Updated: Apr 28
Whole house fans are among the most cost-effective ways to create a cooler and more comfortable home, but how do you use one?
Knowing how to use a whole house fan ensures you're maximizing the benefits and prolonging the life of your fan. While today's fans are incredibly reliable and require little to no maintenance, using a whole house fan incorrectly can damage the motor or other vital components, leading to repairs or a full replacement.
How To Use A Whole House Fan
Whole house fans are ready for use as soon as the system is installed, but following these best practices will maximize the fan's cooling and cost-saving benefits.
First, check to see if temperature is cooler outside than it is inside your home. Using a whole house fan during the cooler times of day — usually in the morning and evening — will cool your home more efficiently and help maintain temperatures throughout the day.
Next, open a few windows to create airflow. Whole house fans rely on a fresh, cool air intake to create airflow throughout the home. It is vitally important that you open windows and doors enough to support the fan — use the fan grate in the ceiling as a reference for opening windows.
For QuietCool whole house fans: Open windows equal to 1-times the size of the fan grate on low speeds, and 2-times the size of the grate on high speeds for more powerful cooling. For gentler cooling, open windows 2-times the size of the fan grate on low speeds, and 4-times the size of the grate on high speeds.
For Traditional whole house fans: Window openings should equal 8-12 square-feet for 24" to 30" whole house fans, and 18-25 square-feet for 36" to 42" whole house fans.
For morning use, open windows facing north or west (away from the sunrise) where the air will be cooler. In the evening, eastern-facing windows (away from the sunset) will help draw cooler air.
PRO TIP: Opening windows strategically before using your whole house fan can help direct airflow through specific parts of your home — perfect for cooling individual rooms, or getting rid of odors, smoke and other airborne annoyances.
Now it's time to turn your whole house fans system on. Whole house fans can be controlled by wall-mounted timers, switches, RF remote controllers, or bluetooth-enabled "Smart" switches. Simply adjust the speed and timer settings as you like.
Can I Run A Whole House Fan At Night?
Running a whole house fan at night, or while you sleep, will lower temperatures in your home dramatically. Traditional whole house fans are not designed to run all night long, but more advanced models can be used through the night. QuietCool Stealth Pro whole house fans, for example, come with an additional low-speed setting for overnight use and whisper-quiet operation.
Depending on the overnight temperature, using a whole house fan while you sleep may make bedrooms and living spaces uncomfortable as the fan replaces the air inside your home with the cold air form the outside.
For the best results, use your whole house fan for at least 10 minutes first thing in the morning. Before outside temperatures begin to rise, turn off the fan and close the windows, doors and blinds on the sunny side of your home to keep the cooler air inside. When outside temperatures begin to fall again in the evening, open the windows on the shady side of your home and turn your fan system back on.
PRO TIP: Use your whole house fan during the day to push air out of the attic, or in tandem with your A/C unit, by directing airflow from either the basement or the shady side of the home.
How Many Windows Do I Need To Open For A Whole House Fan?
Open as many (or as few) windows and doors as you like before running your whole house fan — it's more important how much you open them. Make sure your window and door openings are at least equal to the size of your whole house fan grate to prevent damaging your system.
It is important to ensure you have provided enough air intake with any combination of window openings, but keep in mind more openings will result in a gentler breeze coming from each window.
How Do I Direct Airflow With A Whole House Fan?
You can direct airflow through specific parts of your home using your whole house fan and opening specific doors and windows. If you want to direct a strong airflow through your bedroom, for example, open windows in that room only.
You can also experiment with your whole house fan settings and airflow to help you maximize both comfort and performance.
Do Whole House Fans Require Any Maintenance?
Newer whole house fans should not require any maintenance besides occasionally cleaning the dust from your ceiling shutter or grate. That said, there are other preventative measures you can take to prolong the life of your fan system, like removing any insulated inserts or other obstructions from the grate before use.
If you get a new roof installed on your home, make sure your roofers install the same amount of ventilation as there was when your whole house fan was installed. Any reduction in ventilation will compromise the ability of your fan to move air, make the fan run louder, add strain to the fan motor, and potentially void the manufacturer warranty. Don’t assume your roofer will know the right amount of ventilation needed for a whole house fan.
If you have had a new roof installed, or notice any problems with your whole house fan, please contact us before using your system.
Knowing how to use a whole house fan will make the most of your home cooling system, reducing energy costs and maintaining a healthy, comfortable home for years to come.
Colorado Home Cooling & Daylighting is Colorado's top-rated home ventilation and daylighting providers, offering unmatched customer service, quality and craftsmanship since 2003.