What size pan did you use on the induction cooktop.? It might have been too large for the cooktop

I have not noticed any unevenness with my induction cooking. I do not have any all-clad, but do have pans from 3-4 different manufactures, and have not noticed any bad spots. I would suggest putting water in that pan and bringing it to a boil, and see if the bubbles are uniformly over the bottom of the pan or not. You may want to try different pans on that burner and that pan on different burners.

You could have a bad spot in the pan where it's not as "magnetic" as other spots or it is slightly warped and not coming into good conatct with the surface. Then that spot won't heat like the rest - that will be noticable when simmering water.

If it happens with different pans on the same burner, the problem is the cooktop.

I re-read, you are using an induction hotplate. Then I would suggest moving the pan around on the burner if you notice a "bad" spot. This would be to see if the spot stays in the same location relative to the pan, or relative to the burner.

Another option is that you hotplate has zones, and because of the size of the pan, maybe it is only heating in a smaller zone because of the pan size. - though with my cooktop, this does not happen unless the pan is bigger than the largest zone. Then there is a noticable different in the heat on the bottom of the pan (the outer portion does not get hear as hot as the part on the zone).

And it could be that you simply got the pan way to hot - very easy to do with induction.

Bill,

It was 11" - a little narrower than the larger zone on the plate.

Macy, I was cooking on a medium heat - according to the manufacturer's instructions. If it got too hot - wouldn't it burn all over, not just in three places?

I bought All-Clad because it was supposed to be the 'best' among the 'more affordable' ones (not talking about Demeyere :-)).

And the d5 line was 'allegedly' designed with induction in mind. I am a little puzzled.

I'll try your suggestions. Thank you!

We have the Elux Icon induction cooktop (a year now).
We have the Emeril-ware--a cheaper version of All Clad alto we like them very much.

We have not noticed any heat problems you describe, and it fact I have checked the bubble pattern several times on our large skillet and at first, if you put it on the small "6inch" hob, you can see a circular pattern caused by the smaller hub, but it quickly (less than a minute) spreads to the rest of the pan. We dont recommend cooking this way, but I did this test in answering a post on another thread.

You can also watch our water boiling contest (Mojavean & I) and I kept the camera aimed at the water in the pot so you could see when and where the boiling began.
Anyway, I have not seen any other posts with the type of problem you describe, You may want to give the make and model of the induction unit you are using now,---as many people have posted, the cooktop themselves have far better qualities than these portable ones, but most of the portable ones have been usefull (in most cases), in introducing folks to induction.

I think you will be like most, when you get your actual induction cooktop or Stove, Very Pleased!
Good Luck!

Gary

What brand/make/model portable induction hob is this?

I've been using AllClad for some time now. The only thing I notice is that it heats faster (less thermal mass) than some of the heavier (Circulon) stuff I have. The D5 is a 'new' thing for AllClad. It is 5 layers instead of 3. (Fe-Al-Fe-Al-Fe). I've been curious to see how it works in relation to what I already have.

On my 1800wt unit, '5' would be too hot for pancakes. It would definitely smoke the oil at that setting.

You should put the pan on the unit, put enough water in it to cover the bottom about 1/4 inch, then turn the unit on. Watch the pattern of the bubbles on the bottom as the water starts to boil. It should be like a doughnut, a round ring with a hole in the middle. It should boil evenly all around.

Your results sound very weird. I know my portable is much pickier about pans than my built-in. Clad pans work on induction in general, but it's possible that there are spots in the steel that are denser than others. It's also possible that the way the hotplate works to modulate power is to heat in patches rather than to heat evenly, lower. I know some microwaves do that.

My advice would be to made some batter and take it and your pan to a showroom where they have the unit you're getting plugged in, and try it out. It might be fine.

Even if it's a problem, I'd get a new pan rather than sacrifice the cooktop and go back to gas only. My pots have always been cast iron. I did make pancakes on my Mr. Induction and they came out fine. Actually heated more evenly than the old gas.

The hotplate is Magneflux 3003 Induction Unit.

This evening, I experimented with the heat level and also tried making pancakes in both skillets (9" and 11" - they came as a set) but did not like the results. Though I was watching closely and did not burn the pancakes they did cook unevenly and did stick.

I seriously doubt that the problem is with the skillets because they both do wonderfully on gas and require minimum attention.

