Fabricating an Evaporator Pan

[Urban Hillbilly]

I'm moving up incrementally from the batch method using a double burner turkey fryer with two 40 qt stockpots to a cinder block arch in the back yard tapped into the natural gas line from the house. I have an ultimate dream of building a multi-use rig on a trailer (evaporator/BBQ pit/grill/griddle/pizza oven) but that is for a future season.

Trying to be cost conscious, I have a local commercial welder who will fab an evaporator pan for less than I can find on line and no shipping charges. I am looking at a 2x6 continuous flow flat bottom pan with a draw off valve. I have a couple of questions.

- Is there anything magic about the fact that almost all the pans I see on line are 22 gauge? My guy is telling me 16 gauge will be a lot easier to work with. Any reason that will be a problem if I am not that concerned with weight?

- I'm not looking for a piece of art so is there a real reason for mirror finish if I don't care about it?

- I realize there is a constant hunt for efficiency but knowing that I can make perfectly good syrup in an old camp pot over a fire, are there any known pitfalls a newbie building his first pan would likely make thus should be known going in to this?

Thanks,
Urban Hillbilly

[Starting Small]

I dont know much...even my wife will tell you that....but from what I understand Stainless Steel is a poor conductor of heat, so by going with a thinner material (22 guage) more heat will be transferred to the sap that if a thicker guage is used. The other questions I am not sure of the answers to. Good luck!

[jmayerl]

16g will not transfer much heat thus not really evaporate very well. Most any person can weld stuff that thick. 22g needs to have heat sinks when welding, not to mention you have to be pretty good at it. That is why it cost more to get a real pan made.

[Big_Eddy]

Thicker will take longer to get up to speed and will not transfer heat quite as efficiently, but it doesn't really matter. Just put the gas to it and boil away. You're going to see such an improvement from the stock pots that you won't need that last bit of efficiency.
16 gauge is a lot easier to weld but will cost more to start.
You don't need a mirror finish - heck you don't even need stainless really.

A 2x6 flat pan needs lots of trees to keep it boiling and ~150 gallons boiled off before the first draw. Plan on 100+ trees or lots of storage space. Otherwise my suggestion would be 2 2x3 pans linked together with a valve instead of 1 large pan. More flexibility and you can fill one pan with water on a slow day if needed.

Good Luck with the expansion - love to see growth.

[smokeyamber]

Ok, first post this season. For cheap do your pans in mild steel. You can go thicker since mild steel transfers heat better. You can also mig the mild steel and it is much easier. I built my 2x5 setup with a 2x2 and 2x3 mild steel pan combo and I certainly am not a expert welder.:confused: You can eventually go stainless, but my syrup was plenty tasty from steel :D

[Urban Hillbilly]

Thanks for the comments. I don't have that many trees so I think I will go with the 2 pan strategy. Very good point.

Another question:

When I link them together with a valve, is it simply a matter a gravity that causes it to flow from one pan to another assuming that my back pan with the less concentrated syrup is more full?

[ericjeeper]

Thanks for the comments. I don't have that many trees so I think I will go with the 2 pan strategy. Very good point.

Another question:

When I link them together with a valve, is it simply a matter a gravity that causes it to flow from one pan to another assuming that my back pan with the less concentrated syrup is more full?
I disagree with the two pan theory. You are going to have to keep the back pan wet at all times..It will boil off as much as the front.. Why carry water, when you can be evaporating sap.. I have a 2x6, just pull it off and finish in a pot if you do not have enough sap for a full batch. roughly 2.5 gallons of syrup, to keep pan wet.

[jluckay]

i made mine from 22gage the guy had a real hard time welding it(thin). should be some pics on my profile , 17x54 flat pan, i had it modified last year. i had a amish guy put drop flues in it, we pull the pan off & finish in a turky fryer. seemes to work pretty good. i get ruffly 15-18 gph. on wood with forced air through the ash door. i used a old riteway wood burner for the arch , cut the back out & lengthened it. i also ran copper tube around my flue, that goes from my holding tank to a piggyback prehetar pan, the sap runs thru the tube to quickly to be effective, i have a ball valve to reguale the flow but its usually wide open to keep up, so i wouldent recomed it, although it looks cool . lol

[jluckay]

one more thing, i dont know how your planning on setting yours up? when i made mine i first made a frame out of angle iorn that my pan would fit into firmlly, that way u can disign your arch around the angle & simply weld it on, i also ran fire rope or door gasket around the angle so it would seal good, i welded nuts on the outside of the angle (4 places) . that way with long bolts & washers you can clamp your pan in so it will not warp. just my two cents if it helps.

[Big_Eddy]

I disagree with the two pan theory. You are going to have to keep the back pan wet at all times..It will boil off as much as the front.. Why carry water, when you can be evaporating sap.. I have a 2x6, just pull it off and finish in a pot if you do not have enough sap for a full batch. roughly 2.5 gallons of syrup, to keep pan wet.

Eric - I respect your opinion, but I still suggest a 2 pan setup adds flexibility that benefits the syrup-maker with fewer trees.
A 2x6 1" deep holds 7 gallons of sap/syrup. When carefully managing the final boil down before taking off you can get that down to 3/8" or so, assuming a dead level pan and very careful monitoring of the heat. 3/8" is ~2.5 gallons of syrup as you say, or about 100 gallons of sap into the pan.

For someone with 20-30 trees, a joined 2 (or more) pan setup allows them to either run a semi-flow process, or to split into 2 batches and take off syrup from the front pan while still boiling sap in the rear. Other than a bit more welding and a valve, there is no downside, but the additional flexibility is useful if you don't have a lot of sap. While you have sap - boil in both pans. As you're getting down to the end, get all the almost-syrup into the front pan, close the valve and fill the back with 2" of fresh sap. Now you can finesse the front pan to syrup without worrying about burning the back pan.

Otherwise you end up trying to reduce 2-3 gallons of semi-syrup down to a gallon in a pot, and that takes so much longer than in the pan.

Different perspectives.

[smokeyamber]

+1 on two pan... the connection plumbing isn't hard and as mentioned you can isolate down to a small front pan when you run out of sap... real handy.

On connections I would suggest dropboxes, particulary on the syrup pan so you can drain it fully.

I ended up with only 1/2" of near syrup last season and lifting the front pan to drain it was not fun... :o