Modern Evaporator

Modern evaporators use a similar flat pan technology (flue pan) with the addition of short walls of metal extend up into the sap creating a maze of channels that would conducted heat from the bottom increasing the surface area allowing the sap to be heated even faster.

From placing hot rocks in the sap to a round kettle over a fire and then a flat pan and flue pan the process is the same we have just made improvements to be more efficient.