These are two separate things: thermostat will close and open based on surrounding temp., the actuator on the other hand opens and closes based on energizing a heating element that is driven by a separate thermostat.
Wax motors are pretty cool things. They rarely fail and do their job even in damp environments. I take care of my better half's hotel with approx 100 of these installed and we replace one of these once every couple of years.
Thermostatic valves are ambient at both sides - they expand and contract naturally with the existing temperature, so they are not motors per se, because there's no actuation beyond the temperature.
Edit: also, the actuation from the wax motor only happens while it is absorbing (or losing) heat, even if it later ends up in a steady state with no heat flux.
That's why it's a motor, like in dishwashers, not a thermostat like in e.g. greenhouse windows or radiators.
It doesn't need to be persistent, but without some way to create a state that is different than ambient, it's not a motor.
There are commercial thermostats where the wax element itself is both the temperature sensor and the actuator, eg Thera-100 T1002W0.
> Its principal application is in automotive thermostats used in the engine cooling system.
It's a simple mechanism that used buoyancy to either open or close valves as water level changes in a container.
I've been looking for actuators to use in damp/wet environments and sealed actuators are rather expensive and supposedly don't last too long
I've struggled to protect eletronics. Waterproof enclosures all fail over time. Though I have some ideas for immersion in mineral oil. But finding actuators that could work has been a bit of a struggle. These look cool, though maybe not something one could run off 5V :) Ill keep looking around
Mayne you know, are the internal components already designed with corrosion in mind?
