Note: Descriptions are shown in the official language in which they were submitted.
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1 FIELD OF THE INVENTION
The present lnvention relates to a high performance
chimney generally made from a plurality of interlocking
chimney sections for use on solid fuel burning stoves,
fireplaces and the l;ke, capable of producing extremely
high exhaust temperatures.
BACKGROUND OF THE INVENTION
Over the last few years there has been a substantial
increase in the popularity of solid fuel burning stoves
and the like. A typical example is for use in cottages
where the stDves provide both heat to the cottage and a
surface for the cooking of food. In other cases, these
units are being used in family rooms and the like where
they both have functional and decorative features.
These solid fuel burning appliances are capable of
producing extremely high exhaust temperatures. For
example, with the burning of either wood or coal it is
not uncommon to produce a creosote fire directly within
the exhaust flue of a solid fuel burning stove. These
creosote fires which may burn at temperatures in excess
of ~000 degrees fahrenheit are extremely hard on
conventional exhaust flues due to the distortion caused
by the high temperature within the flue which generally
tends to buckle inwardly into the flue opening as a
result of expansion caused by the extreme heating. From
a safety standpoint this can be a severe drawback in that
it restricts the opening through the exhaust flue and
inhibits proper exhausting of the glue gases.
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1 A further consideration and concern is the overall
diameter of the exhaust flue. Typically conventional
exhaust flues for use on solld fuel burning stoves have a
Hall thickness of up to three inches which in combination
with a flue bore of for example eight inches, produces an
overall diameter of fourteen inches. This large diameter
makes the installation of the exhaust extremely awkward
through a wall or a ceiling where the supports are
typically spaced about sixteen inches from one another
having little room for clearance to either side of the
exhaust. In fact according to some testing
specifications of these high temperature chimneys there
should be a two inch clearance between the chimney and
any wooden surfaces through which the chimney extends.
Accordingly a conventional chimney having an outside
diameter of fourteen inches is not generally acceptable
for fitting through wooden supports spaced sixteen inches
from one another. Furthermore with conventional
insulated chimneys it is not merely a case of reducing
the thickness of the wall since the insulating ma-terial
presently available is not capable of providing adequate
insulating properties when reduced in thickness.
SUMMARY OF THE PRESENT INVENTION
The present invention provides a high performance
chimney which is generally made from chimney sections
with each section being adapted to withstand extreme
exhaust temperatures typical of those found on solid fuel
burning stoves and the like. Each chimney section has a
chimney wall defining a flue gas conduit, with the
chimney wall consisting of an inner metallic flue liner,
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1 an exterior wall cover and insulating material between
the flue liner and the exterior wall cover. According to
the present invention the flue liner is provided with a
first end which is located by guide means having a stop
surface for receiving the first end of the flue liner
with the guide means being deformable to allow clearance
of the first end past the stop surface of the guide means
as the chimney section is heated. This enables
longitudinal expansion for reducing radial distortion of
the flue liner when it is subjected to the extreme
exhaust temperatures.
According to a preferred embodiment of the present
invention the chimney section is insulated with a solid
pack insulation comprising a mixture of silica and an
expanded rock particle. With this particular insulation
the wall has a thickness of about one to two inches to
substantially reduce the overall diameter of the chimney
section relative to conventional chimneys.
BRIEF DISCUSSION OF THE DRAWINGS
The above as well as other advantages and features
of the present invention will be described in greater
detail according to the preferred embodiments of the
present invention in which:
Figure 1 is a perspective view looking down on a
section of a high performance chimney according to a
preferred embodiment of the present invention;
Figure 2 is a top view of the chimney section shown
in Figure l;
Figure 3 is a sectional view of the chimney section
shown in Figure l;
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1 Figure 4 is an enlarged sectional view of the
chimney wall region of two unheated coupled chimney
sections according a preferred embodiment of the present
invention;
Figure 5 is a view similar to Figure 4 with the
chimney sections being heated; and
Figure 6 is a further enlarged sectional view
through the wall of two coupled chimney sections when
unheated.
DETAILED DESCRIPTION ACCORDING TO THE PREFERRED EMBODIMENTS
Figure 1 shows a chimney section generally indicated
at 1. This chimney section is one which can be coupled
with other similar chimney sections for forming an entire
chimney for a wood or coal burning stove, a fireplace,
gas or oil heating appliances or any other type of device
having a heated exhaust. Although the chimney section
can easily be used with exhaust oF relatively low
temperature it is specifically adapted to withstand
extremely high exhaust temperatures. In fact, according
to United States UL 103HT and Canadian ULC S629 testing
requirements a chimney constructed from a plurality of
these chimney sections must be capable of withstanding
rigorous testing at various extreme exhaust -temperatures
for different durations without substantial internal
distortion.
Chimney section 1 which has a male end 3 and a
female end 5 for coupling with other like chimney
sections as well as other chimney fittings such as T and
elbow fittings and comprises a chimney wall generally
indicated at 9 in Figure 3. The chimney wall defines a
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1 central flue gas conduit 7 of for example six, seven or
eight inches depending upon the particular application
for which it is used.
Chimney wall 9 comprises an inner flue liner 11, an
outer wall cover 15 and insulating material 13 sandwiched
between the flue liner and the outer wall cover
Both the flue liner and the wall cover are
constructed of metallic material, preferably stainless
steel. Flue liner 11 has a thickness in the range of
eighteen to twenty four thousandths of an inch to make
the liner structurally stable while keeping the weight of
the liner at a reasonable level.
