If you’re wanting one just for an exhaust fan, they’re fairly cheap ($42 from Grainger). The big-boy humidistats for AC units that use variable speed motors to run in a low speed, humidity control mode can be bit pricey though, yeah. But they’re not super common any ways.
Let me just… sense… the humidity and turn the exhaust fan off.
https://en.wikipedia.org/wiki/Humidistat
If you’re wanting one just for an exhaust fan, they’re fairly cheap ($42 from Grainger). The big-boy humidistats for AC units that use variable speed motors to run in a low speed, humidity control mode can be bit pricey though, yeah. But they’re not super common any ways.