Sap Ladder To vent or not?

[TunbridgeDave]

I've been looking through the posts and I can't find a definitive answer. I'm putting in a star manifold ladder for about 60 taps and will add a valve to drain the bottom line. But I can't see the reasoning for introducing an air leak into the system. Yeah it makes it look like sap is jumping through the tubing but so does an air leak anywhere else in the woods. I see leader sells a special vent for sap ladders but can someone explain why you should use one?

[spencer11]

i have heard not to use one, i have no experiance with one, but what i know is that it looks like sap is flying though the tubing but its mostaly air, you want the sap to look like its hardly moving. thats what i heard

[Potters3]

I Have 2 of these lifts, I put a small hole (needle) at the ends of the lines. It adds are so it works like a percolator. One day the hole plugged and the sap didn't go up the lines just sat there with all the lines full. I broke the ice of the hole and it started perculating again.

[spencer11]

what ive heard is that the sap may look like its sitting there but it really is moving

[Thompson's Tree Farm]

When the lines are full and just sit there sap is moving. You just can't see it because there are no bubbles or anything so you can see the flow.

[Thad Blaisdell]

no vent. ever

[noreast maple]

HEs asking about a sap ladder not your regular lateral lines. potters3 is so far the only one addressing this.

[noreast maple]

my understanding of it is you need a small very small amount of air at the bottom of your ladder to make the sap jump up the star lines . there is a couple of videos of them on you tube , they have the valve about five to ten feet further down from the ladder and just barely crack it open to make the ladder work . when they close it the sap stops climbing. can also be used for drain if needed.

[Sunday Rock Maple]

We put in a few ladders last year and (in the interest of time) only put valves on some. We did try cracking the valves on the ones that had them but decided against it as it seemed to me that the rush of sap that I was hearing was making me feel good that the sap was moving but was really not very efficient due to the leak. We ended up just using them at the end of the year to drain. Our ladders were dual 1" pipes though and not stars --- don't know if that's an issue or not.

[Thad Blaisdell]

As stated no vent, ever. The gasses from the tree will be enough to make the ladder work. If you want a valve then by all means dont let me stop you. But you can bet your bottom dollar that none of mine have a vent and well that sap flows. When you disturb it by venting and then stopping it there is time needed for that section to reestablish itself. basically you have gotten all the excess sap up the lines so now there isnt enough sap to make it work properly. Now the next question would be why would you walk your bush looking for leaks to stop, and here introduce your leak..... now maybe just maybe you need one with a two pipe lift system, but I use the star system with 5/16 and that you do not need a leak. But as stated do as you see fit.

[Beweller]

In general there is an optimum amount of air/gas that results in the smallest vacuum loss. The optimum depends on the amount of sap, the lift of the ladder and the characteristics of the vacuum pump.

Increasing the amount of air/gas relative to the amount of sap reduces the vacuum loss caused by the lift of the ladder. However, increasing the amount of air/gas loads the vacuum pump and reduces the vacuum possible at the pump. These two effects trade off to cause an optimum.

The effect in the ladder is to replace a solid column of sap with a column partly of sap and partly of air/gas, which has a lower density than pure sap.

[Thompson's Tree Farm]

HEs asking about a sap ladder not your regular lateral lines. potters3 is so far the only one addressing this.

You bet I'm talking about ladders. I agree 100% with Thad. No vent ever! You don't need air to lift sap.

[tuckermtn]

no vent here either. Both two pipe and star fitting ladders.

[spencer11]

HEs asking about a sap ladder not your regular lateral lines. potters3 is so far the only one addressing this.

i was talking about ladders to, not sure how you thought we were talking about lateral lines...

