What is a Whole House Fan and How Does it Work?

Homeowner changing filters on a whole house fan.

Tired of the summer heat making your home feel incredibly uncomfortable? No one enjoys having their back stick to a leather chair, or feeling like every time you get up to get a glass of water you've just ran a marathon.

As much as beautiful summer days can be a blessing, more often than not homeowners across the United States want to beat the heat while relaxing at home. There are numerous ways to keep your home cool—including central air conditioning, of course. However, another option many homeowners don't even know about is to install a whole house fan.

This system is an excellent option to keep your home cool, whether as an add-on to your current cooling strategy, or as an alternative to AC. Installed in your attic or roof, it works by pulling air into your house through open windows and pushing it out through your attic. This cools your home by moving cool air in and hot air out.

We're sure you have questions about whole house fans, which is why the HVAC experts here at Aire Serv created the following blog post. In it you'll find answers to common queries, insights from our pro team and more.

How Does a Whole House Fan Work?

A whole house fan pulls in fresh, cool air from open windows and exhausts hot, stale air through the attic and roof. Hot air naturally rises, so this system works with that in mind as the machine pushes more and more hot air into your attic space, eventually, the air is forced out of soffit vents and other attic vents. Thus, creating a cooling effect throughout your home. This house cooling effect is similar to how a conventional ceiling fan works, however on a much larger scale.

When working correctly, a whole house fan should provide your property with 3 to 6 air changes per hour—although this will depend on your local climate and your home's floor plan. For most models, you have the option to choose the air-change rate. A big factor in what air-change rate you choose is how much you will depend on the system to keep your home cool. For instance, the method could be what you rely on completely to drop interior temperatures, or it could be complimented by an air conditioning system.

What Are the Benefits of a Whole House Fan?

There are a number of benefits to using a whole house fan to keep your property cool. We've outlined a few of these numerous advantages below:

  • Quickly lower temperatures to a more comfortable level by circulating the air throughout your home. This cooling method is an excellent way to rapidly decrease temperatures without having to install or turn on your AC.
  • Reduce energy bills and increase your home's energy efficiency. Perhaps one of the greatest benefits, using a whole house system helps to reduce your energy costs as it requires less electricity to operate than other cooling methods.
  • Feel good about using an environmentally friendly method to cool your home down, as they don't use any refrigerants and require little electricity to operate. Even modern-day refrigerants that don't deplete the ozone still emit greenhouse gases. If you're serious about decreasing your carbon footprint, it's well worth considering installing this cooling method.
  • Breathe fresh air due to improved air flow, as this method constantly circulates the air in your home, which even helps to remove odors from cooking, pets, smoke and household cleaners. This can be very beneficial for individuals with respiratory illnesses—not to mention, who doesn't enjoy a breath of fresh air?
  • Enjoy cool air with little noise disruption, as correctly installed models have low sound levels and last for years. Whether you're sensitive to noise and the AC keeps you up at night, or you have a new-born who wakes up at the smallest sound, this cooling method is a great way to keep interior temperatures comfortable without the constant buzz of an AC unit.
  • Enjoy lower set-up costs than other cooling strategies. Purchase and installation costs are much lower than air conditioning systems. Depending on your climate, you may actually be able to avoid installing AC entirely.
  • Increase your home's resale value. Installing a whole house fan will make your home more attractive to prospective buyers, especially as Americans are becoming more and more eco-conscious. This means that homes with higher energy ratings are more desirable.

What Are the Drawbacks of a Whole House Fan?

Although there are many advantages to using this cooling method, there are a few drawbacks that homeowners should be aware of as well. Primarily, if enough ventilation isn't provided, the system can cause a backdraft in your furnace, water heater or gas-fired dryer. This may pull dangerous gases such as carbon monoxide into your home. To avoid this worrisome situation, it's imperative to open the windows throughout your living spaces while using this cooling method. This prevents concentrated suction in one location and reduces the risk of carbon monoxide poisoning. It's also very important to have carbon monoxide detectors, with updated batteries, on every level of your home.

How Energy Efficient Are Whole House Fans?

This cooling method is significantly more energy efficient than using an air conditioner. Using a traditional AC unit can seriously add-up during the summer months. According to the U.S. Energy Information Administration, cooling can account for as much as 27% of your total electric bill. This can easily translate to hundreds of dollars added to your energy bill—which we're sure most homeowners would agree, is less than desirable.

