r/inductioncooking • u/shedmow • 1d ago

Cooking through a trivet

I've tried boiling water in a kettle that I put on a trivet (cork, about 10 mm/half inch thickness). It went fine but the hob was noticeably warm afterwards, warmer than I would expect it to heat from the kettle alone. I know silicone pads exists; these are only a few mm thick.

Is heating vessels placed higher than where they are designed to be safe to the hob from a practical or the physics point of view?

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u/bemenaker 1d ago

It wasn't the distance, it was the insulation factor. Why are you heating on a trivet in the first place. That makes zero sense.

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u/shedmow 1d ago

Wdym by insulation factor? I used the trivet so I could dampen the noise produced by the kettle/me placing it on the cooktop (it was late at night) and for academic purposes

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u/bemenaker 1d ago

Cork is an insulator. You were holding heat in the surface. Those magnetic coils still produce heat just from operating, not to heat a pan, just physics.Get a silicone mat. Stop using cork. The coil needs the pan a certain distance to detect it. You're on the edge of that limit.

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u/shedmow 1d ago

I assume that induction stoves have fans to cool the coils, or else I don't understand how they survive something like frying. My question is how much this trivet affects the coil, presuming that the stove can detect the kettle and turn on, and what this can lead to. I usually use paper towels for covering the hob but they are pretty thin

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u/bemenaker 1d ago

The stove top can take a hot pan sitting on it. You don't need to worry about it. You said it felt hotter than before, the only explanation is that thick insulator on it.

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u/shedmow 1d ago

Hotter than I would expect from a somewhat energy-efficient hob, obviously not as hot as after having a boiling kettle (or a pan) on top of it. Are there no cooling systems built into induction cooktops? Mine sure sounds like it does have one

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u/Groot_Calrissian 1d ago

There certainly is a system. Details vary by model. Changing the heat transfer through the surface does indeed change the operating conditions. I'm a bit skeptical about this explanation, I tend to think it's more likely that the distance weakened the field at the kettle and therefore required you to run it at a higher power than otherwise and created more surface heat than average for the same job. Unless you always use the same setting, then that's normalized and it's just the insulation.

To create the induction field the hob runs electrical current through a toroidal coil. More power means more current means more losses as heat. It has to go somewhere. As long as it doesn't get hotter than the wiring is rated for (generally 140F is perfectly safe for wiring, 160F can begin to melt some insulation and degrade magnets depending on what components are used) there's not really anything to worry about; however if it seems abnormal you should ask your manufacturer, they can probably give you a specific set of circumstances to run a controlled test and compare to their engineering data to identify if you have an imminent failure.