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Comment by kergonath | Hacker News Reader

> You have the mother of all hotspots on the pan (less relevant for boiling) where the induction ring itself is and getting simmer right is harder.

Not at all. There is no significant hot spot as heat is actually produced by the bottom of the pan and not the coils themselves.

> Induction as implemented right now is on/off with full blast for the duration and just increased downtime. It is not the same as low constant output.

Again, not at all. All the devices I have used were perfectly fine generating a low, constant heat. what you describe may be the case for bargain basement ones, and it was the case for most resistive cooktops, but is definitely not the case for inductions ones.

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I guess you could have a hot spot on the pan if the coils are ill-designed or you’re putting a large pan on a small burner?

The pan will only heat up near the coil, so if the coil covers only the center third of the pan, only that will heat up (though some pans have a heat-spreading layer to mitigate this, and sometimes to add some more inertia depending on the pan’s purpose).

> I guess you could have a hot spot on the pan if the coils are ill-designed or you’re putting a large pan on a small burner?

Yes, but then it’s hardly a problem with the technology if you put a large pan on a small burner.

As for the rest, in all cookers I have seen, the coils cover the whole surface, except for a small spot in the centre. Besides, induced current does not happen only where the cookware is closest to the coil. The magnetic field is more spread out than that and the heating surface is larger than just the surface of “contact” (there is no real contact, but anyway).

I assume there could be an exceptionally badly designed induction cooktop with hot spots (it’d have to have a very weird geometry, though), but that would take some effort.

With most cookware it's pretty obvious where the coils are when trying to simmer. With thinner stuff like carbon steel the hot spots can be pretty nasty: https://www.youtube.com/watch?v=pifD__DIxGU

> All the devices I have used were perfectly fine generating a low, constant heat

I have never seen an induction cooktop that could generate low, constant heat. Even pretty pricy ones (eg. a 3000€ Bora hob with integrated extraction) showed a clear on/off cycle at the lowest heat settings. But maybe tech has improved in recent years, and there are hobs now that have constant low power output?

Maybe the effect also just depends on your cookware? On pots with a heavy bottom with aluminium or copper core you probably won't see the coil patterns and the on/off effect will be less pronounced. If you have a pot with a thin stainless steel bottom, you will definitely see uneven heat, the power from an induction coil is not completely homogenous.

All of the cheap tabletop cooktop I have seen have terrible cycling at lower powers, there seems to be two power levels and when you need something below the lower one, it cycles power at ~10s frequency. In contrast a Bosch integrated cooktop from a couple of years ago also does cycling, but seems to have more power levels available and the cycling is faster, around 1Hz or so. At least for me that is good enough.

My issues with it are more about inaccurate placement causing hot and cold spots and if you move a pot it can triggers cookware detection, which then clicks different coils on and off for 5-10s before it is satisfied with the new configuration. Both of those issues are probably exacerbated by the "FlexInduction" system that promises one large automatic cook area.

I'm hoping that power electronics development for electric cars creates some innovation in this area, but it's really hard to tell because there are no useful review sites and there aren't any places that let you take a cooktop for a testdrive.

> there are no useful review sites

Right! The only thing there is are occasional reviews on shopping websites, but people can usually only compare it to their previous one, so there really are no useful reviews (spoiler: most induction hobs are faster than whatever people had before, and people seem to hate touch controls)

Especially once you get to the fancy features (eg. internal and external temperature sensors) there are almost no reviews at all and all you have is the manufacturers marketing.

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