I had very similar until I made a hood. My hood was made out of aluminum flashing and pop riveted together. I bent it on a trim brake, but back when I was in the heating business at times I bent sheet metal (stiffer than aluminum) using 3 pieces of 2x4, 2 to clamp the sheet at the spot I wanted to bend it, and a third to bend it. My hood on my 2x6 took about 90 minutes to shape and then maybe an hour to pop rivet together, drilling each hole one at a time, riveting it then doing the next. I formed a gutter on the inside edge and at the corners I used silicone caulk to seal it. I then had a small fitting for a drain to a hose, it was just a male adapter but I used a nut on each side and sealed it with silicone. On a larger hood for my 3x8 I made it out of heavier sheet aluminum and used 1x1x1 channel for the gutter. If I were doing that again I'd get 1.5 x 1.5 x 1.5 channel.
On all of my hoods including my current manufactured hood with 2 @15" steam stacks, I have aluminum stack suspended from a SS rod in the cupola and it hangs down into the stack coming up. My current on is 13" hanging into the 15" stacks. Even with it like that I get no buildup of steam in the sugarhouse, even when there is a heavy fog outside and I get almost no dripping off the underside of the steel roofing. From time to time I can see a drip where it hit the floor but it's near zero drips.
I have the telescoping method because it allows me to hoist the hood by cranking on a small boat winch and the suspended stack simply allows the bigger stack to go up without any problems.
My cupola on my 3x8 boiling about 75-85 GPH is thus venting into and out of the cupola which is only 2' across by 6' long and which has a flip down door of 4'6" x 16" on each side. Even when I get a funky breeze and can only open one side it vents perfectly.
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.