Note: Descriptions are shown in the official language in which they were submitted.
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FIREPLACE HEAT ABSORBING AND
TRANSMITTING APPARATUS
F ELD OF THE INVENTION
This invention is directed to a novel appara-
tus which can be mounted above the firebox of a conven-
tional fireplace in a dwelling for the purpose of
extracting heat from hot flue gas emitted by fuel burned
in the fireplace and utili~ing the extracted heat to
warm air which is transmitted into the room in which the
fireplace is located.
BACRGROUND OF THE INVENTION
In recent years, there has been a dramatic
increase in the cost of heating of dwellings by burning
oil or using electricity and as a result, dwelling
occupants have sought less expensive alternative heating
methods. Many dwellings have traditional brick fire-
places in the living rooms or dens. Occupants have
utilized such fireplaces as supplemental heat sources.
Hiowever, the fireplaces are not a viable alternative
because they inefficiently allow most of the heat
generated to escape up the chimney along with the flue
gas.
~5 A large number of innovations have been made
to improve the efficiency of the conven-tional fireplace.
These include various types of metal inserts, convection
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grates, and the like. Many new homes have installed in
them metal fireboxes and chimneys rather than tradi-
tional brick fireboxes and chimneys. These new heat
conserving metal fireboxes are usually equipped with
glass front doors, or the like, which shield the occu-
pants of the room from the Eire in the firebox. While
such systems are more efficient i.n that they extract
more of the heat from the burning fuel, they reduce the
romance and aesthetics associated with the crackling
sound of the burning fuel, the visual e~fects and
radiant heat of the fire in the fireplace.
Another disadvantage with these new heat
conserving systems is that they are difficult to clean
and, when they are equipped with glass doors, the doors
become fogged and dirty, thereby reducing visibility.
The applicant is aware of the following refer-
ences which disclose various fireplace conservation
apparatus or systems:
Vnited States
Patent No. Inventor Issue Date
3,888,231 Galluzzo June 10, 1975
3,998,203 Jensen
4,010,728 Hempel March 8, 1977
4,141j336 Fitch February 27, 1979
4,147,153 Buckner April 3, 1979
4,169,458 Shaw
4,349,009 Patterson Septe~ber 14, lg82
4,280,474 Ruegg July 28, 1981
4,224,921 Petresque
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SUMMARY OF THE INVENTION
This invention is directed to a novel appara-
tus which is used in association with a fireplace within
a dwelling, the fireplace being constructed of a firebox
and a chimney mounted above and connected to the fire-
box. The novel apparatus functions as a heat exchanger
and includes therein an enclosed interior vertical
passageway whereby the hot Elue gases generated by the
fuel burning in the firebox pass upwardly through the
passageway before entering the chimney. The heat
exchanger includes a communicating means to draw ambient
air from outside the dwelling into the heat exchanger.
As the hot flue gases pass through the interior of the
heat exchanger, the apparatus extracts heat therafrom
and transfers the heat to the ambient outside air. The
warmed air is then delivered into the interior of the
dwelling by communicating means connected with the
apparatus.
An advanta~e of the apparatus is that it is
located above the firebox and is hidden from view. It
therefore does not detrimentally affect the appearance
of the fireplace.
An apparatus for use in association with a
fireplace located in a dwelling, the fireplace being
constructed of a firebox and a chimney connected with
the firebox comprising: ~a) passage means associated
with the apparatus for enabling hot flue gas generated
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by fuel burned in the firebox to pass proximate to the
apparatus before passing up the chimney; (b) means
enclosing at least a part of the passage means (a)
adapted for extracting heat from the hot flue gas as it
passes upwardly through means (a); (c) means associated
with partial enclosing means (b) for enabling ambient
air to be drawn exterior to the clwelling in which the
fireplace and chimney are located into the enclosing
means (b); and (d) means associated with partial enclos-
10 ing means (b) for enabling air heated in the enclosing
means (b) by heat exchange with the hot flue gases to be
conveyed to the interior of the dwelling.
The heat exchanger may have a plurality of
annularly disposed walls with air heating chambers
15 between each wall and communicating with each other.
The heat exchanger may also be equipped with a dampening
means which is located in association with the enclosing
means and which is adjustable from the inside of the
dwelling.
In the apparatus, the enclosing means may
enclose all four sides. The heat exchanger is typically
constructed of a heat transmitting jacket which is
impermeable to flue gases. There may be three jackets
annularly arranged with respect to one another.