All-Clad offered me to send them back for testing but before I pay those high shipping fees - or return the skillets to W-S, I'd like to figure out if the problem is with the hot plate.

Thank you so much for the suggestions!!!

I'll boil some water in the morning and report back to you.

Eleena

This IS weird. My only speculation is that the 5-layer pan has issues due to that middle layer of steel.

You might talk me into getting one and testing it on my Cooktek.

BTW: you aren't using a temperature setting on that Magneflux, are you?

Weedmeister,

What do you mean?

It has 3 levels of heat (Low, Mediaum, and High), each with 3 temperature settings: 150, 175, and 200 for Low, 250, 300, and 350 for Medium, and 400, 450 , adn 500 for High. I have not used the High settings recently because the instructions for all my cookware said not to use high heat.

So far, I have used all 3 Medium heat settings (up to 350) and the higher two on Low (175 and 200).

Any thoughts?

Eleena,

Because of the way clad pans are made, and because of the way induction works, a pan that works perfectly well on gas could indeed be funky on induction. With All-Clad, only the steel layers will create heat.

Induction uses magnets to excite the molecules in iron (steel). There are a few ways of making this happen, so it's also entirely possible that different induction units behave slightly differently.

Re temperature settings, some fancy units have sensors that try to determine the actual heat of the pan. Other units (including my hotplate), use a temperature label as a reference point to help users understand the meaning of settings 1-9. These aren't actual temperatures the unit achieves, just the temperature the engineers expect is most likely to develop on that setting based on their design (and, hopefully, testing). That is, it's imprecise.

Some people are very satisfied with clad pans on induction, but not everyone is. Clad is great on gas because the steel gives you density and the aluminum and/or copper spreads the heat faster than iron alone. On induction, the heat develops in the steel layers and then has to make a thermal transfer to the other layers. Sometimes this leads to buzzing. The pans heat differently if the cladding goes up the sides or is just across the bottom. Some people have clad pans they like just because the sides don't get hot. Others only want pots where the sides get hot. An all steel or all cast iron pot heats very evenly across the bottom. It will also up the sides, though the greatest control (fastest response) is where the pan is in contact with the glass surface (or, on most built-ins, within 1/4" of the surface). I don't know if cladding aids the thermal transfer up the sides, or hinders it.

In my own experience with non-clad pots and pans, my favorite pots on gas aren't my favorites on induction. The ones I liked with gas had curved bottoms. Chefkev once explained why this shape was so great, but I forget. On induction, however, I like the ones with more flat bottom surface in contact with the glass. On gas, the flared sides of the rounded pans heated from the heat lost where the flame heated the air around it. As the air rose, it heated the rounded sides. My flat bottomed, cast iron pot wasn't a favorite because it took a long time for the sides to get hot through thermal transfer, because the hot air just went on by the straight sides. Same pan is my new favorite on induction because it heats faster/has more control, with the larger contact area, and the sides heat faster than the rounded ones because the pan heats faster in general. Whereas the rounded and flared old favorite has significantly smaller bottom area for the inductors to excite, and much more side area waiting for the heat to spread on up, since there's no hot air rising to heat the sides. I don't know if I explained that well. Jist is, you'll probably find that you like different pans best with induction than gas, even if the material they're made of is exactly the same on both.

I'll repeat, however, that I wouldn't let a pan get in the way. If you're able to go do some experiments, see if they have some different kinds of pots for you to try.

did i miss something? I think it's worth testing whether the portable induction appliance causes the same problems with various and sundry other steel pots and pans. Thin ones will reveal heat flaws more readily than cast iron ones.

Both my old Stupentown and my current CookTek have temperature modes of operation. They are different than the straight power setting mode. In temperature mode, there is a sensor. It uses full power until it sees the selected temperature. I burned a lot of meals until I realized what they were doing. Now I use it to maintain a current temperature but not to start cooking.

However, reading the user guide for the magneflux, it sounds like the temperatures are meaningless. So that kinda brings me back to the D5 pan. That middle layer of steel is there supposedly to strengthen the pan and prevent warping over time. Steel is not a good conductor of heat, but aluminum is, as well as copper. Perhaps it is interfering with the normal induced heat pattern some how.

But that would be strange.

Here is what I did.

1. Made hash-browns in a cast iron round pan on the induction plate. The pan definitely required a higher temperature than All-Clad. If All-Clad started burning food at 350, the cast iron was merely simmering the potatoes at that temperature. I had to go to 450 to get the desired results.

