Sap flowing wrong way on vacuum

[MarquisVII]

Hi all,

I am on day 2 of a completely new setup this year with a Shurflo connected to a manifold of stainless tees. You can't see the vacuum gauge in the pic, but it's running at 24in of mercury at the pump. I have about 12 taps each on lines 3-5 all flowing great. My issue is line 2, which has only 4 taps and it's the shortest run directly next to the pump - about 40 feet with a one or two foot drop from the end tree to the pump. On this line I consistently get backflow of sap for short periods of time before again flowing the correct way, then stalling out and running backwards again.

I figured this line would flow the best because of the short run and its close proximity to the pump (which is why I plumbed it where I did - I figured it would work sort of like a redundant recirc line).

Any ideas? At 24" vacuum, and no audible leaks I'm at a loss of why this particular line is giving me such an issue.
https://mail.google.com/mail/u/0?ui=2&ik=f5fcf23953&attid=0.1.1&permmsgid=msg-f:1757773814073484559&th=1864ddf88755650f&view=fimg&fur=ip&sz=s0-l75-ft&attbid=ANGjdJ8jagv1uVkTd2XONJBJpsD_hdRU9GzZjvDnTRw Cp9HDLVlCDeN3lR20O0yNSag2TQypmQ3NufC0T0cHMBIT8QhJF QGorHxIY7gyuGIGIm_uXXJ5FTTEfSKDX_4&disp=emb

[CTSap4Maple]

Check your fittings for any wood shavings or other gunk that may be stopping the flow.

[TheNamelessPoet]

See if it is sagging at all. Does the sap get caught in a low spot, or something like that?

[TapTapTap]

I don't see a photo.

[MarquisVII]

Check your fittings for any wood shavings or other gunk that may be stopping the flow.

Nope, everything is clean.



See if it is sagging at all. Does the sap get caught in a low spot, or something like that?

No sags. For any reason would the location of this line on the manifold combined with this being such a short run be the culprit? That would seem counterintuitive to me, hence the reason I plumbed it this way.

[littleTapper]

Sounds like that "problem" line builds more vac than the others occasionally and then pulls back. I've seen similar behavior on my setup. If you had a gauge on the end of each line, I bet you'd see higher vac there at times.

To note, I have less of this now with a manifold where there's no possible way for one to flow any sap into another. The original design I had, when I noticed this more, was flat in its layout. Now, all lines enter more vertically in a V shape into a larger pipe sloped down toward the pump.

[MarquisVII]

LittleT, that's helpful, thanks.

[Sledheed]

Is your collection vessel filling up? If it is, stop staring at it. Or if you have the x keep staring at it. 4 taps, is hardly enough to fill a short 3/16 line on the best run. Once season is in full swing, and you are running out of places to store sap, you will spend less x looking at it. Hope you have an excellent season!!!

[maple flats]

Un-equal vacuum is my guess too.

[MarquisVII]

Thanks all. I finished tapping 38 taps about 51 hours ago and I already have 160 gal of sap which is what I used to get in an entire season (see signature)!!! I am feverishly fabricating the new oil tank evap and then picking up my Smokey Lake pan on Friday just in time for the first boil on Saturday! Once I get past this weekend I'll be adding another sap line with at least 5 more taps.

[blissville maples]

Vaccum fluctuations. If one line is at 24" and air is introduced (or higher pressure-less vaccum) you will see the sap move to equalize this pressure. Behind this sap you have highwr vacuum than in front of the sap so the sap move to equalize it

[steve J]

i had similar issue with my pump this year. I have had this set up for about 5 years and its worked well until this year. I have one line with 15 taps on 3/16, the second line is a 3/4 inch main line necked down to half inch at the pump. this line has 3 laterals with 40 taps total. The Main line kept running backwards. I eventually gave up on the pump and ran natural vac. But in doing so I basicly lost my production on the 3/16 line as that was very little slope on that line. very frustrating as I never had an issue before.