continuous flow vs batch pan

[theguywiththename]

I'm geting ready to construct a pan for maple syrup. I have 18 taps on roadside maples that by the end of the season, yield an average of 1.75 gallons/day. My dad wants to just get 3 20"x12" steamtable pans and use them. I would like to see a continuous flow 2x3 pan for many reasons including less of a risk of burning the syrup. His only concern is that my average day, 31.5 gallons, would not enough to run the pan like a continuous flow pan. Is he right? From my research, I have decided that after the 17.3 gallons to fill it up, it should work fine. So that begs the question, which is better a batch system or a continuous flow pan?

[Pibster]

I would go with the continuous flow pan. It sounds like you wouldn't have enough sap most days to batch boil.

[psparr]

It depends on the size pan you make. With the steam pans you'll get about 6 gallons an hr.
With a divided pan the same size your boil rate would be the same. About 5 hrs. boiling a day. After the 30 gallons you still wouldn't have a draw off, and once you shut down you will lose your gradient. If you leave it in the pan and wait for more sap to boil again, it will basically be like a batch boil. At least with three separate pans you could keep your densities seperate, by scooping from pan to pan. Doesn't sound like a lot of fun but it will give you something to do while waiting for all that water to evaporate.

Good luck with whatever setup you choose.

[optionguru]

I've never had a continuous flow pan so I can't compare the two but last year I had a similar situation to yours and I made an oil tank evaporator with 3 6" deep steam table pans and boiled every couple of days. Worked out great, long days but lots of fun and everything worked well. I got an evaporation rate of about 7gph. Made some modifications for the coming year to up that a little and more than double my taps. My deciding factor was I made my whole set up from stuff I had laying around the shop. For the amount I produce I couldn't justify spending lots of money on pans.

[jrgagne99]

After the 30 gallons you still wouldn't have a draw off, and once you shut down you will lose your gradient. If you leave it in the pan and wait for more sap to boil again, it will basically be like a batch boil.

You can preserve your gradient from day to day if your dividers are seam-welded (not just tacked), AND if you make some slide-in baffles to seperate the channels after shutdown.

[Ausable]

I'm geting ready to construct a pan for maple syrup. I have 18 taps on roadside maples that by the end of the season, yield an average of 1.75 gallons/day. My dad wants to just get 3 20"x12" steamtable pans and use them. I would like to see a continuous flow 2x3 pan for many reasons including less of a risk of burning the syrup. His only concern is that my average day, 31.5 gallons, would not enough to run the pan like a continuous flow pan. Is he right? From my research, I have decided that after the 17.3 gallons to fill it up, it should work fine. So that begs the question, which is better a batch system or a continuous flow pan?

Howdy - I have boiled sap both ways. Batch boiled for years on a 30" x 30" pan with about 40 taps and did ok - I could start a boil with 30 or 40 gallons of sap and take it down to syrup - no trouble. I have had a small home built 2' x 5' continuous flow pan for about 5 years now and I have 55 taps of my own in and my Son and Grandsons tap another 50 - 100 trees and haul the sap up to me to boil. For the small 2' x 5' continuous flow pans I need at least 100 gallons of sap to even think about a boil or it is not worth firing up. Even a little continuous flow rig like mine is much faster than batch boiling. Batch boiling is more relaxed and You really don't have to watch things to close till you get near syrup. My continuous flow is a basic setup - no float control or auto draw-off and it keeps me busy and I have to pay attention to business when boiling by myself - but - I really like it. Yep - Your Dad is right - You have to have lots of sap for a continuous flow - the larger it is - the more you need. Hey! Have lots of fun making maple. -----Mike-----

[Ausable]

You can preserve your gradient from day to day if your dividers are seam-welded (not just tacked), AND if you make some slide-in baffles to seperate the channels after shutdown.

