We had out 4,000 taps this year and averaged .4gpt syrup and 27 gpt sap. approximately 1,000 aare reds mixed in with the sugars. Vacuum levels stay around 24". In the small woods behind our house,about 100 taps 98% reds, we used to run gravity tubing and gave up on it because it rearely gave us enough sap to bother with. This year I retubed th woods, added vacuum and we ended up with 13 gpt. The vacuum we added was terrible. The bender releaser I was playing with would not cooperate and I was only able to maintain 11-13 inches vac on it. And only half the time did it have this vacuum on it. As soon as the releaser was half way to the dumping point the sap would start to back up in the mainline untill there was enough pressure to push through the chack valve and make the thing dump. I had bigger fish to fry than play with this little woods. So next year I will attack it again. So back to the point of this thread. I think that with at least moderate levels of vacuum you will produce a decent crop, gravity I don't think I wqould bother. Aslo on a side note. The sugar content of the small mostly red maple woods would be.1% less than the other big woods with higher vacuum adn mostly sugars.
shrunken producer, from 8,000 taps to 4,000 to 5800 to 9500 to 11,000 vac
5x16 woodchip fired evaporator with 5x10 max flue and 5x6 revolution front pan
CDL 20+ RO
Double 10"filterpress
sp-11, bb2, airtech L63, L160, L230 vac pumps
CDL low profile electric releaser
MES 8000 electric releaser
CDL 4000 tap mechanical releaser