Insulating an oil barrel arch and stainless pan build question.
I have been reading everything on this site I can find regarding oil barrel arches. I plan to build mine this winter but I have a couple questions. First is on insulation. I realize the reason for using firebrick in the firebox, but is there a reason that in the area where the gasses are passing under the pan back to the stack can it just be insulated with 4 inches of sand instead. and then just run brick on the outside edge of this area? This would be much cheaper (free) and I would think would insulate well. Also, I know that if you use heavier gauge stainless to build the pan you slow your GPH boil rate, but how much do you actually lose. If I were to build it out of 18 gauge verses 16 gauge would there be a noticible difference? Thanks for any input.
2016-two straws stuck in tree by the kids-1 pint syrup
2017-40 taps 8 gal. syrup
2018-70 taps...19 gal syrup
2019-90 taps....18.5 gal syrup
2020- 100 taps....25 gal syrup.....new oil barrel arch
2021- 85 taps....unknown season