To make a maple syrup evaporator, first gather all the necessary materials and tools, including cement blocks, mortar, and however many steam-table trays are desired. These trays will determine the dimensions of the evaporator. Create the foundation of the evaporator using the cement blocks and leaving space for the chimney. Use mortar to secure the blocks. Lay the steam-table trays so the lip rests on the cement blocks with wood underneath. Add a flue and chimney to the cement blocks.
The maple syrup evaporator must be constructed on a stretch of ground. The width of the maple syrup evaporator should be such that the lip of the steam-table tray rests on top of the foundation of cement blocks, while the height of the evaporator should be such that the trays are a foot above the ground. Determine the desired boiling capacity of the evaporator, and then divide that number by the maximum capacity of the chosen steam-table tray. Round this number up to get the number of steam-table trays needed for the evaporator. The length of the evaporator must be long enough to accommodate the number of steam-table trays needed to reach the desired boiling capacity.
Lay another cement block over the top of the chimney space, and insert the flue into this space. Construct the chimney around it. The flue should either open horizontally or be several inches above the ground so that it has enough space to funnel out smoke. Lay firewood beneath the trays to be lit on fire when the trays have maple syrup in them that is ready to be evaporated.