« on: March 06, 2012, 11:03:03 AM »
There is another important factor in the selection of material type for kettles and that is heat transfer coefficient.
Depending on how you are heating your wort and kettle, that should be an important factor. I formerly heated my kettle on a gas burner. An aluminum kettle has a far better coefficient of heat transfer than stainless steel. That means that you will heat your wort quicker in a aluminum kettle.
Martin, I don't agree with this. If you look at the Overall Heat Transfer Coefficient the conductivity of the metal is the lowest resistance in the circuit. If you heat with fire, the gas to metal has the highest resistance, the liquid is the next highest. If you run the numbers, there is negligable time difference. I actualy ran a test for 2 pats I had that were the same size and geometry. One was SS and the other was AL. The SS kettle got to a boil faster! I expected the AL to be a little faster. I think it was due to more bubbles in the AL acting as insulators (rougher finish) and more loss of heat through the side walls in the AL.
Aluminum will spread the heat better so you avoid hot spots.
This explains what I am talking about. The example is very good.