Refractory baffle insert for fireplace

There is disclosed a refractory baffle for use in a fireplace which dispenses, via apertures provided therein, preheated combustion air over the central combustion zone of the fireplace. The refractory material substantially avoids warpage, flame quenching and other limitations associated with metal baffles.

FIELD OF THE INVENTION 
The present invention relates to a fuel burning fireplace and more 
particularly to an improved baffle for use in such fireplaces. 
BACKGROUND OF THE INVENTION 
Generally speaking, hollow baffle structures are used in wood stoves and 
fireplaces to provide preheated combustion air. This provision reduces 
emissions and enhances combustion of the products within the stove or 
fireplace. 
Presently, metal baffles are used in the art. Although baffles composed of 
metal have utility, they are susceptible to warping from the heat and are 
believed to quench the flames which may cause an increased in emissions. 
The cost of replacement of an ineffective baffle as well as the potential 
for combustion product deposit within the chimney of a stove or fireplace 
indicate that a more effective arrangement is required. 
The prior art has provided several baffle structures, typical of which is 
illustrated in Canadian Patent Application Serial No. 2,001,309. This 
reference teaches a generally triangular hollow baffle composed of metal. 
Apertures are provided in a localized area of the baffle for directing 
preheated combustion air over the flames in the combustion area. There is 
no discussion or contemplation for the use of a refractory composition for 
the baffle. 
Canadian Patent Application Serial No. 2,004,553 discloses the use of a 
ceramic material of which the baffle is made. The combustion air is not 
preheated and dispensed through the baffle. The baffle is devoid of 
openings over its surface and thus cannot enhance combustion by the use of 
preheated air. 
Canadian Patent Application Serial No. 2,008,981 teaches a primarily 
mechanical arrangement for introducing preheated air into the path of 
solid fuel combustion residues. The arrangement includes metal parts and 
accordingly, may be susceptible to warpage. 
Further, Canadian Patent Application Serial No. 2,040,556 teaches a baffle 
including a heat exchanger, primarily composed of metal. The arrangement 
provides a tiered structure having an opening therein for the passage of 
preheated air. The unit may be susceptible to overheating the air to the 
point where the air is expanded too much to be effective. 
SUMMARY OF THE INVENTION 
One object of the present invention is to provide an improved baffle 
construction suitable for use in a fireplace. 
A further object of the present invention is to provide a baffle suitable 
for use in a fireplace, the fireplace having a central combustion zone and 
a first air inlet, the baffle comprising: 
a hollow body of refractory material having a first upper wall and a second 
lower wall, the walls being in spaced relation, an open end and a closed 
end; 
inlet means for receiving air from the first air inlet; 
the lower wall including at least one opening therethrough for passing air 
received in the inlet means through the lower wall and into the combustion 
zone. 
The baffle, being made of a refractory material substantially reduces the 
limitations associated with metal baffles, such as warping, overheating 
and emissions. 
As a further attendant feature, the baffle is lightweight. Reinforcements, 
e.g. stainless steel pins, may be added to impart additional strength when 
required. 
Suitable refractory materials for use in the baffle include, for example, 
aluminum and silicon containing refractory compositions. 
In an alternate embodiment, the baffle may be cast integrally with 
refractory walls and a base thus forming a central combustion zone with 
the baffle positioned above the combustion zone. 
Further, the baffle may be divided into separate compartments by partitions 
disposed internally of the baffle. 
The baffle may also be simply employed in retrofit applications. 
A further object of one embodiment of the present invention is to provide a 
fireplace for burning solid fuel comprising: 
a central combustion zone; 
a first air inlet for supplying air to the central combustion zone; 
an exhaust outlet for removal of combustion exhaust; 
a hollow baffle composed of a refractory material disposed above the 
central combustion zone, the baffle having inlet means in fluid 
communication with the first air inlet, a first upper wall and a second 
lower wall in spaced relation, an open end and closed end, the second 
lower wall including outlet means for passing air from within the baffle 
into the central combustion zone. 
