Tubing - longer drops not draining-how to fix?

[SevenCreeksSap]

Since this is my first year with gravity tubing, I'm not sure if this is how it usually works. I have a mainline running parallel with the hill and my lats going up, and the hill is steep, about 100 ft drop over 500 ft of distance. On this lat I have a couple of longer drops(20-25 ft) to pick up single trees. these drops run somewhat parallel with the hill like the main, but they all do drop at least some. They are tied in the "main" 5/16 lateral with tees.

It seems like at the tee, these longer drops dont drain into the lateral very well. They get full enough to sag and then wont drain right. Does the tee cause enough interference in the flow to cause a backup due to friction with the water? Like a miniscus bubble.
It seems like the downhill lines drain great.
Another question I have is does the inside get "slicker" as more sap passes through so it may get better, or does the tubing get slower with use? Is there a break in period on new tubing.

I know the answer is Vacuum but thats not in the cards in the near future. I guess I'd get better flow if I tied those in farther down hill on the lat but I'm about out of tubing. any other suggestions?

[danno]

You should be fine with the longer lats as long as you can keep them from drooping. Find a way to support them (side tie or support with branches) and they will drain. Ideally, you want good pitch. Even if they droop, the pressure from the tree extracting the sap will force the sap through a drooped lat, but ofcourse, tight and pitched is where you want to be.

[highroadsyrup]

If you have a long lat line with a tap or two on it, its going to have sap in it most of the time. With gravity you need some taps to create natural vac, fear not it will eventually get into your main. You may be tempted to vent the line....DON'T do it....been there and done that.

[maple flats]

You should not have tees joining laterals. Tees are just to add a drop for a tap into the lateral. Then just wait, the sap will get to the tank, any sap in the line adds natural vacuum if you have slope. Do not vent or try to drain it.

[Hop Kiln Road]

Nothing wrong with your initial setup. Couple of modifications to consider: angle the single tap laterals downhill more and use a Y connector. On a gravity system make use of all slope by lowering the laterals running up the hill off the mainline, this will also allow tapping lower on the trees. With this open winter the tapping area is probably going to be 18" to 24" off the ground which will produce more taphole pressure. Make sure your entire drop is above its lateral. Get the whole system as snug as possible. Use that slope!

[wiam]

You should not have tees joining laterals. Tees are just to add a drop for a tap into the lateral. Then just wait, the sap will get to the tank, any sap in the line adds natural vacuum if you have slope. Do not vent or try to drain it.

What Dave said. We are all looking for the most sap from our trees. Look around at what better producers are doing to get more sap and you will not see any of what we use to call "flying tees". You will never keep them tight. And you should not own a 5/16 Y.

[SevenCreeksSap]

Flying tees seems right. they're out there in the middle of a line. Learning for next year when I'll run more real mainline differently. Answwers my question about the lines not draining. I understand about not venting to get better vac, same principle as siphoning. if you break the water seal it doesnt work. guess I'll have to tweak for this season and improve next.