Jimmy Brochtrup walks us through a typical manual draw-off cycle on his 2×4 Corsair with Hybrid Pan. He is using a 0 – 50 Maple Thermometer to monitor progress and a Murphy Cup with Hydrometer to verify his density.
THOUGHTS ON TEMPERATURE:
Maple Syrup is said to have a boiling point that is 7º higher than the boiling point of water. (That is why a maple thermometer is calibrated in boiling water.) But what is the exact boiling point of water? If you said 219ºF, you might be correct… Sometimes…. The boiling point actually fluctuates with barometric pressure. In fact, boiling points can change dramatically throughout a single day. For this reason, we use the maple thermometer to monitor progress, but we use the Murphy Cup and Hydrometer to verify our actual density. Jimmy demonstrates how he adapts to changes in barometric pressure.
THOUGHTS ON DENSITY:
We recommend drawing off your syrup either at perfect density or slightly over density. If your syrup is over-dense, you can very simply reclaim perfection by mixing in additional sap or distilled water. Voila! No extra boiling necessary! In contrast, if your syrup is under density, you would end up needing to boil it a second time on a stove top which results in a bit more work.
THOUGHTS ON ADDING WOOD DURING A DRAW OFF:
You will notice that opening the fire door will affect your temperature reading on the thermometer. Having the door open can slow the boil, causing the needle to dip. Once you have a good charge of wood in your firebox, the boil will return and your needle will climb again.
THOUGHTS ON DRAW OFF SPEED:
It is best to strive for long, controlled draw offs. This is because all the liquid you are drawing off needs to be replaced with incoming raw sap on the other end. Throttle your valve for slow, controlled draw offs. This will help you run your evaporator with smoother consistency and maintain proper depth throughout the system.