How to Operate the Sapling Evaporator

November 6, 2017

Fortunately, operating the Sapling Evaporator, shown here in “experimental blue” is easy! Unfortunately, the experiment suggested we stick with black for now.

Technical poststhe sapling evaporator in bluetechnical posts, and more technical posts! Ask and ye shall receive, here at the Vermont Evaporator Company. This week, let’s talk about the basics of operating the Sapling Evaporator!

First, you’ve got to prepare your Sapling for use. Here’s how to do that:

  1. Remove the pan.
  2. Using shims and a two- or four-foot level, level your Sapling front to back and side to side.
  3. CAUTION: You must place a layer of sand and/or ashes in the bottom of your barrel to protect the metal from the intense heat. For added protection and to increase efficiency, you may also choose to line the inside of your barrel with fire brick or “half-brick,” available at your local hardware store. You can also aid air flow by putting an old grill grate in the bottom of your barrel first, before lining the sides and back with brick.
  4. Coat the exterior of the barrel with a thin layer of vegetable or olive oil.
  5. Replace the pan. Using your level, confirm that your pan is level front to back and side to side.
  6. Before you boil your first sap, you’ll want to remove any residual materials from the pan. To do so, prepare a solution of 10 gallons of water combined with 2 tablespoons of baking soda. Fill the pan to 2 or 3 inches with the solution. Start by building a small fire in the barrel and gradually build to a larger fire. We don’t recommend heating your Sapling to over 600 degrees (as measured just above the elbow at the exit pipe) at any time. You may want to use a magnetic stove thermometer to track your Sapling’s temperature throughout operation. Boil the solution for approximately 30 minutes, making sure the solution in the pan remains at approximately the 2-or 3-inch level by adding more solution, as needed.
  7. Check to see that there are no leaks at the fittings in the pan, that the pan is boiling evenly and that your valve is working properly. Check to see that your Sapling is drafting and venting correctly so that the smoke is generally only coming out through the stack.
  8. Allow the unit to cool, drain the pan, and rinse the pan thoroughly with clean water and dry.

Then, we sugar! CAUTION: you can never fire the Sapling without liquid in the pan or allow it to cool without liquid in the pan or the pan will burn through. Otherwise, the operation of the unit is relatively non-intimidating!  Here are the details:

  1. Add 2 inches of sap in the pan. This is about 5 gallons of sap.
  2. Start your fire.
  3. Get the sap boiling in all three chambers. This is easy to do by keeping your fire between 350 and 550 degrees as measured above the elbow on the exit pipe.
  4. After the sap has boiled down to half of its volume, gradually add more sap at the back, right corner of the pan until the sap level is back up to 2 inches. Continue to add sap at this location gradually as needed to keep the level at 2 inches.  Do this for several hours.  The Sapling will boil off 4 to 8 gallons of sap per hour depending on conditions and the skill level of the operator (we get better at this every year).
  5. There are a number of ways to tell if your syrup is “done.” The most sophisticated is to use an instrument called a syrup hydrometer to measure sugar content. Another is to measure temperature: syrup boils at about 7 degrees F above the boiling point of water (so, approximately 219 degrees F). Therefore, when the temperature of the liquid close to the exit valve measures 219 degrees F, you can draw off syrup (this will take several hours). The syrup should have an amber color and have the consistency of . . . syrup.
  6.  Get a clean container and place it under the valve exit.
  7. Open the valve and watch your exit temperature.
  8. If possible, simultaneously add fresh sap at the introduction location.  If not possible, add some before you draw off and some more after.
  9. Continue to draw off syrup until your exit temperature drops below 219°.  You will likely get less than a pint of finished syrup per draw.
  10. You may also choose to draw off a bit early into another pot or pan and “finish” on, for example, a propane burner outside, or on the kitchen stove inside, where it may be easier to control and monitor the temperature. Do not feel badly about choosing to go this route, especially at the beginning. Finishing on the Sapling requires practice and skill. You, too, will get better at this every year!
  11. At the end of your boiling day, draw off about a gallon of the sap closest to being syrup.  You can finish it as described above, or use it the next time you boil for a faster startup.
  12. Monitor your evaporator until the boiling stops and the fire has died out.

Extra Tips:

Don’t add too much new sap at one time, and try to maintain a constant boil. This will result in a more efficient process and lighter syrup.

To obtain high, even heat, use dry, mixed (hardwoods and softwoods) wood that is thinly split, and load often (every 5 to 15 minutes) with small amounts of wood to maintain a consistent level of heat.

Think you need more air flow to sustain optimal temperatures? Open the bung on the bottom of the back of the unit (if your unit has one) before you fire up next time – that might just help.

Yep! It’s that easy. Ready to try? 

Talk at you again next week!