One of the main concerns with respect to prior art
structures is the maintaining of the structural integrity
of the flue liner as it is heated, particularly when
temperatures rise as high as those encountered in the
test specifications mentioned above. The problem arises
due to the expansion of the flue liner under severe
heating and in accordance with conventional practice the
flue liner tends to buckle inwardly into the flue opening
causing substantial distortion within the chimney section
and choking off the exhaust opening through the chimney.
The chimney section of the present invention is
specifically adapted to substantially overcome this
difficulty through the method of mounting the liner
within the chimney section.
ore specifically liner 11 is mounted in a manner to
allow its longitudinal expansion upon heating which
substantially reduces radial distortion which might
otherwise occur. The liner includes a first end lla at
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1 the male side of the chimney section and a second end llb
at the female side of the chimney section. End lla is
used for locating the liner in position while as best
seen in Figure 3, end llb is substantially free within
the chimney section. Also provided at the male end of
the chimney section is a chimney section cap 17 having an
axially projecting skirt portion 19. This skirt portion
terminates in a stepped region 21 interiorly of the flue
liner with this stepped portion providing a stop surface
for locating end lla within the chimney section during
assembly as shown in Figure 4. This located position of
the flue liner is maintained by a frictional engagement
between stepped portion 21 and end lla of the flue liner.
As the chimney section is heated all of the metallic
components have a tendency to graw due to thermal
expansion. This causes the skirt portion 19 to move
radially outwardly as it is heated and since the skirt
portion is secured at its upper end and free at its lower
end it expands outwardly by an increasing amount from the
secured to the free or stepped end of the skirt portion
as best seen in Figure 5. As the free end of the skirt
portion deflects outwardly it has a tendency to push
outwardly on end lla of the flue liner and at the same
time to angle the stop surface of the stepped portion
relative to the end of the flue liner. This provides a
cam effect which allows previously located end lla to
clear past the stop surface and expand longitudinally of
the chimney section as shown in Figure 5 whole it is also
expanding radially to further clear past the stop
surface. At the same time end llb of the flue liner is
1 allowed to move longitudinally of the flue liner due to
its substan-tially free floating within the chimney
section. Since the overall liner is allowed -to expand
leng-thwise there is very li-ttle -tendency to buckle
inwardly thereby substantially reducing radial distortion
of the flue liner.
In the event that the liner should become dislodged
within the chimney section a retaining ring 25 is
provided at the female end of the chimney section. This
retaining ring includes an inwardly extending shoulder 29
which is normally Free of end llb of the flue liner and
if necessary is adapted to engage a bead 12 running
around the flue liner as shown in Figure 3 should the
liner be released within the chimney section. For
purposes of easing the fitting of the retaining ring over
the flue liner end llb of the liner is fluted which
provides increased clearance between the flue liner and
the flange portion of the retaining ring.
For purposes of coupling similar chimney sections to
one another, as shown in Figure 6, cap 17 at the male end
of the chimney section is provided with a plurality of
teeth 23 around its outer edge while retaining ring 25 is
provided with a plurality of teeth 27 on its inner
surface. The cooperation of teeth 27 on the female end
of one chimney section with -teeth 23 of the male end of a
second chimney section provides a bayonette type locking
ac-tion between the two chimney sections as best seen in
Figure 6 of the drawings.
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1 It will be noted that the insulating ma-terial within
the chimney wall extends comple-tely to the male end of
each chimney section. Therefore when two or more chimney
sections are coupled with one another there is a
continuous wall of insulation material along the entire
length of the chimney even though the female end of each
section is uninsulated.
Referring in more detail to the chimney wall, it has
been found in the past that when using most conventional
insulating materials a wall thickness of over two inches
has been required to properly insulate a chimney in order
to pass the United States and Canadian test
specifications. Accordingly where the chimney has a flue
conduit size of eight inches and a wall thickness in
excess of two inches, the outside diameter of the chimney
is something over twelve inches. However, according to
the above tests, a specified clearance of typically two
inches should be provided around the entire chimney which
means that a chimney of an outside diameter of more than
twelve inches should not be fitted through a building
with supports spaced sixteen inches from one another as
is the case with most buildings.
According to the present invention the wall can be
reduced in thickness to two inches to pass Canadian
requirements and to about one inch to pass Unlted States
requirements, which are less strict, due -to the
construction of the chimney including a solid pack
insulation comprising a mixture of silica and expanded
rock particle. The weight of the insula-tion keeps each
chimney section, which may for example come in lengths of
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1 about three feet, within a very reasonable weight range
for purposes of do-it-yourself installations.
It will now be seen from the above that the chimney
section of the present invention is one which is
specifically adapted for use on devices producing a
heated exhaust with each chimney section of the overall
chimney being adapted to withstand extremely high
temperatures while remaining relatively free of
distortions within the chimney. Furthermore a chimney
which is constructed with chimney sections of the present
invention is one which has reduced overall diameter
relative to conventional chimneys and is therefore
suitable for installation in a standardized building
construction.
Although various preferred embodiments of the
present invention have been described herein in detail,
it will be appreciated by those skilled in the art, that
variations may be made thereto without departing from the
spirit of the invention or the scope of the appended
claims.
