3/16 vs 5/16 and vacuum overall yield

[Ryan Mahar]

Hope I am not repeating a question here but here is my ?: So if the amount of vacuum generated from 3/16th varies based on slope, number of taps etc...... that will overall create a variation in expected sap flow from the entire sugarbush. Each line being different and so some line under producing and others doing well. My experience with the 5/16th under vacuum is that the entire system is under a constant vacuum value. Our gauges showing each mainline maintaining the same vacuum throughout. So you can predict Volume of sap production more consistently and accurately if you have everything on 5/16th and under vacuum. I understand the loss of vacuum daily with leaks etc, but that would be same for both systems............So why would you not want to just stay with everything under mechanical vacuum pump and 5/16th??? Thanks for educating me on this with any replies!! Ryan.

[village idiot]

If you develop a second sugarbush that has good slope but no power you would have to buy a gas powered vacuum. It's not difficult to do, but it is expensive and requires some maintenance, fuel, oil changes, ideally under a roof... Also you will need a releaser that has its own cleaning, maintenance...

Or you could run 3/16 and get approximately the same yield with way less capital investment/ overall headache.

I don't think anyone is saying 5/16 is on its way out. In some places it works really well. It's just we have other options that may be just as good in certain situations.

[Super Sapper]

The amount of vacuum on 3/16 is not dependent on slope but elevation change. You get about 0.88 inches of vacuum for every foot of elevation drop regardless of slope. This is for gravity situations, with added mechanical vacuum you should be getting more vac at the tap hole than on 5/16.

[ryebrye]

Hope I am not repeating a question here but here is my ?: So if the amount of vacuum generated from 3/16th varies based on slope, number of taps etc...... that will overall create a variation in expected sap flow from the entire sugarbush. Each line being different and so some line under producing and others doing well. My experience with the 5/16th under vacuum is that the entire system is under a constant vacuum value. Our gauges showing each mainline maintaining the same vacuum throughout. So you can predict Volume of sap production more consistently and accurately if you have everything on 5/16th and under vacuum. I understand the loss of vacuum daily with leaks etc, but that would be same for both systems............So why would you not want to just stay with everything under mechanical vacuum pump and 5/16th??? Thanks for educating me on this with any replies!! Ryan.

People don't care about predicting sap production, they care about achieving sap production.

In a 3/16 + mechanical setup you will have a similar situation at the mainline... if you have your mainline under 27" of vacuum, you know that the minimum amount of vacuum you will have on your lowest tap will be around 27" - but if you have any elevation drop at all, you will also be gaining additional vacuum on the 3/16 lines.... how much more depends upon how full the lines are with sap. Sure, you might not be able to tell if it's going to be 28" at the tap or 28.5" at the highest tap - that may vary by day, but given the choice between having a lower (but predictable) amount of sap vs a higher (but perhaps not completely predictable) amount of sap - I'd go with the one that gave more sap.

It will give at least the same amount, if not more than the 5/16 if you have even a slight elevation drop that you can use to gain more vacuum with.

In general, it actually is pretty predictable on a 3/16 system - I only had 110 taps on 14 laterals with 3/16 going into a mainline under 27.5" - but the vacuum gauges at the top of my laterals were all pretty consistent... usually above 28" of vacuum and sometimes higher (the max vacuum is the max barometric pressure - and on high barometric pressure days, the vacuum gauge at the top of the line would clearly be reading higher than it was on days the pressure was lower)

The gauges are only accurate for +/- 2% or something, but they didn't vary much day to day when the sap was running.

I believe I squeezed out at least an additional inch to an inch and a half of vacuum on every tap in my setup by using 3/16 laterals based on the elevation difference between the taps and the mainline - and that additional amount of sap for that increase in vacuum actually is pretty predictable.

[lpakiz]

As someone who has negligible slope (1.4%) and no power, I could only wish that 3/16 could work for me. Sounds like you never had to carry gas into the bush, start engines, adjust stuff, try to guess when to head the 7 miles over to the woods to turn the whole system on, find out I was too early (still froze, so stall awhile while it thaws) to late and darn, shoulda been here 2 hours ago, etc.
I understand that the 3/16 gravity system self-starts every day, takes no gas, no equipment, no attention other than leak patrol.
Oh yeah, I also had to buy the pump, engine, releaser, mainlines, wire, gas, oil etc. Wish it would work for me.......

[Flat Lander Sugaring]

if they are saying 15 taps per Lat. why cant you just use 35/40+ taps of 5/16 and then not worry about change over or adapting 3/16 to 5/16 or main line. If you fill the 5/16 line with sap it will create more vacuum. we took over some taps this year and there were at least 25 to 30 taps per lat. my buddy took a video of sap coming out of 3/4 main line. We had 200 on this bush, we showed the video to a guy that had 600 he said he had never seen his bush run as hard as that 200 bush and his bush is 10 to 15 a lat.

[DrTimPerkins]

if they are saying 15 taps per Lat. why cant you just use 35/40+ taps of 5/16 and then not worry about change over or adapting 3/16 to 5/16 or main line.

You CAN develop natural vacuum in a 5/16" line if it is set up properly, however it is nowhere near as reliable or self-starting as it will be with a 3/16" line, thus your yields will be lower.

[CampHamp]

I've got an equal mix of 3/16 and 5/16 on the same main lines on a small (120 tap) bush. Since the 3/16 is a column of flowing sap, I don't believe much "vac power" is wasted (i.e. propagated) on those laterals so my vac setup can be much smaller ($150) and still produce high-vac (27").

[brookledge]

Ryan asked why someone would want to use 3/16 instead of 5/16 and mechanical vacuum. The answer is simple. Not all sugar bushes are concentrated enough to warrant them. I have seem many producers who have 15 to say 30 taps on a fence line or stone wall and that is all that is there. Go down the road another 1/4 mile and the same thing. You certainly are not going to put in mechanical pumps for those locations. But if you have the elevation drop then using 3/16 is the way to go.
I only have high vacuum on all of my taps. This year I got .6gal per tap so I'm not sure I can do much better but after listening to Tim Wilmot from the UVM extension talk about hybrid systems I might experiment with that
Keith

[Ryan Mahar]

thanks for the replies, I was mostly looking for confirmation that really it still is a toss up. My situation specifically is adding a new bush with 1500 taps , not tremendous slope, all within access of power for vacuum. So staying with what I know in using 5/16th and mechanical vacuum will be best for me......thanks for the various replies. It all helps for sure!