Note: Descriptions are shown in the official language in which they were submitted.
't3~
PRIOR ART
It is no~ well understood ~y those skilled
in the art that most fireplaces are really uneconomi-
cal in that they draw healed air frQm the home intothe fireplace to help effect the combustion of the
fire and then forcing a great deal of that already
heated air out the chimrley. There have been many and
various attempts to provicle glass firaplace doors, or
the like, in order to prevent this discharge, and
indeed there further have been many stoves and fire~
place inserts developed to likewise combat this pro-
blem.
However, these prior art attempts have
lS not provided for a good sealing relationship of the
insert with respect to the face of th.e fireplace or
the fireplace housing itself, and hence air still
leaks from the house into the fire and up the chimney.
~urther, when the fireplace is not in use, there can
be cold air leaking from around the fireplace insert
down through the chimney and effec~ing adverse energy
efficiency in the home.
It is further believed that these prior
art fireplace insert approaches have not achieved
sufficient insulation of the firebox in combination
with air circulation therearound so as to obtain the
most effective heat transfer from the firebox and for
transmitting such heat back into the room. Further,
these prior art attempts have not incorporated a good
sealed relationship of the firebox itself by having
an airtight door arrangement to prevent air leakage
around the door.
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OBJECI'S OF l`HE I~7ENT~CON
It is the general object of the present
invention to a~oid and overcome the oregoing and
other problems of the prior art practice~ by providing
a fireplace insert that has a firebox performing
efficiently as a heat exchanger by utilizing a well
insulated air shroud or casing~ and air circulation
features axound the firebox of inside room air to
effect the most efficient: heat transfer thereto,
with the minimum of heat exiting up the chLmney. This
object is achieved by providing a very efficient
arrangement of a large portion of the insert extending
on to the fireplace hearth in order to circulate air
most efficiently with only slightl~ over hal of the
insert extending into the fireplace itself.
A further object of the in~ention is to
¦ provide a unique flared front hood arrangement to
achieve an excellent air seal of the fireplace insert
against the fireplace face because of the flared hood
and the use of thick insulation between the fireplace
face and the flared hood.
A further object of the invention is to
pro~ide an improved airtight door that preYents heated
air from being drawn back into the fire and keep
soot, smoke, and sparks from blo~ing into the room.
A further object of the invention i~ to
provide a specialized baffle arrangement within the
air shroud around the firebox to provide for the most
efficient flow of air and heat transfer around the
firebox~ and yet maintain the flared front hood in a
a ~
cool condition so as to prevent being burned by
coming into contact therewith.~
A ~urther object of the in~ention is to
provide a fireplace insert wh~ch can optionally
utilize power blowers convenientl~ associated with
the intake air portion of the flared hood to achieve
optimum air ~low and heat transfer from the firebox.
The aforesaid objects of the invention
and other objects which will become apparent as the
detailed description proceeds are ach~ved by pro-
viding a fireplace insert for a fireplace having a
front face surrounding the fireplace opening thereto
which comprises: a firebox having a ~ront openin~;
a door select.ively closing the opaning; an air shroud
surrounding the firebox and creating an air space
around the sides and top of the fire~bx; an exhaust
flue at the top back of the firebox and communicating
in sealed relationship through the air shroud; a
front hood attached to and communicating with the air
shroud and defining a flat surfac~ to engaye with.the
face of the fireplace when the insert is posîtioned
thereinto; seal means between the hood and the fire
place face to provide a substantial fluid seal ~etween
the insert and the fireplace; and means to provide
entrance of roQm a;r into the hood to circulate around
the firebox and discharge back into the room,
BRIEF DESCRIPTION OF THE~ WINGS
~or a better understanding o~ the inven-
tion, reference should be had to th.e accompanying
drawings wherein:
Fi~. l is a xont eleYational viaw of the
fîreplace insert comprising the preferred embodiment
o~ t~le invention;
Fig~ ~ is a partially broken away side
ele~ational view of the fireplace ~ Fig. l;
Fig. 3 is a top broken away plan view
of the firepl~ce of Fiy~ l;
Fig~. 4 i~ a top broken away plan ~iew
of the door construction; and
Fiy~ 5 ;s an enlarged cross-sectional
view of the door construction a~ taken rom line
5-5 of Pig.. 4.
