In Table 1 we have included eight different means of processing sap to syrup. The wood-fired and oil-fired evaporators are basic means of boiling sap. The sap pre-heater increases the efficiency of boiling sap, by recycling steam from the evaporator to warm the fresh sap. The piggyback (steam-enhanced) unit uses both recycled steam and forced air to warm and concentrate the sap before it enters the evaporator. The reverse osmosis, freeze concentration, vacuum evaporator, and vapor compression evaporator use different means to concentrate the sap before it enters the evaporator.

All of these systems have been created by maple producers who enjoyed designing and experimenting with new ways of processing sap. Even today, some of these systems, such as freeze concentration, are still experimental and not commercially available. If you get an opportunity to visit maple producers, you may find some who have designed other systems to recycle steam and increase efficiency. And you may be able to come up with new ways of increasing the efficiency of producing syrup from sap.

We have included "functional" designs of the different systems to help you understand the overall process of syrup production. We also hope these designs will get you thinking about other energy-efficient systems to produce syrup from sap.

For detailed designs of the different evaporators, contact the manufacturers or access the U.S. Patent Office web page.