Choosing the Right Quiet Cool Fan

Whole house fans are rated according to the amount of air they can move. This is measured in cubic feet of air per minute, or CFM. In order to be effective, a whole house fan’s CFM rating should be 2 to 4 times the square footage of the house. For example, a 1,500 square foot house should have a whole house fan system capable of moving 3,000 to 6,000 CFM of airflow.

Overall attic venting is the only limiting factor on how many CFM can be efficiently moved. Attic venting can be easily increased by adding vents. Too many CFM of airflow without the proper attic venting can cause undue stress on the whole house fan and pressurizes the attic and walls. Too little CFM's will not provide the desired minimum of air exchanges per hour as recommended by national ventilation experts and may not provide the cooling draft to lower house, attic, and skin temperatures in a timely fashion.

When viewing our sizing chart, we recommend that you select at mininum the "Good" level of airflow. The "Poor" category of the chart is often what other whole house fan brands are recommending. The "Poor" level of sizing may not produce the desired cooling and ventilation results.

*The QC-1500 series of fans can be installed on a vertical wall instead of a ceiling if there is adjacent attic space and sufficient attic venting.