I am installing a bathroom fan system to vent out my equipment room. I have seen several people use attic fan thermostats to turn the fan on/off based on temp in the equipment area. Those attic fan thermostats are ugly since they are made for the attic.
I came across line voltage thermostats for cooling systems. Here are the two main ones I have found that look viable:
Ive used one similar to the Lux model, no idea which one it is since its just a plain box but it worked very nicely. Pretty easy to install given Im no electrician. I use it in my 'server room' in my basement to vent hot air out a basement window. It looks very professional and clean.