I have always added the defoamer right where the inflow of sap first enters the pan. From the float box sap (or in my case concentrate) flows in thru a tube, that tube then goes to the front of that section and finally enters the pan there. That is where the defoamer should be added. Until this past season I added it manually, but this season I got an automatic defoamer and I mounted it there, in the hood, directly above the spot where that tube ends and the sap enters the pan.
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.