Fan to exhaust 2nd story hot air?

I used to sell Nutone and Broan products and they had thermostatically controlled eave vent fans that would automatically evacuate the air from the attic at certain temperatures. You should add louvered eave vents with equal square inches to the whole house fan area with one of these fans at each vent. I did that to my last house and it made a huge difference in upstairs comfort. In conjunction with the 36" whole house unit I rarely had to use AC at all and I was in a hot humid region of the Midwest.