Question about CV's

[SevenCreeksSap]

I see a lot in the June journal about new check valves and have a question. Are they mainly for use with a vacuum setup? I just have gravity tubing mostly on really good slope, but we noticed the tubing stays pretty full of sap> I'm assuming this is because of a reasonably tight system so it doesnt drain, and the next days sap just pushes it out.
I understand the concept of the Cv's so the tree doesnt pull the sap back in with negative flow. what kind of difference is there with CVs on a gravity setup where most of the lines have good drop? I mean my hill is 150 ft elevation change top to bottom.
I guess a second question is would CV's help the lines drain better? could the reverse flow be holding the sap in the lines?

[ennismaple]

This topic has been discussed several times so you should find your answer by doing a search of the old threads. I believe Cornell has done research on the yield of CV's on gravity flow.

[SandMan]

I have nearly 500 taps on gravity. One main-line is fairly steep. I did use CV's the past two years (on gravity). I will not be using them again until I go to a vacuum system. A couple things, none of the "research" that has been actually published shows any benefit using CV's on gravity systems. I can say that from my personal experience, the CV's will actually lower your output on those marginal flow days with late thaws. There is just not enough pressure in the tree to push the "slush" (sap) through the CV until the line, tap and tree are completely thawed out.

Also, you are expressing concern about your lines being full and not draining when the tree's shut down. This is actually exactly what should happen with slug flow on gravity. The lateral lines should stay full in between runs. If they are emptying out, you have a leak some where.

Mike

[500592]

I don't know why you would even want them on a vac system just run your pump till it freezes up and before it thaws or do what I do is run them 24/7 I am gonna try stubbys with seasonals.

[sapman]

That's pretty much what I did this year, and was disappointed with my results. I'm going back to cv's next year. One piece design makes them even a bigger plus in my mind.

[Thad Blaisdell]

I think everyone was disappointed with any results that they got this year whether or not it was CV's or not.

[PATheron]

Ive got to say that I think the cv's work myself. I never thought I needed them becouse running the pump 24/7 but I think they do help a lot unless the setup is pretty perfect. I had all cv's this year and was totally tapped in in January and when I Pulled taps in April my stuff was still running pretty darn good even after all the hot weather. We had a year like that a couple years ago and my stuff did finally stop.. This year it never did. Got down to .6 or .7% and I just got sick of doing it and quit and even after I pulled taps I saw wet trees after that. Im feeling confident enough that I may try tapping in December this year. May not matter though with the next three years looking like cold ones. May not even be syrup down here till march. Theron

[lew]

OK Theron, I'll bite. Why are the next 3 winters going to be cold ones? Are you the greatest meteorologist of all time? I need to know. Because if you are, I need to buy stock in whatever TV station you are going to predict Weather for. LOL.

[Maple Hill]

After you turn 35 they are all cold

[red maples]

I don't see any benefit with gravity and Cv's on my gravity lines I just use seasonal taps!!!

The other thing I see is that even if your running the pump 24/7 and until freeze up. don't forget every time your releaser has to dump and then re pressureize it creates a pretty forceful back flow in the line and can go up to the tap holes and even though there may be an air gap preventing most of the sap from getting back into the hole, that small fraction of now bacteria contaminated sap is going back up to to the tap hole infecting so to speak. So its not just back flow during shut down that needs concerning!!!

[ennismaple]

Agreed that unless you live in the far east of Quebec you were likely disappointed this year, no matter what taps, tubing, pumps you used! CV's were of no benefit to us this year because our season was 11 days long. We could have used 20-year old spouts and gotten the same yield.

It's been posted here before by Dr Tim that CV's were designed for vacuum systems. They may provide a benefit to gravity systems in some situations but not to the same extent and with vacuum. Some on this forum have had good results with them on gravity, some not.

Because I don't believe everything I'm told by sales reps, we did our own test before switching over our woods to stubbies and CV's (all our taps are on vacuum). In 2010 we used CV's in just our 400 tap woods and they out-produced our 1450 tap woods over the last 4 days of the season - not sap per tap but in total sap! It wasn't a perfectly controlled, apples to apples comparison worthy of a doctoral thesis but the results were significant enough for us to spend the time and money to switch everything over.

[DrTimPerkins]

Agreed that unless you live in the far east of Quebec you were likely disappointed this year, no matter what taps, tubing, pumps you used! CV's were of no benefit to us this year because our season was 11 days long. We could have used 20-year old spouts and gotten the same yield.

Basically true. Some were happier than others though. Really hard to compare this year given that some people had 2-seasons....one with good syrup, one with buddy syrup. You need to know the conditions in order to compare the results.


