Creosote is a product of the slightly incomplete process of wood
combustion. In a traditional fireplace the fire burns very completely
due to the large supply of available air for combustion. This
situation produces little creosote in the smoke. The flue is so
hot, the draft is so great, that most of the creosote is completely
out of the chimney before it condenses out of the flue gases. So it
gets deposited on new fallen snow, etc.
Airtight stoves have developed a terrible reputation about producing
creosote. Their method of controlling the fire by suffocating it
causes very incomplete combustion, and therefore a lot of creosote in
the smoke. If "secondary combustion" worked, the problem would
be reduced, but independent tests have established that "secondary
combustion" does not regularly occur in airtight products.
As more and more heat is removed from the flue gases, there is a
tendency for the creosote to condense out sooner, often in the
chimney. This forms a syrupy (when hot) or brittle (when cold)
black material on the inside surface of the chimney. This tends
to accumulate. If later a very hot fire is built in the stove,
the creosote can ignite (called thermiting) and burn very furiously
at up to 5000°F, a potentially dangerous situation if the
chimney system is not up to snuff. This is a common concern with
JUCA products reduce this problem by not suffocating the
fire (our products are NOT air-tight). As in an open fireplace, the
fire burns very completely so there is little creosote in the smoke.
This allows us to remove tremendous amounts of heat from the smoke
(thereby increasing overall efficiency) without a massive creosote
accumulation. Since there was little creosote in the smoke to begin
Of course, SOME creosote accumulation is bound to occur
with any wood burner. There are several ways to control the amount.
First, avoiding the use of "green" (wet) wood will minimize the
accumulation. Second, regularly the chimney should be checked and
cleaned if necessary. Third, use the fuel-limited mode of operation
(See your operator's manual for details). The smoke has a lot
less creosote in it in this mode, so less can condense out in the
There actually are some people that clean their chimneys by causing
a thermite. They apparently have great confidence in the structure
of their chimney. It is extremely dangerous to do this and we
DEFINITELY do not recommend it. Don't DO IT!
The total effect of this is that the JUCA generally produces much
slower creosote accumulation compared to airtight stoves.