Interesting discovery. What brand is the carafe and from what material do you think the bottom of it is made?

I have a stainless steel turkish coffee pot. Magnets don't stick to the surface, just like there are stainless front fridges that magnets don't stick to. But it's still steel and the iron molecules still jump around.

I think this is more of a misunderstanding about the magnet test. The test is "Carry a magnet in your purse. If it sticks well to the bottom of the pot, it'll work on induction." That doesn't mean that it won't work if it doesn't stick. Just that it's unknown if it'll work, or that it might not work as well as something that sticks well. The magnets in your cooktop are a lot stronger!!

It also depends on which cooktop. The turkish coffee pot doesn't register at all with Mr. Induction (Sunpentown portable), but works on the Gaggenau (though the Gaggenau makes a funny sound--not sure if that's because of funny steel or because the pot is barely big enough. It's a low rumble that seems to be coming from the unit, not a whine like comes from the pan). The Gaggenau also works with my Le Creuset grill/griddle which has a lip edge. Mr. Induction does not.

If your old cookware has aluminum or copper bottoms there's probably too much mass between the inductors and whatever steel content there is to make it work.

Solution to the riddle: There are things on the margins that work so long as they have iron in them.

Or you have a lot of iron in your water supply.

=P

certianly those carafes are not glass! But they are probably steel, not aluminum.

Thanks for the clarification. Yes, I thought they were aluminum until I tried them on the Miele cooktop. They're some kind of plastic on the top, and the bottom half must be steel. I was really glad my old cookware didn't work on it, since I had already replaced it based on my testing it on a portable hob. :)

The carafe is probably stainless steel. There are several types of SS formulated for differing applications. Not all are magnetic.

Induction cookers don't absolutely require magnetic cookware to work. They do require conductive (metal) cookware. Ferromagnetic cookware works best. Anything else that works with the cook top will be less efficient.

Non-magnetic metal cookware may not work well, but it may still heat up to some degree, unless the induction unit's pot detection circuitry doesn't "like" the pot and shuts the hob down.

Magnets are primarily attracted to ferrite. Ferrite is iron molecules arranged in a body centered cubic structure.
The most common stainless steel is the 300 series with a high percentage of nickle along with chrome. This material is primarily Austenite. Which is iron in a face centered cubic structure. this is non-magnetic in the annealed state, but may become slightly magnetic when heavily cold worked. It is not hardenable by heat treating.

400 series stainless contains a high percentage of chrome but usualy little or no nickle. it contains a high percentage of ferrite and is attracted strongly to magnets. It can have corrosion problems when heat treated to a high hardness. This is likely the cause of some complaints about "stainless" that rusts.

A couple other metals are very weakly attracted to magnets, but my memory fails me . I can't remember which ones.

If your pot is layered with a magnetic material on the inner layer, that could also cause some strange behavior. a typical refrigerator magnet is very small and has very little range. It will seem to be super strong when you pull it off a metal surface, but if you hold it even a 1/16" away, it will just drop off. this would make it seem that your pot is "non-magnetic" . Your stove is sensing the magnetic inner layer.

Thanks for the deetailed explanations. The water in the carafe came to a boil quickly, which sort of surprised me. I tried a small magnet inside the carafe and outside. It wasn't attracted at all to the carafe. I think I'll try a stronger magnet and see if there's any attraction at all. It certainly doesn't seem so. And we were actually relieved to confirm that our old cookware was incompatible, since we had already 'traded up' for magnetic cookware.

On another note, one of the small hobs is quite finicky, and doesn't work most of the time. It will (usually) go on, but it shuts everything off when we try to adjust the heating level. So we already have to make a service call to Miele.