spa heater thermostat

The thermostat of a hot tub is the component that allows you to adjust the water temperature.
In modern spas, a temperature sensor is typically connected to a circuit board, with the topside control panel serving as a remote control.

Spas that are around 20 years old generally utilize potentiometers and solid-state probes for temperature control.
For even older spas, specifically those that are 30-40 years old, a mechanical thermostat equipped with a capillary bulb is commonly found.