It's been posted here before by Dr Tim that CV's were designed for vacuum systems. They may provide a benefit to gravity systems in some situations but not to the same extent and with vacuum. Some on this forum have had good results with them on gravity, some not.

Correct. CVs were designed and intended for use with vacuum. We've never tested them on gravity....Cornell has. They can provide some benefit under gravity, however because the overall yields are much smaller, the economic equation is very different. Example.....say you get 15 gal/tap normally, but get 20 when you switch to CVs (33% improvement). You gain 5 gallons of sap, worth perhaps $1.50-2.50 (depending upon what sap is worth to you). Costs you $0.36 for the CV, so you net $1.14-2.14 per tap. Way worth it. Now you do the same comparison on gravity. Maybe you get 8 gal sap per tap, and let's say you get the same 33% improvement (unlikely, but maybe you do). So you get 10.6 gal of sap with CVs. That's 2.7 gal more sap, or $0.81- $1.35 worth more sap, which nets you only $0.45-0.99 more per tap. The economics are far less favorable in that case.


Because I don't believe everything I'm told by sales reps....

:lol: Smart.


we did our own test before switching over our woods to stubbies and CV's (all our taps are on vacuum). In 2010 we used CV's in just our 400 tap woods and they out-produced our 1450 tap woods over the last 4 days of the season - not sap per tap but in total sap! It wasn't a perfectly controlled, apples to apples comparison worthy of a doctoral thesis but the results were significant enough for us to spend the time and money to switch everything over.

The number of possible combinations of tubing and spout ages, cleaning methods, operation methods, releaser and pump type and method of operation make testing all combinations very challenging. In general, there are practices where CVs will help a lot, and practices where CVs won't do much at all (for example, on a brand-new system). An information sheet has been available on this since the day the CVs went on sale (see attached), and was printed in the Maple Digest.....so I really don't understand the mystery and confusion. Leaving vacuum on 24/7 does tip things more towards the "helping less" side, but there are still releaser tips, sap rushing by lateral lines causing turbulance and sap backflow up the lateral (got some great video on this in 2012), power outages, releaser failures, etc. We run our pump 24/7, and we still see significant increases with CVs under most circumstances.

The CV2 was designed and produced because a sizeable segment of maple producers asked for a one-piece CV spout that was made of clear polycarbonate. That's pretty much the way businesses run. If there is a niche not being filled, and there is an economic argument to filling it.....they will.

5800

[maple flats]

I used the CV's 3 yrs ago on gravity and was disappointed in the results, I had very few areas with good slope and those that did, had good slope at top and marginal slope at the bottom on the laterals. For 2011 I used the CV's in my bush with vacuum (550 taps) and was very pleased with the results. In 2012 I used CV's in both bushes, 1100 taps total. Even though the season was a bust, I was pleased to see wet tap holes as I pulled the taps. I finished tapping 2/6 and didn't pull taps until 8-9 weeks later. Even after the 2 weeks of 70-80 degrees in mid March most holes had not dried up yet as the taps were pulled. I think that shows good results. My drops varied from 6 yrs old to new, and all showed the same results. I have now decided however that I'm going to change drops after 4 seasons, 5 max.

[DrTimPerkins]

..... I have now decided however that I'm going to change drops after 4 seasons, 5 max.

After droplines (and spouts) are 5 yrs, you can expect (on vacuum) that your production will be (on average) approximately 55-60% of what you could expect with a brand new system. If you replace spouts each year, it'll be about 65-75% of a new system in the 5th year (on average).

[PATheron]

Lew- I just listen to whatever Joe Bastardi says. He's claiming next three years should be very cold. He studies weather patterns and says after years like weve had with the warm trends and ocean patterns and whatever the winters will be real cold like in the 70's. Hes really into weather like we are syrup. He probly wakes up in the middle of the night and does emergency snow flake checks and stuff like that. He WANNNNNNNTS it.. So I just go with whatever he says. Whatever the weather is Im doing the opposite of everyone else. Im not waiting till spring and watching the weather like a hawk for two weeks of good sugaring temps. Im going to watch the weather like a hawk this fall for the first two weeks of freeze up. Thats going to be my winter and during that two weeks of winter Im tapping in. Then Im going to get my sap. Theron

[Mark]

I would like to see a stainless check valve that could be washed each year. Just pop the ball out, wash, then replace the ball with a new one with a tool designed to do that.

