Whole House Fan Size Calculator

For a whole house fan, the recommended size typically ranges from 2,000 to 6,000 CFM (cubic feet per minute) for an average-sized home of around 2,000 square feet. However, the exact size should consider your home’s specific square footage and ventilation needs. It’s essential to strike the right balance to ensure effective cooling and energy efficiency.

Here’s a table with recommendations for whole house fan sizes based on the square footage of your home:

Home Square Footage	Recommended Whole House Fan Size (CFM)
Up to 1,500 sq. ft.	2,000 – 3,000 CFM
1,501 – 2,000 sq. ft.	3,000 – 4,000 CFM
2,001 – 2,500 sq. ft.	4,000 – 5,000 CFM
2,501 – 3,000 sq. ft.	5,000 – 6,000 CFM
3,001 – 3,500 sq. ft.	6,000 – 7,000 CFM
3,501 – 4,000 sq. ft.	7,000 – 8,000 CFM

These are rough recommendations, and it’s important to consult with a professional to determine the most suitable fan size for your specific home and climate conditions.

FAQs

How big should my whole house fan be? The size of your whole house fan should generally be based on the square footage of your home. A rough estimation is that you’ll need around 2 to 3 square feet of attic ventilation per 1000 square feet of living space. So, for a 2,000 square foot home, a whole house fan with a capacity of 4,000 to 6,000 CFM (cubic feet per minute) should suffice.

How much ventilation is needed for a whole house fan? As mentioned earlier, a rule of thumb is 2 to 3 square feet of attic ventilation per 1000 square feet of living space. So, for a 2,000 square foot home, you’d want 4,000 to 6,000 square feet of attic ventilation.

How many windows do I need for a whole house fan? You typically need at least one or two open windows in the home when using a whole house fan. Having multiple windows open in different areas of the house can improve airflow and cooling.

Can an attic fan be too big? Yes, an attic fan can be too big if it’s not properly balanced with the ventilation in your attic. It’s important to have an attic fan size that matches the attic’s ventilation needs. Having an excessively large attic fan may create negative pressure in the attic, drawing conditioned air from your living space.

Can a whole house fan be too big? Yes, a whole house fan can be too big for your home. If it’s too powerful, it might create excessive drafts and noise. It’s essential to choose a fan size that is appropriate for your home’s square footage.

Is it cheaper to run a whole house fan? Yes, running a whole house fan is generally cheaper than using air conditioning. It uses significantly less electricity and relies on natural cooling through ventilation.

Do whole-house fans vent into the attic or outside? Whole house fans typically exhaust air directly outside through attic vents or roof vents. They should not vent into the attic, as this can lead to moisture problems and reduced effectiveness.

What are the disadvantages of a whole house fan? Disadvantages include noise, potential drafts, and the need to open windows for proper operation. Additionally, whole house fans are less effective in very humid climates.

Should a whole house fan be on all the time? No, a whole house fan should only be on when you want to cool your home. It’s not meant for continuous operation like HVAC systems.

What happens if you run a whole house fan with the windows closed? Running a whole house fan with windows closed can create negative pressure in your home and may pull air from undesirable places, such as the attic. It’s essential to open windows to allow fresh air in and maintain proper airflow.

Should you run a whole house fan in winter? No, whole house fans are primarily used for cooling in warm weather. They are not suitable for use in cold or winter conditions.

How long can you run a whole house fan for? You can run a whole house fan for as long as needed to cool your home, but it’s typically used for a few hours at a time to exchange indoor air with cooler outdoor air.

What’s the difference between an attic fan and a whole house fan? Attic fans are designed to ventilate the attic space by expelling hot air, while whole house fans are installed in living spaces and are used to cool the entire house by drawing in cooler outdoor air and exhausting warm indoor air.

What are the cons of an attic fan? The cons of attic fans include the potential for increased energy consumption if not properly sized, noise, and the need for maintenance.

