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VENTING '
Chimney Com lectors
and
Chimn,us
Draft
Draft is widely misunderstood.
It
is important
that you, the stove operator, realize that draft is a variable
effect, not a given quantity. Stoves and chimneys do not
have draft, yet draft is the key to your stove's perfor-
mance.
Draft is
aforce, produced by
an
operating stove
and the chimney to which
it
is attached.
It
is created by
hot
gases rising up the chimney, creating a pressure dif-
ference between the inside
of
your home and the outside
air.
It
continually moves fresh combustion air into the
stove, and hot exhaust gases out
of
the stove; without this
constant flow, the fire will go out.
Other factors, such as barometric pressure, winds,
the airtightness
of
the home, the total inside chimney vol-
ume, chimney height and the presence
of
venting devices
such as exhaust fans also play a role
in
maintaining an
adequate draft. Low barometric pressures, super insu-
lated homes and exhaust fans
can
reduce draft; winds
can play havoc with draft; and too large or too small a
chimney volume can cause reduced
draft
due to the excessive
cooling
or
not
enough
room
to
vent
exhaust gases
,j
Introducing outside air directly to the stove
may
help
remedy a low draft problem. Some signs
of
inadequate
draft are smoking, odor, difficulty in maintaining the fire,
and low heat output. Overdraft
can
be
caused
by
a very
tall chimney even
if
it is the recommended size, and
can
cause overfiring
of
your stove. Signs
of
an
overdraft
include rapid fuel consumption, inability to slow the fire,
and parts
of
the stove
or
chimney connector glowing red.
It
is important that you follow the chimney guidelines
in
this manual, including size, type, and height to avoid draft
problems.
When
installed and operated according to this
manual, the Oakwood will produce enough hot gases to
keep the chimney warm so that adequate draft is main-
tained throughout the
bum
cycle.
Chimney Connectors
In
general, following these guidelines will ensure
compliance with all national and provincial codes; prior to
beginning your installation, check with your local building
code official to check on additional local regulations which
may influence the design and placement
of
your venting
system.
The Harman Oakwood
may
be
installed with
(.6 mm) 24 gauge chimney connector pipe. Size
of
the
connector should correspond to the size
of
the flue collar
opening. Do not use makeshift compromises. No part
of
the chimney connector may pass through an attic
or
roof
space, closet
or
other concealed space,
or
through a floor
or ceiling. Whenever possible, avoid passing the
COnnec-
16 Oakwood Wood Stove
tor through a combustible wall;
if
you must, use an ap-
proved wall pass-through, described later in this section.
Assemble the connector beginning
at
the flue
collar, with the crimped ends pointing towards the stove
(to keep debris and creosote flakes inside the system).
Each joint, including the one to the stove's flue collar and
the
one
to
the chimney itself should
be
secured with
at
least three sheet metal screws. Screws may
be
a maxi-
mum
of
3 inches apart. A
1-114"
(30 mm) overlap is
required at each joint, including the flue collar attachment.
No more than two
90
degree elbows should be used,. and
the total length
of
connector should not exceed 10 feet (3
m). All horizontal runs
of
connector must have a mini-
mum
upward slope
of
114"(6 mm) per foot (20 rom per
weter).
Chimney connector should correspond to the size
of
the flue collar opening. Do
not
use makeshift compro-
mises. No part
of
the chimney connector may pass through
an attic or
roof
cemented in place with refractory ce-
ment.
For
details on the other three options, refer to the
most recent edition
of
the NFPA 211 code.
Wall Pass-througbs
Occasionally it is necessary to pass the chimney
connector through a combustible wall to reach the chim-
ney. Depending on your local building codes, and the
pertinent provincial
or
national codes, there are several
choices for accomplishing this safely. Before beginning
your installation, contact local officials, and also the chim-
ney COnnector and chimney manufacturer for specific re-
quirements.
Canada. Three methods are approved by the
Canadian Standards Association. The diagram shows
one method requiring an 18"
(450 rom) air space between
the connector and the wall.
It
allows use
of
one
or
two
covers as described
in
the diagram. The two other meth-
ods are described in detail in the current issue
of
CAN/
CSA B365, the national standard.
United States In the U.S., the national code is
NFPA 211. While many localities adopt this standard,
be
sure to check with local authorities before beginning your
installation.
The
NFPA (National Fire Protection Associa-
tion) permits four methods for passing through a combus-
tible wall. A commonly used method to pass through a
wall directly to a masonry chimney is to clear a minimum
12"(300 rom) around the entire chimney connector, and
fill
it
with brick masonry which is at least 3.5"(90 mm)
thick. A fireclay liner, minimum 3/8" (9 mm) wall thick-
ness must run through the brick wall to the chimney liner
(but not beyond the inner surface
of
the liner).
It
must be
cemented
in
place with refractory cement. This method
is illustrated.
For
details
on
the other three options, refer
to the most recent edition
of
the NFPA 211 code.
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