In regards to the ro systems. My set up will yield 12-14% with a starting percentage of 1.8. If I am getting behind I can run it faster at a lower finished percentage. It takes about 7 hours for me to reduce 50 gallons of sap to 7 gallons of finished ro.

Here is a link to the site that I used to build my ro system.

https://sites.google.com/view/mattatuckmadnessmaplesyrup/parts-list-for-ro

I still got some of those old cow milker buckets from the farm.

I cut the barrel so the pans just fit in on long side edges. Then bent the metal down on barrel short side of pan. So the pan is setting on the lip I bent back into the barrel..So yes really just sitting over hole I cut..Does that description make sense? The doors on the barrels are just the pieces I cut out. Sheet metal screws holding small hings where cut out came from.. I really don't close doors much. I run the blower in the bung hole on bottom below the door or even right in the door..
I did screw some metal I cut out back along the edge of the big pan. That was more about the amount of smoke coming up along side the pan, thean holding it. Had some fine white ash coming up there falling into the pan. My set up is not air tight around the pans so smoke and small bit soot does come up around them. But most draws up the stacks and I try to set up so wind is not back over pans.
The only thing I welded was the stands to hold the barrels. Made it from pipe and stuff had in my scrap pile. Like said only use them barrels stoves 3-4 days a year to cook sap. The rest the year they sit along side the small shed in left of the photo. I saw this set up several years ago when I did syrup for the first time using LP. Wanted to play around like I do with a lot of things. Use my wood burn up some of my brush and older wood piles. Just use LP to finish cooking. The only thing I bought was the pans at restaurant auction. Barrels I got were new but given to me along with 3 nice stainless bucket. Rest the iron and stuff I scrounge out my stuff.
Just Remembered I did buy the stack boot I cut in back the barrel..Originally had the old blue type pipe I scrounged from some where. That rusted away sitting around second year so I did buy the pipe in pcture.



Mac