Sap ladder on gravity?

[Wmmaple]

I was wondering if it's possible to do a sap ladder on gravity or if it has to be on vacuum? I have 3 runs of 3/16 with 20 taps on two and 18 taps on one. Fall is 30' on two of the lines and if the ladder is possible 11' on the last run. 600' of mainline if it works. Plan on running 1/2" main and if I can do a 5' elevation rise with a ladder I'll be able to get it beside one of my main trails in a 150 gallon tote for transfer to the shack. Any opinions? Thanks.

[DrTimPerkins]

It might be possible, but I'm having a hard time understanding exactly what you're trying to do. Can you make a profile sketch of it (roughly to scale and labelled) to help explain it better? You certainly wouldn't get as much as you would without the ladder (true of ladders with both natural and pumped vacuum), but something is usually better than nothing if it can't be otherwise avoided.

[Wmmaple]

It might be possible, but I'm having a hard time understanding exactly what you're trying to do. Can you make a profile sketch of it (roughly to scale and labelled) to help explain it better? You certainly wouldn't get as much as you would without the ladder (true of ladders with both natural and pumped vacuum), but something is usually better than nothing if it can't be otherwise avoided.

Thanks Dr Tim. I'd be happy to do a sketch if someone can advise the best way to post it on the site. I have 60 Sugar Maples at the rear of my property that I tapped with buckets. They are great producers but the logistics of gathering on the 8-9 % slope after crossing a wet area isn't appealing this year. There is aprox 60' of swampy hemlock grove at the bottom of the slope and a 9' natural rock outcrop with my trail on the other side, making it the reason for the ladder idea. I am going to use tubing for the first time, adding 100 taps, 160 if this works, so for the first part of my question, is it possible to do a ladder on gravity, or is a vac required? I'm off grid on the property so I have to rely on gravity. My bush is late so I really only have a 3 week season, so the extra taps will help. Appreciate any feedback thanks.

[Haynes Forest Products]

This is what I know and some is what I think. I know you can be fooled by sap pushing up thru a ladder into the releaser as a wondrous thing. But its just a combination of natural slope and higher pressure in the trees. I know vacuum is what makes sap ladders work. I think you will want your natural vacuum sap ladder right after the last tap so the column of sap will suck it thru the ladder.

At the top it will suck it up and then down the mainline. At the bottom it will push it up thru the ladder........but not as well.

[Wmmaple]

This is what I know and some is what I think. I know you can be fooled by sap pushing up thru a ladder into the releaser as a wondrous thing. But its just a combination of natural slope and higher pressure in the trees. I know vacuum is what makes sap ladders work. I think you will want your natural vacuum sap ladder right after the last tap so the column of sap will suck it thru the ladder.

At the top it will suck it up and then down the mainline. At the bottom it will push it up thru the ladder........but not as well.

Thanks Haynes. I get where you are going with that and wasn't thinking of it that way. First time with tubing, my family loves buckets, I don't. Appreciate the advice.

[Haynes Forest Products]

Don't let me the last word on the discussion. Draw up a simple diagram and post a picture of it so we all see your thoughts.

[n8hutch]

A few thoughts/questions
Will there be taps in the 3/16 tubing below the "Ladder"?
How many?
How much drop below the "Ladder"?
You said there is an outcropping of sorts that your trying to go over? Is there any chance that you could go around it? Even if you needed another roll of tubing, you would most likely do far better sap wise.
Can you run your line a little higher at the low end of the ladder so you dont have to lift as much ? If you could go from an 5 foot rise to say 1or 2 feet the sap is going to move better.

The reason I ask about taps below the ladder is because it may struggle to get going if there are no taps below the ladder

Finally in my opinion and after some trial and error on my own part and a lot of reading an 11' drop is not very effective on 3/16 tubing, it may even be counterproductive. I would use 5/16 personally on that kind of drop. Also you may want to use 5/16 drops down to your 3/16 lateral lines, according to research sap can travel upwards of 12' backwards in a 3/16 line when the trees freeze up and or shutdown at night, it won't be a big deal the first season but in subsequent years you'll be drawing dirty sap back into your tapholes.

Maybe you already knew a bunch of those things or were already considering using 5/16 drops. If so I apologize for over sharing.

[Wmmaple]

A few thoughts/questions
Will there be taps in the 3/16 tubing below the "Ladder"?
How many?
How much drop below the "Ladder"?
You said there is an outcropping of sorts that your trying to go over? Is there any chance that you could go around it? Even if you needed another roll of tubing, you would most likely do far better sap wise.
Can you run your line a little higher at the low end of the ladder so you dont have to lift as much ? If you could go from an 5 foot rise to say 1or 2 feet the sap is going to move better.

The reason I ask about taps below the ladder is because it may struggle to get going if there are no taps below the ladder

Finally in my opinion and after some trial and error on my own part and a lot of reading an 11' drop is not very effective on 3/16 tubing, it may even be counterproductive. I would use 5/16 personally on that kind of drop. Also you may want to use 5/16 drops down to your 3/16 lateral lines, according to research sap can travel upwards of 12' backwards in a 3/16 line when the trees freeze up and or shutdown at night, it won't be a big deal the first season but in subsequent years you'll be drawing dirty sap back into your tapholes.

Maybe you already knew a bunch of those things or were already considering using 5/16 drops. If so I apologize for over sharing.

Thanks Nate. I had a local guy come out and look as I’m a tubing newbie and he said pretty much what u did and told me not to try what I wanted to do. Rerouted the mainline and he’s confident should work. All my drops will be 5/16” with zap bac spiles. I didn’t realize about the backfeed on the 3/16 with the freeze thaw. Always appreciate advice from you guys as trial and error sucks with a short season. Thanks again

[DrTimPerkins]

Glad you were able to get your question resolved. To complete this thread for others who might look it up in the future, it IS possible to have a sap ladder on 3/16" natural vacuum if things are set up properly. However, the best option is to not do that if you can avoid it (mainline or lateral line going around, even if it is long).

If you had a section with a good drop AFTER the ladder, with several trees on that lower section (but still with drop after them) to generate the vacuum, then it can work. Tim Wilmot (UVM Extension retired) tried this and was able to get it to work well going over our road. You'd want to chat with him or look into his publications for more details.