The neoStat 12v V2 is IP20 and therefore not suitable to be placed in a bathroom. This is because damp could get into the circuitry and reduce the live span of the thermostat. Therefore like any of our thermostats it would need to be outside the bathroom with a wired remote probe wired to the thermostat which will go into the bathroom.
If you have towel rails, it is better to have the probes in the floor and read floor temperature as reading air temperature will be affected by the towel rails and therefore underfloor heating may not come on properly.
However if you are using the thermostat for radiators, then using the probe as an air probe is fine.
Our Wireless Air Sensors are also not suitable for bathrooms.