They are wonderful for cooling your house, especially in the summer. Here is some basic information:
A belt driven fan is quieter than direct drive. But even direct drive is not particularly loud, in my opinion.
The size to get is based on the square footage you wish to cool. They typically come 24 or 30 inches square.
You will need adequate attic ventilation for it to work correctly. The fan instructions will tell you how many square inches/feet of ventilation you need. You should be able to look up the instructions online before you purchase one, to read up on that first.
Run it at night. Choose particular windows to open to create the wind path you desire. Shut it down in the morning before the outside air gets too warm. An additional tip - shut all of the interior doors in your house during the day. If one room gets hot, this will help contain the heat to just that room.
Don't open your windows all the way - many people make this mistake and then think the fan doesn't perform. Think of it like this - let's say the fan moves 5,000 cfm, and it has a 24"x24" opening. If you open one window all the way and its opening is 24"x24", you will get 5,000 cfm through that window. If you open 24 windows all the way, you will only get 208 cfm per window. If you want to open a bunch of windows to cool every room in the house, typically you just want to open each one about 2 inches - this will create a nice breeze through each window.
Air Vent is a popular brand, and is made in the U.S.
By the way, Menards carries Air Vent and they are having an 11% off sale this week. There is one in Livonia and another in Toledo.
1500sq. ft/4500cfm model:
http://www.menards.com/main/buildin...23378193-c-13258.htm?tid=-2342685155873155667
1900 sq. ft/5700cfm model:
http://www.menards.com/main/buildin...23378541-c-13258.htm?tid=-2342685155873155667