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.