1) If I spread the pan over two burners will they both operate? -

Only if enough pan base is on each burner to meet the requirements of the pan sensing circuitry. These vary with manufacturer. I would suggest either centering a pan on a burner or having a pan large enough to straddle most of two burners. (The Viking layout may not be optimal for very large pans, but 9-inches should handle most.

Does
recognition of a pan size generally start at the center of the element?

A common approach is to ping the coil with a pulse and observe the decay rate of the resulting oscillation to determine whether there is enough inductive/resistive material above it to meet the power transfer requirements. The short, definitive answer is: Probably no.

2) Is it imperative that the full contact of the pan base gets "juice" from the induction cooktop?

No (within the context of the answer to question 1), but heating of the pan base could be uneven.

kas

Pan sizing: have you checked the user guide? It seems to say that the pan sizes range from as small as 5" bases to as large as 12" bases. MIght try calling Viking technical support for further clarifications.

Straddling burners:

Best ask the dealer or call Viking. It is a new model and this is the first post I've seen about it. With other induction ranges and cooktops reported here a couple of years ago, there seemed to be a very rough rule of thumb that a pan needed to cover at 60% least of both burners. But that was a very rough rule of thumb and was quite variable. Again. best to ask tech support about this or find a dealer with one hooked up for a demo. (If you find an answer, let us know.)

Does
recognition of a pan size generally start at the center of the element?

Well, that is how most induction makers want you to think about it. You do realize that almost nobody has an actual pan size sensor? Induction heats only the pot above it, so it seems enough like pan size recognition for marketing types. As Kas says, the electronics are actually looking for "enough inductive/resistive material above it."

Is it imperative that the full contact of the pan base gets "juice" from the induction cooktop?

Not sure what you meant. Are you asking about having absolutely flat bottomed pans (as opposed to slightly warped ones) or are you asking about oversize pans with bases that overhang the edges of the induction hob/zone? If the the first, would not make much difference on most induction burners. If the later, then the heating could be uneven as Kas said. How uneven depends on pan construction and design. Some materials and designs do a better job of spreading heat than others.

kaseki

jwvideo

Thank you both for the responses. At the showroom, they had a cooktop installed, but the power wasn't connected. However, I'll go back to investigate further. Your responses were helpful.

For question 3 regarding "juice", the responses covered it. I was thinking about the later example from jwvideo - the full diameter of the pan base having contact to the hob - with feedback that the heating could be uneven depending on the construction of the pan. But it was interesting to note that flat bottom vs. warped may not be much of an issue.

What I meant was that if the pan overlaps a hob then the part of the pan base outside the hob isn't directly heated by induction; heating is by conduction across the base and/or via the food inside the pan.

I do not have this unit and am not recalling seeing much about this 36" Viking model here in the last couple of years since this thread was active. You might have better luck attracting responses from current owners and users here if you started a thread of your own and put the model number in your thread title.

As for using your large LC pans, I'm not sure I know what you are asking. Have you used induction before? If not, maybe you are not quite understanding how to ask the questions. Let me take a stab at what you might be asking.

* Are you asking if the full size Viking induction cooktops like this one have the same problem recognizing LC pans that that the old Viking single-burner portable induction cooktop units (PICs) once had back in the previous decade? The answer to that is that the full size cooktops and the Viking induction ranges have never had that problem. The problem was limited to those old and long discontinued PIC models.

* Or, are you asking if there will be a problem operating a burner with a pan larger than a particular induction hob space. Say, your LC pans have 12" diameter bases overtop the 9" square hob spaces of the Viking cooktop?

The answer is that your LC pans will all work, but may intrude sufficiently into the adjoining hob spaces that the LC pans don't leave enough space for pans on the other three burners. For example, maybe you want to use a couple of 12" LC frypans --- one on the front right hob and another on the left front hob --- and then want to plant a large LC dutch oven on the middle hob in the back. So, how big are the pans you want to use at the same time on the other three burners? For that matter, how often do you figure you will be using all six burners at the same time and need to be running two or three 12" diameter (or larger) LC pans?

Frankly, the best thing to do to find out how the cooktop will or will not work is to take your array of pans to a dealer and see if and how they all fit. If you can't find a showroom example, try using the dimensions shown on the installation instructions to draw a full scale layout with a sharpie or magic marker on a piece of newspaper.

* Or, are you asking if a nine-inch square induction hob will evenly heat the entire base of a large LC pot or pan with, say, a 12" diameter (or larger) base. The answer is that you will have the same behavior with LC pans that you will have with any cast iron pan on any burner (gas, electric, or induction).

IOW, no problem with braises, soups and stews, where you have liquid to even out the heat, but you will need lengthy pre-heating to get an even spread of heat across any cast-iron base when you want perfectly uniform heating as for searing or browning out to the edges of the base. This is a property of all cast iron, not just LC.

If the VIking cooktop had some burners with larger diameter induction fields (large enough to encompass the entire base of your big LC pans) the cast iron would still heat unevenly. Preheating to evenness might take a bit less time with the larger burner, but it still will take quite a while. That's just the nature of cast iron cookware. FWIW, Cook's Illustrated has been recommending that you put cast iron pans in a hot oven for a half hour or longer to preheat CI skillets for stovetop searing like cooking steaks. Then you run the stovetop at lesser heat which is sufficient to maintian the searing temps for the cooking session.

Again, the preheating and unevenness will be no big deal for tasks like braising, boiling water, deep fat frying, stocks, soups and stews with a lot of liquid. Probably not a problem, either, for making a very long simmered tomatoey ragu or long-cooking of beans. But where you will need workarounds will be for stir fries or browning where you need every square inch of base surface to be perfectly evenly heated for the meat or bacon or veggies or whatever that you want to brown. Again, you would need the same workarounds with any stove where the burners are not sized for large pans, whether gas or regular electric burners as well as induction.

jwvideo Thanks so much - you answered my questions perfectly.