locality; or
the cold air may, if desired, be taken directly from the external atmosphere instend
of from the locality to be heated.
The casing of the stove has a sufficiently large door to enable access to be readily
gained to the fuel chambers for filling them, and for clearing the grates and ash pits
when required.

page_text: As the fuel chambers contain a column of fuel of some height, which gradually
sinks down as it is consumed, they only require attention and refilling after com-
paratively long intervals of time. As the burning fuel is entirely enclosed in the
fuel chambers, and these are again enclosed by the casing, it will be seen that this
construction of stove offers great security against fire, rendering it specially applicable
for prisons, schools, hospitals, railway stations, and the like; while its great heating
surface in proportion to its size, and facility with which the heated air may be con-
veyed from it to a distance, make it also applicable for heating railway trains or
other localities where a number of separate chambers require to be heated by one
and the same stove.
Fig. 1 shews a front elevation of my before described improved hot air stove; Fig. 2
shews a sectional plan; Figs. 3 and 4 shew respectively a front view and vertical
section of the fuel chamber; and Fig. 5 shews a detached elevation of the flue pipes.
Within the cylindrical casing A is the fuel chamber, consisting of two separate
compartiments B, B, closed at top by a loose cover C fitting into a trough with sand
lute, as shewn. D, D, are the fire and ash pit doors, in which are valves E for
regulating the admission of air. The fuel chambers, which are of rectangular section,
and formed of sheet iron plates joined at the corners by angle irons, as shewn, both
communicate at top with a flue pipe F leading downwards, and branching at its
lower end into two other pipes F', F', which rise up to near the top of the stove,
and are there connected by bends to two other pipes F2, F; these lead down to the
bottom of the stove, and are connected by bends with other pipes F, Fs, which are
united at top to one and the same escape pipe F leading to a chimney fluo. Thus
the gaseous products of combustion passing from the combustion chambers B into
the pipe F divide at the lower end thereof into the pipes F¹, F1, in which they
ascend, and passing down the pipes F2 and up those Fs, escape through F* to the
chimney.
At the same time the external air enters the casing at bottom through the
openings G, G, provided with regulating valves, and in passing up in close contact
with the extended beating surface offered by the pipes F, F1, F2, F³, becomes
effectually heated, and issues from the casing again through the apertures G', G',
also provided with regulating valves. If required, the apertures G, G³, may be
connected to tubes or passages for taking the air supply from any locality, and for
delivering the heated air to any locality at a greater or less distance from the
stove.
The pipes F1, F2, F³, are provided at the bends at top and bottom with openings
closed by caps H secured by screws as shewn, so that they can be readily cleared of
any deposit therein. For this purpose also the top A¹ of the stove is made remove-
able. The casing A is provided with a door A³ for gaining access to the fuel
chambers B, B, for charging them with fuel through the covers C, and for removing
the ashes.
It will be readily understood that the hot air from such stoves may be used not
only for heating purposes, but also for drying, cooking, or any other purpose to
which hot air is applicable.
Having thus described the nature of my said Invention, and in what manner the
same is to be performed, I claim,―
First. The construction of hot air stoves, wherein one or more fuel chambers
enclosed within a casing have a flue pipe branching into two or more sets of flue
pipes passing alternately upwards and downwards within the said casing on their
way to a chimney flue, the air to be heated being introduced through apertures at
the bottom of the stove, so as to become heated by ascending in contact with the
said flue pipes, and issuing through other apertures at the upper end of the casing,
substantially as herein described.

page_text: Second. In hot air stoves, the combination of the casing A with air openings
G, G', fuel chambers B, B, and flue pipes F, F1, F2, F³, with covers H, H, arranged
and operating substantially as herein described.
In witness whereof, I, the said August Kohlhofer, have hereunto set my hand
and seal, this Fifth day of May, in the year of our Lord One thousand eight
hundred eighty.
AUGUST KOHLHOFER. (L.S.)