Lexington Forge SAVANNAHSSW40 Owner's Manual page 8

STOVE SET-UP
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.
8 63D4002