This is our goal - maple syrup. It takes 42 gallons of sap for a gallon of syrup. You're shooting for 66% sugar content.
Here's the unit we're using this year to boil.Mike Bell is on the right. Mike designed this arch ['arch' is what you call a sap boiling unit.] from a filing cabinet. He used a barrel stove kit [available at Menard's] and put a door on one end and a chimney on the other. The left side is where the fire goes. They built up the floor to ascend toward the chimney - pushing the heat up to where the sap pans go.
The chimney end.
You can see in the center of the photo the grate where the fire goes. They're using fire brick to line the ascent to the chimney at the other end.
The assembled arch with the pans in place. The chimney is at the left of this photo.
The fire end, packed and ready to burn.
This is Mike using a propane torch to dry out the wood and get the fire going. [It's been raining and raining and raining here....]
We heart fire!
Sap in the pans, ready to go. The darker stuff on the right has been boiled down some already. We put the new sap in the left and as things boil down, we move the sap to the right. The pan on the right will be syrup first.
Boil, boil, boil!
This is our starter pan. We heat the new sap up on this fire first before we put it in the pans. It speeds things up.
At the end of the day, we take the darkest stuff inside and finish boiling it on the stove. This is so fresh that it isn't filtered yet. Filter through cheese cloth or other food filters to get the ash out. It's prettier that way.