How to Choose an Induction Hob

[Edislaw]

If I understand the technology correctly induction hobs use an electromagnet which has a high-frequency alternating current (AC) passed through it by an electronic oscillator. This resultant, rapidly alternating, magnetic field generates eddy currents in the pot which create heat in materials like iron. The heat is generated inside the pot enabling very rapid heating.

From this I read in various places that:

1. The control system shuts down the element if a pot is not present or not large enough because the hob can detect whether a pot is present by monitoring power delivery.

I understand that a minimum area of the hob must be covered before the pot will heat – 30{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} in the case of one manufacturer, two thirds in the case of another. Is this because different hobs operate in different ways? It also seems odd to read that a hoob can operate then 70{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} is not covered but that optimum performance is achieved by covering 100{e5d1b7155a01ef1f3b9c9968eaba33524ee81600d00d4be2b4d93ac2e58cec2d} of the heating area. Does this mean that power is wasted if a small pot is used on a large ring?

2. Wiki claims that “On most hobs only ferrous metal can be heated.” Does this mean there are hobs which can heat other metals and if so which ones?

3. I have read noise complaints from induction hob owners and am led to believe this can come from less sophisticated induction hobs which regulate heat delivery by switching the field on and off relatively slowly. How is it possible to determine which hobs use this method?

4. It has been claimed that a pot with a thin bottom will allow the temperature to fluctuate markedly due to the low thermal inertia of the small amount of metal in the base. If this is true then what is the minimum thickness advised?

5. Some manufacturers, apparently advise a maximum pan size. Clearly, there are physical constraints to the size of a pan on any hob but are there special considerations with induction hobs?

6. I understand that aluminium foil can melt onto a hob leaving permanent damage. I have read, however, that for frying the ideal pan has a ferrous base welded to an aluminium body to encourage rapid heat spread. Does this type of pan have inherent risks attached from melting of the pan sides?

7. I understand that some hobs’ internal cooling fans produce a small amount of noise and that a whistling or whining sound can come from the electronics in the hob. A hum or buzz may be produced by pans with loose parts exposed to high magnetic fields, particularly at high power. Any tips of hobs to avoid for this reason would be very welcome.

8. Some hobs have slider controls others touch sensitive controls. Is there any advantage to a slider control or is it just another way of accessing fixed heating levels? Is there any benefit from a larger number of heat levels?

9. Some hobs have bridging facilities which join more than one heating zone together to cope with large pans or to enable a single zone to take up to five pans. How does this feature equate to the need to cover a certain area of the induction coil? How does the hob operate when a single pan partially covers more than one coil?

[Martin]

Re: How to Choose an Induction Hob

Never ask a shop floor salesman how it works or what utensils to use, they usually haven’t a clue (well not in Currys or John Lewis anyway). They will answer yes to all your questions in order to convince you that you cannot possible survive unless you buy one now.

Induction hobs have been around for many years now and are increasing in popularity all the while. But one fact remains,and covers all makes and model variants, in that their failure rate is high and very often expensive to repair too.

It is a very novel way to fry and boil I must admit but not the choice of professionals, they use gas. And the novelty wears off when they keep going wrong in the midst of a fry up Sunday brunch!

[Author]

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