Combustion Process; User Controls - Vermont Castings 1920 Installation & Operating Manual

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, bathroom, 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 includes
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 seasonal circumstances.
D. Combustion Process
How the Aspen Works:
Combustion control is achieved in the Aspen through two
separate air delivery systems.
The primary air control lever, located at the left rear corner
of the stove, controls the amount of incoming primary air for
starting, maintaining, and reviving the fire. More air entering
the stove makes the fire burn hotter and faster, while less air
prolongs the burn at a lower heat level.
For the greatest air supply and maximum heat output (but
the shortest burn time), move the lever to the straight up (12
o'clock) position. For a fire that will last longer with less heat,
move the lever to the right. You can set the lever anywhere
in between the left and right extremes.
The Aspen features an automatic thermostat to ensure an
even heat output at any manual setting you select. As the
fuel burns, the thermostat reacts to the heat radiating from
the stove surface and, consequently, adjusts the air shutter
attached to it . As the fire intensity (and heat output) builds,
the thermostat slowly closes the air shutter, thereby restricting
incoming combustion air. As the fire intensity then wanes (and
heat output lessens), the thermostat responds and gradually
opens the air shutter which allows more combustion air to
again enliven the fire. This ebb and flow action functions
continuously to prolong the burn cycle until the fuel bed is
exhausted.
Another separate supply of oxygen is delivered to the upper
area of the firebox to support combustion of gases released
from the main fuel bed. This Secondary Air enters the stove
through two, unrestricted inlets and is heated while passing
through separate channels before being delivered through
three stainless steel multi-ported tubes located at the top of
the firebox.
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Vermont Castings • Aspen 1920 Owner's Manual_R32 • 08/17
Burn Only High-Quality Wood
THE ASPEN IS DESIGNED TO BURN NATURAL WOOD
ONLY; DO NOT BURN ANY OTHER FUELS.
You will enjoy the best results when burning wood that has
been adequately air-dried. Avoid burning "green" wood that
has not been properly seasoned. The wood should be no
longer than 16" (410 mm) in length, however, you will find
that shorter wood lengths ease refueling and promote the
most efficient combustion.
The best hardwood fuels include oak, maple, beech, ash,
and hickory that has been split, stacked, and air-dried outside
under cover for at least one year.
For areas that do not have a supply of hardwood, commonly
burned softwoods include tamarack, yellow pine, white pine,
Eastern red cedar, fir, and redwood. These too should be
properly dried.
Keep wood a safe distance from the heater and keep it out
of the areas around the heater used for refueling and ash
removal.
E. User Controls
Use the Air Control Setting that Works Best for You:
No single air control setting will be appropriate for every
situation. Settings will differ depending on the quality of the
fuel, the amount of heat desired, and how long you wish the
fire to burn.
The control setting also depends on your particular installation's
"draft," or the force that moves air from the stove up through
the chimney. Draft is affected by such things as the length,
type, and location of the chimney, local geography, nearby
obstructions, and other factors.
Too much draft may cause excessive temperatures in the
Aspen, and could even damage it. On the other hand, too
little draft can cause backpuffing into the room and/or the
"plugging" of the chimney.
How do you know if your draft is excessively high or low?
Symptoms of too much draft include an uncontrollable burn
or a glowing-red stove part. A sign of inadequate draft is
smoke leaking into the room through the stove or chimney
connector joints, low heat, and dirty glass.
In newer homes that are well-insulated and weather-tight,
poor draft may result from insufficient air in the house. In such
cases, a slightly opened window or door, near the stove on the
windward side of the house will provide the fresh air needed.
A more effective option for delivering ample combustion air
to the stove is to duct air directly from outdoors to the stove.
In fact, in some areas, provisions for outside combustion
air are required in all new construction. The optional Aspen
Outside Air Adapter #1897 is available from your dealer.
When you first begin using the stove, pay attention to the air
control settings. You will quickly find that a specific setting
will give you a fixed amount of heat. It may take some time
to determine the amount of heat and the length of burn you
should expect from various settings.
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