How To Use a Whole House Fan In A Two Story House (Easy?)

Do you want to learn how to properly operate a whole house fan to cool your home if you have a two story house?

You are in the right place.

This article will give detailed instructions on the best way to use a whole house fan to cool your home.

In this guide you will learn…

  • Why you must open a few windows or doors for a whole house fan to work
  • Always close your fireplace dampers
  • Only use a whole house fan when it is cooler outside (if cooling is your goal)
  • Always turn off your whole house fan when you aren’t home
  • Why opening windows away from direct sunlight is the most energy efficient
  • And more…

It may seem like all you have to do is flip a switch and a whole house fan will work exactly as intended — but there is much more to the proper operation of a whole house fan.

There are things that you need to know to get the best cooling and the best cost savings when using a whole house fan.

Let’s get to our guide!

Read Also: Our Top Picks For Whole House Fans

Do You Need To Keep The Windows Closed Or Open?

A whole house fan works through suction by pulling in the cooler outdoor air into the home’s interior.

In order for this to happen, you will have to either…

  1. Fully open a few windows
  2. Slightly open (a few inches) several windows
  3. Fully open 2-3 doors

You will have these three options, or maybe a mix of each. Experiment with what works for you.

It is also a good idea to keep in mind which windows and doors you choose to open for the intake air.

Ideally, you should open the windows and doors that are north facing or otherwise in the shade because the air will be cooler in these areas.

Also, make sure the windows and doors have insect screens to keep out bugs and debris.

When Should I Turn On The Whole House Fan?

The most important thing to remember is to use a whole house fan when the outdoor air is cooler than the indoor air.

The entire point of using a whole house fan is to use the outdoor air to cool the interior of a home.

If you use the whole house fan when the outdoor air is warmer, then it defeats the purpose of the fan.

Most users will use the fan in the morning and the evening hours when the sun is low on the horizon or has completely gone down.

Some homeowners only operate their whole house fan for 20-30 minutes, and then turn the fan off.

Other users like to keep the whole house fan all night long, and then turn it off in the morning.

Experiment with what works best for you.

How Do I Turn On A Whole House Fan?

There is usually a wall switch below the whole house fan for it to turn on.

Most whole house fans will have metal louvers that automatically open when you flip the switch.

If you turn on the fan without opening a few windows, doors may slam shut, potentially injuring someone.

The suction power of a whole house fan is incredible.

During one home inspection in Virginia, I absent-mindedly turned on a whole house, and the bathroom door quickly closed, making a loud whack sound — startling my client.

You may also want to install a remote control for your whole house fan.

There are remote adapters that plug into the outlet in your attic, and then the whole house fan plugs into the adapter.

You will then be able to turn on and off the whole house fan from anywhere in your home.

Should I Close Fireplace Dampers?

It is good practice to close fireplace dampers when you use a whole house fan.

Most fireplaces and flues are filled with soot, ash, and debris, and you don’t want this debris being blown into the home.

Also, keeping a fireplace damper open can allow in insects and other pests.

Should I Turn On a Whole House Fan With Gas Appliances?

If you have a gas-burning appliance such as a water heater, kitchen oven, furnace, or boiler — you should be aware that there is always a degree of risk when the whole house fan is in operation.

A whole house fan creates a massive negative air pressure in your home — the suction — which is what draws in the cooler outdoor air.

If you have a natural gas burning appliance, the exhaust fumes may be pulled back into your home and possibly poison the occupants with carbon monoxide.

This is why you will need to have open an adequate number of windows or doors for the intake air so your appliances don’t “backdraft” exhaust fumes.

It is highly recommended that homes with natural gas AND a whole house fan to always have a carbon monoxide detector on each level of the home.

Should I Leave The Attic Stairs Open?

If you have pull down attic stairs (or even just a hatch), you shouldn’t leave it open when you are operating a whole house fan.

When the whole house fan is in operation, it will first pull in the warmer interior air into the attic, and expel it out of the attic vents.

If your pull down attic stairs is open, this warmer air will go back into the home, ruining the effectiveness of the whole house fan.

Read Also: Our Top Picks For Solar Attic Fans

Do I Leave The A/C On When a Whole House Fan Is In Operation?

The best way to use a whole house fan is when you turn off the home’s air conditioning.

If you have the air conditioner turned on when you are using a whole house fan, it would defeat the whole purpose.

You will be pulling in the cooler exterior air into the home, and pushing out the warmer interior air to the outside.

If you run the air conditioner at the same time, you will be cooling the interior air that will just be pushed to the outside anyways.

To learn more about whole house fans, check out our article on “Do whole house fans truly work?”

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Arie Van Tuijl

Arie Van Tuijl

Arie is a licensed home inspector who owns a residential and commercial inspection company in the state of Virginia. He also does specialty testing such as radon gas, termites, air quality, and mold.

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