How high is too high to tap a tree on lines?

[DrTimPerkins]

... whatever pressure is lost in the tree by moving the tap up the trunk will be gained in the tube by that same amount of sap pressure there. This assumes 3/16 lines that keep the sap in them.

Correct, but then you need to subtract frictional losses through the fittings and lines. 1 ft of sap theoretically equals 0.88 in Hg. In practice, it's usually less than that.

[DrTimPerkins]

... Dr Tim will point out that I lost sap potential.

No problem tapping up high if you need to do that to collect sap from certain trees or areas. It can alleviate the need to use sap ladders in some cases. Yes, the yield will be lower, but acceptable if this is the only way to do it or if the cost of doing it another way is prohibitive.

[johnallin]

No problem tapping up high if you need to do that to collect sap from certain trees or areas. It can alleviate the need to use sap ladders in some cases. Yes, the yield will be lower, but acceptable if this is the only way to do it or if the cost of doing it another way is prohibitive.

You can solve all the above with a Clear Press. Let the season begin…<grin>

[Pdiamond]

John, I think your clear press must be able to solve all kinds of problems. hehe

[MarquisVII]

Too high? Maybe, but some sap is better than no sap. Years ago I had one section where I had trees out beyond the end of my mainline that fell off in elevation. This was before I had vacuum on that section of my woods. I tapped high, even using an extension ladder in order to get the sap and tapping as high as 12-13' off the ground on the lowest trees.
Later I added vacuum on my lines and in that section I lowered the tap height along with changing from 5/16 laterals to 3/16 laterals. The sap flowed quite well while on 26-27" vacuum. Those lower areas were actually pulling sap from below the mainline. I was sold on 3/16 with vacuum.
My tests were not scientific by any stretch of the imagination, but I liked watching the sap flow uphill anywhere from 3' to 7' below the mainline.
I have no flow numbers and Dr Tim will point out that I lost sap potential. My way of thinking was that I was getting decent sap flow at a much lower cost in tubing and fittings than if I'd done it the best way.

Dave, are the 3/16 laterals the entire lateral, or is it: drop > 3/16 > 5/16 > mainline?

I have a nearly identical scenario. Only difference is I have no mainline so my Shurflo manifold has six tee'd off valves barbed to 5/16 sap lines. Ideally I would just extend to those lower trees by adding to two existing 5/16 lines that are only about 150-200ft with 12 taps each - and I was already on a ladder at the end of each of those. With my setup, what are your thoughts on adding a reducer on the end of the 5/16 lines and then running another 100ft or so of 3/16 at "normal" tapping height to reach another 10 taps per line?