using piggy backs

[Flatlander]

I have a question for piggy back users. When you are near finishing the boil, do you allow the piggy back to empty out into the flue pan or do you maintain a full level of raw sap in the piggy back?

I always drain mine down at the end of the boil cycle. I don't know if this affects the quality of syrup or not. I guess it may since the steam heat may "burn" any residue on the flues but I really never notice anything.

Your answers and methods are appreciated.

[JoeJ]

My 3 x 10 evaporator is oil fired, so when I shut off the burner, the only heat inside the fire chamber is the residual heat from the fire brick and steel. I always completely empty my steamaway. After using the Leader steamaway that I have for a few boils, I figured out that as soon as the last sap enters the steamaway float box, it is time to shut the burner off. I then let the remaining sap in the steamaway flow into the back pan to make sure that there is enough sap always covering the bottom of the back pan after any further evaporation from residual heat. I have not seen any problems with syrup quality caused by emptying the steamaway.

[Flatlander]

Thanks Joe. I don't add any wood once the level drops about 1/2 way. When the sap level drops out of the sight glass (I have about an inch and 1/2 left) I usually remove whatever coals I have in the fire box then draw off the sweet so it doesn't sit over the hot box the rest of the night. I know this ruins the gradient but I always figured it might be better for a lighter syrup in the end. Maybe not?

There is enough sap in the piggy back to cover the the removal of the sweet and to cover the remaining evaporation of the sap pan.