Vermont Casting 2461 사용자 설명서

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Your stove is only one part of a system that includes the 
chimney, the operator, the fuel, and the home. The other 
parts of the system will affect how well the stove works. 
When there is a good match between all the parts, the sys-
tem works well. 
Wood stove operation depends on natural (unforced) draft. 
Natural draft occurs when exhaust gas is hotter (and there-
fore lighter) than the outdoor air at the top of the chimney. 
The greater the temperature difference, the stronger the 
draft. As the hot exhaust gas rises out of the chimney, it 
generates suction that draws air into the stove for combus-
tion. A slow, lazy fire when the stove’s air inlets are fully 
open indicates a weak draft. A brisk fire, supported only by 
air entering the stove through the air inlets, indicates a good 
draft. The inlets are passive; they regulate how much air can 
enter the stove, but they don’t force air into it.
The efficiency of a modern woodburning appliance, (in which 
the amount of air available for combustion is regulated), 
depends on the chimney to keep exhaust gases warm all the 
way outdoors. The characteristics of your chimney - whether 
it is steel or masonry, interior or exterior, matched or mis-
matched to the stove outlet, - determine how quickly it will 
warm up and how well it will sustain the optimum tempera-
tures necessary to maintain strong draft and efficient com-
bustion. Here follows a description of various flue system 
characteristics and the related effects on stove performance.

Although masonry is the traditional material used for 
chimney construction, it can have distinct performance 
disadvantages when used to vent a controlled-combustion 
woodstove. 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. 

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 a masonry chimney; this makes the steel chimney 
support a good draft more quickly than masonry does. Steel 
chimneys are not as attractive as masonry, but they are very 
durable and generally outperform masonry. 

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 from 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.

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 vol-
ume. As gases cool with expansion, draft strength decreas-
es. If an 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 or masonry flue.

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 a 
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 stove top 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 appli-
ance 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 prob-
lems. Use double-wall stove pipe for longer runs.