Evaporation rates

[acorn roadster]

After many years of using buffet pans I'm looking to upgrade to a real maple syrup flat pan. Can you remind me, is the evaporation rate still going to be determined by surface area? I'll be boiling with wood, over blocks w/ fire bricks. I could hit 8-9 gallons/hr on 5 buffet pans (24x12x4). What size pan should I get to stay around 8-10 gallons an hour? I would like to get a smaller pan but 5-6 gallons an hour is slower than I'd like.

[Kbrooks80]

Yes. But drop flue or raised flue will increase surface area. I would at least go with a divided pan and add a float box so you can go continuous flow. this changes every thing.
Add an RO unit to increase your over all rate that you can process sap.

[berkshires]

It depends on the arch, on whether the sap is preheated, whether you have blown air or just natural draft, how high the sap level is in the pan, and how efficient you are at firing. All that being said, you should expect in the range of 1 to 2 gallons per hour per square foot from a divided flat pan on a good arch running pretty efficiently with dry wood. On my Mason 2x3 with a pre-heater and AUF last year I got between 11 and 12 GPH. But another user here - Aaron Stack, just down the road from me, gets 10+GPH on a 20x30 flat pan. That's 2.4 GPH! I dunno how he does it, but I guess it can be done with a flat pan!

Gabe

[Pdiamond]

Aaron probably runs that pan at no more than an inch and a half and keeps a close eye on it. He may also use a continuous feed system.

[82cabby]

Since you’re on blocks, flue pans and the like are probably out. If you can swing a 2’x4’ divided pan you could do well and that might fit the layout of the block arch you have set up, but it’s tough to pull off the fire. As the previous folks have said a 20 x 30 is a really convenient and workable size. If there is anyway to add a small blower your rate will increase.

Choose a pan size that would work with a conventional evaporator for when you want to upgrade that aspect of the operation.

Don’t discount the possibility of a small RO, like the RO bucket or the ones d.roseum describes on his web site. (https://m.youtube.com/@RoseumMapleSyrup). A small one will push at least 1/2 the water out of your sap which reduces your boiling time.

[Gord]

Kbrooks80 mentioned the RO. How do you calculate GPH between 2 of the same evaporators? One guy has 100 gallons of raw sap at 2%. Another has 100 gallons of concentrate at 8%. They both have the same evaporators. Are they both going to finish at the same time?
When you talk about GPH, are you talking about what you physically started with, regardless of sugar content?

[buckeye gold]

You don't say how many taps your running or if this is something your planning to do long term. If you have long term plans I suggest you go ahead and purchase a full evaporator set up. You will never regret it. I think it's worth it even if you have to finance one. Look at Maple trader https://www.facebook.com/groups/1833366010251173/?hoisted_section_header_type=recently_seen&multi_permalinks=3903208123266941. There's a lot of used ones for reasonable on the market. It might take time, but you'll find one close enough to purchase and at an affordable price. Personally I'd buy new. All the manufacturers have hobby sizes. I modified an old half pint arch to accept a Smokey lakes hybrid pan with a float box and it was the best thing I ever done. If your making enough syrup to sell some you'll recover that cost in time....go for it, you'll be glad you did.

[82cabby]

Kbrooks80 mentioned the RO. How do you calculate GPH between 2 of the same evaporators? One guy has 100 gallons of raw sap at 2%. Another has 100 gallons of concentrate at 8%. They both have the same evaporators. Are they both going to finish at the same time?
When you talk about GPH, are you talking about what you physically started with, regardless of sugar content?

I missed kbrooks80’s comment, he’s spot on.

I think the above question is kind of apples and oranges. The person with 100 gallons of 8% started with something like 400 gallons of 2% and I would think you would take that into account. I guess for me the question is, overall, how many gallons of water do you remove from the sap in an hour Regardless of the method.

I think I have the math right so here goes: the guy with the 8% will net about 9 gallons of syrup so he needs to remove roughly 91 gallons of water. The guys with the 2% sap will net about 2.25 gallons of syrup so he needs to remove about 97.75 gallons of water. The guy with the 8% will finish first. I’m winging it here so someone check my math.

My trees generally run about 1.2% to 1.4% sugar so I have to remove a lot of water. I run two homemade ROs and that really reduces my boil time.

