Side sap control tank
This is the side sap control tank on the evaporator. It is controlled using a float device. Once the sap that is almost syrup gets so low, then the tank's float goes up and allows more sap into the tank. On the left side of this picture you see a piece of steel that is hanging partially out of the tank. This piece of steel has a plug on the end of it, so that the person watching the process can take the plug out and let more sap / syrup into another compartment in the tank if need be.