DETAILED DESCRIPTION OP TE~E PR$FER~ EMBODrMENT
1 5
With reference to the embodiment of the
invention illustrated in Figs 1 through 3 of the
drawings, the numeral lO indicates gene~ally a
fireplace insert which comprises a firebox identified
genexally by numeral 12, an air casing or shroud
identified generally by numeral 14 surrounding the
firebox on all three sides and t~e top, and a
~lared front hood indicated by numeral 16 mounted to
the shroud 14 and providing the means for input and
output air as more fully descrîbed hereinafter.
~ he firebox 12 is preferably made from
welded metal pieces, but could be cast, ir desiredi
and includes ceramic fire brick, preferably of about
two-inch thickness on the floor, indicated by the
numeral 18, ànd split ~ire brick of abou-t one and
three~eighths inch thickness around the sides and
back, indicatea by numeral 20. The ceramic fire
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brick of t~o inches in the floor is sufficient so
that no heat is transfer~ed down through the Eloor
into the base, and h.ence t:he shroud 14 surrounds
only the sides and the top and thereby operates in an
extremely efficient manner in transferring heat
generated from within the firebox, as deiined herein-
after.
A ~eature of the invention is the
damper indicated generally by numexal 22 which has
a direc~ and sealed communication to the top rear
of the firebox through a substantially rectangularly
shaped opening as seen best in ~ig. 3 of the drawings.
The damper plate 24 is pivotally mounted on pins 26
so as to be actuated in pivotal ~ovement by lever
arm 28 fixedly ~ounted to one side thereo~ and pivotally
receiving rod 30 which is connected th~ough the
front o~ ~hroud 16 to an actuating kno~ 32 so that
a simple straightforward push or pull of knob 32
will cause pi~otal action of the damper plate 24
around pins 26 to effectively op~ or close the
damper. It has been found that it is most efficient
to operate the fireplace insert with the damper
~ery nearly closed so that only about four square
inches of damper area, as opp~sed to a normal
approximate llO square inches of damper iII a standard
thirty-six inch ~ireplace r will be capable of allo~-
ing approxLmately 40 pounds of hard ~ood to completely
~urn up o~er an eight~hourperiod, pro~iding a heat
output of 38l850 BTU at this reduced four-square inch
damper openi~g position~ As indicated above, the
damper housing identi~ied by numeral 22a is connected
in sealed relation~ip at 22~ to the firebox 12~ and
likewise pa~ses in sealed rel~tîonship throu~h the
shroud 14 so as to provide a direct and sealed com-
munication ~rom the firebox throu~h th~ damper, and
hence into the chimney wh.ell the fireplace insert is
appropriately positioned into the fireplace for use
as will be descrihed h.erei.nafter.
A further import:ant ~eature o~ the in~ention
i~ in the flared front hood 15 wherein, as ~est seen
in the top plan view o~ Fi.g~ 3, the siaes of the
front hood extend at approximately a 62~ angle towards
each other, indicated ~y numeral 17, to create a very
pleasing aesthetic appearance in the room, as well as
proYiding larger side face su~iaces 16a and 16b, which
achieve a larger surface area to e~fect heat transfer,
and also to att~in a cooled relationship on these
surfaces, thus enhancing the safety feature of the
insert to prevent ~urning of any one or anything
coming into contact with.these sur~aces 16a and 16b
during the use of the fireplace insert. The flaring
oE face surfaces 16a and 16b also then results in
large flat side surfaces 16c, d, and e, on the side
and top portions outside the shroud 14, all as best
seen in Fig~ 3~ Th.ese flat surfaces 16c, d, and e,
: 25 cooperate with a recessed relationship of the shroud
14 at the sides, as indicated at 14a and 14h in Fig~
3 so that fiberglass-type insulation 30 can be in-
serted into the recess provided there~y and stay in
position to allo~ a co~pressed fluid seal when the
fireplace insert is pos~tioned into the fireplace.
