We were trying a Thermador induction cooktop this afternoon, and we saw something that puzzled us. We think the unit was faulty, but we'd like to hear from someone who owns one to verify that what we saw was not normal.

The model we saw was the current 36" / 5 ring model. That model has a triple burner in the middle, with 9"/11"/13" coils. What we saw was the 11" coil never seemed to produce any heat in any of the pans we tested. The 9" and 13" coils clearly produced heat with a 14" pan. The 9" coil produced heat in a 12" cast-iron skillet and an 11" All Clad saute pan.

When we tested a Bosch induction cooktop a couple of days ago, the cast iron skillet and All Clad saute pan definitely got heated by both the inner and outer rings of the 7"/11" double burner.

The easiest way to check this is to take a roasting pan that is bigger than the center element, add about 1/2" of water, and set the center element to about 7. You will see clear rings of bubbles where the coils are heating the pans. We saw a ring around the outside and a ring in the middle, but an obvious cold ring in between.