DRAWINGS
In the drawings which disclose an embodiment
of the inven-tion:
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Figure 1 illustrates a side partially~
sectional view of the fire box and chimney and the heat
exchanger which is mounted above the firebox;
Figure 2 illustrates a frontal perspective
view of the heat exchanger;
Figure 3 illustrates a top sectional view of
the heat exchanger taken along section line A-A of
Figure l; and
Figure 4 illustrates a side sectional view of
the heat exchanger taken along section line B-B of
Figure 3.
DETAILED DESCRIPTION OF ONE
EMBODIMENT OF THE INVENTION
.
Figure 1 illustrates a side section view of a
conventional fireplace with firebox and chimney. The
fireplace 2 is connected to a chimney or flue 4 at its
top region. The fireplace heat exchanger 6 is posi-
tioned at the location w~ere the firebox 8 of the fire-
place 2 connects with the chimney 4. Fire brick 10
linas the back and sides of the firebox 8. When viewed
from the front, the heat exchanger 6 is mounted behind
the brick fireplace front 11 and is not visible. Thus
it does not destroy or reduce the aesthetics of the
fireplace 2.
The lnterior of the heat exchanger 6 is
hollow, and permits hot gases generated by fuel burning
in the firebox 8 to pass upwardly through the interior
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thereof and up the chimney 4 by means of flue exhaust 18
located at the top of the heat exchanger 6. The rate of
passage of flue gases up the chimney 4 is controlled by
means of butterfly damper 12, the rotational position of
which can be manually regulated from the front of the
fireplace 2 by means of damper control 14. Damper
control 14 extends from the dampe!r 12 through the brick
fireplace front 11. A hot air outlet 1~ extends from
the upper front area of the heat exchanger 6 and through
brick fireplace front 11. The outlet 16 permits warmed
air to be emitted into the interior of the dwelling in
which the fireplace 2 and heat exchanger 6 are located.
Outside air is drawn in from outside the
dwelling through fresh air intake 20, which at one end
is connected to the rear outside of the fireplace 2 and
at the opposite end is connected with the rear side of
the heat exchanger 6. The outside air is drawn in by
means of a fresh air suction fan 22. A weather pro-
tector 21 protects the exterior end of the intake 20
from weather and small birds, rodents and insects. The
operation of fresh air suction fan 22 is regulated by
means of a thermostat which is located in the interior
of the dwelling in which the fireplace is located, as
will be explained in more detail later.
Figure 2 illustrates a perspective view of the
heat exchanger 6. The heat exchanger 6 lS typically
constructed with four walls or skins 7 in the form of a
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truncated pyramid, although other shapes are possible if
required to fit the space between the firebox and the
chimney of any particular fireplaceO The flue exhaust
connection 18 is located at the t:op of the heat ex-
changer 6 and communicates directly with the chimney 4.The hot air outlet 16, which deli.vers the warmed outside
air to the interior of the dwelling, is located in the
upper region of the front face of the heat exchanger 6.
A skirt 24 surrounds the base of the heat exchanger 6.
As seen in Figure 1, the skirt 24 enables the heat
exchanger 6 to be sealed into the masonry at the top of
the brick liner 10 at the rear of the fireplace, and the
masonry of the brick fireplace front 11. The seal pro-
vided by skirt 24 ensures that hot gases generated by
fuel burned in the firebox do not circumvent the heat
exchanger 6 but are forced to pass through the hollow
interior of the heat ex~hanger 6. If required, mortar
containing insulation material, eg. vermiculite or the
like, can be poured over the exchanger 6:after it is
installed in order to improve heat transfer efficiency~
Figure 3 illustrates a top section view taken
along section line A-A of Figure 1 of the construction
of the triple-jacket heat exchanger 6, showing the
interior skin 2~, the intermediate skin 30, and the
exterior skin 7. The wavy arrows on Figure 3 denote the
flow pattern of the air as it travels from the outside
through fresh air intake 20, past fan 22, and then into
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the outer chamber formed between the exterior skin 7 and
the intermediate skin 30. Subsequently, after passing
through the outer chamber, the air proceeds in reverse
fashion through the interior chamber formed between the
intermediate skin 30 and the interior skin 28. Ulti-
mately, the air is conveyed over the top areas of the
heat exchanger 6 through hot air outlet 16 (see Figures
1 and 2). In other words, the outside air whlch is
drawn in through fresh air intake 20 by means of fan 22,
is forced to travel virtually twice through the outer
and inner chambers of the heat exchanger 6, before the
air is emitted into the interior of the residence
through hot air outlet 16. Thus, when hot flue gases
generated by fuel being burned in the fireplace pass
upwardly through the interior of the heat exchanger 6,
an effective heat exchange takes place whereby heat
drawn from the hot flue gases is transmitted through the
walls of interior skin 28 and intermediate skin 30, and
warms the air passing through the interior chambers
created by the three skins. The outside air is there-
fore effectively warmed before it is passed into the
interior of the residence through outlet 16. In this
way, a considerable amount of the heat which is present
in the flue gas is salvaged and used to heat air which
is drawn in from the outside of the residence.