(It has been my experience with this unit all along that switching temperature setting does make a difference).

It also took a lot longer than when I made hash-browns in All-Clad last time.

This is consistent with the All-Clad's claim of needing lower heat to cook and cooking faster.

The potatoes did not burn in cast iron but I am not sure how even was the cooking - I had to turn them a few times.

2. Boiled water in an All-Clad 4 quart pot. The bubbles developed in a doughnut pattern around the center. I waited a few minutes and did not see any real bubbles anywhere else (except for a very few tiny ones).

3. Boiled water in the same pot on gas. The bubbles were mostly around the bottom edge but there were also a few across the entire bottom.

4. Boiled water on the induction plate in a 6 quart Tramontina pot with a sandwiched bottom. The bubbles were again mostly in the middle with quite a few tiny ones along the edge. This time, it was not a doughnut pattern but - more or less - the entire interior of the formed circle in the middle had bubbles. There was also some 'humming' with this pot (not so much with All-Clad or cast iron).

Does any of it MAKE ANY SENSE and provide any evidence about the origin of the problem?

I did a LOT of reading on this website before deciding to spend a 'small fortune' on All-Clad. I thought it was supposed to heat evenly (due to 'layering' of steel and aluminum) and to conduct the heat from (however uneven) source evenly across the bottom and to the sides. Am I missing the point?

Thank you!

Is the stock pot a D5?

The All-Clad pot was d5 brushed stainless while the skillets are d5 but not brushed.

I have a set of Circulon Infinite and one enameled Chantal pan. The Circulon is Al with a Fe bottom. It makes noise on the induction cooktop, mostly on higher settings. The Chantal is silent. The Circulon heats fairly evenly, but not as fast as the Chantal. My wife makes pancakes in the Circulon griddle and they looked pretty good to me. The Circulon cleans up very easily. The Chantal cleans up pretty well, but the enamel is not as good as true non-stick. I like both pans for different reasons. The All-Clad was too pricey for me. If I were going SS clad I'd either do the Tramontina or those new pans from Marcus what's-his-name.

I won't be buying any more Circulon. One of the pans in the package was damaged and they promised to replace it but they never did. I'd happily buy another Chantal. I want to try SS Clad, probably Tramontina.

Texas,

Not all my cookware is clad. I have two Tramontina stock pots in two different sizes and several cast iron pieces. I had some other older SS pieces with sandwiched bottoms but got to the point that I did not want to cook in them anymore.

After doing much research, I bought a small All-Clad sauce pan to test-drive clad and noticed that both DH and I were always reaching for it first (with the old ones still around). So I added a 4 qt pot and two skillets to complete my 'collection' (though still debating whether I need an enameled cast iron dutch oven). Yes, they are expensive but they are supposed to last lifetime and look good after many years of use. When I add the cost of the "cheaper" cookware I had to replace, it turns out not so cheap after all.

I was cooking on gas and did not get the induction hot plate out till a few days ago when the heat wave came. I did not notice any problems with either the sauce pan or the pot because I was only boiling things in them (e.g., oatmeal or quinoa - don't have time for "real" cooking now). The 'trouble' started when I made hash browns and pancakes in one of the skillets as I described above.

What confuses me is that AC d5 is made with induction in mind and I cannot figure out what's wrong with the picture.

Just made pancakes on the induction plate in the cast iron pan I used yesterday for hash-browns. (Why didn't I think to compare apples-to-apples to begin with? Didn't think it was that important, silly me.)

It required high heat as at 350 it did not cook at all but at 450 started burning.

"Uneven" does not come close to describing the result. I barely finished the first batch and used All-clad for the second.

So, I believe the problem is with the plate, not the cookware. I am going to take it to a local showroom and try it on Wolf induction integrated module I have been "eyeing".

I'll report the results.

I'm going to guess that you're using too high a power.

My technique is to use a higher power to pre-heat, then I turn it down to cook. The AllClad heats very fast. I expect cast iron to take longer to heat up.

Remember that induction furnaces are used to melt stainless steel. So it can get plenty hot.

I hope the showroom trip helps. The Wolf should give you a more definitive result.

To answer your question, yes, you did miss something. Induction isn't a heat source. It's totally different. Radiant electric, gas, wood (anything burning) is a heat source. Induction uses magnetic fields to induce your iron to become a heat source.

