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Madison Woodburning Stove
30001453
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 an open fireplace or another
appliance, the draft will also pull air in through those
avenues. The additional air flow will lower flue tem-
peratures, 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
appliance can even impose a negative draft and result
in a dangerous draft reversal.
Fuel
Even the best stove installation will not perform well if
poor fuel is used. If available, always use hardwood
that has been air-dried (‘seasoned’) 12-18 months.
Softwood burns more rapidly than hardwood and has a
high resin content conducive to creosote production.
Decayed wood of any type has little heat value and
should not be used.
All unseasoned (‘green’) wood has a high moisture
content. Much of its heat value will be used to evapo-
rate moisture before the wood can burn. This signifi-
cantly reduces not only the amount of energy available
to warm your home, but also the intensity of the fire
and temperature 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
appearance and weight or use a commercially avail-
able moisture meter for an exact measurement.
Unseasoned 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, the dryer the wood is.
Purchase your fuel from a reputable dealer.
Creosote
Creosote is a by-product of low-temperature stove
operations, weak draft or both. It is a tar that results
when unburned gases condense inside the flue system
at temperatures below 290°F. Creosote is volatile and
can generate 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
chimney design and the use of operational techniques
that encourage good draft and complete combustion.
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 is generating more. Volatile gases
build up within the firebox until reaching a density and
temperature at which they ignite. With this ignition, you
may hear a muffled popping sound and see a bit of
smoke forced out of the air inlets.
This condition is most likely to occur in the spring or fall
when moderate outdoor temperatures and low intensity
fires combine to inhibit draft strength. If your stove
backpuffs, 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.
Negative Pressure
Good draft also depends on a sufficient supply of air to
the stove. The chimney cannot pull more air than is
available. 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, bath-
room, etc. If the chimney draws well when all such
equipment is turned off (or sealed, in the case of the
fireplaces and/or other stoves), you simply need to be
attentive in timing the use of the other appliances. If
you need to crack a nearby window or door to enable
the chimney to pull well, you should install an outside-
air intake to bring combustion air directly to the stove.
Consult your Vermont Castings dealer regarding an
adapter to attach to the stove to connect an air duct for
outdoor combustion air.
Conclusion
Woodburning is more an art than a science. Art in-
cludes technique and since installations, homes and
fuel vary, the stove operator must also vary technique,
(mostly timing), to achieve satisfying results. Over
time, you will become familiar with the intricacies and
nuances of your particular installation and you will be
able to identify cause and effect in a variety of sea-
sonal circumstances.