3/16 Vacuum Mainline Pooling

[Sap Raider]

I have about 40 taps on a 1" mainline all with 3/16 laterals, and a second mainline with 180 taps this one has 5/16 laterals. Both mains come to the same location and have ladders to lift about 7 feet. The ladders are set up with 6 star on both. The ladder on the main with the 180 taps have five top and bottom. The main with the 40 taps has 2 stars top and bottom. Vacuum is between 25 and 27. The two star setup is not lifting the sap and the main can sometimes be full of sap. As an experiment I put 3/16 lines on the one the two star main line. Still doesn't lift very well, and the line can sometimes can be completely full. What can I try next. I can go back to the 5/16 lines on the stars, but it really didn't work before. The other main line seems to lift pretty well, so I am confused. I should add there is a micro leak at the very end of the two star main line.

[DrTimPerkins]

Two thoughts:

1. Your system is likely too tight. You need some air to help move the sap along. You may need to put a small leaker in get the sap moving.

2. You might need a few more stars added to the two-star line.

[maple flats]

About 30' before the sap ladders install a 1/8" needle valve for a controlled leak. It will give the sap an air bubble to ride up. It helps. You only need to open the valve until you see good action in the ladders. Do not over do it.

[Sap Raider]

So we did put a pin hole in the main and that seemed to the trick. You are right Dr. Tim very tight system. Thanks for the help.