I just bought a Duxtop Pro portable induction hob and tested it out with an oversized pan with a little water in it. I expected it to not be totally efficient considering it was hanging over the sides a little bit but what I didn't expect was for the hot spot to be one single ring in the center about 4" in diameter. Not a disk but literally a ring. Is that possibly a defect or is this normal?
EDIT: I uploaded a better picture with a cast iron pan that fits perfectly within the larger ring for max pan size. Since it's black it's easier to see the ring of bubbles where it's heating up. I've written the manufacturer but just figured maybe this is a normal thing experienced people would recognize immediately. Or, conversely, that it's not at all normal.