Note: Descriptions are shown in the official language in which they were submitted.
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COMBINATION HEAT T~ANSFER PANEL AND WALL SHIELD
FOR USE WITH STOVES AND OTHER RADIANT HEATERS
BACKGROUND AND GENERAL STATEMENT OF THE INVENTION
This invention pertains to a combination heat transfer panel
and wall shield for use with stoves and other radiant heaters. Due
to the limited nature of the supply of fossil uels, it is apparent
that t.hese fuels should be reserved for areas in which they are
uniquely useful and most critical. Residential and commercial space
heating is not necessarily one of those areas; thus, we have wit-
nessed in recent years new interest in exploring alternative systems
of harnessing energy for space heating, energy which can be derived
economically from inexhaustible or replenishable sources. Such sys-
tems include nuclear reactors, geothermal and solar devices, wind-
mills, ocean-wave-mills, etc.
Included in this category of alternative energy systems is the
wood or coal burning heater/stove. Although wood is not an inex-
haustible source of energy, it is replenishable. The revival of the
traditional Franklin iron stove has been accompanied by the develop-
ment of numerous refined embodiments of the traditional stove. New
features include the principles of air-tightness, thermostatic con-
trol, preheating of combustion air, etc. All such features tend to
increase the efficiency of combustion so as to maximize the extrac-
tion o useful heat from a given amount of fuel.
Although the recent proliferation of iron and steel heater/
stoves may well help to ea~e the burden on petroleum supplies, their
installation in conventional wood-frame structures can present prob-
lems of safety and convenience. One fundamental problem is the fact
that such radiant heaters must be installed with specific minimum
clearances from combustibles, if they are to be installed safely.
Such clearances can exceed three feet in some cases. This means that
the floor space behind such a stove can be virtually useless to the
home owner, floor space for which he has paid dearly.
Although radiant heaters are most effective when installed in
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the middle of a room, the vast majority of installations are not of
this type; rather, for aesthetic or practical reasons, the heaters
are placed as close as possible to walls or corners. One negative
effect of this type of installation, from an efficiency point of
view, is that a significant portion of the heat which is radiated
from the rear of the stove is absorbed by the back wall and perhaps
lost to the outdoors. Some manufacturers design their stoves with
steel baffles attached to the rear of their units in order to mini-
mize the amount of radiant heat produced there. Although reduced
10 clearances can be achieved in this manner, it is clear that such a
baffled unit produces less total heat than does an unbaffled stove
and thus runs counter to the aim of extracting a maximum amount of
heat from a given amount of fuel.
Prior art directed toward distance reduction for radiant heaters
has for the most part been restricted to specified procedures of
field masonry. For example, brick walls are constructed with care-
fully maintained air spaces behind them to insure a free flow of cool
air along the back side. One drawback to this method is the cost
involved - in some cases additional footings are required to carry
20 the load of the additional masonry. In many instances such footings
are not feasible.
Another method of distance reduction involves the use of pre-
fabricated steel wall panels, hollow sheet metal pans filled with
insulation. Whether or not this method of wall protection is truly
effective~ from a safety point of view, these panels do suffer from
the standpoint of aesthetics.
Other methods include the use of various factory-made precast
cement panels which are installed with spacers to insuxe the free
flow of cool air on the backside. In various ways, these panels
30 all suffer from problems of weight, cost, inconvenience, and aes-
thetics.
It is a purpose of this invention to provide economical,
convenient, aesthetically pleasing, and functional protective
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coverings for combustible walls, when these walls are exposed to
sources of high ra~iant heat.
In addition to its function of protecting combustible surfaces,
another primary function is to provide an effective means of utili-
zing heat energy from a radiant heat source and redirecting or con-
verting it in such a manner that lt proves most useful for the pur-
pose of heating space.
Another important function of the device described herein is
that of utilizing heat that normally is absorbed and lost by the
walls located directly behind radiant heaters.
Still a further purpose of the invention is to provide a comb-
ination heat transfer panel and wall shield for use with stoves and
other radiant heaters which is simple in construction, efficient in
operation, low in cost, easily maintained, and attractive in appear-
ance.
The hereindescribed apparatus accomplishing the foregoing and
other objects of the present invention broadly comprise a case
adapted for location either against, or in spaced relation to, a
structural wall behind a stove or other radiant heater~ The case
comprises a base, a header and side panels.
The front of the case facing the heater has a central opening
permitting the entrance of radiant heat. At its lower end prefer-
ably~ or, alternatively, at the sides, it is provided with a cold
air inlet or inlets. At its upper end it is provided with a hot
air exhaust.
Curtains hang from the header and are arranged substantially
parallel to each other in the plane of the case in spaced relation
to each other as required to provide first and second convection
chambers communicating with the cold air inlet and the hot air ex-
haust. The outermost curtain pre~erably is adjustable between afirst position in which it absorbs the radiant heat, transferring
it to the convection chambers, and a second position in which it
re1ects the radiant heat away from the interior of the case.
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Conduit means may be associated with the cold air inlet and the h~t
air exhaust ~or drawing cold air from, and circulating hot air to,
selected space areas.
