2 things. Earlier you were asking or wondering about draw off frequency, just do it by temperature and don't try to time it. Actually back when I had a 2x6 I attended a seminar by Glen Goodrich and he said he draws continually. Yes his evaporator was far bigger, but I started doing continuous draws. As the temperature got to syrup, I cracked the draw off valve slightly. Early when I tried I was able to get 15-20 minute long trickle draws before I had to close the valve. In time I got better and a few times I got draws of 45-60 minutes. Then I graduated to a 3x8, the draws got longer. However after fighting getting an auto draw I finally got one, WOW, so much easier.
Cupola, they are easy to build. It's common to make them the same size as the evaporator. Just make them a little house on the roof with both sides openable and closeable, from below, at floor level.
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.