Is Stack base funnel length critical ?

[West Mountain Maple]

I am thinking of making up a stack base and wondering if anyone knows if the length of the funnel itself is important for draft. Also, has anyone made one up welding heavier plate steel, like 3/16, would there problems with this?, seems like it would last a while. and opinions on using galvanized duct material for the base or the stack itself, I have a connection that can make it up but he says not to use it because of poison gas released when heated. Is galvanized stack material actually any different? Also, does the double the length of the evap in stack length rule apply no matter how long, does a 14' arch really need 28' of stack?

[wiam]

I would think that 3/16 would be overkill but should last.

Duct material is thinner than stove pipe.

Most stacks that are not stainless are galvanized.

Double the length means double the length.

[dgp219]

My old Ham-Nord arch from Quebec came with a plate steel base stack, the issue you will have is at the top. Mine has a constriction before going into a 9 in. pipe. I can't complain about its performance getting about 40 gpm evap. rate on a 2x8 with 4 ft. flue pan. I will NEVER need to replace it!

[Bucket Head]

They don't reccomend welding galvanized because of the fumes that come from it when its heated that high. Your stack/pipe won't get that hot. Will your rig have forced draft on it? If so, you could probably reduce the stack height some. The double the length thing goes way back to when natural draft was the only option. The height was required for good draft. They would also mount the arch up on concrete blocks so more draft air could reach the grates from underneath the unit. The ash cleanout/draft door was too small for good air intake. If your putting a fan on it for draft, your creating the draft that the long stack/raised arch provided. The stack on my arch is not double the length, and the first year I used it with the base stack thats on it now, I did'nt have any pipe over that! The base stack is about five feet long and the arch is six. My forced draft did just that- it forced it to burn well, regardless of the pipe length.

Steve

[Brian Kloepfer]

I made my base funnel out of 16 gage sheat stealI have one seasone use out of it and it still looks good. I paintes it black with hiegh heat grill paint. It is about 2 feet tall and it worked great on my 2X6 arch.

http://i584.photobucket.com/albums/ss287/bckloepfer/New%20arch/IMG_4980.jpg

http://i584.photobucket.com/albums/ss287/bckloepfer/New%20arch/IMG_4981.jpg

http://i584.photobucket.com/albums/ss287/bckloepfer/New%20arch/IMG_5246.jpg

[wiam]

That looks good Brian.