I agree 100%. In my little rig I have isolation plugs with handles - same idea as the gates. I have an isolation plug between my last sap section and my first syrup section and another between my middle and last syrup sections. When You run out of sap or just want to shut down and keep your pans sweet so you are ready to go at the start of the next boil - You just insert the isolation plugs or close the gates. As the rig cools down and if the gradient is getting low just scoop ahead to the next isolated sections and add sap to the sap sections till you are happy with all the levels. When You fire up again - check all your sections level - Start making steam and remove your isolation pugs or open your isolation gates and you are back in business. Kind of basic - but you get the idea. Hey! - Don't be offended - this information is for the new syrup makers. Have Fun making maple. -----Mike-----

[eustis22]

Um..how much sap would you say one would require to make a continuous flow 2 X 3 pan effective? When I batch boiled last year I boiled 2 times a week when I had at least 50 gallons. I spent some money on a divided pan, because upgrading is what EVERYONE does :)). Now I'm wondering if I jumped too soon. I don't think my pan has plugs (will check tomorrow) for the dividers to maintain gradient. Are these handmade or manufactired by someone? I figured niter wouldn't build up in continuous flow but clearly I am wrong about that....I can switch ends easily enough but how bad will the buildup get? Will it necessitate me stopping midseason to empty the pan and clean it?

I'ma gonna have to drop more more taps in, aren't I?

Rats. :)

[Big_Eddy]

The decision that you need to make is whether you want to finish off ALL your sap each time you boil, or if you want to leave sweet in the pans between boils.

Assuming that you want to finish off each boil (batch)
With a 2x3 pan (no dividers), you need somewhere near 80 gallons of sap to be able to finish off in your pan. That would be your minimum batch size if you want to empty the pans out after each boil and not have to further reduce substantially in a smaller pot. With steam table pans, you would only need 30-40 gallons as you end up with almost all your sap in the last steam table pan and can fill the other 2 with water when finishing.

Assuming you plan to leave sweet in the pans (flow)
With either 3 steam trays or a divided 2x3 pan, you will need ~40 gallons of sap before the first syrup comes off, after which you will make a gallon of syrup for every 40 gallons of sap you add. At the end of every day - with the 2x3 you will be leaving the equivalent of 40 gallons sap in the pan in a semi finished state. With steam trays you finish the last tray and you're leaving about 20 gallons of sap semi-sweet in the other 2.

My recommendation for someone with <50 taps is to batch boil every few days, collecting sap until 50-100 gallons on hand, then boiling and finishing it all off. Steam trays are more flexible than a non-divided flat pan as they can support smaller boils. I feel that leaving 40 gals (2 days sap and a whole day boiling!) worth of semi-sweet in the pans between boils is too high a risk for me - when I get it to that state - I want to finish it off and get it into bottles.

Once you go over 50-100 taps - my recommendation changes.

[eustis22]

Thanks Big Eddy..it's a divided 2X3 and I can say that I will increase my taps to at least 50..I have the trees.

that should give me 100 gallons between boils, though I may add a 3rd day of boiling a week if it's a good season

[supersapper]

Howdy - I have boiled sap both ways. Batch boiled for years on a 30" x 30" pan with about 40 taps and did ok - I could start a boil with 30 or 40 gallons of sap and take it down to syrup - no trouble. I have had a small home built 2' x 5' continuous flow pan for about 5 years now and I have 55 taps of my own in and my Son and Grandsons tap another 50 - 100 trees and haul the sap up to me to boil. For the small 2' x 5' continuous flow pans I need at least 100 gallons of sap to even think about a boil or it is not worth firing up. Even a little continuous flow rig like mine is much faster than batch boiling. Batch boiling is more relaxed and You really don't have to watch things to close till you get near syrup. My continuous flow is a basic setup - no float control or auto draw-off and it keeps me busy and I have to pay attention to business when boiling by myself - but - I really like it. Yep - Your Dad is right - You have to have lots of sap for a continuous flow - the larger it is - the more you need. Hey! Have lots of fun making maple. -----Mike-----
Do you have any other pointers? This sounds like what I will be running this year.

[miner1]

With our 2x3 I boil about 30-60 gallons at a time. Try to draw off about 3 gallons at shutdown and pour (slowly) it back into the sweet side and crank the sap to the other side at start up to preserve gradient. I also tend to batch out the pan every 2nd or 3rd boil and finish it with a steam pan over propane. I tried to sweeten the pans and do the draw thing over the course of several boils but it makes for darker syrup and lots of niter build up.

[SevenCreeksSap]

I'ma gonna have to drop more more taps in, aren't I?

Rats. :)


of course you are.