After watching friends tap trees this spring, I've ordered myself some spiles and plan to take part next year.
When it comes to the evaporation phase, I know it's all about surface area. Most of my friends use the old pans on a barrel stove approach or a stack of brick/block with a fire underneath.
But I've been wondering how I might employ a j-tube burning system to do the evaporation step. Beyond adding some aluminum channelling to keep the heat on a pan longer, what modifications might I consider to make a good clean and hot burning evaporator?

My advice, coming from my first year of evaporating, is to insulate insulate insulate. No matter what type of burner you end up with, keep it sealed well. I made my evaporator from an old fuel oil tank, making the mistake of NOT using fire brick (or anything for that matter) on the inside of the tank. I also didn't use anything to help seal the small gaps where my pan sat on the burner. These two things combined resulted in several hours of burning for minimal results. The last burn of this year was about 7 hours to boil down only 25 gal. of sap next year WILL NOT be the same for sure.

Just for kicks, here's my burner without the pan