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Perhaps you would consider adding that information? That's would be an interesting addition!

The "See Also" has "Wax thermostatic element" [0] which seems focused on automotive applications, so perhaps it was there and grew large-enough that it got split off.

> Its principal application is in automotive thermostats used in the engine cooling system.

[0] https://en.wikipedia.org/wiki/Wax_thermostatic_element

Seems as though it's been filed under a different page:

https://en.wikipedia.org/wiki/Wax_thermostatic_element

They were also used for cold-start idle air control in at least some cars before throttle-by-wire.