Question - sap movement using two steam tray pans

[berkshires]

Hello forum. Noob here! This is my first time sugaring. I helped out on an operation when I was a kid, and now I'm trying it myself. It's a lot of fun!

About my little operation: I am starting small. I put out six taps on buckets and have been boiling it the last month or so on a home made evaporator. I took an old sheet-metal wood burning stove, moved the chimney from to top to the back, and cut holes to fit two steam tray pans on top. Here's a photo of it after my modifications:
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So in another post, someone with a similar setup to mine asked about sap movement, and the answers surprised me, and I didn't understand how to do what was suggested. He was doing the same thing I've been doing: Add the sap to the cooler pan, and once it's near boiling, transfer it to the hotter pan, where it then does most of its boiling. So for me, my hotter pan is the back one. I start out with maybe a gallon and a half of sap in each pan, and within a short time my back pan, which is the hotter one, is at a good hard boil. After the front one finally heats up I'll move a couple of quarts of hot sap from the front to the back, and add another half gallon to the front one. When I get close to done and run out of sap for the day, I just let them cook down a little. My back pan has lots of near-syrup in it, and the front pan has a couple quarts that I could either combine in or save for the next boil. I then finish the near-syrup on my stove in the house.

It seemed like the suggestions the other guy got were to boil his sap on the hotter pan, and have his syrup on the cooler one. But I don't understand how this would work. Let's say I start off with my gallon and a half in each pan. Say about an inch to an inch and a half. In a little while the back pan is going gangbusters, and a little while later the front pan comes to a simmer. So I'm supposed to dribble sap a little at a time into the back pan, and then do what? It seems like if I ladle some of the back pan into the front pan, the front pan will just keep getting more and more full of hot sap. If I keep the back pan at an inch full, I'd essentially be using the back pan to warm up the sap, and the front pan would just wind up with 10 inches of hot sap!

This is confusing. What am I missing?

If it helps, here's a pic of it in action:
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I'm collecting sap during this cold snap and will do my final boil of the season (assuming the sap is okay) this week. Hoping to try out the new more efficient method, if I can understand how to do it!

Thanks in advance for any helpful tips!

GO

[Bricklayer]

You will have to transfer the sap in relation to you evaporation rate. If your back pan is boiling like mad then it is obviously be getting a better evap rate then your simmering front pan. Try to transfer to the front pan while keeping a steady level then you won't end up with 10" of sap. As you take some from back pan replace it with raw sap.

[Super Sapper]

As Bricklayer said, maintain a level in the front pan by adding from the back pan when needed. Add fresh sap to back pan as needed to maintain that level. You will be adding to the back pan more often because it is getting a better evaporation rate but this is the same as using regular pans with a float.

[Tom59]

I boil the same way as you. I use a turkey frier as a pre heater. My back pan boils the hardest, so I put the raw sap in the back pan, trying to maintain 2 inch depth. As the front pan gets low I ladle from the back pan to the front, keeping it around two inches deep. Over time the front pan gets more concentrated, closer to syrup. Because the back pan boils harder, it gets refilled faster than the front. Also putting boiling sap into the front pan keeps the boil going, not slowing it down. Putting cold or pre warmed sap into the back pan will come to a boil faster than putting it into the front pan. Tried both ways and back to front netted the fastest boil rate for me. Hope this makes sense. Good luck. Tom

[berkshires]

Okay I get it. Thanks all! Here's hoping the sap is still good for my next (and last for the season) boil!

GO

[CampHamp]

I made siphons like this one using instructions from a post on this forum when I cooked on pans.
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I put them on the far corner from where I added fresh sap to help form a gradient.

[berkshires]

I had one last day of boiling yesterday. Used the new method, and made a few other changes that all improved my setup. I wound up boiling at 35% faster than my previous boil rate. Sweet! However, I discovered that I now have to keep more in the pans. I had one corner burn a tiny bit when I wasn't paying close enough attention. Oops! I'll see what it's like after I boil down the nearup. If it's too caramelized, I'll just keep it for myself (not that my friends and family will care about it, but it's a matter of pride.) :)