A solution that popped into my head is to get a proportional thermostat and hook it up...they are designed to heat/cool something continuously by adjusting voltage to maintain a set temp instead of on/off only operation.

Edit: Just checked out what you said you were looking at & it's the exact same thing only marketed specifically for fans...and not digital
redtails Reviewed by redtails on . What is the best fan controller for my needs? :rasta: **Warning - long winded post ahead, feel free to move on. ** :smokin: I'm looking for a fan speed controller that lets you set temperature (and/or humidity) and it will adjust fan speed to move just enough air to maintain those settings. I feel like the SMSCOM twin controller would be near to an ideal setup for me, but it appears to be a U.K. only device. I liked it because it never turns the fans completely off - it just tries to dial into a speed that maintains the temp you set Rating: 5