DESCRIPTION OF A SPECIFIC EMBODIMENT OF THE
INVENTION
In the drawings:
Fig. 1 is a foreshortened vertical elevation of the combina-
tion heat transfer panel and wall shield of my invention, with parts
broken away to show interior construction.
Fig. 2 is a foreshortened transverse sectional view taken along
line 2-2 of Fig. 1.
Fig. 3 is a foreshortened longitudinal sectional view taken
along line 3-3 of Fig. 1.
Figs. 4 and 5 are ragmentary views similar to Fig. 3 but
illustrate alternate operating positions of the panel.
The hereindescribed combination heat transfer panel and wall
shield is adapted for use with non-solar radiant heaters such as
wood and coal burn~g stoves and fireplaces; oil, kerosene and alco-
hol burning heaters; and electric heaters. It is designed particu-
larly for use with wood and coal burning stoves.
As shown particularly in Fig. 3, the device is adapted for
placement directly against a structural wall 10, which it shields,
and behind a stove or other radiant heater, not illustrated, located
nearby on the side opposite the wall.
The device is housed in a case comprising a base 12, a pair o
upstanding side walls 14 and a header 16. These structural elements
are astened to each other by means of bolts, welding, or other
suitable securing means.
The back of the case pre~erably has a large opening 18 to con-
serve material. The front of the case has a large central opening
20 which faces the radiant heater and admits radiant heat to the
interior of the device.
In cross section, header 16 has the general conto~r o the let-
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ter G, arranged face down, It may be formed integrally rom a sin~lesheet of bent sheet metal, It comprises a short back wall segrnent
22, a top segment 24, a front wall segment 26, and a reversely bent
inner segment 28, 28a, The floor 28a of the reversely bent inner
segment is provided with opening 30 the purpose of which will appear
later,
Front segment 26 is provided with a long opening 32, This
serves as a hot air exhaust vent for the assembly.
The case above described houses two spaced curtain assemblies
arranged parallel to each other in the plane of the case. The first
curtain assembly, indicated generally at 34, is toward the front and
serves the primary ~unction of controlling the admission of radiant
energy into the interior of the case. The second curtain assembly~
indicated generally at 36, serves the primary purpose of providing
a heat shield to protect wall 10.
Both curtain assemblies serve the further purpose of directing
the flow of heat trapped and/or generated by the apparatus out hot
air exhaust vent 32.
To this end the two curtain assemblies are spaced from each
other and from the structural wall in such a manner as to provide
a first, or outer, convection chamber 38 and a second, or inner,
convection chamber 40. It will be observed that in the illustrated
embodiment structural wall 10 itself provides one of the defining
surfaces for inner convection chamber ~.
The first or outer curtain assembly 34 preferably comprises
a plurality of vertically or horizon~ally arranged louvers which
preferably are arcuate in contour and which preferably are components
of the venetian blind sub-assembly illustrated in Fig. 3.
The construction of the venetian blind sub-assembly is sub-
stantially conventional, It cornprises a plurality of vertical,ladder-shaped straps 42 made of fiberglass threads or other flexible,
non-combustible material. The straps support a plurality of hori-
zontally arranged louvers 44, and a base rail 46 in the usual manner.
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Straps 42 are supported on rollers 48 which in turn are ixed at
spaced intervals to a sha~t S0. The shaft in turn is supported
rotatably on brackets 52 mounted on the floor 28a of the reversely
bent terminal segment of the G-shaped header 16.
By pulling on straps 42, or on a conventional pull cord, not
illustrated, the louvers 44 may be shifted between a first position
in which one of their faces is toward the front, a second position
in which the other of their faces is toward t.he front, or to any
intermediate position. This makes possible adjusting the curtain
so that it either absorbs the radiant energy entering through opening
20 or reflects it back to the exterior.
This is accomplished by painting one side of the louvers 44
with a white, metallic, or other radiant-energy-reflecting coating
and painting the other side of the louvers with a black, or other
dark colored radiant-energy-absorbing coating. Thus, for example,
when the louvers are in their Fig. 3 position, with their light
colored convex surfaces facing outwardly, they present a barrier
which reflects radiant energy back into the space in which it is
generated. However, when the louvers are in their Fig. 5 position,
the radiant energy is absorbed by the louvers and is transmitted
to the interior of the case.
The venetian blind assembly may be positioned and spaced by
means of the wire clip spacers illustrated particularly in Figs.
1 and 3.
The spacers are indicated generally at 54. They include a
central, reversely bent central segment 56 which is secured to the
adjacent side wall 14 by means of bol~s 58.
A bent anchoring segment 60 penetrates the adjacent end of
rail 46. The opposite terminal portion 62 extends downwardly and
abutts against the inner front of the case, thereby insuring a
properly spaced relation between the outer curtain assembly 34 and
the inner curtain assembly 40.
