Vermont Casting 2478 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 system works well. 
Wood stove operation depends on natural (unforced) 
draft. Natural draft occurs when exhaust gas is hotter 
(and therefore 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 combustion. 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 mismatched to the stove outlet, 
- determine how quickly it will warm up and how well 
it will sustain the optimum temperatures necessary to 
maintain strong draft and efficient combustion. Here fol-
lows 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-combus-
tion 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 volume. As gases cool 
with expansion, draft strength decreases. If an over-
sized 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 disappoint-
ing. 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 ex-
haust 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