Because of that difference, cladding works differently in pans and is of significantly less use.

I don't know anything about portable induction, but I made crepes on my kenmore induction stove the other day. They turned out perfectly (about 10 crepes). I set the burner to "5" and kept it there the entire time. Pan was a perfect, consistent temp each time I poured batter into it.

I used the non-stick SS kenmore pan that came with my stove.

A few months ago I attended a cooking session at the Nor Cal location of Purcell Murray. The gal had been very helpful in persuading my husband that induction was worth it and I wanted to thank her and ask some questions afterwards.

One of those questions was what is the best way to heat up our cast iron grill plate?. She said to start low around 2-3 to warm up the plate for about 5 minutes and then crank it up to 5. The next time we used the grill plate, I did it this way and was amazed at how even the heat stayed despite lots of veggies being grilled.

So, eleena, it might be worth doing a moment of low pre-heating of your pan before you try something like crepes or pancakes again.

Good Luck!

Thank you everybody for very helpful suggestions!!!

Here is my report.

Plllog, whether it is an actual source like gas or the pan itself magnetized by an induction coil, there is still some "source" of the heat. And good induction cookware should conduct the heat to other parts not in direct contact with the place being heated IMHO.

And it does! In my "Wolf test", All-Clad won over cast-iron hands down! But it did not cook as evenly as it did on gas.

BTW, this was a very good experiment for me because of which I am NOT getting Wolf integrated modules as I had planned!!! And I am re-thinking the whole induction thing.

Earth_pal, thank you for the info!

I tried but it did not quite work because the Magneflux plate is defective (by design or because of a failed element) and heats only inside the smaller zone.

I left a message for their Customer Support but the unit is out of warranty and shipping+repair may be more expensive than the unit itself, I am afraid. I'd say "don't buy it!". BTW, Cooks Illustrated did not recommend it either. I wish I had seen their report before purchasing mine... Oh well, it was not all that expensive... And it "saved" me from spending $$$ on Wolf integrated modules - so I should actually be grateful... :-)

I am now researching Bosch, Thermador, and Diva induction cooktops. DH wants to stay with gas. We are back to "square one" - but that's normal in the world of kitchen remodel, isn't it?

Thank you all again!

Eleena - What did you not like about the Wolf integrated modules? Thank you!

I know that my DH was hoping I would consider sticking with gas, but after having him do some research on gas, and seeing how fast induction can heat up a large pot of water for pasta and have it instantly come back to a boil...

Maybe your DH might be similar? Sometimes it really helps to see it in action. We really like our Bosch 500 series induction cooktop. So much easier to keep clean and it is extra counter surface!

Good Luck!

Eleena, I'm glad you found out what you needed to know at the store. There's nothing like one's own experience for making these decisions.

I would like to thank all of you once again for your helpful suggestions!

I have tried them all and now I understand much better the pros and cons of induction cooking.

Earth_pal, I am especially grateful for your tip to pre-heat slowly.

Here is a summary of what's happened since my last post.

Based on CI review, I got a Max Burton induction unit when I saw it TM for ~half-price.

Got an 11" Proline Demeyere pan (at a promotional price).

(I am giving the price-details so nobody would think I am trying to waste money - LOL).

It gets more interesting from here. According to the instructions for cooking on induction, one should preheat the pan on high, then lower to medium. Well, I did that and the pan failed my "pancake test"! Very upset, I tried the opposite: preheated on the lowest simmer setting and then switched to medium. It made a world of difference! The results were quite satisfactory - and much better than with AC.

The problems is that all (or most?) portable units have small induction coils (4-5" in diameter) and it seems that the larger pans do not get as hot (as one'd wish) close to the edges.

I am guessing that "real" (drop-in) induction cooktops have a larger coil (or more than one) on larger 'plates' and that is why you are getting better results.

I am going to start a new post about it because I called several companies and had very little luck: CS always sends to tech support and those never answer their phones.

It is very hot here and I don't want to use gas during the day. I am AGAIN inclined to do a gas-induction "combo", instead of using portable induction units in summer. After all, I need to use my top-of-the-line Demeyere pan, don't I? :-)

Sailorgal,

I did not like the sizes of cooking "areas" on Wolf integrated units.

I have the same 'hot spot' problems on my very expensive Viking induction range using D5 cookware. The center of the pan, no matter what size pan, is much hotter in the center than all areas around it.

