3/16" line only at the end of a run?

[tuolumne]

Has anyone tried to run the 3/16" only after the last tap? We have one 3/16" line up with 20 taps - it was running slow today with a 10" vacuum and none of the 5/16" lines were running with similar slopes and tap numbers. I observed that the line is comprised of pockets of sap with air bubbles between them. On average, with todays run, it seems that the ratio was about 50/50. This estimate corresponds with the vacuum number considering an overall drop of 35' or so to the highest tap. If the line were closer to full, the vacuum pull should be higher. This caused me to wonder if it would actually improve the situation if the 5/16" line was acting like a funnel to collect sap and use it keep the 3/16" line full....like pouring the sap in at the top. If I have 20' vertical from the last tap to the collection, and it was full of sap, the vacuum number should be higher than the 35' total running at half air, half sap. I would welcome any thoughts. Either way, I plan to add 3/16" to the last 10 vertical feet of one of our 5/16" runs to see what happens.

[psparr]

I would like to see how it works too. My thought though is the air in the line eventually has to leave the system. That means down the 3/16. Defeating the purpose of a full line. Maybe?

[ryebrye]

Where in VT are you? I'm in Hinesburg and yesterday's flow was really weak - but overnight it didn't get below freezing and so it kept building up, and by this morning my lines were (all 3/16) were all flowing much better.

At the moment I only have a gauge on one of my 3/16 lines (I have only 35 taps on three 3/16 lines) - I also had a 10" vacuum on mine yesterday with the weaker flows, but this morning before I left for work it was up to 21 1/2" of vacuum. I had a 10" vacuum with the weaker flows over the weekend, and I was wondering if I had leaks in the line (and potentially a leak at the vacuum gauge itself) - seeing it hit 21.5" makes me think any leak may be minimal - I'll see where it gets to later today since it was supposed to hit 40 degrees today I think there might be a lot of flow

It does seem to take some time to establish the natural vacuum - I'm assuming part of this time is getting all of the air out of the line.

The line still wasn't full with the 21 1/2" of vacuum so I think it has room to go higher. The net vertical drop to where I have the gauge is about 100' or more. I'm going to install gauges on my other lines before that looks like it is coming on Saturday, and I'm going to install one at the lowest point of my drop before it goes down to my collection area to get an idea what my minimum vacuum is.

(I have a pretty steep drop-off and on top of that drop-off are where all my trees are... which is why I've gone with 3/16 gauge vacuum)

[steve J]

I just got back from mu Sugarbush in Middlesex my buckets were barely dripping but temp only hit 39 and was dropping when I left we had no sun at all. But my 3/16th has me puzzled. one of the lines appears to be full right down to the last tape which is about 6ft from main line. It appears to be stalled right at that T and the T appears open nothing blocking it. So from that T to main line it looks like its empty? The other ones have air bubbles in them but were not moving. My since is if we could get two good warm days back to back it would break loose but this business of one good day followed by deep freeze is the issue.

[tuolumne]

Today the vacuum got up to 14. Surprisingly, with a high temperature of 45 degrees, things did not really open up much today. We collected a total of 225 gallons of sap off 522 taps (400 buckets and 122 on lines). This is from yesterday and today. The 20 taps on 3/16" contributed 18 gallons to that total, so they clearly ran better than the rest.

I also added a 3/16" line at another location - 800' long, 25 taps, 150' vertical with 60' vertical from the last tap to the collection. I strung the line uphill, then tapped on the way back; I could not add drops walking downhill as fast as the sap was passing, and it came out each time I cut the line. Watching sap move in 3/16" can be very interesting.

[ryebrye]

Yesterday with temps in my area peaking around 42 degrees, the flow was pretty good. With 34 taps on 3 different 3/16 lines, I got 17 gallons - overnight I may have gotten another 2 or 3 gallons in my collection drum.

The highest vacuum I've seen so far is 22" it sustained that vacuum all of yesterday - the one that is showing 22" is the only one I have a gauge on at the moment and I suspect that I may have a very small leak at the gauge itself - the sap flows slightly faster in that line than my other two lines and I see some small bubbles around the barb in that fitting. I'm going to try to fix that before the next run that looks like it might come on Saturday here.