Switching from buckets to Shurflo on solar vacuum help

[DrTimPerkins]

Sap still flowing at under 32 F? I didn't know that could happen. I guess I still have alot to learn about maple tree physiology.

It's quite simple. Air temperature and tree temperature are not always the same thing (and frequently are not). Air temperature can change rather quickly...tree temperature is buffered and thus changes more slowly and unevenly (not surprisingly considering the tree is about 70% water). Not only is there a difference in temperature between air and the tree, there is considerable variation in temperature even within the tree. South sides of trees and fine branches will thaw faster (especially if it is sunny), north sides and larger branches will thaw more slowly.

It is somewhat more common for sap to stop flowing on tubing systems because the tubing freezes than because the tree freezes. Different portions of the tree may be thawed and exuding sap while other parts are freezing and taking up water (from the soil) at the same time.

https://www.themaplenews.com/story/w...ly-season/362/

[Openwater]

the recirculation line will likely not freeze so the pump will always have sap in it.

why wouldn't the line freeze when the pump shuts off at 29F?

Ok Dave, so if I do this recirc line thing and put a length of 5/16 onto the 3rd point of the 3-point star fitting and the other end in my 35 gallon collection tank with some kind of in-line valve to restrict flow to a trickle, how do I keep the other end of my stiff 5/16 30p in the bottom of my 35 gallon tank? I'm always a little leery of putting any foreign objects in the collection tank for fear of introducing germs/bacteria/infections into the sap.
I figure each day when I empty the 35 gallon tank, I can just leave a little residual sap in the bottom for the recirc line to use.

[Biz]

why wouldn't the line freeze when the pump shuts off at 29F?

Ok Dave, so if I do this recirc line thing and put a length of 5/16 onto the 3rd point of the 3-point star fitting and the other end in my 35 gallon collection tank with some kind of in-line valve to restrict flow to a trickle, how do I keep the other end of my stiff 5/16 30p in the bottom of my 35 gallon tank? I'm always a little leery of putting any foreign objects in the collection tank for fear of introducing germs/bacteria/infections into the sap.
I figure each day when I empty the 35 gallon tank, I can just leave a little residual sap in the bottom for the recirc line to use.

I would attach something like a stainless steel fitting to the end of a small hose hose and drop it in the tank. If there is a drain, you could attach the recirculation hose to the drain valve, if you don't want something extra in the tank. Or you could connect up a rigid suction line from PEX or PVC. The sap already has bacteria in it by the time it reaches the tank.

Dave

[DRoseum]

Dr. Tim - is there much research on recirculation lines on small diaphragm pump vacuum systems and effect on yield?

Does it increase yield? Decrease yield? No statistical significance?

[DrTimPerkins]

Dr. Tim - is there much research on recirculation lines on small diaphragm pump vacuum systems and effect on yield?

Does it increase yield? Decrease yield? No statistical significance?

No need for research. Recirc (if done properly) will increase vacuum. Increased vacuum will increase sap yield by 5-7% per inch Hg of vacuum.

[Openwater]

Is there any quantitative data or even approximations regarding the realized gains from using recirc lines to keep a diaphragm pump 'wet' vs letting it run 'dry'?
I'm just curious about how much sap production I'd be missing out on if I choose not to run the recirc line. I'm still assuming that any vacuum will make my reds produce more than last year's 5/16 drops into buckets.

[Biz]

You will still get good vacuum from your diaphragm pump without a recirculation line. I have been running one or two diaphragm pumps every year without recirculation lines and get over 20" of vacuum on my red maple lines. The recirculation line gets you a "jump start" in the morning, so you get good vacuum quicker rather than waiting for sap to start running to generate the vacuum. Once running well, the recirculation line isn't helping much. The reds seem to respond well to vacuum, even with a small amount. I have not had any success with buckets on reds.

Dave

[DrTimPerkins]

You will still get good vacuum from your diaphragm pump without a recirculation line. I have been running one or two diaphragm pumps every year without recirculation lines and get over 20" of vacuum on my red maple lines. The recirculation line gets you a "jump start" in the morning, so you get good vacuum quicker rather than waiting for sap to start running to generate the vacuum. Once running well, the recirculation line isn't helping much. The reds seem to respond well to vacuum, even with a small amount. I have not had any success with buckets on reds.

All of this is correct. Recirc will help. These types of pumps are designed for moving liquid as opposed to air. They will move air (to generate vacuum), just not terribly efficiently. Wetting increases their performance, but once sap is flowing, recirc is redundant.

Red maples seem to be considerably more reliable on vacuum, however we still see the occasional dry or low-producing tapholes even on vacuum. In general however, on vacuum, you'll get good amounts of sap.

[Openwater]

Thanks for that reassurance. I think I'll forego the recirc line for this year since the tubing and mech vacuum is already new to me.
I thought my reds did pretty well last year on the buckets, but I didn't have much to compare to except for the stingy black walnuts on buckets the year before.
Heck, even if I only get 10inHg of vacuum, that's still 60% more sap production than I had on the buckets, right? For my 20 red taps on the tubing, do you think my 35 gallon collection tank is big enough if emptied every 24 hrs?

[RC Maple]

While I'm not switching all my taps from buckets, I am tapping my own woods for the first time. There are only 6 sugars and 3 silvers big enough to tap this year. The silvers though are big and have multiple trunks of tappable size. I will have 13 taps this year on these trees with three runs of 5/16. The low areas that hold water have always kept me from being able to count on carrying sap by hand to the sugarhouse. My solar powered system will have a manifold with 5/16 hose barbs for my 3 lines. I have a recirculation valve and will put a 3/16 hose barb off of it and run a 3/16 length of tubing into the tank to restrict the flow vs a length of 5/16. When sap is running and the system working, I can shut the valve off. That's my plan...