Harman Coal Stoker VF3000 - Manual (Page 10)

10
3-90-70741R13_05/13
Venting
Chimney Connectors and Chimneys
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
tightness 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 the 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
appliance will produce enough hot gases to keep the chimney
warm so that adequate draft is maintained throughout the
burn 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(s)
regarding any additional local requirements or regulations
which may influence the design and placement of your
venting system.
The VF3000 may be installed with (.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
components.
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.
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 maximum of 3 inches apart. A 1-1/4" (32
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 (3m) All horizontal runs of connector must have a
minimum upward slope of 1/4" per foot (20 mm per meter).
wall Pass-thrus
Occasionally it is necessary to pass the chimney connector
through a combustible wall to reach the chimney. 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 chimney connector and chimney
manufacturer for specific requirements.
Canada. Three methods are approved by the Canadian
Standards Association. The diagram shows one method
requiring an 18” (460 mm) air space between the connector
and the wall. It allows use of one or two covers as described
in the diagram. The other two 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 Association) 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”(305 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. For details on the other three options, refer to
the most recent edition of the NFPA 211 code.