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Caternary Arch Brick Kiln Firing Unevenly- Help!


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I posted this question in another spot but maybe its own topic is better.

I have an old fashioned  28 cu ft caternary arch gas fired brick kiln. I have had to rebuild parts and now I have uneven firing. I am going to cone 6 and the centre fires to that before the top or bottom does. The top and bottom ports show the cones down at 4 only while in the middle 4, 5 & 6 are completely down. I though I had enough spaces in the bag walls and the floor but perhaps not? I am pretty sure I haven't blocked anything with the shelves. The heat goes up behind the bag walls & then down - downdraft thru the floor and out to the chimney. Help!!!!

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To help you I would like to know more about the interior space-like the dimensions  inside,the sheve layout the space under the floor (is the bottom shelve above the flue opening?-A photo would really help as well-is this propane or natural gas and is it natural draft or forced air.

Details are needed as the variables are many to fix this.Is this a soft brick or hard brick kiln or a fiber kiln?

Details please.

Mark 

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I'll take pictures in a day after it cools. Plus get the exact dimensions. But yes one of the shelves is at the back of the kiln about an inch off of the floor that leads to the flue. It is a hard brick kiln. 6 burner. Let you know the rest after I unload. thanks,

Terri

 

ok- tried to put my pictures in here and even selected smallest size thru pixlr but this program insists the file is too big!

However, I see after comparing my kiln to comments that the bag wall ends at about middle shelf height so I think that has to go higher. 

After the kiln was turned off, it soaked and the final cone results were 5 1/2 on the top, 6 in the middle and 4 on the bottom. I understand the bag walls needing to be higher but what about the lower shelves at 4? My stacking is very loose with wide spaces for large objects- nothing packed in tight. Should I space the floor bricks further apart and maybe put the sheves at the bottom up a bit higher, esp. at the back over the flue?

The  hard brick kiln is 44 inches from floor to arch, about 52 inches across the floor, and 35 inches from front to back. Bag walls are currently 23 inches tall but I will make them higher and move them in a bit in order to do this. Any more ideas about that 4 on the bottom?

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One of the things to consider is how the heat flows thru a kiln-where it can it will try to exit the fastest. Really a good design makes that flow stay in the kiln and move thru the load. The bag walls move the heat up and keeps it from going out the flue so to even the fire you need to consider flow and how its gets out.

Mark

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I have had several catenary Arch kilns. You probably need to adjust your stacking.

Send pictures of how you are stacking. Is the bag wall solid? Do you have target bricks?

Maybe move the target bricks up 1/4 of the distance and keep adjusting to find the right spot. How is the draught of the flu. Are you using a softer licking flame to circulate?

There are a lot of factors to consider.

 

 

Marcia

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You mention holes in the bag wall. Try making your bag wall a solid wall of bricks. Then you may have to raise or lower a row of bricks off the top. Sounds like the heat is just shooting across the middle.

If this doesn't work, try lowering your stack.

You have too much draft through the middle.

Where are you from? I see you spelled centre the correct way. :rolleyes:

TJR.

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