[red maples]

OK good question. I had a friend ask this very question just the other day to a leader rep, who came out to take a look at his tubing set up because he has a particularly stange things he needs to do, (backwards slopes, flat ground, must go under a bridge, and a few other things. Anyway, he said its 6 in one, 1/2 doz the other. Basically he said that if you need to watch and see what happens if there is no movement in the sap you might need to let in an air leak, but he also said you need to check it during good runs if you go out to check it on a slow day he said its just gonna sit there because the trees aren't running good and and releaasing enough sap or gases to help lift the sap that is coming out. He said its also a matter of opinion some do it some don't everyone has their reasons. Now that being said, I have have 1 star lift right now its about 3-4 ft I guess and has about 35 or so taps on it. Everytime I check it it seems the sap is 1/2 way up the tubes and just sitting there, the design of the star fittings there are 6 fittings off each one now if you let in an air leak and it starts to perculate being there is a and even amount of fitting on it they are right across from each other so when that bubble shoots up its going right across to the other side and back down I noticed this with a 2 pipe design I had and it was very counter productive. So I changed the design. but I only use it in case of emergencies(flooding high water in the swamp)

He also mentioned that you must have a ball valve at the bottom of the ladder, leak introduced or not to drain it so it doesn't freeze.....what? the tubing will freeze up before it has a chance to drain no? I have never purposly drained a ladder and had any issues at all. I am thinking what do the big producers do that have many ladders do you go through and open them everynight? I had an air leak in mine last year and I put a bucket just to see if any sap drained out and there was never anything in the bucket. I am gonna try it without an air leak this year. I am also adding in a dry line and picking up another 80 taps in one section that is very flat and long and will require a few small lifts in it. I would guess that a few smaller lifts are better than one big one?

The other thing with the original post I noticed yoou said a star lift with 60 taps I though the max on a star lift was recommended at 35-40 taps? just saying.

[Thad Blaisdell]

The other thing with the original post I noticed yoou said a star lift with 60 taps I though the max on a star lift was recommended at 35-40 taps? just saying

To answer this..... on a star one 5/16 is good for 10 taps. so a 4/star is good for 35-40. a 6/star is good for more.

[Potters3]

I'll agree with Thad 10 taps per tub,

I use a small vent hole but I put the hole at the very end (away from the lift ) of the line.The extra air ( I think) does more good then the little bit of vaccum I am lossing. My hole was put in with a tiny finish nail. On the bottom of the pipe, had one on top but it would ice over and the sap did not lift as well. My two lifts are 50' from the sugarhouse and lifting around 15' to get acrossed my driveway. One side has 60 taps the other now has 250 we will see what this year brings. Last year both side where around 60.

[Potters3]

TYPO, I got to read better when I type, hard to when I am looking at my finger. 150 on the second lift.

[maple flats]

I think Leader sells them because some producers THINK the air is needed, not because Leader thinks they are needed. They are just preying on those who think a leak is good!!! I have 3 ladders, no vents and sap climbs well in all. My biggest issue is getting all leaks fixed, I surely don't want to make one!

[TunbridgeDave]

I guess the debate will go on. In my mind I don't see the reasoning behind adding a leak. I was hoping Dr Tim would weigh in with some research on the subject but maybe none has been done at Proctor.

Red, my plan was to use at least one 6-way star to lift about 12 feet.

[red maples]

I didn't know you could go that many with a star lift thanks guys. the other thing in there that I mentioned, if you need to lift say 6 ft(random number) is it better to lift in one spot the full 6 feet or 2- 3ft lifts or 3- 2 ft lifts over a longer distance? or does it not really matter?

[Sunday Rock Maple]

We have 350 taps on an 11' grade that we do with two 6' lifts about 200' apart (both 1" dual pipes). It works well, but my issue with it is that we have 26" of vacuum going in but only 18" on the other side. I'd like to replace them with a reverse slope releaser to keep the higher vacuum levels.

[mapleack]

I'll fan the fire with my opinion/ observations. You do need tree gas or air to make a star ladder work. If your system is tight to perfection, no hollow trees, etc, the laddder fills with sap and the vac level past the ladder drops. I put in a new line with 40 taps going into a 12' high star ladder with 4 vertical tubes. I watched it fill and only occassionally move. I said to my self I wonder whats going on, do I need a leak or is it just feel good watching the sap go? I installed a vac gauge beyond the ladder. When the ladder was full I had 22" at the releaser and 12" past the ladder. Every time the ladder would rip and empty the vac past the ladder would go up to 18", then the lines would fill and vac would slowly go back down to 12". So, I intalled an extra saddle with a piece of 5/16 with a needle valve on the end. I fine tuned a tiny leak, allowing the ladder to work and vac past the ladder stayed at 18" or above ALL THE TIME. Yes leaks are bad, but I'd rather have a leak and 18"+ than no leak and 12". In most situation there will be enough tree gas or existing leaks to work fine, but I believe that my observations show that there will be rare intstances where an introduced leak will be beneficial.

