3/16" on mechanical vacuum. Sap not moving..

[Austin351]

Got my three 3/16" lines up today (22 taps at 500', 16 taps at 350', 14 taps at 550'), hooked to a 4008 Shurflo pump. The 22 tap line was pulling well but the other two were not. I could see sap / air bubbles in them but were not moving.... Plugged T? Air leak in the manifold? etc?

Thoughts as to why the 2 lines were not pulling?

TIA

[VTnewguy]

Was the sap running well enough to fill the line? Was the pump on long enough to build up pressure? I would look for plugged Tee's and leaks for sure.

[Road's End]

Definitely look for a plugged T. Even without vacuum the line should be running... It's not hard to get a wood chip to plug a T on 3/16 line. I had multiple clogs on new lines last year. I've gotten a lot better at drilling clean holes so I haven't seen any issues this year.

[Ghs57]

I have something similar going on with a 3/16th gravity line. This line has about 25 taps and about a 20 foot drop. The vac gauge at the top reads 0", and there is no visible movement. The lines are full. The next line over has about the same number of taps, same drop, and is pulling 22". This line was running fine a week ago, even after I added half a dozen taps at the top. This line also had several breaks one day last week. The older tubing separated from a few of the couplings.

What's the best way to find a block? Break the line at various points, starting from the top, and observing the flow? If there is none from the uphill side, I would assume the block would be between me and the top. If it flows, it's between me and the bottom.

We are a bit froze up right now, but there was some movement on the other lines. The trees were definitely flowing in the cold sunshine today.

[mol1jb]

Its hardest to find leaks when trees are moving slow. Once flows increase leaks become more obvious.

[n8hutch]

Got my three 3/16" lines up today (22 taps at 500', 16 taps at 350', 14 taps at 550'), hooked to a 4008 Shurflo pump. The 22 tap line was pulling well but the other two were not. I could see sap / air bubbles in them but were not moving.... Plugged T? Air leak in the manifold? etc?

Thoughts as to why the 2 lines were not pulling?

TIA

I would guess that you have a Leak on the line that is moving good, the sap in your line should run slow and steady , next time it thaws pinch off the line that is flowing good and wait to see if your vacuum comes up or if the other lines start moving.

[Diesel Pro]

Austin,

If the trees are not ready they will not flow plain and simple. Mine did the same thing. I had to add a recirc loop to the pump to keep the diaphragms wet and even then I had vacuum with lots of air coming as the trees are just beginning to get rolling.


Ghs,

I am adding bleed valves at my vacuum gauges. Handy for venting and draining the end of the line after rinsing. In this case one could open the bleed and let some air in to see if this initiates flow or not. Alternatively pull the top end tap and use an air tank to give the line a boost then walk it and see if you can spot the floater(s) You may have to snip the line to drain the chunks unless you can pulverize with a mallet with the line against a tree or something. I had a partial block that I ended up draining.

[Austin351]

I am adding bleed valves at my vacuum gauges. Handy for venting and draining the end of the line after rinsing. In this case one could open the bleed and let some air in to see if this initiates flow or not.

Thanks for the responses. All three lines did flow yesterday but the 2 problem lines were creeping along, like maybe a foot per minute and most of the drops were approx.half full. Perhaps the trees just aren't giving up enough sap yet. This is the first try with a new 4008 pump and only saw about 5" on the long line gauge (don't have them on the other two lines, need to add so I can see what is going on with each line)

I may try that Diesel, it should tell me if I have a blockage when opening up the bleed valves (If no improvement...)

[Diesel Pro]

It helps to have a vacuum gauge at the tank hub to see how the pump is drawing as well. To test the line simply without a bleed you could pull the top tap and watch it evacuate. I have my gauge connected to a 2 port end hook and what I find is that liquid gets up in the line and will not drain.

I suspect that you have some trees that just are not ready to give just yet. Hard to be patient, but that is what it takes.