8
20300058
VSW30 Series Wood Stove
STOVE SET-UP
NOTES ON ChIMNEY ANd STOVEPIPE INSU-
LATIONS:
Maintaining a clean chimney is important. Chimneys should
be inspected regularly for creosote buildup. A straight
chimney is easier to clean than one with 45 or 90 degree
bends. A bend requires the pipe to be removed for cleaning.
The stove baffle must be removed when cleaning the
chimney. Chimney sweepings will build up on top of baffle
causing a blocked flue and/or a fire hazard.
Steel Chimney
Most factory made “Class A” steel chimneys have a layer
of insulation around the inner flue. This insulation keeps
the smoke warm and protects the surrounding structure
from the high flue temperatures. Because the insulation is
less dense than masonry, the inner steel liner warms up
more quickly than masonry chimney; this makes the steel
chimney support a good draft more quickly than masonry
does.
Indoor/Outdoor Location
Because the chimney’s function is to keep the smoke
warm, it is best to locate it inside the house. This location
uses the house as insulation for the flue and allows some
radiant heat release form the flue into the home. Since an
interior chimney doesn’t continuously lose its heat to the
outdoors, less heat from the stove is required to get it warm
and keep it warm.
Flue Sizing
The flue size for a controlled-combustion appliance should
be based on the cross-sectional volume of the stove flue
outlet. In this case, more is definitely not better. Hot gases
lose heat through expansion; if a stove with a six-inch flue
collar (28 square inch area) is vented into a 10" x 10" flue,
the gases will expand to over three times their original
volume. As gases cool with expansion, draft strength
decreases. If the oversized flue is also outside the house,
the heat it absorbs will be conducted to the outdoor air and
the flue will remain relatively cool.
It is common for a masonry flue to be oversized for the
stove. Such a chimney can take quite a while to warm up,
and the stove performance will likely be disappointing. The
best solution to an oversize flue problem is the installation
of an insulated steel chimney liner of the same diameter
as the appliance flue outlet. The liner keeps the exhaust
gas warm and the result is a stronger draft. An uninsulated
liner is a second choice—although the liner will keep the
exhaust restricted to its original volume, the air around the
liner will require time and heat energy to warm up.
Check your local codes. You may be required to install a
flue liner in any oversize masonry flue.
Masonry Chimney
Although masonry is the traditional material used for
chimney construction, it can have distinct performance
disadvantages when used to vent a controlled combustion
wood stove. Masonry forms an effective “heat sink”—that
is, it absorbs and holds heat for long periods of time.
The large mass however, may take a long time to become
hot enough to sustain a strong draft. The larger the
chimney (in total mass) the longer it will take to warm up.
Cold masonry will actually cool exhaust gases enough
to diminish draft strength. This problem is worse if the
chimney is located outside the home or if the chimney
flue has a cross-sectional volume much larger than the
stove outlet.
Pipe and Chimney Layout
Every bend in the flue will act as a brake on the exhaust
as it flows from the firebox to the chimney cap. The ideal
pipe and chimney layout is straight up from the stove
through completely straight chimney. Use this layout if at
all possible, as it will promote optimum stove performance
and simplify maintenance.
If the stovepipe must elbow to enter a chimney, locate
the elbow about midway between the stovetop and the
chimney thimble. This configuration lets the smoke speed
up before it must turn, keeps some pipe in the room for
heat transfer, and allows long-term flexibility for installing
a different appliance without relocating the thimble. There
should be no more than eight feet of single-wall stove pipe
between the stove and a chimney. Longer runs can cool
the smoke enough to cause draft and creosote problems.
Use double-wall stove pipe for longer runs.
Single Venting
Your stove requires a dedicated flue. Do not connect the
stove to a flue used by any other appliance. Chimney
draft is a natural form of energy and follows the path of
least resistance. If the stove is vented to a flue that also
serves open replace or another appliance, the draft will
also pull air through those avenues.
The additional airflow will lower the flue temperatures,
reduce draft strength and promote creosote
development; overall stove performance will suffer.
The effect is similar to that of a vacuum cleaner with a
hole in the hose. In some extreme instances, the other
appliances can even impose a negative draft and result
in a dangerous draft reversal.
