Vermont Casting 1610CE Manuel D’Utilisation

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they must turn, it leaves some pipe in the room for heat 
transfer, and it gives you long-term flexibility for install-
ing a different stove 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 exhaust enough to cause draft and 
creosote problems. With prefabricated chimney, bring it 
down to six to eight feet from the stove. With a masonry 
chimney, arrange the pipe so that it turns into the chim-
ney within eight feet of the stove. 

Each ‘airtight’ stove requires its own flue. If an airtight 
stove is vented to a flue that also serves an open fire-
place, or a leakier stove, it’s easier for the chimney draft 
to pull air in through those channels and performance of 
the stove suffers. Imagine a vacuum cleaner with a hole in 
the hose to understand the effect here. In some cases the 
other appliance can even cause a negative draft through 
the stove, and result in a dangerous draft reversal.

Creosote is a by-product of slow wood-burning. It’s an 
organic tar that can condense in the flue if it is present in 
the exhaust, slow-moving, and cools to less than 290°F 
(130°C). Condensed creosote is volatile, and can gener-
ate chimney fires if it gets hot enough. All the features that 
affect chimney draft also affect creosote condensation 
- so use whatever combination of installation features and 
operational steps that will encourage good draft and mini-
mize creosote production.
Because letting the exhaust cool off and slow down is one 
of the keys to creosote accumulation, it makes sense to 
line a chimney to match the stove’s outlet size, for safety 
reasons as well as performance.  Consult a qualified 
installer and check local and national codes for recom-
mended chimney sizing.

Even the best stove installation will not perform well with 
poor fuel. The best fuel is hardwood that has air-dried 12-
18 months. Softwood burns, but not as long as hardwood. 
‘Green’ wood has a lot of moisture in it; it will burn, but 
some of the heat potential is used to boil the extra mois-
ture from the wood. This reduces the amount of heat that 
reaches your home and can contribute to a creosote prob-
lem. There are moisture meters available for firewood; you 
can also judge your wood by its appearance and weight. If 
you get it green, lift a piece and get a sense of its weight; 
it can lose a third or more of its weight as it dries. Also look 
at the ends of a log; as it dries it shrinks and often cracks. 
The more weathered and cracked a piece is, the drier it is.       
Dry wood burns readily with a good chimney draft. But 
with modern stoves, wood can be too dry and too vola-
tile. Smoke and combustible gases can ‘gas out’ from the 
wood quickly and densely enough to overload the combus-
tion system. If you hear a rumbling or roaring noise (like a 

propane torch) from the stove, that is a sign that the stove 
is overfiring.

  

Back-puffing results when the fire produces volatile gases 
faster than the chimney draft pulls them out of the firebox. 
The gases back up in the firebox until they are concen-
trated enough and hot enough to ignite. If your stove back-
puffs, the stove needs to cool down. You should open the 
damper to let the smoke rise to the flue more quickly, allow 
more air into the firebox, avoid big loads of firewood and 
check that the wood moisture is not too low.

  

An easy way to test your chimney draft is to close the 
stove’s damper, wait a few minutes to let the airflow stabi-
lize, then see whether you can vary the strength of the fire 
by swinging the air control open and closed. Results are 
not always 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’s no change, then the draft isn’t strong enough 
yet to let you close the damper, and you’ll need to open it 
for awhile longer and manage the fire with the air inlet until 
the draft strengthens. If you keep track of your burning 
habits and relate them to their effects on the stove’s opera-
tion, you’ll be rewarded with good performance and a safe 
system.

 

Good draft also depends on a supply of air to the stove; 
a chimney can’t pull in more air than is available to it. 
Sluggish draft results when a house is tight enough to 
prevent the ready flow of air to the stove, or by competition 
between the stove and other equipment that sends indoor 
air outside - especially power-driven equipment like range 
hoods, clothes dryers, etc. If the chimney draws well with 
all other equipment turned off (or sealed, in the case of 
fireplaces and/or other stoves), then you simply need to 
be careful with timing the use of the other air consuming 
equipment. If you need to crack a nearby window or door 
to enable the chimney to flow well, it may be a good idea 
to install an outside-air intake to bring combustion air di-
rectly to the stove. An outside air kit is available to connect 
the stove directly to a source of outdoor combustion air.

In many cases, local or national codes require the installa-
tion of permanently open air vents, particularly with larger 
appliances (i.e. above 5 kW). Refer to these codes to 
determine specific requirements for your installation.

Wood-burning is an art rather than a science. Once the 
stove and chimney system are in place, you can only 
vary your technique, mostly your timing, to achieve good 
results. If you keep track of your burning habits and relate 
them to their effects on the stove’s operation, you’ll be 
rewarded with good performance and year of reliable heat-
ing.