[red maples]

Lew- I just listen to whatever Joe Bastardi says. He's claiming next three years should be very cold. He studies weather patterns and says after years like weve had with the warm trends and ocean patterns and whatever the winters will be real cold like in the 70's. Hes really into weather like we are syrup. He probly wakes up in the middle of the night and does emergency snow flake checks and stuff like that. He WANNNNNNNTS it.. So I just go with whatever he says. Whatever the weather is Im doing the opposite of everyone else. Im not waiting till spring and watching the weather like a hawk for two weeks of good sugaring temps. Im going to watch the weather like a hawk this fall for the first two weeks of freeze up. Thats going to be my winter and during that two weeks of winter Im tapping in. Then Im going to get my sap. Theron

I like that idea...The only person that had a banner year down here that I know of anyway was morningstar farm and he took a chance and started tapping mid january I think he did his first boil around the 21st of january and he did great!!!

[Amber Gold]

I frequently have to re-seat my spouts during the season...either because the reducer's loosened from the tree, or the stubby's loosened from reducer. I've been told the polycarbonate spouts are grippier and greatly reduce the first problem, and by eliminating the stubby/reducer, the second problem is eliminated. My woods is already setup for stubbies w/ reducers, so I'll keep it that way, but I'm opening a new mainline this year, and I'm going to try seasonal's on it this year.

[SevenCreeksSap]

So on gravity to better prevent bacteria I may be better off investing in new taps as opposed to Cv's. All My taps were new last year so should last another year or two. Thanks

[DrTimPerkins]

So on gravity to better prevent bacteria I may be better off investing in new taps as opposed to Cv's. All My taps were new last year so should last another year or two. Thanks

It is almost always economically advantageous to use new spouts each year whether one is on gravity or vacuum. The sap gain will almost always pay for itself. The CV is an added insurance policy that some decide to use and others may not (depends upon a number of factors). On vacuum, almost every reasonable, controlled scientific study has shown them to provide increased sap yields significantly above that of using a new spout alone.

[spud]

After droplines (and spouts) are 5 yrs, you can expect (on vacuum) that your production will be (on average) approximately 55-60% of what you could expect with a brand new system. If you replace spouts each year, it'll be about 65-75% of a new system in the 5th year (on average).

Dr Tim.

That still would not be good enough for me. I would like to know how I could stay above 90% every year. The only thing I can think of is use the new CV2 and replace drops every two to three years instead of waiting 5 years. It would cost me $2875.00 to change drops but if I did it every three years then thats just $958.00 each year. By doing this would I stay above 90% production? I would need about 7500 gallons of sap to pay for new CV2 and drops each year. I should get that in one day. If the CV2 and new drops extends my season by 7-10 days then I could make $20,000-30,000 more per season then if I use old drops and any other spout other then the CV2s. Is my understanding correct? I want the most sap possible out of my trees each year.

Spud

[DrTimPerkins]

Is my understanding correct? I want the most sap possible out of my trees each year.

Yes, your understanding is correct. As long as you're using CVs, you could probably stretch the dropline replacement interval to 4-5 yrs easily without seeing much (if any) drop-off in production. We have some lines that are 8-9 yrs old and only see about a 4-5% drop-off in production on them with CVs. In years like 2012 (very hot SUNNY weather), the CV2 (clear polycarbonate) will outperform the original CV because it will not overheat as much. Fortunately those types of seasons are quite rare.

If you do dropline replacement, it is probably best to replace a certain percentage each year (maybe 10-25% annually, which would be a 4-10 yr replacement interval) rather than all in one year. That spreads out the reward you get from the new drop, but also spreads out the cost and the risk. The big risk is that you go to all the expense and work to replace all your drops in a year like this past one (2012), and wind up getting very little benefit from it. Very costly and a huge economic loss (in terms of net return) that could take several years to overcome. The whole idea behind the development of the CV (or CV2) was to get sap yields really close to the yield of replacing drops (or putting in a new system), but at a moderately-low cost with a moderately low effort....so a high net economic return at a low cost.

[red maples]

I think if were on the yearly % plan of changing drops, I would skip changing a year after a season like 2012. I personally don't think if you miss 1 year using the CV's is going to THAT much difference.

[sjdoyon]

We went with 100% CVs in our system last summer and ended up with four pounds per tap this spring. Neighbor's trees dried up end of March and we continued boiling into the third week of April when we started producing buddy commercial so we stopped. When pulling the spouts, holes were still wet and dripping sap. We contribute the extended season to the CVs since we were the only producers locally using CVs and we gained an extra two/three weeks of production compared to the other producers in the area. We'll see how next spring goes but we're happy with the CVs so far.

[wkies]

I have used CV for two years on a small gravity system. I go back and forth whether to use them or not. Let's say I was to go back to using regular taps, besides the fact that it is better for the tree - should I use 5/16 or 7/16?

I was told to use 7/16 on small gravity system for the greatest flow.