A couple of points.

Some forums elsewhere on the net try to discourage new threads and want you to post questions in some existing thread, however old, as long as the topic has something remotely to do with what you want to ask. The culture here is different. In case you do not get much response here (and you might not because of the age of this thread), you can feel free to start your own thread with a title tied to your specific question. For example: "Hot spotting with D5 pans on Viking induction range."

So, on your specific question, I have no hands-on time with the Viking induction range, but the resident expert on them here has been Luv2Putt. Might try contacting him.

Also, have you tried what eleena recommended her last post? That is, instead of cranking the burner to high to preheat a pan and then turning power back down when the pan is hot, have you tried preheating on lower settings and then cranking up the heat to where you want to cook? (That gives the pans time to conduct the heat more evenly.)

If you have done the recommended low and slow preheat and are still getting major hot-spots, there may be something wonky with your stove. Is you stove new or at least still in warranty? Might be time for warranty service.

D5 has one additional stainless layer in the clad, which actually reduces the heating evenness in exchange of higher thermo capacity. You could check here:

Heated by gas: https://www.centurylife.org/cookware-even-heating-rankings-butane-propane-natural-gas-etc/, delta T - Stainless: 92.8; D5: 109.7

Heated by induction: https://www.centurylife.org/cookware-even-heating-rankings-induction-and-electric/, delta T - Stainless: 128.5; D5: no data, but expected worse

You can also see gas heats the cookware more evenly than induction (except induction cooktops with many little coils), i.e. for same evenness, induction requires better cookware.

Myth: Induction heating is so even-heating that it negates the need for quality cookware.

Fact: The opposite is true. In most cases, induction is more stressful than gas and electric coil/radiant in terms of spreading heat evenly:

• Induction: All existing portable induction cookers, and most non-portable induction cooktops and ranges, use large induction coils. These induction coils generate an “O”-shaped hotspot in the cookware above. This is extremely stressful on the cookware because so much energy needs to move away from that circular hotspot.
• Gas: Gas burners have a very hot visible flame and will produce a similar “O” shape, but the process of burning natural gas also produces hot carbon dioxide and water molecules (think water vapor), in addition to heating up air. These hot gases also heat a pan, so unlike induction, gas produces a hot “O” shape but also a hot wave of heat across the rest of the pan bottom as well, which promotes more even heating than induction coils.
• Electric coil/radiant/solid metal hotplate: As for electric coil/radiant, the hot coil/heating element area is a spiral or filled-in circle, rather than an empty “O” shape, so it’s possible to get even heating as long as the heating element area is not too undersized relative to the bottom of the pan above it.

https://www.centurylife.org/how-to-choose-a-cooktop/how-to-choose-a-portable-induction-cooker-countertop-burner/

Do I take your point to be that slip888's All-Clad's D5 pan are not "quality cookware?" ;>)

Three qualifying points from the "fine print" in Franz's interesting testing at his Centurylife.org site.

One is that Franz mentions this about his testing of pans on a gas burner: "Unlike induction, the initial hot “O” shape never closed for most cookware by the time maximum safe temperatures were reached." He goes on to say that he got a different pattern of heat disparities with gas than he found with induction. https://www.centurylife.org/cookware-even-heating-testing-methodologies/

Second, he was measuring temperature differentials at the time the hottest part of a pan reached 350°F. That certainly made his point about the need for quality cookware. However, as eleena mentioned above in this thread, giving a slower and lower preheat seemed to mitigate the hot-spotting even with her set of All Clad D5 pans.

Third, the induction tests were run with portable induction cookers from Cooktek and Vollrath. While these are best-in-class for PICs, they still have rather small induction fields resulting in what he reports as hot-spots corresponding to a 4.5 inch field for the Cooktek and a 4.3 inch field for the Vollrath.

In theory, then, slip888's Viking should be doing better than that because it is supposed to have bigger coils with bigger fields. IIRC, the VISC range is supposed to have an 8" diameter burner, two 7" burners and a 6" burner.

But, maybe those are aspirational sizes rather than the actual ones?

If slip888 can repeat eleena's recommended lower-and-slower" preheat with D5 cookware, we may find out whether the Viking VISC's large burner really does (or does not) have an 8" diameter field. That certainly would be disappointing in a range that costs over $8k.

