Raeburn to replace boiler/hob/oven

[Huge]

This is interesting, if a little noddy;

[The Natural Philosopher]

Mmm. I very much doubt it would damage them. After all you can expect people to take pans off completely without switching off the hob.

One manufacture whose manual I skimmed seemed to have a telltale to indicate when a pot was 'good' I suspect this means 'a decent amount of primary current being drawn'

Presumably al, especially thin al would not draw as much...

Making the relationship between power setting and actual heat outpout rather problematic and pot dependent. Of course software to keep primary in phase current steady, would sort that, but white goods manufacturers are not very sophisticated really.

[The Natural Philosopher]

MM. there they say its iron's specific resistance that helps it be effective, plus a bit of hysteresis loss.

The specific resistance is non-essential. You can design for any specific resistance you think likely.

The hysteresis you cant. But solid iron at the sort of frequencies in play is useless anyway die to eddy currents dominating things.

I am beginning to lean towards the magnetic thing as being 'has iron in it, which has decent resistance, so works better' and nothing to do with its magnetic properties as such.

[Huge]

The two induction hobs I've tried both had this function.

[polygonum]

Induction hobs detect removal of pans and switch off the ring.That operates pretty quickly.

[polygonum]

In the dingy kitchen at my mother's old house, you can pretty well see the flames. But in a nice, bright kitchen with sunlight, it can be difficult.

It is also difficult to see how high/low a burner is when there is a pan on it. At least with most (all?) induction hobs you get a nice clear indication of the setting for each ring. Saves using the "how badly did the hairs on my hands/arms get singed" technique traditional to gas burners.

[Clive George]

I don't get that one - surely the position of the knob makes it easy to see? Certainly works for us.

[polygonum]

Very much depends on the design of the cooker. On my mother's cooker, the knobs are nearly vertical, along the front edge. If you are near the cooker, they are difficult to see properly. Maybe it is me? Where I stand, how tall, etc. Visually it is difficult to determine the position of the knobs from close to. I have to take a step back from the cooker to see them properly. They are poorly designed.

[Clive George]

Fortunately that's fairly easy to work out when buying the thing :-) Our hob is just a hob, so vertical knobs as you describe aren't an option.

I think "traditional to gas burners" was inaccurate - though possibly "traditional to gas cookers" may be, I don't have much experience with them. Though when I have used them I don't remember ever having a problem with controlling them.

[Dave Liquorice]

doesn't

I assumed you already had or knew... B-)

Which are *induced* by the varying magnetic field. B-)

A flat piece of foil gets kicked into the air, crumpled just sits there. It does get just warm but there isn't much mass to heat up. But the ring sulks, displays ERR and beeps. About every 5 seconds or so it tries again with a very short burst. Think "tick".

'cause at least my hotplate complains and refuses to work. That's with a copper bottomed (about 1mm thick) stainless pan or plain stainless one. I might see if I can find a thicker bit of ali to try, we don't have any ali pans.

Found an offcut of 2 mm thick ali sheet about 6" x 2". It just sits there, doesn't get warm, the ring complains.

That's an odd statement stainless steel isn't magnetic. Or do they mean stainless steel with iron/ordinary steel inlay?

That's probably it, also to get decent I^2R losses in copper/ali needs somewhat heftyier currents than the same losses in iron. ISTR from investigating CCS "CW1308" that the restivity of copper v steel is 1:7. Not only do you have more resistance you also have higher flux density to drive the eddy currents. I think...

[polygonum]

Not quite true: