I also can't find the origin of the name "arch", I googled it but only got a definition, not the origin. Potters3 is correct, but AOF (air over fire) is little more that that. The AOF blows down into the fire with a high pressure blower to mix in more oxygen for more complete combustion. Doing that gives you more heat under the pans and less wasted in or above the stack. That means faster boil using less wood. AOF will not likely be feasible for you until your addiction grows bigger.
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.