When using a kettle to boil two lots of water, the thermostat still thinks the water is hot (because the air is).
So why not put the thermostat in the water, and actually detect how hot the water is, rather than the steam filled bit at the top.
Neil-- Did I say that, Apr 06 2001 I just go by the whistle of escaping steam, which only happens when the water itself is boiling.-- bookworm, Apr 06 2001 listening/watching for bubbling works for me...-- mihali, Apr 06 2001 This would also work for heating water to a specific temperature below boiling; proper for most green teas. (hence, probably, baked in Japan...)-- hello_c, Apr 06 2001 And coffee, which the water for should not be boiled...
<wipes remnants of exploding brain off keyboard> Sorry about that. No sleep...
"And coffee, for which the water should not be boiled..."-- StarChaser, Apr 07 2001 Do you know of such a product that is available for purchase? Please tell me where I can purchase one, or contact Harney & Sons Teas and tell them about it. They have some very fine tea. Cindy Eaton-- Cindy Eaton, Jul 09 2003 if i understand correctly, the idea is to allow the kettle to boil 2 lots of water in quick succession. This is currently difficult on most kettles as when the water has boiled, and you refill it with cold water, you can't switch it on again immediately as the thermostat still thinks it's at 100C. If the thermostat was in the water, it would switch off once the cold water was inserted.
(although having a variable thermostat would be handy as well, bit like a toaster - you could choose to have white boiled water, or a golden brown boiled water)-- pjd, Jul 10 2003 Thermostats in kettles are either in the bottom (near the element) or near the top (in the handle). When the water boils steam is generated which (by having a lid and a spout baffle or filter) is forced into a steam tube which guides the steam to the control. The control heats up rapidly and turns off. If the kettle is poorly designed then the control can't cool quickly enough and it takes a while before you can switch it back on.
The problem with a thermostat in the water is that to switch the power off at boiling point the thermostat would have to be set to exactly 100C. If it was 101C it would never turn off and less than about 98C and the water would never boil. Kettle controla have to be cheap and it is not possible for them to be that accurate. Because they currently work with steam and steam is only generated (in large quantities) when water boils they can be set to much lower temperatures (80-90C).
The other problem with thermostats in the water is that the current technology means you cannot turn the control back on until it has cooled by about 5-10C which doesn't really matter if it is out of the water as it is cooled very quickly by the ambient air temp. If the thermostat was in the water you would not be able to switch the kettle back on until it had cooled to close to 90C (assuming you can get a control to switch off at 98C). This takes quite some time, maybe 5-10 minutes, and if you're like everyone else in the world you instinctively switch the kette back on to re-boil the water if you are a bit slow in getting your cup/tea/sugar/milk sorted out.
Right, I'm boring myself now.-- Vinny, Jul 25 2003 random, halfbakery