3/16 vac question

[Mini_Maple_Men]

I have 4 runs of 3/16 down a nice steep grade. 3 or the 4 runs have 22+Lbs natural vac on them, one has around 8lbs? I went and checked all my taps and connections and have no leaks, this run only has 4 trees on it, is my lack of vac just due to not enough sap in the line to create vac? Thanks Lee

[BlueberryHill]

It could be not enough sap like you said. Or it could be a leak possibly. On 3/16 they dont hiss like on a vac pump. You have to look for lots of bubbles in the line and chase it up to where the bubbles are starting.

Oh, also could be a bad gauge or some sort of blockage somewhere

[DrTimPerkins]

I have 4 runs of 3/16 down a nice steep grade. 3 or the 4 runs have 22+Lbs natural vac on them, one has around 8lbs? I went and checked all my taps and connections and have no leaks, this run only has 4 trees on it, is my lack of vac just due to not enough sap in the line to create vac? Thanks Lee

Is the total elevation drop (height from the topmost tap to the end of the line going into the tank) on the line with low vacuum the same as the other three? If so, then you probably have a small leak somewhere. If you're only getting 8" vacuum, go up the line in elevation (not in horizontal distance) about 10' (from the height of the line going into the tank) and look above there a little bit. Natural vacuum systems are very intolerant of leaks compared to pumped systems.

Could be a bad gauge too....try swapping gauges or putting a new one on that line (but you'll have to wait for the vacuum to build back up again).

[eustis22]

wait, there's not supposed to be bubbles?

[Woodsrover]

The gauge is the key. 8" may be a leak or it may be the lack of sap in the line.

Yes, there are bubbles...More at the top than the bottom but there are bubbles. By the time the sap flows past the last drop the bubbles are pretty much gone.

[dbeitz1891]

You should see some bubbles moving due to the natural gasses released by the tree. I would check for a plug somewhere in your line, right at a T or inside of 1. Look at every drop and see if you have sap moving on side quicker compared to the other. May have a slight blockage inside the T to where it's only pulling from that drop and none above. I've ran into a few of these problems with 680 on 3/16