How To Install an Electric Whole-House Fan

A whole-house fan can cool your house without significantly increasing energy costs. This powerful ventilation system pulls cool air in through open windows and pushes out hot air through the attic. The fan is mounted on the ceiling of the home’s highest floor and quickly cools the house in the evening hours. In this article, we’ll explain how to install an electric whole-house fan. This Old House general contractor Tom Silva demonstrates the installation process in the video above.

Considerations Before Fan Installation

There are a few things you’ll need to consider before you decide to install a whole-house fan:

• Attic ventilation: The space needs to have sufficient venting so that the system can expel the air pushed up by the fan. This can include everything from a soffit vent to a gable vent.
• Climate: Whole-house fans work best in areas that have cool nights and low humidity.
• Cost: Whole-house fans are generally less expensive to install and operate than central air conditioning. According to Angi, whole-house fan installation costs between $800 and $2,400.
• Home heating system: If you have a gas heating system, make sure it has an electronic ignition rather than a pilot light.
• Noise levels: Some fans are noisy, so select your system’s location carefully.

Choosing the Right Whole-House Fan

Each home has unique needs, so know the difference between fan size, capacity, and features when you’re deciding which whole-house fan is right for your house. 

How It Works: A whole-house fan generally mounts in the ceiling of the highest finished floor of the house. When you open the windows at night and turn on the fan, cool air is drawn in through the windows and warm air is forced up into the attic. The air is then pushed out through any existing attic vents—soffit vents, ridge vents, gable vents, or roof vents—effectively cooling the entire house.

Fan Size and Capacity

Your home’s size determines the fan capacity you need. As a general rule, choose a fan that can change the air in your home 15–23 times per hour. In the video, Silva suggests that a 1,600 cubic feet per minute (CFM) fan will cool down a 2,000-square-foot home.

Fan Features

When you’re shopping for an effective whole-house fan, look for the following features:

• Automatic shutters: Shutters prevent air leaks when you aren’t using the fan.
• Insulated fan housing: If your fan is insulated, it will help reduce noise and improve energy efficiency.
• Multiple speeds: Finding a fan with multiple speeds allows for adjustable airflow.
• Remote control: Having a remote to change your fan’s settings is more convenient.

Real-World Experience: Homeowner Dwight Okahara of Santa Clarita, California, found that his whole-house fan required some fine-tuning to get the best results. “I had to spray foam insulation where the fan’s frame meets the rafters. You need a tight seal to get the optimal air draw,” he says. After getting it dialed in, the Okaharas only needed to run their central AC when the outside temperature hit 85 degrees.

Whole-House Fan Installation Process

If you want to install a whole-house fan, you’ll need moderate do-it-yourself (DIY) experience. Hiring a professional will guarantee proper installation and optimal performance. Whether you decide to work with someone to install your whole-house fan or go it alone, here’s a step-by-step look at the installation process:

1. Identify an appropriate location in the attic to install the fan. It should be close to an electrical outlet, between two ceiling joists, and not near any pilot light.
2. Remove the insulation from between the joists in the fan’s location.
3. Install solid blocking between the ceiling joists. Cut the blocking from the same 2x lumber as the joists.
4. Fasten the blocking by driving 3-inch drywall screws through the joists and into the ends of the blocking. Use a layout square to ensure the blocking is square (perfectly straight up and down).
5. From the room below, use a drywall saw to cut the ceiling opening for the fan. Use a wet/dry vacuum to catch the dust while sawing.
6. From inside the attic, apply a continuous bead of acrylic latex caulk along the top of the joists and solid blocking.
7. Set an insulated isolator on top of the joists and press it down into the caulk.
8. Secure the isolator by screwing its metal tabs to the joists with 1¼-inch drywall screws.
9. Run a continuous bead of acrylic latex caulk around the top of the isolator, then set the whole-house fan on top.
10. Secure the fan by driving 1-inch sheet-metal screws down through the fan’s flange and into the isolator.
11. Plug the fan’s power cord into the nearby electrical outlet.
12. From the room below, screw the louvered vent to the fan to conceal the ceiling hole.

Ensure Adequate Attic Ventilation: During a This Old House whole-house fan installation, Tom emphasized that all of the exhausted air coming into the attic has to have someplace to go. Some will exit through soffit vents on each side of the house, some through the ridge vent, and a significant amount can escape through gable-end windows. If your attic has gable windows, Tom recommends keeping them open all summer long to provide adequate airflow for the fan to work effectively.

Pro Tip: Tom Silva notes that the weather stripping between the fan and the framing also cuts down on any vibration the fan might create, so don’t skip this step when setting the fan into the opening.

Operating Your Whole-House Fan

Now that you’ve installed your whole-house fan, there are a few things to consider when you use it. Follow these operating guidelines to maximize the system’s benefits:

• Close windows and turn off the fan during the hottest parts of the day.
• Experiment with different window combinations to find the most effective cooling strategy.
• Open windows before turning on the fan to increase airflow.
• Use the fan during cooler hours, typically in the evening or early morning.

Safety Considerations When Installing a Whole-House Fan

Whole-house fans are generally safe when installed correctly, but you can take some extra safety precautions:

• Guarantee proper ventilation to prevent the gas appliances from back-drafting.
• Install carbon monoxide detectors in your home.
• Keep children and pets away from the fan’s opening.
• Never operate the fan during a fire because it can spread smoke throughout the house.

Maintenance and Care for a Whole-House Fan

You can make sure your whole-house fan works efficiently and extend its lifespan by maintaining the system properly. 

Perform the following checks annually:

• Check the belt tension (if applicable).
• Inspect the fan blades for dust and debris.
• Lubricate moving parts according to the manufacturer’s guidelines.
• Make sure the louvers open and close properly.
• Verify that attic vents are clear and unobstructed.

In addition to the annual inspections listed above, there are a few steps you’ll need to take in colder climates. Complete the following tasks when the temperatures start to dip:

• Close and seal any exterior vents associated with the fan.
• Consider removing the fan belt to prevent wear during the off-season.
• Cover the fan with an insulated cover to prevent heat loss.

Energy Savings and Efficiency With Whole-House Fans

Whole-house fans consume less energy than air conditioning systems and can cool a house quickly during cooler evening hours. To maximize energy savings, follow these steps:

• Check that your attic is properly insulated to maintain cooler temperatures.
• Seal air leaks around windows and doors to improve efficiency.
• Use the fan in conjunction with your air conditioning system.