[Brian]

The thing is evaporation rate is the same except if the wood changes or the oil nozzel is altered or changed.The barmetric pressure is a big factor in evaporation also. The thing is like Mom adding salt to macaroni to make the water boil at a less temp because it breaks the surface tension, that being said, the water will boil at a lower temp. The depth of liquid is a big factor, the deeper it is the more btu's it takes to maintain the boil, the shallower it is the faster the evaporation happens. The ro just removes the water, it don't change the evaporation rate. I hope this makes sense

[Brian]

(I forgot this)The sugar in the sap changes the boiling point of the sap, the pure the water the higher the boiling point.

[Gord]

(I forgot this)The sugar in the sap changes the boiling point of the sap, the pure the water the higher the boiling point.


That's how I see it Brian. You would have to know if the original poster was boiling raw sap, or concentrated sap, in order to come up with a GPH rate. Also, all the considerations berkshires brought up. I have a flat pan and baby sit it, running 1" depth. I also added a blower 2 years ago. That blower made a huge difference in GPH. I also preheat the sap, so the actual boil never stops. I'm never introducing cold sap to the pan. 2 years ago I was running a 3" depth in the pan, until a friend stopped by and told me to try less sap, but keep on top of it. So many variables, going from 3" of sap with no blower, to adding a blower, to going to a 1" depth, changed my GPH for the better at each change in methods.

[berkshires]

One thing - I think I've heard a few times over the years, people who put blowers on block arches wind up with a lot of smoke and ash blowing out all over the place. A blower might not work out for the original poster. But even without that, a flat pan is going to give you a lot higher GPH than a bunch of buffet pans. With buffet pans there's a lot of wasted space between the pans, and a lot more outer surface area that cools the sap, rather than being exposed to the fire. But if you do get a flat pan, I wouldn't go any higher than 20x30 or so unless it's a divided pan. Seems to me that batch boiling in a big pan is big trouble when you have to move that big pan.

Cheers,

GO

[acorn roadster]

Thanks everyone for your input. I think 2 smaller pans are what I'm going to go with. I am only running about 30 taps for 10-12 gallons a year, nothing for sale, and cooking out in the woods with no electricity or shack, no RO, no AUF. I kind of like keeping things "pioneer style" and not spending much on it. I've made a ton of syrup with these buffet pans, they're just kind of a pain sometimes and I'm looking forward to trying some more serious hardware.

[Pdiamond]

My very first evaporator was given to me, and it had a flat pan that was 24" x 36". On the long sides of the pan were handles set about 18" or so apart. It took 2 people to empty the pan when it was close to syrup, as it did not have a draw-off valve. Based on my experiences with this set-up at the minimum have a draw-off valve on the pan if you get a flat pan. The better option is a divided pan, as this will usually have 3 channels, and you will be able to set up a draw-off channel opposite the incoming sap channel. Also, as was previously mentioned if you look on the facebook mapletrader you may be able to get the whole set-up you are looking for relatively cheap. Best of luck to you this year.

[Vtmbz]

Pioneer style has a lot to offer you. How I’ve seen the small batch traditional style done here: 2x3 or 4 flat pan. They came with wood handles or large rings on both sides. Charge with available sap, as deep as necessary. Boil all day until it comes to syrup, tested by sheeting off the ladle, then two people remove from the fire and pour off. This was a common method before sugar making got so intensely automated/monetized.

Im so far from that home model, I mostly think of myself as a plumbing technician, not a sugar maker. It was more fun, though much harder work for less syrup.

[Andy VT]

This is cool, I love reading about people's backyard setups.
Mine is what I call a continuous flow batch system (actually I made that up just now).
I start in a 2x3 flat plan, being fed by a hotel pan with 2 small holes drilled in a bottom corner ("valved" with toothpicks. Not really a warming pan because I offset it pretty far, and tip it toward the holes)
Thanks to a draw off valve, I feed a full-size hotel pan from there, drip by drip, which is on a round propane burner.
The hotel pan does not have a draw off valve but when it gets to where I'm ready to finish indoors, I pour that off into a stock pot to go on the kitchen stove.

The 2x3 and the hotel pan are always boiling concurrently. Sometimes the stock pot is concurrent as well. This year I plan to give myself the option of doing all 3 outdoors for more "concurrency".

One of the most fun discoveries for me getting into maple is to find out how much respect for backyarders the "big guys" have (and vice versa).