A whole-house fan is an effective alternative or complement to home air conditioning. The concept is simple. Bringing cooler outdoor air into the house takes advantage of nature’s own cooling system.
Calculating the Fan Size and Ventilation
1. Calculate the interior square footage of your home's living area. Don't include the garage, attic or basement.
2. Multiply this number by 3 to obtain the fan size.
Example: 2,000 square feet x 3 = 6,000 CFM (Cubic Feet of air moved per Minute)
Because a whole-house fan exhausts stale, warm air into the attic, a properly sized attic ventilation system is also required to exhaust that air out of the attic.
To determine how much attic ventilation you need, divide the fan's CFM by 750.
Example: 6,000 / 750 = 8 square feet of attic ventilation needed
There are two types of whole-house fans, and installation instructions for the two differ. Read the instructions for belt-driven fans or direct-drive fans carefully. For both installations you'll need a helper.
Direct-drive fan’s blades attach to the motor shaft. A belt-driven fan’s blade assembly is separate, using a pulley and belt to circulate air. Belt-driven fans are generally quieter.
Always hire or consult a qualified electrician who is familiar with local and national electrical codes.
Installing Belt-Driven Whole-House Fans
Search the attic for the proper location. The ideal location is the center of the hallway ceiling with no obstructions from ducts, plumbing or electric wires.Step 1
Mark the joist to be cut by pushing a nail through the drywall on each side of the joist. These nails will be easily seen from the hallway for correct shutter placement.Step 2
Cut out the template that's included with the fan.Step 3
Using the pushed-through nails in the ceiling as guides, place the template on the hallway ceiling and staple in place.Step 4
Trace around it, and then cut the drywall by the lines drawn.Step 5
The joist must be cut with a 1 1/2-inch setback to accept the framing of the joist cross supports.Step 6
Nail 1 x 4 lumber to the joist and joist supports to create a platform for the fan housing to rest upon.Step 7
Pass the fan through the opening. Center and attach the fan to the platform.Step 8
Secure the fan frame on all four sides by nailing wooden blocks to the platform.Step 9
Flip the fan motor and rebolt it to the struts. Slip the fan belt into position. Slide the motor as necessary to achieve proper tension. Be careful not to overtighten.Step 10
Mount the two-speed switch at the appropriate location along with the automatic ceiling shutter.
Installing Direct-Drive Whole-House Fans
Search the attic for the proper location. The ideal location is the center of the hallway ceiling with no obstructions from ducts, plumbing or electric wires. Ensure that all factory-installed belts are tightened.Step 1
After choosing the ceiling joist on which to mount the fan, make a cutout (1 inch by 2 inches) on either side of the ceiling joist from the attic. This allows quick recognition from the hallway for the automatic shutter installation.Step 2
Cut out and align the template (included with the fan) on the ceiling in the hallway using the punched holes as guides for your joist.Step 3
Tack it into place and trace around it.Step 4
Cut out the drywall with a jigsaw, following the drawn outline on each side of the joist and remove.Step 5
Mount the saddle brackets to the fan, tighten the bolts and pass the fan into the attic.Step 6
Center the fan above the ceiling joists over the cutout and mark the saddle bracket holes.Step 7
Remove the fan blade and set aside. Drill the holes for the saddle brackets, and mount the fan to the ceiling joist.Step 8
Now replace the fan blade with approximately 20% of the blade height outside of the rim. Tighten the blade securely.Step 9
Attach the skirting to form a vacuum box.Step 10
Mount the automatic shutter. From the hallway, attach the pull chain.