Drafty Windows and Cooling Fans | Home Solutions
Determining the correct fan (24- to 36-inch diameter) for your space is as simple as figuring the square footage of living space and matching it to the manufacturer’s size recommendation. Note that if you have a medium to large house, a belt-driven fan will be much quieter than a direct-drive model (blades attached to the motor shaft). Many contractors recommend W.W. Grainger’s fans. At grainger.com, type in the keywords “whole house fans” to see tech specs and coverage in square feet. A 36-inch-diameter, two-speed, belt-driven fan that will cool 2,300 square feet lists for $284.25.
After publishing this answer, Yankee home editor Polly Bannister heard from NH Public Utilities Commissioner Clifton Below who has more information on whole-house fans. Scroll down to see his suggestions.