If you choose a high-speed fan, you need to make sure there’s enough venting for it. A good rule of thumb is 1 square foot of venting area for every 750 CFM. Another way to look at it is, provide the same amount of venting as the size of the shutter hole in the ceiling.

Whole house fans are generally easy to install. Direct-drive models are the most do-it-yourself friendly since no attic joists need to be cut. Belt-drive whole house fans use an integrated pulley system, which takes longer to install, but a belt-drive unit provides a more smooth and quiet operation.

For a 2,300-square-foot house, the recommended size of a belt-drive unit is 36 inches (which will cover 6,900 CFM). Both belt-drive and direct-drive units for a 1,900- square-foot house require a 30-inch unit and will cover 5,700 CFM. For a 1,500-square-foot house, the direct-drive 24-inch unit, which covers 4,500 CFM, is recommended.