Oh, maybe there is one other question for slipp888. Theinductionsite.com lists the VISC as have infinitely variable heat settings (as opposed to the ten or twenty stepped settings on most induction cooktops and and ranges.) Have you found that to be so?

The test just shows what the third stainless layer with total same thickness brings in D5. But it doe not mean D5 is not quality cookware and it is still much better than many others, including those the website did not bother testing.

These tests helps the users understand normal IH stresses more on the cookware than gas due to how IH works. Gas heating area (especially in the case of open burner) is not as clear cut as IH does. Lower-and-slower heating causes longer time to reach targeted temperature, so there is more time for heat to spread within the cookware. So Eleena's observation totally makes sense. But the benefit of this method also applies to gas heating (e.g. when heating cast iron pan on gas).

I think the intention is that user can work with the cookware and IH (e.g. using the hub matching the size of the pot, heating a bit gently, etc.), instead of throwing out the cookware, so to speak.

Regarding the coil size, https://www.centurylife.org/product-review-vollrath-mirage-pro-portable-induction-cooker-countertop-burner-59500p/ states that the coil size is 8.3 inch. So it appears that Viking's 8 inch burner is not larger. The O hotspot circle happens at place where magnetic field is strongest and it should not be at the edge of the coil. According to the test, roughly 4 - 5 inch in diameter. Inside the circle, it will be hotter than the outside (forming center hotspot area) because it is much less mass to be heated up by heat spread from O circle even though inside and outside of O circle are both relatively not heated as much by the coil.

"Regarding the coil size," that sounded like a possible explanation explanation for the hot-spotting that slip888 has been seeing. However, we do not know what size coil Viking uses for its 8" burner, do we?

It seems to me that when other induction stove makers specify burner sizes, the diameter spec tells us the largest size the pan we can use on that burner and expect relatively even heating. Nobody really says anything about the size of their inductors' coils.

We know the size of the coil in the Vollrath Mirage Pro PIC because Franz/Centurylife disassembled his unit to measure that coil. With slip888's Viking maybe still being under warranty, it probably would be best to leave that exercise for a warranty service tech, eh?

So, in the absence of that data, it still would be good to hear back from slip888 on whether the pre-heat and lower heating suggestions above help mitigate the hotspotting on his/her Viking range.

Oh, I thought by saying 8" burner you meant 8" coil. :-D

Thank you jwvideo & eshmh for your input.

I will test the low-slow preheat method and post results.

FYI, I do have one old All Clad LTD which I use with a Burton induction interface disc and I don't get the same horrible central hot spot.

Could we have more specifics, please?

Please take this as an invitation and not as an attack. The culture here is to add specifics to work out reasons for differing experiences and options. The specifics help move the discussion beyond the all too commonly seen pattern elsewhere on the 'net of exchanges that sound like: "I love induction;" "Well, I hate it;" "Then you must be an idiot" "No, you are the idiot and your opinions are worthless because real cooks always prefer gas" etc., etc., etc. ad infinitum.

For specifics, it might help to know the brand/kind/size of cookware you used. The fifteen minute preheat makes me think cast iron, which I've always found to heat slowly and unevenly on every kind of stove, and takes a long time for preheating to reach approximate evenness across the base. Also, IME, infrared thermo guns don't work well with stainless steel -- it is too reflective. Another possible question: what kind of pan (dutch oven, fry pan, saute pan, etc.) and what did you mean by "sides." The term "sides" can mean different things to different people. Did you mean heating on the base out beyond the middle or did you mean sides like the the sides of stock pot or fry pan? (I ask because some cooks very much want the sides of stockpots, suacepans and saute pans to heat up for their cooking while others are indifferent about it.) What brand, type and model of induction cooker? (Portable, range, or built-in cooktop?) What heat levels?

Yes, please. All those questions are important.

The culprit probably is the pan. The big thing about induction is that it isn't about the fuel--it's about the pan. The inductors cause the electrons to run around and heat up the pan, so how that happens in the specific materials and design becomes relevant. Some pans are called "induction ready" but just have a big slug of steel in the bottom of an aluminum pan and while some seem to be good, some just really don't cook well (my takeaway from reading many user reports).

