[Cob] wood stove

[Shannon C. Dealy]

On Wed, 25 Aug 2004 Raduazo at aol.com wrote:

[snip]
>     I am not too sure about that, consider this: Suppose you had a
> conventional stove with a conventional chimney, except you insert two T-connectors into
> the chimney at points A and B going up the chimney. Then you insert a line of
> pipes that goes from point A through a cob bench to point B by hooking in to
> the two T-s.
>     You start a fire in the conventional stove and it draws smoke up the
> chimney going through the A T-connector and the T-connector in the conventional
> way.
>     Then once the chimney is drawing well you insert a metal plate between
> points A and B completely blocking the direct path up the chimney.
>     Now in order for smoke to flow from A to B it must flow out the A
> T-connector, through the bench and back into the B T-connector to get up the chimney.
>     If this was a pot belly stove or one of those stoves where the chimney
> exits from the top of the stove it would be difficult to make the connections,
> but if it is a stove where the smoke exits out the back of the stove, I think
> this would be easily doable.
> Ed

Sorry, this won't get around the problem.  The "draw" created by a chimney
is a function of temperature and chimney height, doing as you suggest will
get the fire going and the chimney heated up which will create the draw,
then when you switch over to route the exhaust through the bench, nearly
all of the heat will be dumped into the bench (or at least that is the
intent if it is designed correctly), so the temperature of your
exhaust gases reaching the chimney will immediately drop to possibly under
100 degrees F. which will cool the chimney and result in a massive
reduction in the draw.  The only way to get around this is to make the
chimney taller and/or make your bench less efficient at extracting heat
from the exhaust gases (which kind of defeats the purpose).  The reason
the bench stove works is that the "chimney" (heat riser) is placed before
the bench and creates a draw (through the use of a short but very hot heat
riser/chimney) which is independent of how much heat the bench is able to
extract.

Shannon C. Dealy      |               DeaTech Research Inc.
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