DIYbanter - View Single Post

J Burns

On 10/23/14, 3:56 PM, wrote:
I live in NW Washington. It rains a lot here, 69 inches so far this year, so
my firewood never gets real dry. Consequently, it produces a lot of smoke.
Compounding the problem is the length of the chimney; the distance from the
top of the stove to the top of the chimney above the roof is almost 25 feet.
I clean the chimney at least once every year and sometimes twice. Opening
the stove door almost always allows some smoke to escape unless the fire is
really hot and often a really hot fire is not necessary. So I'm stuck with a
smoky house. Is there some way (mechanical or otherwise) of creating a good
draft when it's necessary to open the stove door?

I had a similar problem about 30 years ago. A hot fire worked, so I
knew adequate air was getting into the house.

The problem was that when the fire wasn't pulling much air, cold air
would flow down into the 8" flue. A balloon needs hot air to lift off,
and a chimney needs a "stack" of hot air to draw.

In a couple of minutes I bent some aluminum flashing into a sort of
dunce cap for the flue, reducing it from an 8" square (64 sq in) to a 3"
circle (7 sq in). Kind of like a hose nozzle.

That made the "muzzle velocity" 9 times faster, to keep cold air from
sneaking in. It was the start of a windy, rainy weekend, but that jury
rig stayed in place. There was plenty of draft with the stove door open
and a big fire, and there was still a draft after letting it burn low
for hours. Keeping the chimney warmer also reduced creosote and helped
warm the house.