Induction Interface Disc

This is NOT and "ELECTRICAL ENGINEERING" question. Please seek out advice in a homeowner's forum somewhere.

Ask Vollrath.

Thank you. I thought of that too, and have left a message for them. Am awaiting a reply.

I could certainly do some googling, but I'll just ask--what is the advantage of induction cooking (over, specifically, an "ordinary" electric resistance coil)? Is it more energy efficient? Does the pan heat up faster?

And, finally (for now)--is that what those glass top (electric) stoves typically are?

yes, to both questions. glass top electrics do not come near what inductions accomplishes. google and you will see, even videos. this technology is the best ever.

i am a serious cook, and it seems their r&d folks have not considered all the issues (maybe they're not serious cooks). for example, a larger interface disc should be available. there should be more information about what size discs may be used with a specific a size "eye" and pan/pot.

this is frustrating to a serious cook. we need all the information, not partial. i will figure out things with the help of my engineer friend, hopefully. thank you for your comment.

There are MANY advantages, and at least a couple of definite or possible disadvantages.

Yes, it is much more efficient. The efficiencies of induction cooking are in the 80-90+% range (energy in food/energy consumed), compared to 30-50% for gas and ordinary electric cooking.

Safety: Since the heat is formed directly in the pan, the cooking surface only gets warm. The first time I tried an induction cooker, I placed a sheet of newspaper between the cooker and the pot. After making a batch of jam, cooking between 3&4 hours, the newspaper had not even turned brown. The cool surface also means that food does not burn on to the cooking surface. You just wipe it with a damp sponge and you're done.

No, it is NOT the ordinary glass-top cooking surface, although it may look the same. Those are referred to as radiant. We have an Electrolux cooktop with two radiant burners and two induction surfaces. My wife still uses the radiant side occasionally, but I never do. If I can't do it on the induction side, I do it in the microwave or the barbeque.

We also have a single portable induction surface, which we only use occasionally.

Another advantage is speed. It heats up and cools down much more quickly than other methods of cooking. We use a pressure cooker quite a bit. With a little more than half an inch of water in the bottom, it is boiling within one minute, and has reached full pressure within 2 minutes. 2 Jumbo artichokes are done in 15 minutes. If it starts to boil too vigorously, I lower the setting, and the adjustment takes effect in one or two seconds. I mentioned cooking jam; previously it was a big problem with bubbles coming to the surface and popping. As the bubbles pop, they spray hot syrup/jam on you, the stove, and even the ceiling. With induction, you have such precise control there is no such popping of bubbles.

The biggest disadvantage is the cost. Here in the US, induction is not well known, so there is little competition, although the prices do seem to be coming down. I understand that in Europe the prices are much lower, at least for the portable units.

A second disadvantage seems to be reliability. My cooktop failed well within its first year. After three in-home visits, the service person declared it unrepairable, so we got a replacement unit, but that did take a 2 or 3 months! When it failed, my wife was in the middle of a major cooking project. We live in a small town, and on a Friday afternoon, there was only a single unit available: a Viking portable unit with a list price of $500. It had been in the back of the store for a couple of years, so we got it for $300, which sounded pretty good for a supposedly top-of-the-line brand. I was aware that much cheaper units were available on the internet, but we needed to finish cooking. It did the job, but it too failed after only a couple of months. Similar repair story: it took a while, but we did get a new unit. So far so good on the replacements.

The third disadvantage of course is the need for magnetic cookware, as mentioned in my previous post.

A couple or three years ago, Andy Germany had a good thread here on CR4. He's the one that got me started.

Hi DKWarner

You got it all covered well.

Due to a few different factors a few years, we only bought cheap portable units and only one ever went wrong and it was immediately replaced.

We have two double units and two single units, total cost around €240. If one goes wrong after the guarantee runs out I will just bin it.

They have already paid for themselves. We keep them in a drawer and bring out just enough when needed, having 6 hotplates is very flexible, a double one goes camping with us.

A quality fixed unit costs up to €5000........and cannot go camping and if it goes wrong, you are shafted!!

The cheap ones are fantastic.

We have had several CR4 blogs about it all.

Generally it is quicker and cheaper (uses less power) and far less dangerous to anyone near to it, especially children.

You cannot get an oil fire as it shuts down before a pan is hot enough to let oil burn....

