Sometimes whole house fans are called attic fans. However, the whole house fan is an entirely different concept. Whole house fans draw air in through the windows of the house and blow hot house air out through the attic. Of course a whole house fan would never be used simultaneously with an air conditioner.
We recommend that you do not operate the whole house fan during very hot days when you need to run just the air conditioning and have all the windows closed to keep out the very hot summer air. Your attic will still heat up, so the extremely hot attic air will need to be vented out. Do not use your whole house fan as you will be blowing your cooled house air into your attic. Also, you should NEVER run your whole house fan without opening your windows to relieve negative pressure in the house.
Which one should you get?
If you have an unfinished attic and use air conditioning; we think an attic fan is a necessity and a whole house fan as a preference. You never want your attic to be 150 degrees, even when your not home, while your air conditioning is running, and even if you’re on vacation. That is why an attic fan is needed even if you have a whole house fan. Plus an attic fan acts the same as 4 roof vents to relieve positive attic pressure. Some people just really like it cold in their house so outside air temperatures are rarely cold enough. It depends on the climate where you live. We love our whole house fan. We use it a lot on summer evenings, spring days and in the fall when outside air temperatures are below 82 degrees and when it is not too humid.