Where should an attic fan be placed? Attic fans are typically placed near the roof’s peak to effectively exhaust hot air. Proper attic ventilation, including soffit vents, is essential for their efficient operation.

Does a bigger fan mean more airflow? Generally, yes, a bigger fan can move more air. However, the size of the fan should still be matched to the space and ventilation needs to ensure efficiency.

Does a large fan use a lot of electricity? The electricity consumption of a large fan depends on its motor and usage. Generally, larger fans use more electricity, but they can still be more energy-efficient than air conditioning.

Does a whole house fan improve air quality? A whole house fan can help improve air quality by bringing in fresh outdoor air and expelling indoor pollutants. However, it may also introduce outdoor allergens if not filtered properly.

Why don’t people use whole house fans anymore? Whole house fans are still used, but they are less common in areas with long periods of hot and humid weather where air conditioning is preferred. They also require homeowners to open windows, which may not be desirable for security or noise reasons.

Does an attic fan use a lot of electricity? The electricity usage of an attic fan depends on its size and motor. They are generally more energy-efficient than air conditioning but can still add to your overall electricity consumption.

Where does a whole house fan get installed? A whole house fan is typically installed in the ceiling or attic of a central location within your home.

Where is the best place to put a fan to air out a room? To air out a room effectively, place a fan near an open window or door to create cross-ventilation, allowing fresh air to enter and stale air to exit.

Does the attic fan take air out of the house? No, an attic fan is designed to exhaust hot air from the attic space, not from the living areas of the house.

Should I turn off the whole house fan in winter? Yes, it’s best to turn off the whole house fan in winter because it’s not designed for use in cold weather, and it can lead to energy loss and discomfort.

How do I get the best results from a whole house fan? To get the best results from a whole house fan, use it during cooler outdoor temperatures, open windows to allow for airflow, and ensure your attic has adequate ventilation.

Is it better to have windows open with the fan on? Yes, it’s essential to have windows open when using a whole house fan. This allows the fan to draw in fresh outdoor air and expel warm indoor air, providing effective cooling.

Should you open or close windows with a fan? You should open windows when using a fan to allow for proper ventilation and air exchange. Closing windows can disrupt airflow and reduce the fan’s effectiveness.

Can you use a whole house fan without opening windows? Using a whole house fan without opening windows is not recommended, as it can create negative pressure and reduce its efficiency.

How do you cover a whole house fan in the winter? You can cover a whole house fan in the winter with an insulated cover or damper to prevent heat loss and drafts.

What can I do with my whole house fan in the winter? In the winter, it’s best to seal and insulate your whole house fan to prevent heat loss. You can also use it as a regular ceiling fan for circulation if it has that function.

Why are whole house fans so expensive? Whole house fans can be expensive due to the quality of the motor, fan blades, and installation costs. However, they can provide energy savings over time.

Do you need ductwork for a whole house fan? No, you do not need ductwork for a whole house fan. It primarily relies on natural airflow through open windows and vents.

How is a whole house fan installed? Installation involves mounting the fan in the attic or ceiling, ensuring proper attic ventilation, and wiring it to a control switch.

Is it worth installing an attic fan? The worth of installing an attic fan depends on your climate and attic ventilation needs. It can be beneficial in hot climates to reduce attic heat, but it may not be necessary in cooler regions.

Why not to install an attic fan? You may not want to install an attic fan if your attic already has sufficient ventilation or if you live in a climate with cold winters, where it can lead to heat loss.

Do attic fans need maintenance? Yes, attic fans require periodic maintenance, including cleaning the fan blades, lubricating the motor, and checking for debris or obstructions.

How much does it cost to install an attic fan? The cost of installing an attic fan varies depending on factors like fan size, location, and labor costs. It can range from a few hundred to over a thousand dollars.

Should an attic fan be on in the winter? Attic fans should generally be turned off in the winter to prevent heat loss and maintain insulation effectiveness.

Do attic fans turn on in winter? Most attic fans are manually controlled, so they won’t turn on automatically in the winter unless you activate them.