bwsaunders

Agreed. It's hard for me to do things like this without clearer understanding. And because I don't build kilns very often, I'm definitely overthinking this. I'm sure it will be fine, I'll do the exit flue in a way that can be reduced, and the chimney such that the damper can control flow. I just get nervous thinking about a 9x4.5" chimney. It seems really small, but at the same time it's a small kiln.

Thanks for the follow-up. I've done a lot of reading since posting (Fred Olsen's The Kiln Book, Nils Lou's The Art of Firing , Mel Jacobsen's 21st Century Kilns, and even Kiln Construction by Joe Finch), and have also plugged in numbers from different kilns in the books and those I have access to locally. Unfortunately, there are no consistent ratios here. I love the idea of the double venturi as described by Nils Lou, but after running the numbers on his MTF kiln (that he uses as an example of a double venturi), I found the area increases after the entrance to the exit flue as follows: 31.5

I have a question regarding some theory I read in the text The Kiln Book. On page 78 of the 4th Edition, it states that: "At the point where the exit flues enter the chimney, they should be restricted so that the chimney cross section is larger than this flue area" In the diagram (3-11) beneath this, it shows decreasing the point of entry to the chimney by 25% (from 4 bricks to 3), coming from the kiln exit flue. What's the thought behind this? I'm happy to trust my elders, but I'd also like to know what the theory is. I'm curious how this decrease affects the fi