Need some pointers and critique for my Arch Design

[wmick]

The opening from the firebox into the angled flue portion is 8 1/4 inches which will drop to about 6 with the firebrick in place. That will angle down to about 2 inches or so at the far end. Does that sound about right?

Hi Dave- This is more of a question than advice... as I'm a newbie arch builder as well.. (built a 2x6 this past year)
I'm wondering... Why taper the back section at all, rather than keeping it at 2" (or less) for the entire length... drawing all the heat close to the pans for the full length ?

[82cabby]

That's an excellent question, especially when using a blower. I think it is to improve the draw. I did it that way because the vast majority of archs i have seen are like that. Maybe someone else can offer more info.

[berkshires]

One thing to consider: you have the back of your preheater right up tight against the flue. That'll help heat the sap a little bit, but it'll mean a lot of scorching. I'd consider at least building it so you can fit arch board or insulation along the top half of the preheater, or else just leave a small air gap between the preheater and the base stack, and you'll have much less scorching.

Gabe

[82cabby]

Good call! I'll pull that back an inch or so or build up that area so the stack starts above the preheater.