Evaporation rate with concentrate

[Mark]

Does anyone have a rule of thumb on how the evaporation rate changes for lets say 20 brix sap? Just counting the evaporation and not draw off, how much would it slow down? Or would it slow down?

[Potters3]

evaporation rate will not change only the amount you have to evaporate to make a gallon of syrup and the thru put of the rig.

[DrTimPerkins]

evaporation rate will not change only the amount you have to evaporate to make a gallon of syrup and the thru put of the rig.

That is correct. The boiling point elevation of 20 brix sap is only about 3.5 deg F, which isn't really enough to make any noticeable difference either way.

[Flat Lander Sugaring]

if i get this straight well see, yes to all above but you will process more sap an hour. because of more draws not that you rig will do more gph.
86/20= 4.3 to 1, so on my rig at 35gph I would make 8.1 gal syrup an hour. Fresh sap has to replace what you draw off so the actual total would be 44.1?
does this sound right?

[wiam]

That is the way I see it. Same evaporation. Draw more syrup

[DrTimPerkins]

if i get this straight well see, yes to all above but you will process more sap an hour. because of more draws not that you rig will do more gph.

Yes, that is correct. The amount of sap you will move through the rig will increase because of the higher draw-off rate (due to higher incoming sap concentation), but your evaporation rate will stay pretty much the same. So total system processing rate (gal of sap fed into evaporator per hour) will increase, and total draw-off rate (gal syrup produced per hour) will increase, but total system evaporation rate (gals water evaporated per hour) will remain constant.