Jeff & Melanie Boock on sat 7 aug 99
Hello all,
I am getting ready to build a hard brick downdraft salt/soda kiln
here in Minturn, CO (8000ft), and I have a couple of questions
regarding placement of cinderblock under the kiln floor, and chimney
height and diameter.
The kiln is 35cuft, and will be fired using natural gas, forced air.
Q1: I am using standard 8x8x16 block under two rows of brick
horizontally oriented(header course), plus one row vertically
oriented (rowlock course), which will give me 9.5" of hard brick on
top of the cinder block. I don't have any IFB's to incorporate into
the floor, hence the thickness I am using. Should I place the block
upright, or make channels under the kiln for circulation by using
them on their sides (for cooling)?
Q2: What kind of height and internal diameter do you think I need for
a downdraft kiln of this size at my altitude? Should I incorporate
venturi? How many and how much does the chimney need to contract to
create the Venturi effect?
Thanks in advance for tackling these questions for me.
Jeff
Mason Batchelder on tue 10 aug 99
All hardbrick is going to cost you $$$$TO FIRE. MY KILN HAS HARDBRICK floor
2x deep on transite over cement blocks all aligned so they are open on the
right and left sides if you face the kiln opening. i used soft 2600s on the
inner walls and arch 2X AGAIN sanded the arch bricks to size after cutting
the rough shapes with a skill saw.the bagwall is not in my kiln I use a
target brick on the flame path 2/3 way from back wall.the chimney is
hardbrick and is only a couple courses above the arch due to forced air
blower burners.the whole kiln is built on a 5"THICK REBAR REINFORCED CONCRETE
SLAB CURED DRY AND ON A BED OF 4" sand.the kiln has a lower and top(AT THE
HARD SKEW BRICK ) horizontal channel iron bolted to corner vertical angle
iron the top of the angle iron extends a foot above the roof arch and is held
together with heavy welded link chain on hardened s's. I have, in the back
of the kiln, two low back ports at floor level and 2 higher ports if ever
needed and for viewing. The damper is a kiln shelf (BROKEN ONE WORKS IF OVER
1/2) on top of the chimney. The door is stacked soft brick and has sides tied
to the back to frame the opening. I leave openings in the door with removable
brick for the viewing and to adjust reduction if needed. I designed the kiln
around 12" x 24'' SHELVES 36" wide 3 shelves deep so 36" deep flush to back
and front bricked door. The sides have 1/2 brick wide ports with the already
mentioned target hardbrick.I put kaowool blanket over the arch and topped it
with a sheet of transite and it sits outside. A tarp is in order if you have
snow or a bad rain prior to a firing expected and if you can build a shed
over it all the better but i never did. I found it fires very evenly the
inside height to the top of the arch is close to 5".
Margaret Arial
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