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The construction of the cooperating inner curtain assembly 36
is illustrated particularly in Figs, 2 and 3,
In the embodiment illustrated, the curtain comprises a sheet
66, preferably a corrugated sheet of highly heat-conductive alumi-
num or other incombustible material. The application of the corru-
gated sheet is preferred because of its increased surface area,
because it can be rolled up for packaging, and because of its in-
creased rigidity and strength,
It will be noted from Fig. 3 that curtain 66 terminates at its
upper end short of header 16 and at its lower end short of base 12,
There thus is provided a passageway which is a continuation of cold
air inlet 64 at the bottom of the curtain and another passageway which
communicates with hot air vent 32 at the upper end of the curtain,
The illustrated means for hanging curtain 66 comprises a plur-
ality of hooks 68 the upper bent ends of which are welded or otherwise
affixed to the undersurface of top segment 24 of the header and the
lower bent portions of which enter openings in the upper margn of
curtain 66, provided for the purpose of hanging the curtain.
In the practice of my inventiona number of alternatives suggest
themselves. These are not illustrated, but are self evident from
the foregoing discussion,
For example, whereas in the illustrated embodiment, the cold
air inlet is provided at the lower end of the case, another em~bodi-
ment Gf the invention might provide for the introduction of cold air
from the sides, either into the front convection chamber 38, or into
the rear chamber 40, or into both. In any case, if cold air is
introduced from the sides, experience indicates that either one or
both curtains should extend either close to or all the way to the
base 12 in order to maximize the chimney effect within the panel.
A back wall o~ aluminum foil or other similar material might
be placed over the combustible structural wall lO to provide addi-
tional protection against the hazard of fire.
Instead of a single inner curtain assembly 36, there might
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be provided a plurality of parallel curtains spaced apart to isolate
a volume of air between them.
A sheet of heat absorbent glass might be placed in front o~
the outer louvered curtain 34 to maximize the chimney effect of
convected warm air in convection chambers 38, 40.
A mechanical blower might be provided to force air through the
apparatus at an accelerated rate.
The space behind inner curtain 36 might be filled with fiber-
glass or other incombustible insulation.
A plurality of louvered curtains 34 might be used, and the
louvers might be arranged in either vertical or horizontal configu-
rations.
The inner curtain 66 might ~e coated with various special
coatings, for example, a selective absorbing coating which absorbs
radiant heat efficiently but which does not radiate heat well,
thereby absorbing heat re-radiated from front curtain 34 and from
structural wall 10.
Further variations within the spirit and scope of the invention
will occur to persons skilled in the art.
OPERATION
Whatever the embodiment employed, the operation of the herein-
described combination heat transfer panel and wall shield is as
follows:
When mounted against a combustible structural wall 10 and
screening the same ~rom a stove or other closely juxtaposed radiant
heater, the heat transfer panel receives radiant energy from the
radiant heater through its front opening 20. If it is desired to
reflect the heat back into the space from which it comes, louvers
44 are arranged with their convex reflective surfaces facing outwa-
30 rdly as shown in Fig. 3.
If, on the other hand, it is desired to absorb and transfer
the radiant energy, the louvers are adjusted with their concave
black heat absorbing surfaces facing outwardly as shown in Fig. 5.
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In this case ~he heat energy is abosrbed and transferred to the first
and second convection chambers 38 and 40, respectively, where a
chimney effect is established. Cold air is drawn into the bottom
of the unit through cold air inlet 64 and passes upwardly through
convection chambers 38, 40. It exhausts from the unit through hot
air vent 32.
Depending upon the intensity of the radiant heat source and
upon the nature of the black wall 10, either of two treatments may
be used with respect to inner curtain 66. The more radiant-energy-
absorptive the curtain, the greater will be the amount of heattransferred to the air ~lowing along its surface. Higher, too,
however, will be the temperature of the back wall 10. The more
radiant-energy-reflective the curtain 66, the greater will be the
amount of heat reflected away from itself and from the back wall
10. The result in this latter case will be a lower back wall temp-
erature, but less heat transfer to the convected air. Different
field conditions may require different treatments to realize fully
both the benefits of heat transfer and of adequate wall protection.
If it is desired to decrease the chimney effect, louvers 44
may be opened to various angles. A minimum chimney effect in front
convection chamber 38 will result from a wide open, that is hori-
zontal, position such as is shown in Fig. 4.
If none of the above intensifying effects is required, the
front Gf the panel may be constructed of a series of fixed louvers.
Although less versatile than the system of movable louvers, the
fixed louver system will by itself intensify the conduction of heat
around the unit due to the irregular surfaces of the louvers and to
the increased surface exposed, as compared to that provided by mono-
lithic flat surfaces.
Inlet and exhaust air may be supplied and delivered in a var-
iety of combinations through associated duct work or dampers, not
illustrated, to suit the needs of the particular installation.
Thus cooler room air may be introduced, circulated through the
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convection chambers and returned to either the same room, to an
adjacent or upstairs room, or out of doors. Cool outdoor air may
be introduced and directed either back outdoors, into the heated
room, or into an adjacent or upstairs room. Adjacent room air may
be introduced and circulated in like manner.
In all of these applications, the unit standing closely ad-
jacent the combustible structural wall 10 serves as a shield which
prevents combustion of the wall. Accordingly, it is possible to
place the stove or other radiant heater much closer to the wall than
otherwise would be possible, thereby conserving a significant square
footage of floor space which then may be put to a useful purpose.
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