Vermont Casting 2479 - Manual (Page 28)

28
Dutchwest Non-Catalytic Convection Heater
30002291
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. Chim-
ney 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 an open fireplace or another appliance,
the draft will also pull air in through those avenues.
The additional air flow will lower flue temperatures,
reduce draft strength and promote creosote develop-
ment; 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 appliance
can even impose a negative draft and result in a dan-
gerous draft reversal.
Fuel
Even the best stove installation will not perform well
with poor fuel. If available, always use hardwood that
has been air-dried (“seasoned”) 12-18 months. Soft-
wood burns more rapidly than hardwood and has a high
pitch content that can result in creosote. Decayed wood
of any type has little heat value and should not be used.
Unseasoned (‘green’) wood has a high moisture con-
tent. Much of its heat value will be used to evaporate
moisture before the wood can burn. This significantly
reduces the amount of energy available to warm your
home, as well as the intensity of the fire and tempera-
ture of the exhaust gas. Incomplete combustion and
cool flue temperatures promote creosote formation and
weak draft.
You can judge the moisture content of wood by its ap-
pearance and weight or use a commercially available
moisture meter for an exact measurement. Unsea-
soned wood will be a third heavier than dry wood. Also,
look for cracks (“checking”) in the ends of the log that
result from contraction as the wood dries. The longer
and wider the cracks are, the dryer the wood is.
Creosote
Creosote is a by-product of low-temperature stove
operation, weak draft, or both. It is a tar that results
when unburned gases condense inside the flue sys-
tem at temperatures below 290˚ F. Creosote is volatile
and can generate a chimney fire. All of the installation
characteristics that adversely affect chimney draft also
promote creosote condensation. Consequently, you can
minimize creosote accumulation with an effective chim-
ney design and the use of operational techniques that
encourage good draft and complete combustion.
Inspect your chimney frequently and clean it whenever
accumulation exceeds 1/4”.
Backpuffing
Backpuffing is a condition that results when the draft is
too weak to pull flue gases out of the chimney system
as fast as the fire generates them. Volatile gases build
up within the firebox until reaching a density and tem-
perature at which they ignite. With this ignition, you may
hear a muffled popping sound and see a bit of smoke
forced out of the stove.
This condition is most likely to occur in the Spring or
Fall when moderate outdoor temperatures and low
intensity fires produce weak draft. If your stove back-
puffs, open the damper to let the smoke rise to the flue
more quickly. Also, open the air inlets to induce a livelier
fire and speed airflow through the stove. Avoid large
loads of firewood at one time. You should always see
lively, dancing flames in the firebox; a lazy, smoky fire is
inefficient and will promote draft problems.
Draft Testing
An easy way to determine whether your chimney draft
is strong enough is to close the stove damper, wait a
few minutes to let the airflow stabilize, and then test
whether you can vary the strength of the fire by swing-
ing the air control open and closed. Results here are
not instant; you may need to wait a few minutes for a
change in the air control setting to have an effect on
the fire. If there is no change, the draft is not yet strong
enough to let you close the damper. You will need to
open it for a while longer and manage the fire with the
air inlet until the draft strengthens.
Keep a record of your operating habits and relate them
to their effects on the stove’s function. You’ll be reward-
ed with safe and efficient performance.
Negative Pressure
Good draft also depends on a sufficient supply of air
to the stove. The chimney can’t pull in more air than is
available to it. Sluggish draft can be caused by a house
that is tight enough to prevent the ready flow of air to
the stove, or by competition between the stove and
other appliances that vent indoor air to the outside; i.e.,
exhaust fans for range hoods, clothes dryers, bathroom
fans, etc.
If the chimney draws well when all such equipment is
turned off (or sealed, in the case of fireplaces and/or
other stoves), you need to be attentive in timing the use
of the other appliances. If you need to crack a nearby