Induction Stove?

[Chief Longwind Of The North]

These things have intrigued me ever since I first read about them in Popular Science back in the mid-80's But I have never known anyone who has oneor who has any experience with them. The induction principle is sound enough, but I wonder about hot-spots, what type of metal pans work best, etc.

From my physics and electronics background, I know that cast iron is a relatively poor conductor of electricity, meaning there is more resistance than in copper or aluminum, which are both great electical conductors. If you pass a current through a resistive element, it produces heat. More conductive elements just allow the current to pass through the metal, producing little if any heat.

So that would lead me to believe that the eddy currents created by the magnetic flux in an induction stove would cause cast iron or stainless steel pans to get hotter than an aluminum or copper pan. But then again, with an encapsulated bottom, or pan with sandwiched copper or aluminum (All-Clad), the steel would still have the resistance to create heat, but the aluminum or copper would help create more even heat distribution.

In any case, I have too little info to determine how well induction stoves work, and the best pans to use with them. And though I'm not in the market for a new stove any time soon, I would think that and induction stove would have similar cooking characteristics to gas stoves, with instant heat intensity changes, unlike the lead/lag time required by radient heat electrics.

Plus, induction stoves are safer than either gas or radient heat stoves in that they can be left on high and won't get any non-metalic thing hot, as electrical induction is what causes the pots to heat up. You could place your hand on a burner thats set on high, and so long as the burner surface was cool when you turned it on, not get burned. Sounds like great technology for places that don't have natural gas available to them. But saddly, how you gonna roast a hot dog on a skewer over an inductive element. I can do that on my gas range.

Seeeeeeya; Goodweed of the North

 

[Robo410]

cast iron, carbon steel, (either plain or enameled) magnetic stainless (such as all clad). Nothing else works on induction. never put your hand on a set induction burner if wearing jewelry or if you have implants.

If your pan is good you will have no hot spots. they are $$$ but can save bucks along the way in ac bills inthe summer as your kitchen stays cooler.

If you have a standard 4 burner stove, you can add a commercial induction burner to a counter top and increase your cooking capacity without breaking the bank. THis is the route I may go as I have too many fine pans that won't work with induction, but enough to make a burner or two worth my time! THe decision will come down to cost and space in new home sometime soon. It gets very high ratings from many chefs including Ming Sai.

 

[Michael in FtW]

I sometimes think Goodweed has a special can opener reserved just for opening a "can of worms"!

Yep - induction stove-top cookware needs iron - cast iron, steel, or magnetic (0% nickle) stainless steel. It appears that the addition of nickle to the SS mix changes the crystalline structure from Ferritic to Austenitic .... making it non-magnetic. When you see stainless steel with a x/x label the first number refers to the amount (%) of chromium, the second to the amount of nickle. 18/10 is 18% chromium and 10% nickle and is non-magnetic (Austenitic). 18/0 SS is magnetic (Ferritic).

Since the magnetic field should be evenly distributed over the bottom of the pan - I can't see any potential for hot spots, unlike either gas or electric elements which provide heat in "rings" and depend on thermal conduction to distribute the heat. I am curious about how far the effective magnetic field extends ... like, will it generate any heat in an empty pot sitting on a adjacent burner?

I was really curious about the All-Clad SS - and why it works on induction stoves. It turns out that their 18/10 SS cookware (only advertised as being 18/10 SS with an aluminum core) is only on 18/10 on the interior layer - the exterior layer is 18/0 SS.

Depending on the range of the magnetic field - there may be equally efficient SS cookware alternatives (bottom encapsulated) from HSN or QVC or other sources.

 

[Chief Longwind Of The North]

The strength of the magentic field is inversely proportional to the distance from the scource. I could look up the info in an old physics book, but off hand, the field strength from adjacent burners should have little to no effect on pots.

And any conductor will have eddy currents induced into it by alternating magnetic flux lines. So I would think that aluminum and copper should produce heat, as they are not perfect conductors either. But I would think that the high, natural resistance of iron and steel would make them more effective cooking vessels as that resistance would generate more heat.

Also, as the magnetic fields interact directly with the base metal of the pots and pans, and there is little radiant heat loss from the source to the to the pan, the energy transfer would be more efficient. And because you can instantly modify the strength of the field, you have instantaneous temperature control, except for the time it takes for the cooking vessel to get rid of the heat it contains.

Thank you both for shedding some light on this subject for me. It will allow me to give more informed advise to my children as well as make future plans for myself.

Seeeeeya; Goodweed of the North

 

[Robo410]

You bring up a good point about temperature control. As cast iron holds heat well, and aluminum encapsulated in 18/0 SS is a moderate conductor either way, one would get the best results with carbon steel such as deBuyer pans, and Dansk casseroles (enamelled heavy steel) Certain Daniel Boulud pans have carbon steel in them (but not all). And of course Carbon steel woks etc.

If you have never tried a deBuyer pan (French restaurant carbon steel) you are in for a real surprize. Nothing browns like them. And the cost is no more than Lodge Logic.

I still think heavy copper/tin lined on gas will give the most complete heat control.

SO I would like 3 cook tops in my new kitchen, and two wall ovens, and...!!!!

 

[Chief Longwind Of The North]

My flat-bottomed Atlas Wok is a high-carbon steel product that is well seasoned, just like my cast iron. And y0ou are abosolutely correct when asserting that the material sears and browns meats wonderfully. And the other great aspect of this very large wok, is that it has a lot of surface area for dissipating heat. That is, it cools rapidly when the flame is removed. However, because it cools quickly, more energy is required to keep it at the desired cooking temperature.

So again, everything is a trade off. To get one quality, you sacrifice another. I think that wok would be a natural for inductive heat.

Seeeeya; Godoweed of the North

 

[Chief Longwind Of The North]

Oops. I gave the wrog formula for the magnetic field strength. The strength of the field is inversely proportional to the square of the distance, or in other words, xgauss=1/(d multiplied by d) where x is the field strength and d is the distance.

Seeeeeeya; Goodweed of the North

 

[Andy M.]

Darn, Goodweed. I was right in the middle of building an induction stove and now I have to go back and start over!

 

[Chief Longwind Of The North]

Darn, Goodweed. I was right in the middle of building an induction stove and now I have to go back and start over!

"Vell, my dear frrrreind, zhust make zhure that you prrrroduce yourrrr stove with prrrecision Doiche trrransformers, and adhere to the Tesla prrrinciples. Ya, then you can be assured that you von't exceed the limitations of the Denmark treaty of 1842, that specifically specifies the requirements for a prrrrroper induction stove field strength, measured in joules of course.

And for all of our Doiche freinds out there, please don't be offended by my weak attempt at humor. In truth, German engineering is a thing of beauty.

Seeeeeya; Goodweed of the North