As a little back story, my family owned and operated a large sugar bush in Michigan's Upper Peninsula for many years. A good years production was generally between 8-12,000 US gallons. Most years saw between 25,000 and 33,000 taps all hooked to a vacuum system to bring the sap flow to the house.
An average tree on an average season will produce between 15-18 gallons of sap with no vacuum and 20-35 gallons under vacuum.
Amount of sap need to produce a gallon of syrup varies by sugar content of the sap. Generally a 2% sugar content is the figure most use. At 2%, it takes 40 gallon of sap to produce 1 gallon of syrup. % varies by time of year, type of trees and weather conditions. We have seen sugar content exceed 3.5%. Once it falls below about 1% (as the season nears it's end and the trees tire) it becomes unprofitable to continue production.
