flues, flats, surface area, and boiling rate

[11-Nick]

Does boiling rate "boil" down to purely the amount of surface area on the bottom of the pan? Considering the vertical and horizontal surfaces on the bottom of a flue pan, would a flue pan with 2500 square inches of surface have the same boiling rate as a flat pan with 2500 square inches? (assuming distance between arch and pan bottoms are the same, material thickness is same, fuel, sap, etc, etc, etc)
If that's the case, then a flat pan with 1250 sq in would boil half as fast as a flue pan with 2500 sq in?

[saekeaton64]

There are quite a few different things that factor into boil rate, but the sub-surface area in contact with heat and the sap is a major one.

Your question about the different pan type with the same sub-surface area. Assuming both arches are the same width; the flue pan will boil faster and better. The flue pan will be much shorter than the flat pan, which means the length of the pan will be closer to the fire source, losing less heat over distance. The next factor is that the width of each flue is narrow allowing both sides of the sap the extract the heat, again heating faster.

One more thing, the sub-surface area of a flat pan is the same size as the sap surface area, allowing the heat to dissipate quickly. The sub-surface area of a flue pan is much greater than its sap surface area. This forces more heat into the sap, improving the boil rate.

[lpakiz]

My 2 foot wide flue pan contains 16 feet of material. Subtracting 3 feet for the sides, that leaves 13 feet for the bottom of your flat pan. Even if the evap rate, per square foot of surface, is the same, (probably is!) a 13 foot wide rig is not very practical.