Please search on the other blogs....

hi lyn,

thank you for the comment. yes, the paella pan is appropriate for induction cooking. i did the magnet test, and i cook-tested by cooking plain rice. the water boiled almost immediately and the inner circle cooked perfectly, but the 8" eye cooked only 8" of the rice, ie, the outer inches of rice in the 14" pan remained uncooked.

i consider this false advertising by vollrath. this particular induction unit is perfect for what it does. however, it does not meet vollrath's literature statement of 'maximum size pan = 14" '. (sorry about that complicated quote.) i made this purchase based on their statement.

so, again, my question is if i can find a 14" interface disc, will enough heat be radiated throughout the disc to solve the problem, w/o purchasing a unit with a larger eye? i am consulting an engineer friend and will trust his opinion, and hope he knows about induction cooking. (he works for a vehicle manufacturer and he's brilliant about technologies.)

if anyone knows where i can purchase a 14" disc, i am open to that test. (I googled ad nauseum already.) it should permit me to use my 12" emile henry pot and other 9"+ non-ferrous containers. a larger disc might be a major benefit and worth the expense.

btw, are the induction unit manufacturers in cahoots with pot manufacturers? they seem to offer minimal help with work-arounds to eliminate purchase of new pots. Max Burton seems to be one exception. But their literature too is lacking in full transparency.

many thanks for your input.

I have mixed emotions about that 14" maximum. It would probably work just fine for a soup or other similar consistency food where convection currents would carry heat from the center to the outside.

The 8" circle of cooking is exactly what I would expect; the units will cease to work if the pan is very far above the burner. The changing magnetic field heats the metal itself.

Placing a disk between the induction unit and the pan would effectively remove the advantages of induction cooking.

Thank you for your comment. If you are correct, the manufacturer, Max Burton, is offering a thin (in appearance), but possibly inferior product. Its 8" circumference may not assist my problem, despite the fact that they state it will work with all non-ferrous pots. Another case of inaccurate advertising?

I may now be stuck with an induction unit that also does not meet the advertising qualities.

Dear Dick,

Thank you for such a comprehensive, intelligent response. It had so much more information than the manufacturers did. BTW, here is the link for the Max Burton 8" interface disc: http://www.amazon.com/Max-Burton-6010-Induction-Heat-Proof/dp/B00213L3PK. They do advertise that this disc will salvage your non-ferrous pots for induction use. Now it sounds like a bad joke.

Anyway, I will share all your data with my husband and engineer friend and see what they come up with. I am still hopeful for a workaround so we can make paella in the patio and keep all that horrid heat out of our tiny kitchen.

Many thanks, DinDC

I am really interested, if I am not alone, maybe you could start a fresh blog?

If you need any help or assistance, just ask.

OK, I'll do it. It may be a while; yesterday was my last free time for at least a week and a half.

It bugs the heck out of me that I don't totally understand how these things work! Especially why that paramagnetic SS tray did work, yet other apparently very similar SS items do not. I can understand why glass and ceramic would not work, but it seems like eddy currents in Cu or Al should heat them...

I would guess that the frequency for different metals is radically different to that of steel. The metals you mention probably need 20 x higher frequency or so......

By the way, I have found that cast iron pots (a frying pan actually), need far less energy to get hot than a "proper" modern induction pan. Like almost half. In fact with what you might consider to be "normal" levels, the Cast iron pan starts to overheat and the induction hob shuts down......Its not a particularly expensive pan either......

This implies to me that the 50 KHZ frequency that most of the Induction hob use is tuned for Iron and steel.....it would seem that the harder a magnet sticks to a pan, the greater the heating effect!!!

Empirically tested!!!

Dear Andy,

Thank you for following up on this issue.

I just got off the phone with the Vollrath techies. Here is what they said about my 8" induction coil and 14" SS pan. His use of similar specs has produced no problem, thus, he thinks the problem is that my pan is not sufficiently "induction ready." So now I have to find a proper pan.

He also said the interface discs sold online will reduce the induction qualities and thus, will not cook properly. So, for now I will forget about the disc.

Why can't they include all this information to save the consumer headaches and educate them at the same time?

Thank you again. Hugs to Guru. DinDC

I did look a bit, and found this:

1 is the lowest setting; 9 is the highest that allows the use of both induction elements. The P setting supposedly 'borrows' energy from the drivers for the unused element to achieve maximum heat.

I had to use a partial screen capture; the editor removes extra spaces and doesn't allow tabs, so you can't see the columns.

Here is the waveform for the 9 setting:

I couldn't find a lot of the data; I'll do it again and document it better as soon as I can.

I wasn't really sure of the best post to reply to to ask this question, so I picked this one ;-)

Does anyone use (or has anyone tried) an induction disk that goes inside a non-magnetic pan (instead of underneath)?

Hello,

I also was going to try one that goes underneath, but I talked with a Vollrath tech today and he said it will reduce the properties of the induction unit. So I'm not going to waste my money.

If you put such a disc inside the pan, are you willing to deal with the food that will probably stick or worse?

The tech also said induction-ready pots are a requirement for this technology, ie, the less expensive pans do not function as well. So I am probably in the market for a new paella pan. My question now is "Are all induction-ready pots/pans equal?" or "Are some brands truly better, and which ones?"

Any help will be appreciated. So far I have not found good reviews on Google.

