Dean on wed 17 sep 08
I had an Aim updraft in the same size range with a similar problem. I'd guess, as mentioned, you need more insulation, less secondary air (smaller inlet ports) and a damper on your exit flue. electric kilns are totally underinsulated for high-fire temperatures, only 2 1/2" thick with grooves reducing the thickness further. I'd fill all the element grooves with kaowool, wrap the outside with 1" kaowool blanket and secure it with aluminum flashing with stainless hose clamps screwed into it to secure the ends. fashion a piece of blanket to sit on the lid or lay a layer of softbrick on the lid and if you want to go all the way, add a layer of softbrick or fiber board under the bottom. this will triple your insulation. I've done this conversion on electric kilns too and cut my power use by about 30%. How do you tell if your kiln if your kiln is underinsulated? How much heat does it radiate? If it's so hot you can't touch it when its at ^06 you're losing the
major part of your heat. ^10 kilns have 9" of brick, who ever thought that 2 1/2" was enough? I can touch the outside wall of my 24' West Coast updraft at ^10 without getting burned. Anyway the other thing is forget the interior damper shelf and put a real damper on the exit flue so you can control the secondary air. Next time you fire, damp the kiln down till you start to get a little flame out of the top peephole and you'll know you're near a neutral, efficient atmosphere. You're probably firing in excessive oxidation now and wasting lots of gas.
blessings from Kauai