friedegg Posted December 6, 2011 Report Posted December 6, 2011 I bought a GE Profile induction stovetop and I'm shocked to find out the manufacturer recommends 12" clearance below the base of the unit to any combustible surface underneath, like to a drawer. I just don't see the undersides of those units getting that hot. The idea is to induce heat in steel above the glass ABOVE the unit. A friend has another brand induction stovetop and says the bottom heats up a little but not enough to ignite something. Anyone know why (other than lawsuits) the manufacturer would set such a distance?
friedegg Posted December 6, 2011 Author Report Posted December 6, 2011 Kurt, do you have some technical expertise with these?
kurt Posted December 6, 2011 Report Posted December 6, 2011 Just cooked on a couple, and I understand the basic function. They get a teeny bit warm when you put the cook pot on them, not enough to ignite anything. No specific technical expertise.
rkenney Posted December 6, 2011 Report Posted December 6, 2011 Is it because this area gets hot or because a magnetic field exists. What would happen if your 'drawer,' closer than twelve inches, is full of steel cooking instruments? Instructions say that the 12" rule does not apply to an oven located under the cooktop. Chances are that an oven is also a ferrous metal, so what's the difference? I don't have the answer mind you, just trying to ask the right questions. Be forewarned, however, installations not in compliance with manufacturer's recommendations could void your warranty.
rkenney Posted December 6, 2011 Report Posted December 6, 2011 If you watch GE's video: http://www.geappliances.com/videos-medi ... ryid=13529 it is apparent that heat is only generated when a ferrous metal is in direct proximity to the inductive coil. The heat generated by objects under the cooking coils is not indicated. You did say however say you wanted storage (drawer) under the cooktop. The thought regarding an oven under the cooktop must be that such would be adequately insulated all by itself and not pose a hazard. The cooktop manufacturer has no control over what you store under their cooktop: ie matches, lighter fluid, combustible cleaners and polishes (many of which are sold in steel cans), etc. A quick look under the average kitchen sink will provide plenty of potentially explosive chemicals. I am sure you would never intentionally cause a hazardous situation, but it happens all the time unintentionally. Best course, no storage within 12" of the underside of cooktop.
Jim Katen Posted December 6, 2011 Report Posted December 6, 2011 I'm not sure whether or not the induction effect can be shielded. If it can't then the requirement makes perfect sense.
friedegg Posted December 6, 2011 Author Report Posted December 6, 2011 The induction effect has to be directional--up--as in focused above the glass top. The base of the unit itself is sheet metal, I think steel (ferrous), so the effect has to be shielded toward the up direction. An oven mounted directly underneath is also housed in sheet metal. There was some mention of ventilation needed for "components" in the unit--but mounting an oven 1" beneath the base of the induction unit would provide for no ventilation, plus the heat of the oven would add to any temperature issue. Makes no sense; doesn't add up--that's why I was looking to someone here for a technical explanation. The GE Tech Support people were of course no help--they have memorized the words "twelve inches" just fine.
Jim Katen Posted December 6, 2011 Report Posted December 6, 2011 Do other manufacturer's have a similar requirement or is it just GE?
friedegg Posted December 6, 2011 Author Report Posted December 6, 2011 I understand they do recommend underneath clearance to combustible surfaces that are greater than for regular electric (and here I'm referring to glass top) stovetops--but I have not researched and compared for specific safety clearances. I'm curious as to the circumstances that might conspire to start a fire. RKenny made a good point that some yahoo could store fireworks and gasoline inside a metal can in a shallow drawer just under the unit, and then IF some downward shielding failed or for any reason the induction became directed downward, well, trouble could ensue! Maybe that's their thinking--the inducer isn't going to heat up metal that's a full 12" away even in the worst scenario, and if it heats up the top on an oven underneath then no problem, it's designed for that heat.
Marc Posted December 7, 2011 Report Posted December 7, 2011 The magnetic fields created by induction stove tops are intended for pots and pans placed upon them but there's no practical way to direct magnetic fields in a device the size of a stove top appliance because the frequency isn't high enough. Directing magnetic fields is what antenna design is all about. Shielding magnetic fields in a stove top appliance consist simply of placing electrically conductive materials in the path of the fields so that currents (and heat) are developed that transform the magnetic energy into heat energy, dissipating the magnetic flux. Probably the best shielding on an inductive stovetop is the pot itself. The manufacturer wants clearance to combustibles because the stove chassis gets hot, it has metal parts that heat up, not because intense magnetic fields will heat up wood. Wood isn't a good conductor and so doesn't develop significant heat in the presence of them. Marc
friedegg Posted December 7, 2011 Author Report Posted December 7, 2011 Thank you Marc. That's the most technical response I've gotten--thanks to all of you, by the way. I used the term "shielding" informally: I meant only that the design must be intended as such to cause the magnetic field lines to be present above the glass (to induce current and heat in an iron pan or pot) and not be present to as great a degree below the chassis. If the design of the unit allowed as great a field immediately beneath the chassis as above the glass, then metal utensils in shallow drawers just beneath the chassis would heat up as the pot above would (explaining the 12" safety distance to a combustible surface underneath). But I refuse to believe they would even allow such a devise as that. We were talking about say, a metal can, in a wood drawer underneath and in close proximity to the bottom of the chassis. If that can contained matches for example, a magnetic field would induce an electrical current and heat in the metal of the can, which could in turn ignite the matches, which could ignite the wood drawer, etc.. I do understand you cannot induced a current in wood. What I'd like to know is that for a new, properly operating unit, just how strong is that field (if any) just below the chassis? And what circumstances would cause the unit to suddenly develop a stronger field there? I assume that coils of some design in the unit generate the magnetic fields above each pot circle (on the glass). Perhaps the engineers fear the coils could unmount and fall to the base of the chassis, unintentionally delivering more of the field underneath--and so possibly heating up some metal there. Think that's on track?
kurt Posted December 7, 2011 Report Posted December 7, 2011 In our line of work, we'd all just say "mfg. says 12"; maintain 12"...." It's hard to know what the designer, mfg., and legal dept. were thinking. Given all the parameters just presented, I'd maintain 12".
Tom Raymond Posted December 7, 2011 Report Posted December 7, 2011 I say install it with whatever clearance you want. Just be prepared to accept the consequences. When the cooktop stops working, or the cabinet starts on fire, or whatever other bad thing that might happen does, it'll all be on you. We can say the stove is hot until we're blue in face, some people still have to touch it to find out for themselves.
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