[Clayart] flue size, etc
mel jacobson via Clayart
Kiln building put me in a place to suggest a few things that worked well for both
Nils and me.
If you take the specs for kilns out of the Leach book, your stack would
Be 26 inches across and 30 feet high.
Nils had a great line, “if your kiln stalls, take off a foot of stack, or put on a foot of stack.”
I have several suggestions.
1. Make your stack tight. A ten-foot piece of spiral pipe about 10-12 inches round is fine for most home built kilns about 25 to 50 square feet. Line the pipe with Kaowool liners. Itc the pipe if you have it.
2. Build a tight hard brick fire box to support the stack. Make sure you follow code if you are going through a ceiling. From the outlet of the kiln to the outlet for the stack is about four feet or less. There is a great plan for that and a perfect size and place for the damper in our book.
3. Nils loved turbulence. He used the spec for size from my first kiln…about 35 square inches.
4. He repeated that size going into the stack. It was his deal and it worked, he called it a “double venturi system”.
5. Our theory was do not let more heat and “fumes” out of the kiln than you can put in. The entire system is made to keep the kiln rising in temperature. My take was “it is like pre-heating your home oven for a pizza to 420F, then leave the door to the oven open while cooking the pizza.”
6. my contribution to Nils’ book was based on weather, wind, snow and stacking.
June first, 82F, lite wind from the West. Clear sky. Perfect…The next time you fire you have a 30-mile-an-hour wind from the East and snow 10 inches deep. The kiln fires differently. If you have a set of dishes and 30 other pieces smashed into the kiln….you have trouble ahead. So much is about using good sense. Leave space around the pots, leave space between the shelves. Leave those pots out of the kiln that you were going to smash in there…
mel
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