What Does A Whole House Fan Do?

If you're looking for a way to cool your home off in the summer time without using a ton of electricity, a whole house fan just might be what you're looking for. While they were the only method of cooling homes in the early 1900s, today they're an inexpensive supplement to your existing central air conditioning unit. Read further to learn how a whole house fan works.

What Is A Whole House Fan?

A whole house fan is a large fan that, when properly implemented, can cool your home significantly during the summer without the need of much modern air conditioning. They are often installed between an attic and the living space below, even though not all homes that use whole house fans have attics at all. Instead, homes without attics, will vent their whole house fan directly with an outside wall instead.

How Does A Whole House Fan Work?

When used on a home with an attic, a whole house fan works by pulling air from inside the living areas of a home up into the attic, which is then vented outside of the house through the roof ventilation.

This can cool a home that has an attic significantly, because during the summer time, attics can reach as high as 160°F, even if the temperatures outside the home are below 100°F! This is essentially a heating blanket over the living areas of your home and it's keeping your home much hotter than it should be during the summer time.

A whole house fan can help solve this problem.

Attic Fan VS Whole House Fan

It sounds like an attic fan and a whole house fan are the same thing, but this isn't true. The big difference is that the attic fan is only designed to cool the air in the attic, because it pulls in air through roof and soffit vents from outside the home instead of through the living area and expels the hot air in the attic outside. It keeps the attic cooler, but does nothing for the rest of the home directly.

Whole house fans are more effective at cooling a home, because they work on the air in the home and in the attic space. A properly set up whole house fan can cool an entire home in about an hour.

One big con of attic fans is that it's possible for them to backdraft carbon monoxide into the house if you have gas appliances, like water heaters, dryers, stoves, etc.

Another con is that a powered attic fan is going to pull air from wherever it can, which often means that it's pulling the air from your living space (that you're already air conditioning with your central unit) instead of pulling it in through soffits and roof vents. Who wants to pay to air condition their attic when their attic should in theory be air conditioning itself with the fan you installed?

It pulls air through any cracks and crevices that it can and can even pull up damp air from crawl spaces under your home up through living spaces and cause mold problems.

Electric attic fans are also illegal in some states in the US, including Georgia. Georgia recently banned them unless they are connected to a solar panel.

Whole house fans are superior in every way, from safety to energy efficiency.

How Much Does A Whole House Fan Cost?

A whole house fan can be anywhere between $1000 and $2000+ depending on the size of your home. The unit itself may be $500, but you'll pay at least that much for installation. Your home may also require additional roof vents for the fan to work properly.

Are Whole House Fans Energy Efficient?

Whole house fans can use as much as 90% less energy than central air conditioning units that are compressor-based. When you're calculating how much you can save on your electricity bill, that 90% adds up fast.

For example, if you're regularly paying $200/mo to cool your home, 90% of that is $180. You could eliminate potentially $180 of your $200/mo cooling bill with a whole house fan alone. That's a significant amount of savings every summer just by switching to a fan instead of running central air conditioning. This means that the installation would pay for itself in as little as a year depending on the weather where you live.

Does A Whole House Fan Qualify For Tax Credit?

Installing a whole house fan will benefit you in the ways we've already talked about, but some say that you may get a tax credit for installing one.

Some websites claim that you can get a $50 federal tax credit for a whole house fan, but this isn't true. The current federal tax credit for an advanced main air circulating fan is capped at $50, but this does not cover whole house fans because they are not connected to a furnace.

How To Choose A Whole House Fan

If you've already decided after reading all of this that you need to save up to 90% of your cooling bill every month, then you'll be needing some tips on how to choose the right whole house fan for your home.

You'll need to talk to your local HVAC installer to find out what type is best for your home and climate. You may think that a larger fan would be better than a smaller one, but the truth is that sometimes other things can get in the way of installing a larger unit. These things can be the requirements of the installation, the appearance of the fan in the ceiling of your living space, the amount of noise the unit produces, and the units overall cost.

The type of fan that may work for one home in one area may not work well for another home in another area. But, to get a general idea of what might work for yours, check out the 3 different types of whole house fans that are currently available below.

Inline Whole House Fans

Ducted whole house fans can be used to cool specific areas of your home and can be quieter than the other types of fans available. Because they're located away from your living space instead of being mounted directly in the ceiling above, they're not as noisy.

Standard Whole House Fan

These fans are exactly what they sound like: standard, low end house fans. “Low end” doesn't necessarily mean that they're low quality, just that they're lower priced and more commonly available. The cost is the good thing. The bad thing is that these fans are essentially a hole in your ceiling that isn't sealed when the fan isn't in use. So, if you're using a central heat and air unit when you're not using your whole house fan, it's going to cause your home to lose heat in the winter if it doesn't have an insulated cover placed over it.

Out of the 3 different types of whole house fans, standard fans move the greatest amount of air.

Insulated Door Fans

These fans solve the problem of the standard fans listed above, because they have insulated panels built in. With these fans installed, you'll be able to completely seal off your unit during the winter time so your home doesn't lose heat out through the attic.

Another pro of insulated door fans is that they are quieter than standard fans.

What Size Whole House Fan Do I Need?

Whole house fans are rated by how many cubic feet per minute of air that they can move throughout your home. The bigger house you have, the higher the CFM rating of the fan that you're looking for.

You can calculate the size of whole house fan that you need by taking the square footage of your home (assuming 8ft ceilings) and multiplying it by 3.

Whatever size fan you decide to get, you need to make sure that your attic is vented properly so that it can allow the air that your fan brings in to be sent back outside. You need around 1 sq ft of venting in your attic for every 750CFM that your whole house fan is.

When Should I Run My Whole House Fan?

You should only use your whole house fan when you're not using your air conditioning. You don't want to expel your cold air that you're paying an electric bill to produce.

You should also only use your whole house fan when the outdoor air is cooler than the air in your house. The fan can cool your house off to at least outside temperatures, but no more than that.

Make sure windows are open in your house to allow the fan to bring air in from outside. If it's not properly vented, the fan cause gas-burning appliances to backdraft fumes into your home that can be toxic to your family. Carbon monoxide is one of these. For this reason, you should have carbon monoxide detectors in your home if you have a whole house fan running, especially at night.

You should also not have a fire active in your home while running your whole house fan, whether gas or a wood fire in a fireplace.

Can I Run My Whole House Fan All Night?

You can definitely run your whole house fan throughout the night. It can help keep your home cooler for longer during the day before the heat of the afternoon hits.

But, you still need to have your windows open to keep the ventilation in the home appropriate for the fan. As mentioned before, whole house fans cannot be run safely without windows or doors open due to issues with causing fume backdrafting from gas appliances.