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Induction cooking & heat distribution

  1. Feb 5, 2015 #1
    I've been trying out induction cooking on a small one-burner unit, with a large cast iron pan. I'm getting the expected hot spot in the center of the pan, and a serious temperature falloff toward the sides. No surprise there - the induction element is about 7" (I dismantled the unit to check), and the pan bottom is about 10.5".

    So I'm wondering what can be done to even out the heat, other than cooking smaller food - and more broadly, why an induction burner would produce worse / less even results than my conventional electric burner of the same size. (Which it does - never had the issue to this extent with the same pan on my conventional stove.)

    On another forum, someone suggested that a 220v unit will have a "different focus for the magnetic fields" and that a 110v unit is doomed to having a hot spot that's even smaller than the element itself. Which sounded a lot like hand-waving, though I'll allow that more expensive sometimes means better engineering, and if it's true that power transfer is highest in the center, more expensive units may try to compensate somehow. So, questions:

    1) Can the heating of the pan be evened out with a diffuser, or clever timing, or some such?

    2) What differences exist, if any, in a "high end" unit that relate to evenness of heat transfer?
  2. jcsd
  3. Feb 5, 2015 #2
    The distribution has a lot to do with the work coil's geometry. A smaller work coil means more local heating.
    If an induction hear were designed for a particular skillet, the coil could be designed to heat in a fairly even fashion.

    It is an unfortunate nature of induction heating that it is greatly efficient with iron, but very poor with aluminum or copper. Thus the very metals that serve to spread heat are no candidates for heat production. It does make one wonder whether a more complex construction could yield a specialized skillet.

    As to why one cooker has proven better than the other, I cannot say except that the coil and the output power is most likely different.
  4. Feb 9, 2015 #3
    Give your cast iron more time to heat up before using it, it takes a looong time to charge a full cast iron skillet. I use cast iron on an induction burner and it certainly gets hot in a hurry, but takes a while (maybe 10-15 minutes) to even out.
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