The same recessed rela~ionship i5 provided along the
top edge of the shroud 16 to receive the -Eiherglass
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seal skrip aa i~ ~hown on the sides 14a and 14b in
Fig. 3, Hence, the fiberglass strip 30 extends con-
tinuously around the sides and top to ~orm a continu-
ous perimeter ~etween the faces 16c, d, and e, and
the face o~ the fireplace as t~e insert 10 is pushed
into the fixeplace. Preferably, the flared front
hood provides that the suraces 16c, d, and e will
be four to six inches long so that a large flush com-
pres~e~ relationship of the ~i~erglass 30 is achieved
between the ~ace of the fireplace and the recessed
relationship defined with the edges 16c, d, and e and
the recessed surfaces 14a and 14~ of the shroud. This
~luid-sealed relationship of the hood 16 to the ~ire-
place face is extremely important so that no cold air
leaks down the fireplace and into the room, and
further so that no warm air ~rom the room leaks past
the fireplace insert and up the chLmney, as it will
tend to be drawn by the hot gases leaving the flue 22
wh~n a fire is burning .in the fire~ox 12, and this
structural arrangement very effectively achieves this
desired result, particularly when the fi~erglass
~aterial 30 is pre.~erably at least four inches t~ick
and is very compressed as the insert 10 is positioned
into the fireplace~ The large four to six-inch over-
hang ensures that the proper seal is achieYed evenwith variable widths and heights of the ~ireplace
opening, and e~en against irregular brick or stone
faces.
~ ~urther structural ~eature o~ the hood 16
is the provision of the inlet cold air ports indicated
generally ~y numerals 32,34 on the lower s~des of
the hoodO These inlets are provided of such size so
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as to receiye ~ ~mall electric motor and fan thereinto,
hence enhancing the forced circulation o air as
desired. The hood 16 has a series o~ outlet holes
indicated generally ~y numeral 36 along the top edge,
and al50 has a top pro;ection 16f extending out to
provide a pleasing appearance and further to receive
the rod 30 in sliding relationship for support there-
throug~, which is open, and allows t~e dlscharge of
hot air being circulated around the firebo~ in a
manner more fully described hereinafter.
The structuxe of the ~ireplace insert
design is then completed ~y having a ~orwardly pro-
~ecting hearth sill ox bottom plate 40, and two support
legs 42 in the rear which are vertically adjustable
so as to allow the positioning o~ the fireplace in
exactly horizontal relationship after it has been
pushed into final position in the ~ireplace, The
legs 42 can be reached by a screwdriver from inside
the fire~ox upon simple re~oYal of a few of the fire
brick, and then screwed up or down to obtain the
proper horizontal level. Pre~erably/ the hearth sill
40 is about three-ei~hths inch lower than the bottom
of the ~irebox 12, and hence the legs 42 will have to
be adjusted downwardly to obtain the proper horizontal
level. Hence, the fireplace insert 10, when fully in
position, is supported on the hearth sill 40 along
the full front edge and then on the two legs 42 at
the rear, normally being fully pushed into position
so as to compress the fiberglass as described above
around the full perimeter of the hood so as to seal
the brick and stone joints normally associated with
the face of the fireplace.
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Th~ ~ire~Qx 12, of course, has an opening
on the front thereo~ and a door ~ndicated genexally
by numeral 50 i~ pro~ided which is hinged a-t 52 and
has a handle 54 and three glass opening~ The door
is designed to provide a sealed a~r~t~ht relationship
with the firebox, and thi~ is provided as best
seen in Figs. 4 and 5, wherein a ~e~d of asbestos
braiding 56 extends around the full outsîde perimeter
on the inside sur~ace of the door SO so that when the
door is positioned and t~e handle latched, there is
a pressure seal on the asbestos ~raid 56 around the
full perimeter to obtain a fluid-~tight closure.
Similarly~ as indicated in Fig~ 5, as~estos braids
60 are pro~ided around the ~ull perimeter of the
glass 60 as held in place ~y the frame so that there
is no air leakage around the glass in t~e door 50,
either.
As a decorative ~eature, the ~ace of the
~irebox ma~ ha~e colored tile.s indicated generally
by numeral 70 as best seen in Fig. 1, adhesively
secured thereto~ A further decorative ~eature is
to add a dummy-brass knob 32a at a ~alanced opposite
position rom knob 32.
