I have another question... on an induction cooker alot of times the heating
is only concentrated in one ring, is this normal? is this the cooker or the
cookware's problem? its NOT fun burning thick soups...

Hi,

> I have another question... on an induction cooker alot of times the heating
> is only concentrated in one ring, is this normal? is this the cooker or the
> cookware's problem? its NOT fun burning thick soups...

Yes, it is common. What you are seeing is the heat signature of an
electrical current being induced from below by a pancake-shaped coil. A plain
steel pan has poor lateral thermal conductivity so that this heat doesn't
readily disperse across the base. Consequently the highest region of heat
will be in the shape of that coil giving you hot spots where the contents of
the pan do not mix easily. Matching the pan size to the ring and frequent
stirring are the only solutions I know of.


Cheers - Joe

Joe McElvenney a écrit :

> Hi,
>
> > I have another question... on an induction cooker alot of times the heating
> > is only concentrated in one ring, is this normal? is this the cooker or the
> > cookware's problem? its NOT fun burning thick soups...
>
> Yes, it is common. What you are seeing is the heat signature of an
> electrical current being induced from below by a pancake-shaped coil. A plain
> steel pan has poor lateral thermal conductivity so that this heat doesn't
> readily disperse across the base. Consequently the highest region of heat
> will be in the shape of that coil giving you hot spots where the contents of
> the pan do not mix easily. Matching the pan size to the ring and frequent
> stirring are the only solutions I know of.

Aren't you confusing induction and halogen? I have been cooking with induction
for the past 5 years, no coils here. And the induced heating is totally even.

Nathalie in Switzerland

Hi,

> Aren't you confusing induction and halogen? I have been cooking with induction
> for the past 5 years, no coils here. And the induced heating is totally even.

I'm afraid not! Because you cannot see it, it doesn't mean that its
not there. Halogen stoves employ lamps which in principle are similar
to those in car headlights and distinctive in that the heat is almost
instantly available and does not need a vessel on top to make it
work.

However, an induction ring most certainly employs a coil beneath its
surface which is excited in the tens of kilohertz region. The flux
emanating from this inductor is concentrated by the presence of
ferrous materials, as is the heat developed, and so doesn't spread out
as that from a gas flame or a conventional radiant coil.

It is possible that nowadays there are special pans for induction
stoves that are made the opposite way round to stainless ones with
ferrous material on the bottom and aluminium on top. The thought has
occurred to me in the past that it might be possible to have a thin
disc of steel, fitted onto the ring and then an ordinary aluminium
pan could be used albeit with some heat loss.

My interest in induction stoves comes from living in bachelor quarters
where the portability (i.e. ease of stowage) and heat control of the
model I had was a definite plus. I still have one in a kitchen cupboard
that is dragged out on occasionally. If you would like a PDF file on
the design of the electronics incidentally, I can send you one.



Cheers - Joe