If the issue were the inductor, if you have a standard circular style inductor rather than a newer oblong plate style one, the real hot spot would be a ring with a gap in it. The plate style ones are very close together, so there would only be a narrow band showing from less "heat". With all of them, a good pan that is warmed correctly (a couple of minutes, not fifteen), won't show hot spots unless you're cooling it off too much during the cooking. I have some thin steel crepe pans for instance. I don't see signs of hot spots when I cook an omelette in one, but if I'm making crepes, pouring cool batter in, then flipping crepes out, rapidly, I can sometimes get more browning right over the inductor. If I slow down a little and let the pan warm up again, that doesn't happen.

Hi Eleena. My Plarinum induction did the same and I took it back today. I am now cooking mynpan half filled with water and before that my small pot a quarter filled. BUT, I AM FOLLOWING THE RULE TO START AT LOW, 500, and I get even diayribution of heat. It is the tactic of building it up from low and I am going to do that just now. (I swithed up to 800 and guessed what?? Even cooking! Heat drops distributed all over the bottom of the pan but after a while, about 1 minute, the so called doughnut formed between the middle of the centre and the upright sides of the pan. I then switched off as I understood that the doughnut should form around the edges off the pan. Any further comments would be appreciated especially regarding the correctness of my doughnut formation. Thank you

A flat circular coil causes a torroidal field. The upper part of the field (above the Ceran) squishes [technical term] flat into the susceptible material in the pan's base. Beyond the coil outer diameter there will be few field lines. At the center of the coil the field will be slight and pan heating at the center will depend on the transverse thermal conductivity of the pan base.

Electrical efficiency comes from these factors: The pan base resistivity is much higher than that of the copper coil; the field below the coil does no work; the field above the coil is almost entirely "pulled" into the magnetizable material. With the coil drive operating at a wavelength around 7.3 km (40 kHz) into a coil that is a tiny fraction of a wavelength in size, practically no energy is leaked as radio waves.

I did a kitchen remodel 2 years ago and got the Grey Monogram induction cooktop. I also purchased a whole set of ALL CLAD D5 cookware. It does not cook even and I always use a burner at least the same size or larger. I noticed with bacon, I have to keep moving it to the other side of pan as 1 side cooks a lot and not the other. i have tried just spinning the pan around thinking maybe it’s the cooktop, but that didn’t work. Also, I have already had to exchange 2 stainless D5 pans as I could not get some burn off bottom. The guy told me I was cooking with temp too high. All in All, I am NOT IMPRESSES with the D5.

i have a thermador induction cooktop which i generally like. However i recently got an All Clad 5qt copper core saute pan and tried to simply toast bread four slices in it for a tomato sandwich. Was very dissapointed to see it does not heat/toast evenly. I never have this problem when i use my Smithey cast iron 10" chefs pan on the smaller burner. Albeit i can only do on slice at a time, but it is very evenly toasted. I then did the water bubble test and i see on the big pan there are two distinct rings of bubbles, an inner and an outter ring. But these are very specific pin point bubbles and the bubbles do not really extend over the pan even after 5 minutes. So unlike gas which of course has a flame that spreads heat across the bottom and even up the sides, induction does not heat spread the heat throughout the pan evenly but concentrates it to these concentric circles. It's not a pan problem its the nature of induction .

Typical induction coils should cover the zone from an inner inch diameter, more or less, to whatever the outer coil diameter is -- fairly wide as I recall of my disassembled (but now dispatched) [Electrolux] Kenmore. On my newer [Electrolux] Frigidaire, I can see the bubble band when initiating boiling in a Revereware steel-only pot on full power. Bubbles seem to be roughly equally vigorous across the band. Center hole size I haven't measured, but image memory suggests about an inch or so. I would not expect the Revereware pot to have enough steel thickness to fully contain the field, but it might be doing so. It is used on a small hob of least power.

Using a large demeyere frying pan on my largest hob to act as a griddle for three eggs, I cannot put the eggs in so closely in time that I can get a true measure of the equal cooking power density I would expect. (Pan is on three pads so it should be level, but does overlap the coil.) However, while the eggs are not equally cooked at any point in time, no hot spots within an egg contour are observed.

Note that while the hob coils are spiral in configuration, the field lines in the pan base are radial and have to terminate, so one wouldn't expect any tangential differences in apparent pan base heating unless the pan itself had partial separation of the layers in one or more areal patches. In such a case, the induction heating of the lowest steel layer would still be uniform (if the steel thickness is uniform), but the vertical thermal transmission to the interior skin of the pan would be non-uniform.