Quote Originally Posted by spencer11 View Post
i have seen that thread to. i dont know why maple companys dont make copper pans just for the heat transfer? i know it would be expensive but i think it would be worth the extra money. i think thats why people use copper tube for drop tube pans instead of stainless. im gonna build a pan with the drop tubes after this season and just see what i get. thanks

spencer
Spencer,

Copper does have a tremendous conduction compared to stainless steel and better than many other metals. It is hard to say whether is is worth the extra cost, and indeed I don't know the extra cost.

Something to keep in mind is that the thermal conductivity is not the only thing that determines the evaporation rate. The heat has to get from the hot flue gasses into the metal, then through the metal, and lastly into the sap. In heat transfer terms, that is Convection, conduction, convection. The heat transfer (convection) from hot gases to the pan is the same regardless of material. Using copper helps the middle term, or conduction, but there is still some limitation on how fast the heat can transfer to the sap ( convection again). That means if we had a thermally superconducting pan, we would not get infinite evaporation rate.

Bottom line: If I was going to make a pan myself, I might use copper. It is easy to solder, you don't need a TIG welder,it conducts better and it looks cool. For home built drop tubes, and for preheaters, there is no question it is a better choice than stainless. One down side is it is not as strong as stainless and probably harder to keep clean.