I did that too on my latest improvement about 3-4 years ago. Before that I made my own triple wall pipe, but my trusses were 9" away. When I built the sugarhouse I set that one truss at 32" O.C. for a 30" space. the 12" stack goes up dead center. I have a 1.5" ceramic insulation with the SS stack inside and a second SS outside, I then cut 1.5" deep slits at the bottom of the outer layer and bent them inward to cover the bottom edge of the insulation.
Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.