Syrup pan sizing?

[Bucket Head]

First, let the record show that I have no short term memory whatsoever. I'd probably be dangerous if I had any memory.

I asked this question, or one similar, a while ago, and can't remember the complete answer.

How are the front and rear pans sized to each other? There are 2 ft. fronts and 4 ft. flues, 3 ft. and 5 ft., sometimes 2 ft. and 6 ft. There are some that are divided 50/50. Why are some quite short compared to the overall length, and others are very long? What is the reasoning, or benefits of one over the other?

Knowing what you guy's know about evaporators, what could the maximum length of a flue pan be on a rig that had a 2 ft. long syrup pan?

I have played with the idea of stretching my arch, but now I'm wondering about possible limitations caused by improper sizing.

Thank's,
Steve

[Uncle Tucker]

I would say 1/3 would bee a good target to shot for. On the smaller drop flue evaporators, they go ½ that way the flues aren’t to close to the wood being loaded. That’s why 2x6 dropped flue is 3’x3’ and 2x6 raised flues are 2’x4’.

[3rdgen.maple]

Uhhh my drop flue 2x6 has a 4 foot flue pan. Most 2x6 i have ever seen are 4 foot. I know they do make a 3 foot dropflue I remember someone telling me for every 2 feet of flue pan = 1 foot of syrup pan. Could be wrong but pretty sure those are good numbers. just my .000002 cents worth.

[danno]

Most important point to me - longer the flue pan, better the evaporation rate. On my old 30x8, I had the 6' flue pan and on my 3x10, I've got the 7' flue pan. I've seen 30x8's with 5' flue pans and 3x10's with 6' flue pan. I much prefer the longer flue pan.

[Bucket Head]

Danno,

I like the idea of a long flue pan too.

I am trying to figure out just how long of a flue pan I could go.

I could go out and buy three flue pans of various lengths and then weld an extension on my arch, and have something like a 30"x 19'. It would not, but lets say my fire/firebox could keep all that flue pan area boiling. Pretty soon I would start to have darker and darker sap in those pans because it would be evaporating quicker than what the "small", or too short of a syrup pan could produce syrup. Right, or wrong? I don't know.

I'm trying to figure out how much flue pan could my 2 ft. front pan support?

Steve

[tessiersfarm]

I have wondered the same thing, what about adding another 4' to 6' flue pan and another 2' syrup pan at the same time increasing them proportionatly would keep the gradients right while improving evap rate.

[WESTVIRGINIAMAPLER]

Maximum is 75% or a 6' flue pan with a 2' syrup pan. Not too many rigs out there, but there are a flue with this setup. Most have a 3' syrup and a 5' flue, but you should be fine with a 6' flue.

[Bucket Head]

If 75% is the maximum, why are there so many 3/5 ft. rigs? They have sacrificed evaporation rate with the shorter flue pan. What was the benefit of the longer syrup pan?

Let's say I went over the 75% flue pan, maybe just a foot, I would risk getting the darker sap in there?

Anyone out there with a lot more flue pan than the 75%? How does it work? Are you getting dark sap in the pan?

Steve

[danno]

I'm missing the principle - I assume one of the more experienced guys would know. I would think larger the flue pan, lighter the syrup. Larger the flue pan, faster the evaporation, quicker the syrup comes off, lighter the syrup.

It's the guys boiling only on big flat pans with no flues that have the long boils and darker syrup.

My 3x3 syrup pan probably holds 10 gallons sap, but I'm only pulling off 2 gallons an hour.

[maple flats]

I don't know about maximums but mine is a 3x8 with the first 2' syrup pan and the last 6' raised flue. This does go 25/75. But I think Glen Goodrich once said in a seminar at the winter conference in Verona, NY one year that he had no syrup pan, just 18' of flue pan. I also have a guy down the road from my sugarhouse that makes several gallons every few years for friends and family and he only uses a 6x6 flue pan over a block arch, but he does do his final finish on a turkey frier.