this weekend, i decided to remake my flue which measures about 4 feet between the back of the kiln and the chimney. i made it this long so that the chimney would not pass through the roof.
shockingly....i had a design error in my damper slot (who me....not thinking ahead??) so i knew i had better tend to it now before it's december...(also..friends are coming to visit this month and he builds kilns for a living so i figured, might as well fix the most embarrassing elements, right?)
after a firing is complete, the kiln needs to be buttoned up so it can cool slowly which means the damper should completely block off the chimney so that the heat stays in the kiln. not so much with my design....i can't even tell you what i was thinking. it has about 1/2 inch gap on either side when it's fully in.in this picture...the damper is the black slot about 3 feet up from the ground. my camera battery charger is in limbo at the moment so i can't take a closer picture.
so the first two firings...after i reached temperature (usually sometime in the middle of the night) i would climb a ladder to the top of the stack and cover it with a piece of kaowool and a kiln shelf...dangerous business as the stack was burning hot. since i've added a couple of feet to my chimney, climbing is no longer an option..it's just too tall. the last 3 firings, i've just pushed the damper all the way in, plugged it with kaowool and hoped for the best.
i decided that the best remedy would be to deconstruct the flue and add a slot where i can drop in a kiln shelf that will completely block the channel.
since the flue was the last thing i made and didn't quite have all of the proper materials...it doesn't hurt my feelings to give it another go. the high refractory mortar that i made ( portland cement, sand, redart clay) hasn't held up that well...it is much better in the stack. i also used some commercial fireplace high temp mortar/crack seal but that isn't faring any better. i think that the 'good stuff' only comes in a 5 gallon bucket (which i don't need), but i will check today at the fireplace/masonry store.
i think i've got it figured out...it will still look a little 'homegrown' but that's how i roll. i'll update on how it functions as i usually only understand design flaws when something is in use.