What is a conductive temperature probe called? They're relatively massy metal rods (5-8mm thick, 5-15cm long) that have a single conductor (NOT 2 conductor wire) to connect to the thermostat.
The connecting conductor wire is reasonably thick to (presumably) conduct the heat effectively to the measuring device.
I replaced one in my oven, and my spa has one too.
(I ask, because I broke the wire on my spa one, and searching the internet without a technical continually brings up thermo couples and other sensors)
Updated to help others: I'm looking at something like this is the sort of thing:
Best Answer
This task is often performed by a theromocouple, such as EMFields describe.
However ...
Your device is a "Capillary Thermostat". The sensor is filled with a substance which increases in pressure with heating and a bellows in the control end actuates a switch at a preset temperature. Once broken they are essentially not repairable.
You may be able to find a direct equivalent elsewhere and other versions which cover the same temperature range and which have the same electrical contacts could be used as a replacement.
As ever, YMMV.*
Another seller here - $ unknown.
Often a very good source if they have something suitable.
[Wikipedia - also known as a 'freeze stat'])(http://en.wikipedia.org/wiki/Freeze_stat)
Real world examples
and more
Lots of pictures - all linked tro related web pages.
*YMMV - Your Mileage WILL Vary.