Having thus generally described the invention, reference will now be made 
to the accompanying drawings illustrating preferred embodiments.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, FIG. 1 illustrates a side view of a 
fireplace 10 having chimney section 11 and a central combustion zone 12 
surrounded by an outer skin 13 or casting. Doors 14 and 16 provide for 
access to zone 12. A refractory lining is provided within zone 12 and 
includes a base 18 and sides 20 and 22. Disposed above the combustion zone 
12, there is included a baffle 24, shown in one embodiment in FIG. 1. 
The baffle 24 includes an upper wall 26 and a lower wall 28 in spaced 
relation and joined edges 30 and 32. Ends 34 and 36 are open such that 
baffle 24 is a hollow structure. Lower wall 28 includes a plurality of 
openings 37. The arrangement of the openings 37 is illustrated in FIG. 4. 
One or both of the open ends 34 and 36 receive combustion air from an air 
inlet 38 beneath base 18 of combustion zone 12. Air entering into inlet 38 
travels upwardly toward baffle 24 and more particularly, in the space 
between either or both of sides 20 and/or 22 and outer skin 13. The air 
may be partially heated during the course of travel. The air enters baffle 
24 as indicated above and is further heated prior to dispensing over the 
central combustion zone 12 via apertures 37. A partition 39 may be 
provided within the baffle 24 for additional strength or for dispensing 
air evenly to both sides of the central combustion zone 12. 
Turning to the baffle 24 in greater detail, successful results have been 
achieved by making the baffle of a refractory material rather than metals 
as previously proposed in the art. Refractory material for use in the 
baffle circumvents warping, overheating of the combustion air and 
significantly reduced flame quenching, all of which are pronounced when 
metal is employed. 
In a preferred form, the refractory compound comprises Plibrico.RTM. 
Plicast LWI 25. The refractory material typically contains a high 
percentage of Al.sub.2 O.sub.3 and SiO.sub.2 as well as Fe.sub.2 O.sub.3, 
TiO.sub.2, CaO, MgO and various other alkalies. The baffle composition has 
low coefficient of thermal conductivity which makes it attractive for long 
lasting use in the fireplace. Further materials may be mixed with the 
refractory composition to reduce brittleness, e.g. stainless steel 
needles. 
The refractory baffle has been found to be particularly effective in 
preventing overheating of the combustion air. Generally speaking, if 
combustion air becomes overheated, the same can become so expanded that it 
is no longer effective in enhancing combustion. 
FIG. 3 illustrates a side view of another embodiment in which common 
numerals from the previous embodiment denote similar elements. 
The embodiment illustrated in FIG. 3 provides a hollow baffle 24 having 
first, second and third staggered and tiered walls 40, 42 and 44 and an 
upper wall 46. Openings 48, 50 and 52 extend between walls 40, 42 and 44. 
The arrangement of the walls and apertures is shown more clearly in FIG. 
5. Air travelling through inlet 38 passes in the space between skin 13 and 
a back wall 54 of fireplace 10. 
An opening 56 in back wall 54 permits entry of the air within baffle 24. 
The air within baffle 24 is at least partially heated before being 
dispensed over the central combustion zone 12 through openings 48, 50 and 
52. 
By making use of the refractory baffle, the air dispensed into the central 
combustion zone assists in enhancing the combustion process which, in 
turn, results in a greater amount of heat being produced. Clearly, the 
refractory composition may be molded to provide a host of hollow baffle 
structures with two or more walls in spaced relation and the specific 
number and structure will vary with intended applications. Additionally, 
the baffle arrangements set forth herein may easily be employed in fluid 
fuel fireplaces, stoves, etc. 
Although embodiments of the invention have been described above, it is not 
limited thereto and it will be apparent to those skilled in the art that 
numerous modifications form part of the present invention insofar as they 
do not depart from the spirit, nature and scope of the claimed and 
described invention.