New to me 36" X 6' Drop flu pan and 36 x 48 syrup pan. No more dumping sap. Firebox q

I have been using a 1' x 2' finishing pan on a rocket stove and a 2' x 5' flat pan on a home made arch. Worked great but not fast enough to boil what I have coming down the hill into a 300Gal IBC Tote. I have had to dump at least one full tank every year because I can not process it fast enough. Fast forward to today I got a good deal on a set of pans without an arch. They are big pans and this system will be 11 to 12' long when built. 6' Flu pan and 4' syrup pan so I have to build a new arch. I have started welding the frame out of 1.5" angle iron 3/8" thick.

With a 36" wide by 48" deep syrup pan over the fire, how big should the fire box be? I was planning to taper it down from the 36" width at the pan to 24" at the grate. I see modern arches built in a similar fashion. How deep should the fire box be under that pan before the ramp? Was thinking maybe 30" grate and then taper the ramp to the transition from the Syrup pan to the Flu pan. That would be an 18" depth on the ramp and the top of the ramp would be the start of the flu's.

Does this sound OK? Just want to make sure I have enough fire under this thing for it to work properly. Will push some air in under the grates with a cage fan. Blanket covered by 1/2 fire brick in the box and under the flu pan. Grates about 16" from the bottom of the Syrup pan.

Sound like the right thing to do?

Now I may need more sap! LOL

I'd need to measure mine, but that sounds close. I think mine might be 18" from the grates to the bottom of the pan. I would suggest 36" grates, then taper up to the drop flues. Be certain the leave space for fire brick and vermiculite under the flues. Buy the vermiculite at a large greenhouse supply, in 4 or 6 CF bage, far cheaper.
Is this pan set soldered? If yes, test for lead now (available at many hardware stores). If it has lead, ouch!!!. Banned.
Unless you have the 3/8 thick angle, 1/4" is quite ample.
Maybe you want to build in AOF (air over fire) now, even if you may not add a high pressure blower right away. AOF will radically improve your efficiency and will save wood, lots of wood. If interested, check out Proctor Maple Research, "Combustion Efficiency" doc.

Yep. You're going to need more sap.

More sap for sure. For your first boil of the season you want at least enough to boil for 3 hrs (if on sugar maples), that is what it take to get to enough sugar concentration to protect the pan from freezing. It will get some slush on top, but won't freeze solid. If on soft maples you may need 2x that. A 4x10 evaporator will boil off at least 120-144 gph x3= lots of sap (360-432 gal minimum)

Seriously? I was thinking somewhere in the 40 gallons per hour range not 120. Will this thing really eat that much sap?

The pans are not that old, I know the flu pan had a leak and it was returned to Leader for repair two years ago. I can probably look that up from the tag to be sure. So you think 36” by 36” for the grate? That would be full width and a ramp to the flu pan about 12” in depth.

it won't just be the sap that rig will eat through... you'll be burning up a LOT of wood! my bare bones 2 1/2 x 8 drop flue boils 60-65 gph feeding it at a casual pace... i went through roughly 4.5 full chords of mix hard and soft wood to make 130 gallons of syrup!

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Originally Posted by tcross

it won't just be the sap that rig will eat through... you'll be burning up a LOT of wood! my bare bones 2 1/2 x 8 drop flue boils 60-65 gph feeding it at a casual pace... i went through roughly 4.5 full chords of mix hard and soft wood to make 130 gallons of syrup!

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Full cords not face cords? The most I can tap on my own property is about 75 taps. They run down the hill in 3/16 lines and it does create a great natural vacuum in the lines. My property drops a couple hundred feet in elevation to the evaporator from the woods and I have a mix of maples but most are sugar maple. I think without any dumping I should be able to produce about 25 gallons for the year

yeah, full cords... 4'x4'x8'. a 3x10 will be boiling in the 100gph range. i don't want to discourage you but you may want to start looking for more trees to tap. i'm not certain, but i'm guessing you will have to wait multiple days to have enough sap to fire up the rig. not a big deal early in the season, but come the middle of the season, holding sap becomes a risky game!

Welcome aboard. You're sliding down that proverbial slippery slope with the rest of us. It's a vicious circle and it's just starting. As soon as you've secured a new sugarbush with about 800 more taps - then you'll need an RO. And it doesn't stop there.

I agree. About 100 gph is what I get with my 30"x10 if it's really humping on dry hardwood.

OK, You guys have helped sober me up. My goal was just to not dump any more sap with the limited time I have to boil so I think what I am going to do is just scale my project back a little and build and arch for the 3X6 Drop Flue pan. I will still need to batch but I will get great rate of evaporation so a night of boiling should produce double the results or more of my old set up and still have enough sap to run the thing for a few hours at a time. I cant wait to have 300 gallons of sap just to fire this thing up, I need to be able to deal when the tank has just 100 gallons in it as well.
Building an arch for a drop flue pan that will sit directly over 24" of fire box may cause an issue because I do not want to damage the Flues when loading wood.Attachment 21653

Will the fire box be to low in this scenario?

Thank you all for your help.

Your 36 x 48 syrup pan is meant to be above the fire and the flue pan begins at the top of the ramp. So your basic drawing is a good start you just need to stretch the arch out more and slope the ramp beginning at about 2/3's the way up the fire box backside. You will need to remember that insulation and fire brick or vermiculite will be needed to fill in the space to within about 1/2 inch of the bottom of the flues. I may be incorrect on this measurement. Dave will probably be able to give us a better answer.

I am back! LOL! First lets just say that you guys / Gals are fantastic to share your knowledge. I will post some pics of the new arch. It is coming along nicely.
New question is will my 8" stack be ok with this new 3 X 6 arch or do I need to increase the size? Looking for a new roof flashing and want to get what I need and not just fit what I have.

Thank you!

8" should be fine.