Induction cooktops - go or no go?
March 20, 2007 7:02 PM   Subscribe

Has anyone had experience with single plate counter top induction hot plates such as these? If there are engineers out there is there some reason why these units shouldn't work as well as inbuilt units? If people have had experiences with induction cooktops in general that would also be appreciated. I've looked around and couldn't find many reviews except those on Amazon.
posted by sien to Home & Garden (9 answers total) 2 users marked this as a favorite
I don't see any obvious reason why a free-standing induction unit should work substantially differently than a built-in induction unit.

As to whether they work better or worse than resistive coils, that's an entirely different question. I would tend to think that they'd be better at heating up and cooling down than resistive coils, but. but...

The "how it works" documentation makes very clear that you have to use steel or iron cookware; aluminum and copper and ceramic and pyrex are no good.

If I had a pacemaker, I wouldn't want to be anywhere near one of these when it was in operation. I bet they'd do a job on a digital watch, too, if the cook is wearing one. A mechanical watch with ferrous parts would be even worse.

They say that maybe, someday, a new version of induction units will work with any kind of metal cookware. If I was wearing a wedding ring I wouldn't want to have that kind of induction unit; it could cost me my finger.

They make some claims about safety here but I don't buy that the situation is quite as absolute as they say, e.g. "while an element is actually working, all of its energy goes into the metal cooking vessel right over it--there is none left 'floating around' to heat up anything else." I believe that most of it goes into the cooking vessel, but I don't buy that there is none at all for rings, digital watches, and pacemakers, the latter of which wouldn't need very many milliwatts to get thoroughly loused up.
posted by Steven C. Den Beste at 7:24 PM on March 20, 2007

Haven't cooked much on them. I needed to have very flat bottom pans for the ones I've used to work. If you have alot of cookware you may not want to give them up.
posted by pointilist at 9:24 PM on March 20, 2007

I've been using an induction stovetop (the inbuilt kind) for the last six months or so & find it pretty good; much better than the crappy old regular hotplates I had before: in my case almost all my pots & pans were already 'compatible;' it's a quick & a responsive heat, although it still doesn't feel as 'natural' as cooking over gas, for example. I wear a wedding ring while I cook & have experienced no problems.
posted by misteraitch at 6:59 AM on March 21, 2007

Best answer: We've got one and use it for cooking in our camping trailer. The propane stove is just too stinky & you have to vent - not fun during a Colorado winter. Yes, you have to use pans that will accept the induction (duh). We picked up a few at Marshall's/TJ Maxx - check for magnetic properties in the store.

Practical How It Works - seems to take longer to boil water than our gas cooktop at home but less that the propane. Everything else takes a little less time.

Safety - It works on the magnetic properties of induction. As in move a magnet through a wire winding & electricity is produced. Any "energy" is transferred directly to the pan because it is the pan that completes the magnet. So, there can't be any energy floating around the unit. The only way to transfer the energy is through direct contact of the unit - with a magnet.
Give it a try. Turn the unit on without a pan on top. Ours won't even start. It knows that the circuit isn't complete without a magnet. There is some latent heat on the top of the unit just like with a regular stovetop. You wouldn't want to put your hand on or near an operable burner no matter what type is it.
posted by TauLepton at 7:06 AM on March 21, 2007

Best answer: The major difference is that most built-in stoves have a dedicated 220V connection that's rated for 20A (I believe). So an inbuilt induction stovetop would be able to pull way more power then a freestanding model, which probably draws 12A-15A at 110V.

Other than that, I would expect them to be the same under the hood.
posted by GuyZero at 8:49 AM on March 21, 2007

I'd almost prefer a standalone unit to an in-built range (or, if ever available, a hybrid range: half induction, half gas). Induction is not always preferable to gas.

Some of the best pans out there just don't work on induction: copper and aluminum (magnetized stainless steel clad pans are available through All-Clad and Demeyere, but these units are usually thinner than their non-magnetic counterparts and have lower heat capacity).

An induction unit would be nice for cast iron and steel-clad pots and pans, though.
posted by stance at 10:21 AM on March 21, 2007

TauLepton, it isn't quite that simple. It's true that the unit has a sensor for whether there's a large magnetic mass nearby and won't turn on if there isn't. But saying "Any "energy" is transferred directly to the pan because it is the pan that completes the magnet" isn't right.

The induction unit creates an intense alternating magnetic field. This creates eddy currents in the steel/iron pan, and since the metal isn't a perfect conductor, the pan heats up from the resistance of the metal.

The magnetic field does fold in on the large metallic mass, but I don't like words like "all" and "nothing" in this kind of case. Like gravitational fields, electric fields and magnetic fields extend forever. The only real question is the amplitude of the field. When there's a pan on the induction unit I'm quite happy with the idea that the effective field strength at a distance of a foot or two is negligible, but in the immediate vicinity of the pan, especially near the edges on the underside, there could be non-negligible fields. Moreover, the eddy current in the pan will itself create a magnetic field, and that's going to extend upwards from the bottom of the pan at least a little ways. (That's how the energy gets transferred: the inductive heater has to fight against the induced magnetic field of the ferrous pan.)

These kinds of things couldn't be sold without government approval, and the groups that do that kind of thing tend to be really conservative, so I'm confident that there is no important danger. But if I had a pacemaker I wouldn't want to come anywhere near one of these things.
posted by Steven C. Den Beste at 11:35 AM on March 21, 2007

My mother, several years ago, put an induction range into their new house. Within a few weeks, she took it back. Why? Because none of her existing pots and pans were flat enough to work with the range. She spent a few months afterword, going to different appliance stores, with her favorite soup pot in hand. All of the induction ranges she tried couldn't deal with her the not-perfect-surface of her cookware, she gave up and went back to a regular electric.
posted by nomisxid at 2:19 PM on March 21, 2007

Response by poster: Hey, just to follow up on this. I bought one of these plates based on the advice here and it is really fantastic.

The control is similar to gas and it's very easy to use.

The only thing is the issue with pots. Some of mine work, some don't. One useful bit of advice for anyone else considering buying these is to test their pots with 'the magnet test'. If you can stick a magnet to a pot it will work on an induction setup. If not, it won't.
posted by sien at 5:42 PM on April 10, 2007

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