[Amber Gold]

I had a similar discovery as Mapleack. I have an 8' star lift with a vac. gauge at the bottom and a valve to drain the lower mainline. I run ~25" in the woods. I first tried it out without venting it, and I also found the vac. levels much lower...say 18" because the lift would plug up solid. I kept it closed for a period of time, and the vac. level was always much lower than the rest of the woods. I barely cracked the ball valve open and the vac. level immediatly jumps to 21-23" once all the sap clears out, and it stays there. Based on this, the valve stays open just a touch.

I have valves at both ends of every mainline, so I can clean the lines out after the season. One thing I will be trying is leaving the valve closed at the bottom of the lift, but opening the valve at the far end of the mainline. I've been told this will maintain higher vac. levels on the mainline, while still giving you the air leak. We'll see.

[Seguin Sugarbush]

Keep the system leak free.Sit at the extractor observe how the sap is coming in.On our sap ladder we had drilled a small hole in the bottom of the first star to let in air as it appeared that sap was not moving but sap coming in to the extractor started coming in sporaticaly.After more observation we concluded that sap flow kept coming in even when it appeared sap was not going up at the ladder.So why make a leak and reduce vac. level in front of 250 taps.

[spencer11]

i second that

[mapleack]

Keep the system leak free.Sit at the extractor observe how the sap is coming in.On our sap ladder we had drilled a small hole in the bottom of the first star to let in air as it appeared that sap was not moving but sap coming in to the extractor started coming in sporaticaly.After more observation we concluded that sap flow kept coming in even when it appeared sap was not going up at the ladder.So why make a leak and reduce vac. level in front of 250 taps.
Every tubing system is different. I watched vacuum levels before and after the ladder and apparent sap flow. My short system past the ladder had higher vac and performed better with a small leak. So long as you have enough excess cfm to overcome a small leak I believe that a leak may be beneficial. Watch vac levels not just flow. To each their own. We need proctor to test this for us.

[sapman]

We need proctor to test this for us.

Along with inverted lats/opposed to ladders, for those of us stuck with flat land. I'm going to try to test this on my tiny backyard plot, but the sample size may be too small to give any meaningful results.

[mapleack]

Here's some physics for the no intentional leak camp to think about. One inch of vacuum will lift sap one foot more or less. Along with that thought, vacuum does not transfer through a liquid. Considering those facts assume you have a sap ladder 12 feet high with 4 tubes, the system is tight with no leaks and 22" of vacuum at the releaser. Sap flow just gets started for the day, not much tree gas is being produced. All 4 vertical tubes fill with sap and slowly climb. When the tubes have filled to a height of 10 feet you're using 10" of vacuum to do that, how many inches do you think you'll have beyond the ladder? 12 inches. Now if you have enough tree gas, existing leaks or an intentional leak injecting air the vertical tubes keep percolating empty, you're not lifting a solid column of sap and vacuum level beyond the ladder will stay almost as high as at the releaser all the time. Watch your ladders, if all the tubes are full at the same time physics dictates that the vacuum level beyond the ladder will be lower equal to the height of the sap column. If at least one tube is always bubbling along then you're fine.
Tim, the same thought applies to laterals running up hill. I've got a few and yes they work to get sap to the main and are better than not tapping those trees, but you'll have higher vac to them with a properly functioning ladder than you will with a lateral full of sap.

[spencer11]

Your always going to get more sap by tapping a tree than if you didn't, the reason for the lower vac level is caused by the sap filling tubes, you will have lower vac levels but you will have more sap coming to the releaser

[TunbridgeDave]

I appreciate everyone keeping this thread going, I was hoping to get a response from Dr Tim as well!

[mapleack]

Your always going to get more sap by tapping a tree than if you didn't, the reason for the lower vac level is caused by the sap filling tubes, you will have lower vac levels but you will have more sap coming to the releaser
I've missed getting back to this thread, and wanted to point out that research shows that higher vacuum levels equal more sap volume, therefore if you're averaging 12" of vacuum beyond a ladder, you're going to get less sap than if you are averaging 18" beyond the ladder with injected air to allow the ladder to function steadier.