When should you not use a whole house fan?

Author: Ayana O'Reilly  |  Last update: Thursday, January 29, 2026

Do not run your whole house fan during the day unless the temperature outside is cooler than the house is inside, though you may want to run the fan during the day to push air out of the attic. To do so, direct airflow from either the basement or the shady side of the home.

What are the negatives of a whole house fan?

Whole house fans which are large enough to create a breeze through the house can sometimes produce unintended effects such as noise, heat loss, and house depressurization. This can be improved with more attic vents and window area to replace the exhausted air. You must open windows.

Should a whole house fan be on all the time?

Whole house fans are meant to run with a few windows open in the early morning, late evening and overnight, when the air outside is cooler than the air inside.

Why are whole house fans not used anymore?

The reason why whole house fans became obsolete is that they don't allow homeowners to really control the temperature or comfort inside the house -- like they can do with air conditioners. If the outside air is too hot and muggy, that is the kind of air that will be brought into the home.

Can you open too many windows with whole house fan?

SHOULD I OPEN ALL MY WINDOWS IN MY HOME WHEN OPERATING A WHOLE HOUSE FAN? No, we recommend that you open very few select windows to match the proper net free venting of your home. The best way to use your system is to crack a window on the opposite side of your bedroom or hallway.

Should I Get A WHOLE HOUSE FAN? [Good Idea or Bad Idea-depending where you live]

What happens if you run a whole house fan with the windows closed?

If you do not open the proper amount of windows, you will increase the chances of back-drafting. Back-drafting happens when outside air is pulled into the home through vent pipes. As a result, polluted air could be entering your home.

Do whole house fans use a lot of electricity?

By contrast, a whole house fan has a motor in the 1/4 to 1/2 hp range, uses 120 to 600 watts, and costs around 1¢ to 5¢ per hour of use.

Do whole house fans bring in dust?

Many homeowners may think their house will get dustier by running the Advanced Whole House Fan. However, due to the amount of air an Advanced Whole House Fan moves when properly sized to the home, dust does not have any time to settle in the home!

Is it a good idea to install a whole house fan?

Whole house fans can be an energy-efficient alternative to air conditioning in some climates. Combined with ceiling fans and other circulating fans, they can provide comfortable summer conditions for many families.

Should I run my whole house fan in the summer?

Extra Hot days (over 100 degrees)

On some extremely hot summer nights, it will not cool off enough to run the whole house fan while you are awake at all. Use your whole house fan system for cooling the attic on these nights, to maximize a/c performance during the evening.

Can you run a whole house fan with the AC on?

Whole House Fans should never be used simultaneously with air conditioning of any kind – central air or window units. These systems can both reside in the same home and be used to complement one another, but they are more relay partners than three-legged-race partners.

How long can I run my whole house fan?

We recommend running the whole house fan all night. The goal is to cool your entire house down, not just the air. It takes time to pull the heat out of the sheetrock, structure and contents of a house.

Can I leave my whole house fan on all night?

For cooling purposes during the warmer months of the year, Whole house fans are designed to run whenever it is cooler outside than inside your home. This is oftentimes during the early morning and nighttime hours. Because of this, most customers run their Whole house fan all night long on a timer.

Why are attic fans not used anymore?

Why are attic fans not used anymore? Due to inefficiencies in relying on existing attic vents for air intake, attic fans have lost popularity. These vents often aren't designed for this purpose, resulting in inadequate replacement air supply.

What's better, an attic fan or a whole house fan?

How To Choose the Right Fan for Your Home. First, consider the main difference between a whole house fan and an attic fan: purpose. A whole house fan will be the better choice for cooling your home, whereas an attic fan is the better option to ventilate warm air gathered in the attic and to lower humidity levels.

Can whole house fans cause mold?

Humidity Issues: In humid climates like Michigan, whole house fans can draw in moisture along with the cooler air. This can make your home feel damp and uncomfortable, and it can also lead to mold growth and other moisture-related problems.

Do fans cause dust mites?

How Ceiling Fans Trigger Dust Mite Allergies. Dust mites breed in dusty areas. Ceiling fans easily become dusty, and mites accumulate on the blades of the fan. When the fan is on, it blows dust and mites all over a room.

Why don't people use whole house fans anymore?

Whole-House Fans

They also have disadvantages. If your climate is humid, the air you draw in will be humid as well, and might not be as cool as hoped for. A whole-house fans requires a large hole in the ceiling that can be difficult to air seal in the winter, causing heated air to leak into the attic.

Is it OK to run the whole house fan all day?

Do not run your whole house fan during the day unless the temperature outside is cooler than the house is inside, though you may want to run the fan during the day to push air out of the attic. To do so, direct airflow from either the basement or the shady side of the home.

Is it cheaper to run a whole house fan or AC?

However, in general, whole house fans can save you up to 50-90% on your cooling costs compared to running an air conditioning system.

When to turn off the whole house fan?

Monitor Temperature: Keep an eye on the indoor and outdoor temperatures. If the outside air becomes warmer than the inside air, it's time to turn off the fan. Use in Conjunction with AC: In some climates, a whole house fan can be used to complement air conditioning.

How many windows should be open for a whole house fan?

Generally, at least one window should be open while using your whole house fan so that the cooler outside air can replace the hotter inside air. Opening two or more windows partway is usually preferable to just opening one window.

What is the point of a whole house fan?

A whole house fan draws cool air in through the windows and can bring down the temperature of your house significantly in less than an hour, depending on the external temperature.

Previous article
Do baseboard heaters wear out?
Next article
What is demon sleep?