Harman Stove Company OAKLEAF 1-90-797000 - Manual (Page 13)

13 Dry Seasoned Wood Only!
Oakleaf Woodburning Stove
Save These Instructions 3-90-798_R9
5
Chimneys and venting
a. 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 performance.
Draft is a force, 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
difference 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
volume, 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 insulated 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. 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 Oakleaf will produce enough hot gases to keep the
chimney warm so that adequate draft is maintained
throughout the burn cycle.
B. 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 Oakleaf may be installed with a minimum
(.6 mm) 24 gauge chimney connector pipe. The 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 connector through a combustible wall; if you
must, use an approved wall pass-through, described
later in this section.
The Chimney Connector shall Not pass Through an attic or
roof space, Closet or similar Concealed space, a floor or
Ceiling.
Assemble the connector beginning at the flue collar,
with the crimped ends pointing towards the stove (to
keep debris or residue 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 maximum
of 3 inches apart. A 1-1/4" (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
minimum upward slope of 1/4"(6 mm) per foot (20 mm
per meter).
The chimney connector diameter 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 cemented in place with
refractory cement.
C. Wall pass-throughs
Depending on your local building codes, and the
pertinent provincial or national codes, there are several
choices for passing the chimney connector safely
through a wall. Before beginning your installation,
contact local officials, and also the chimney connector
and chimney manufacturer for specific requirements.
Canada. Three methods are approved by the Canadian
Standards Association. The diagram on the next page
shows one method requiring an 18"(450 mm) air space
between the connector and the wall. It allows use of
one or two covers as described in the diagram. The
two other methods 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 Agency) permits
four methods for passing through a combustible wall. A
commonly used method to pass through a wall directly
to a masonry chimney is to clear a minimum 12"(300
mm) 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 thickness
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 on the next page. For details on the other
three options, refer to the most recent edition of the
NFPA 211 code.