The essential air flow of the in~ention
is depicted primarily in Fig~ 2 which indicates
input cold air throu~h the opening 32 ~hich prefera-
bly will have a grill work of s~me type thereon,
as shown by arrow 8Q, thence primarily deflected
down and along the backsides bet~een the shroud 14
3Q and the firebox 12 as depicted by arrows 8Qa and 80b,
and achie~ed by a deflection baffle 82 extending
--10~
from the opening 32 to deflect the air as indicated.
In this connection, an important feature of the
invention is that there ic; a small open space 84
between the structure surrounding the opening 32 and
the ~a~fle 82 which allowc, a ~nall portion of the
input air to pass up and along the inside surface of
the side portions of hood 16 so as to effect a cooling
thereof and prevent any person or thing from being
burnt by coming into contact with th~s portion of the
hood.
The air then, by the time it passes at
about the position of arrow 80b, is directed upwardly
along the back o the firebox, around the openings
to either side of the damper 22, as indicated b~
arrow 80c, along the top o the fire~ox at 80d, and
thence either up and out the openings 36 as indicated
by arrow 8Oe, or down and out through the extension
16f of hood 16 as indicated ~y arrow 80f~ Naturally,
because there is a large opening after the air passes
beneath baffle 82 as indicated by arrow 80~ between
the firebox 12 and the shroud 14, some air can and
will pass along the side walls and up towards the
position of arrow 80d and 80e, without extendi~g
clear around the back and up to the position of arrow
80c. Thus, it should be clearly understood that all
uniform amounts of cold air pas~ing around the fully
exposed surface of firebox 12 to effect the most
efficient of this air flow will in effect ha~a the
desired result of hea~ transfer from the firebox 12
to the air w~ich is being discharged back into the
room at 80e and 80fo
3~
As a urther enhancement to the air heat
exchan~e. characteristics of the fireplace insert,
it is extremely des~rable to include a s~eral inch
thick layer of insula-tion around the full~ exposed
surface of the air shroud 14, th.is îndicated generally
by numeral 90 in Figs. 2 and 3. Preferably, this will
be fiberglass insulation with an outer aluminum facing.
It should be understood -that an important
feature of the invention is that the portion of the
lQ fireplace insert extending into the room is 40 to 50
percent of the total depth of the fîreplacer as is
evident from viewing Figs. 2 and 3 of the drawings,
thus ensuring a natural air flow input from the room
to openings 32, and hence a natural air flow around
the firebox because of the larger portion ex~ending
into the room~ The basic design is for approximately
13 1/2 inches to be the depth e~tending into the
fireplace with 10 inches extending onto the fireplace
hearth in order to circulate the air most efficiently.
As best seen in Fig7 1, ~all controllable
opening combustion parts indicated by numeral 100
are incIuded just beldw the door 50.
The fireglass insulated twin wall con-
stru~tion hence is engineered to wo.rk on the principle
of convection with more rapid circulation being
achieved by utilizing the independent electric blowers
in the inlets 32 and 34. Hence~ the cold air drawn
into the bottom inlets 32 and 34 circulates through
the channels between the fire~Qx heat exchanger 12
3~ and the air shroud 14 so that warm air is forced
through the outlets at the top and ront of the hood,
or in opposite relationship to the inlets and back
into the room~
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By appropriately setting th.e damper, a
slo~, even burn will be achieved achieving much
¦ greater heat efficiency than a regular fireplace,
¦ while actually consuming less wood ~n the same amount
of tIme. Naturally, fireplace type glass is utilized
in the door, and the ceiling o the door and the
glass relatîve to the firebox prevents heated air
from being drawn back into t~e fire and keeps soot,
smoke, and sparks from blowing into the xo~m.
Because the ~ireplace insert is made
from heavy metal and utilizes the ire brick on the
floor and the ~ides, it is a hea~ unit that will
effectively remain in place once positîoned sLmply
by gravity, and will provide the seal around the
full periphery of the hood as defined above. It
should also again be stressed that the hood itself
will remain cool, at least relatively so/ whereby
it will not have enough temperature to burn anybody
or anything, even though a lar~e portion of the hood
is in an exposed relationship in the room.
~ hile in accordance with the patent
statutes only the best known Qmbodiment of the inven-
tion has been illustrated and descri~ed in detail,
it is to be particularly understood that -the invention
is not limited thereto ox thereby, but that the
inventive scope is defined in the appended claims.