Good luck, DinDC

Did you see my post earlier today that Cast Iron seems to be the most efficient?

I must admit that I am personally less concerned with a few scratches than you are, but if I was, I would buy a large sheet of extra fine carborundum paper, lay it on a flat service and pull that pan backwards and forwards a few times and see if any high spots need removing. Then I would remove them.....smooth everything off well.....a flat surface will not scratch, only high points or dirt will.....

I do believe that normal house dust and cooking rest may scratch as well, so a quick polish off before using both pan and hob may be a need, though there are many glass hobs around that get used far harder (temperature wise at least) with next to no scratches......and little maintenance.

Andy & Dick,

Please note I have never done a forum thread before this series. So, I hope you will accept my apologies. I attempted to rate your answers and did not do a proper job. They deserve a "10" out of 10. You are both obviously thoughtful, knowledgeable techies and I so appreciate the information you have shared.

And thank you also for your reasonable comments to "Anonymous."

Mil gracias. DinDC

You are most welcome and many thanks for your kind thoughts.

I have been a user of Induction cooking hobs for some years now and I do feel that "we" users, must make sure that anyone else is fully informed, its such a fantastic method of cooking with as far as I am aware no drawbacks other than the price of the fixed units, and the fact that you might need to buy new pots and pans.

On the good side are such things as:-

1) far less likely to burn a saucepan as the heating is SO even, though my wife does occasionally manage to do it!

2) Cheaper cast iron pots and pans work best it would appear, at least two notches down on the control knobs is my experience!

3) its impossible to set fire to oil or fat as the hob just switches itself off before such temperatures are achieved.

4) as only the pot or pan itself gets hot (the hob may get a little warm from contact with the pan, so that it will be uncomfortable on the skin, but not "really" hot), less likely for someone, particularly children, to burn themselves on the residual heat in the hob.

5a) most induction hobs (that I have seen) have touch controls on the top, where small children cannot see them....even if they managed to blindly turn a plate on, if there is no pan on it, it simply does not turn on fully, and turns itself off after a few seconds......

5b) I set my hobs far back against the wall when little fingers are around. (Mine are big by the way!)

6) Energy savings of up to 90% are quoted by the media(?), but I am happy when even 50% happens. I personally have no idea really...

7) There is very little wasted energy to heat up the kitchen, especially important in the summer of course. Cooking with gas is a hot number in the summer, I know, I go camping, but we take a double induction hob with us to use where electricity is available....and eat out when its not!!

8) All the hobs I have used have the possibility to set a timer and or a temperature to run at, the timer is MOST useful.....and I use it a lot, saves setting the kitchen timer more often than not.

Interestingly, water boils differently, due I feel to the even heating with no extra hot patches or areas......its more of a "rolling boil" mentioned in some cookbooks....the bubbles are also different (unbelievably), but I cannot exactly quantify it....

GA

Great reading.

Although I have been lucky with my relatively modern pots and pans bought over here, it would appear that some companies are doing a "cheapy" on the induction side of things.....at least in some countries/areas.....

My finding that a cheap and cheerful cast iron pan of 3 years old or so is SOOOOO efficient, tends to lead me in that direction, what do you think?

I also think that I will have to design a simple tester, similar to those testers for car paintwork thickness, to show just "how magnetic" some pans really are. I was thinking of a strong magnet, attached to a spring in a plastic holder with say a millimeter scale and measure exactly how "far" the magnet was "pulled..... I have never built such a thing but it should not be too difficult I feel. It will not be very linear, but who cares....?

I would use the cast iron pan as my starting point of a good quality/efficiency....

What is your take?

Thanks!

That's an interesting idea to make a device to test the magnetism. It would seem that some electronic device should do the job, but since I don't really know what properties of the material make it work or not, I don't know how to design the device. That makes your mechanical one sound pretty good.

Another item that came to mind is that most people don't have any way of determining the thickness of the pan bottom, to include that variable. I have a Digital ReadOut on the quill of my mill, so I can do that, and intend to do so when I do my next experimentation. Of course I can't take the mill into a store to help choose. For that, a digital caliper with an appropriate gauge block should work for many pans.

I have given it some thought only, I do believe that it will give problems if heating anything thicker than water. Especially if any of the food slips under the disk....

If your induction pans are too cheap, they will only have a very thin disk of magnetic metal......then unless you have a thick Aluminium bottom of the pan as well, the heat will not get transmitted out wards and you will get the problems you mention.....

High quality pans with thick induction bottoms are the only real answer......

Thin metal is simply not good enough even though it will heat...

Is the Paella pan thin metal?

Wow, are we going to discuss the Electrical Engineering aspects of hair curlers next? How about electric pencil sharpeners?

You know when you are totally "off" when you have to post anonymously.....

If you have anything worthwhile to say, it can always be said using your own name.