3/16 into 5/16

[DrTimPerkins]

If the lower section is flat, switching over to 5/16" tubing would help. With only 20 ft of drop, you're only going to get 15-18" Hg AT THE TOP at best. Lower down on the slope you're getting proportionally less (at best). Did you ever check the vacuum level at the top of the lines or observe the flow in the lines? That would tell you whether you actually had any natural vacuum, or you needed to spend more time looking for leaks. Even very small leaks on a 3/16" system will result in little vacuum being generated. It needs to be VERY tight. Another possibility is that you had wood chips plugging up the tees and connectors. You'd be able to see that just by watching the liquid in the lines for a bit while the sap was running.

As someone suggested, maybe separate some lines with the trees on the top on 3/16" and those on the lower slope with 5/16".

[tonka]

While tapping I did find several damaged spots that I did fix and towards the end of the season and while pulling taps I did find a couple very small leaks in 2 lines that I missed. From what I could tell of during season it seemed to be working since I could see the occasional bubbles flowing down several lines. I'll admit that I should have walked around more but seeing a steady stream flowing out into my tank made me think things are working quite well until the end of the season when adding up all the gallons of sap per woods and breaking it down to tap average. I'm wishing I would have had a couple gauges on top to see if any vacuum was being produced. Another thing that has crossed my mind was during season several nights got in the mid to upper teens and with it being a north facing slope, that might have played a little part in the yields too. I'm kind of likening the idea of running 5/16 on the bottom and keeping the top on 3/16, see how that will perform next season. Thanks again to all who have put in their 2 cents, and if there are anymore advise please do share!a