Whole House Fan vs Attic Fan: What's the difference?
The names sound similar, and both fans are intended to keep your home cooler for cheaper than an air conditioner, but what is the difference between a whole house fan and an attic fan?
An attic fan exhausts hot air out of an attic and pulls fresh air through an attic vent. No air inside the home is disturbed. A whole house fan also exhausts hot air out of the attic, but it pulls fresh air in through open doors or windows in the home.
Let's look at the pros and cons of each so you can determine which one fits your needs best.
In the summer your attic retains a bunch of unwanted heat. On a 90+ degree day, your attic could be hitting temps of over 140! It's a tough battle to keep indoor temps comfy with that kind of heat baking your ceiling, not to mention the ductwork carrying conditioned air is just soaking in the heat in your attic too.
If you don't clear that heat out your attic stay hot all night too, like a heated blanket you can't shut off.
These problems are what led to the creation of the attic fan. The concept is powered ventilation with fresh air coming through existing attic vents to replace the hot air being exhausted. Even if you are pulling in 80-90 degree air it still is a lot cooler that it would be otherwise.
There are two basic types differentiated by how they are mounted. Gable attic fans are mounted inside a gable vent. These are the simplest and easiest to install, but if your home doesn't have a gable vent you'll want to look at a roof mount attic fan.
Roof mount attic fans are mounted on the outside of the roof. A hole is cut in roof and fan is installed over it with flashing and sealant. The difficulty of the installation depends on what type of roof your home has. A standard comp roof is a simple install while tile or metal roofs make it a bit trickier.
- Attic fans lower cost to purchase and less work to install than a whole house fan.
- Attic fans are "Set and forget". They turn on and off automatically based on a thermostat.
- Since no air is pulled through the home, there is no chance of dust being pulled in.
- Attic fans are limited in how well they can cool off a home since no indoor air is exchanged.
- Due to how they are mounted, gable fans can cause some noise. This can be mitigated if the fan is mounted above a garage.
Whole House Fans
Whole house fans tackle the same problem an attic fan does but with an extra consideration: changing the air inside your home where you feel it most.
A whole house fan is installed in the ceiling of your home. It pulls outside air through your home via doors and windows, and exhausts it into the attic where it escapes through the attic vents.
Since you are exchanging indoor air that you may have been cooling with an air conditioner, you will only want to run a whole house fan when the outdoor temps are lower than the indoor ones. What this means in a practical sense is you will get the most benefit out of running your whole house fan from late evening to early morning.
To get the greatest cooling effect a whole house fan should be run for 6-8 hours. Sure, you feel instant relief when the fan is on, and air is exchanged every few minutes, but fresh air has no long term cooling power when it is quickly changed then shut off.
Running a whole house fan on low overnight like this is a concept know as Thermal Mass Cooling. By lowering the temperature of all heat retaining mass in your home to the lowest daily temperature then locking the coolness in by closing door, windows, and curtains in the morning you can drastically cut the run time of your air conditioner.
- Feel cooler as soon as you turn the fan on.
- Cool the inside of your home and attic at one shot.
- You can use the fan to exhaust cooking odors and the like in minutes.
- Not automated. You must be home to open windows before turning the fan on.
- Higher upfront cost and more labor intensive install.
Is having both fans overkill?
As you may have noticed, the fans have some overlap in functionality but there's a whole lot about them that are like apples and oranges. It is totally valid- actually recommended to use both fans together.
The attic fan runs when the whole house fan cannot and the whole house fan moves air where the attic fan can't reach and both help keep your home cool and your air conditioner off.
So how does all this save you money?
An air conditioner is the most power hungry appliance you own. It's wonderful- a necessity even- but very energy intensive to run. Any time you can cool with something that uses a fraction of the energy you're putting money in your pocket.
The second way these fans save you is with the hidden maintenance costs of running an air conditioner. This is easy to overlook but in reality the life of your air conditioner isn't measured in years- it's measured in hours of runtime. Reduce the runtime and your ac lasts longer with fewer repairs.
To see prices and find out which fans we recommend for your home take our QuietCool Quiz by clicking the button below. Fill out a few details about your home and get the info emailed to you instantly.