Electrical component identification and wiring help

The blurry device on the left is an Intellitec pump controller, the round device on the right, with no wires connected, looks like a thermodisc for checking temperature (like the ones on Atwood water heaters for monitoring water temperature). If it is a thermodisc, it doesn't matter which way you connect. If it is a thermodisc, what temperature is it monitoring? Just curious.