If you run 12v computer fans with a computer power supply like I am, you could likey use a Household thermostat to switch the green LOW VOLTAGE wire on the psu. Connecting the green wire to any black on the psu switches it on. If you are using MAINS POWERD (120v) fan you may be able to use a thermostat designed for electric baseboard heaters. I have not tried either. From what I gathered the first one I mentioned works with a 24v lead from a furnace. The green wire on the psu apears to have 4v so it may work since it seems to be a "Trigger wire" of sorts and likely does not have much current running through it. The advantage of using the PSU from a computer is it has 12v, 5v, and 3.3v which maybe usfull for running fans at differant levels. Google how to convert computer power supply, lots of tutorials in there. Use Extreme Caution when taking one of those units appart as there are some good size capacitors in there, learn how to discharge them or know how to check. If your not so handy with electronics try something else. It may be easier to wire 120v fans with the electric baseboard heater thermostat if you understand houshold wiring. Just make sure what ever you oare running does not excede the current rating of any device you may use.