Figure 4 illustrates in detail by means of a
side section view taken along section line B-B of Figure
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3, the construction of the heat exchanger 6. As can be
seen in Figure 4, the heat exchanger 6 is constructed so
that it has an exterior wall or skin 7, an interior skin
28, and an intermediate skin 30, spatially arranged
between outer skin 7 and inner skin 28. These skins are
typically constructed of heavy gauge steel. The three
skins provide a triple jacket configuration with pa,s-
sages between the three separate skins. The dual pas-
sages permit air to be circulated twice through the
interior of the heat exchanger 6 after it is has been
drawn initially into the interior of the heat exchanger
6 by means of fresh air intake 20 and fresh air suction
fan 22. As mentioned previously, hot flue gases from
the firebox below the heat exchanger 6 pass upwardly
through the interior of the heat exchanger 6, ie. within
the interior passage ~ormed by interior skin 28, the
rate of passage of such gases up the chimney being
controlled by butterfly damper 12 and manual damper
control 14. In addition to damper 12 and control 14,
Figure 4 illustrates an automatic butterfly shut-off -
damper 26 which is located in the interior of the hot
air outlet 16 at the front upper region of the heat
exchanger ~. This damper 26 i5 regulated automatically
by means oE a thermostat (not shown~ which is appropri-
ately positioned in the outlet 16 or in the interior of
the room in which the fireplace is located. The thermo-
stat and the damper 26 operate in the following manner.
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When the fireplace i5 not in operation, and the weather
outside the residence is cold, the thermostat will
ensure that shut-off damper 26 i3 in a fully closed
position, ie. vertical, so that cold air is prevented
from seeping into the residence from outside. ~owever,
when the fireplace is in operation, the thermostat will
automatically open damper 26 a certain required amount
so as to permit warmed outside air to be transmitted
into the interior of the residence. If desirable, the
thermostat can also be connected to fan 22 so that air
is pumped from outside as required.
Figure 4 also illustrates an optional feature
which can be included in the system. Brackets 32 can be
mounted laterally across the interior of the heat ex-
changer 6 and can be used to support a series of fireresistant bricks 34. The ends of the interior passage
are left open to enable hot flue gases to pass at the
ends of the bricks 34. The purpose of the bricks is to
absorb some of the heat from the hot flue gases for heat
storage purposes or reflect some of the heat do~n into
the firebox 8 where it is dispensed into the room.
Fresh air suction fan 22, and automatic shut-
off damper 26 are automatically controlled to ensure
that outside air is not permitted to enter the interior
of the dwelling unless the air is of at least room
temperature. Thus, on cold days, it is not possible for
outside air at temperatures lower than room temperature
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to be drawn into the interior of the dwelling through
heat exchanger 6. However, when the fireplace is in
operation, and the outside air being drawn in through
fresh air intake 20 is properly warmed, fan 22 and
damper 26 automatically begin to operate so that warmed
air is transmitted into the interior of the dwelling
through hot air outlet 16. The advantage of the heat
exchanger 6 is that it enables a larger quotient of heat
to be extracted from the burning log or fuel in the
fireplace, not only by means of radiation and conduction
from the glowing log, but also by means of extraction of
heat from the generated flue gas which normally passes
up the chimney. Another advantage of the heat exchanger
6 is that only fresh air is emitted into the interior of
the dwelling through hot air outlet 16. At no time, nor
at any location, does an interchange of hot flue gas
take place or mingle with the air being drawn through
fresh air inlet 20. Thus, no noxious gases such as
carbon monoxide, sulfur dioxide, and the like, can
mingle with the air which is drawn in and circulated
through the interior of the heat exhanger 6 before being
emitted into the interior of the dwelling through outlet
16.
As will be apparent to those skilled in the
art in the light of the foregoing disclosure, many
alterations and modifications are possible in the
practice of this invention without departing from the
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spirit or scope thereof~ Accordingly, the scope of the
invention is to be construed in accordance with the
substance de:Eined by the following claims.
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