Alternatively, a whole house fan uses approximately 10% of the amount of energy it takes to power a traditional air conditioning unit. Keep in mind, this doesn't mean you have to choose one or the other. Many homeowners opt to use their AC during particularly hot days, or during the hottest part of the day, and then swap to this more eco-friendly method—especially at night, when temperatures are usually cooler.

How Do I Ensure it's Working at Full Capacity?

Naturally, to get the most benefits from your whole house fan, you need to be sure that it's operating at full capacity—especially if you want this cooling method to help save you money. Use the following tips to ensure you're maximizing this machine's full potential:

  • Always make sure you use the system when the air outside is cooler than inside, otherwise you will simply be filling your home with hot air.
  • Turn the AC off when you are running the system, or else you will be blowing the cool air straight out of your home. While you can use these machines in tandem, do not run them at the same time.
  • Leave it on all night long for your system to operate to its max. Since you want to cool the whole house, it's best to get as much accumulated hot air out while temperatures are at their coolest. Ventilating it throughout the whole night will help reduce your need to use your air conditioner the next day.
  • Most systems have at least two-speed settings. The faster setting uses more energy, so set your system to the lowest speed overnight. This will enable it to run quietly and efficiently all night long.
  • Either open a window or door when the system is running at all times, or else you could create a negative pressure zone in the house and this could be dangerous and might cause back-drafting from gas appliances—resulting in carbon monoxide poisoning.

What's the Best Way to Control Your Whole House Fan?

Most models come with remote controls, although some are available with Wi-Fi controls. If you'd prefer to control the system from your smartphone but it doesn't come with its own app, you can install a Wi-Di enabled switch. This switch will provide easy access and control from your phone.

What Climate is Best?

While any climate can install a whole house fan, this system does work best in cool, dry areas. Humidity is often one of the factors that can make a lot of people feel uncomfortable—it can even make reasonable temperatures feel a lot warmer than they are. Not to mention, that icky sticky feeling that often accompanies humidity.

Since this cooling method draws in fresh, outdoor air into your home, it won't work as effectively in particularly humid climates. Unlike most AC systems which dehumidify air, whole house fans do not. Thus, if you live in a humid climate you'd actually be drawing in more humidity into your home by using this system. States like Nevada or Arizona are ideal for this system, whereas states like Florida or Hawaii are not.

What to Consider When Buying the Best Whole House Fan

When selecting a whole house fan, it's important to keep in mind what size it should be. If you're unsure, the experts at your local Aire Serv are more than happy to help you choose an appropriate model for your home's needs. Additionally, there are a number of other considerations you should keep in mind while researching what system to install in your house.

  • Ensure the model is quiet. A properly installed system should be quiet, but it doesn't hurt to make sure you're purchasing a fan that is as quiet as possible. Fans are rated by "sones." According to the American Society of Heating, Refrigeration and Air Conditioning, whole house fans should not be louder than 1.0 sones.
  • Look for quality shutters. The better the quality shutters, the less thumping noises will occur when the unit turns off. Energy saving fans have self-sealing insulated shutters that close when the fan is not operating to reduce air leakage. This prevents heat buildup from escaping while you're not using the system—which is especially beneficial during the winter months.
  • Purchase a model that has a timer control. For this system, it's better to use a timer control instead of a thermostat. A thermostat may turn the fan on when no one is home, and while no windows or doors are open. This can lead to serious problems such as carbon monoxide poisoning. Also, a fireplace could trigger the fan to turn on if it's controlled by a thermostat, because the thermostat thinks the interior temperature is too hot.
  • Choose a system that operates well at a low speed, which will use less energy and be a bit quieter.
  • Opt for an option that has a simple installation method—especially if you're choosing to install this machine yourself. Many whole house fans are easy to install, which is one of their benefits. Direct-drive models are the most DIY friendly because they usually don't require attic joists to be cut. Belt-drive models that use an integrated pulley system take longer to install, however this option operates more smoothly and quietly. Keep in mind that your local HVAC experts at Aire Serv can install this system on your behalf.

Whole House Fan vs. Attic Fan: What’s the Difference?

There are many similarities between a whole house fan and an attic fan. While both work to cool spaces in your home, they do serve different purposes. 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. It serves to keep the whole house cool.

Contrarily, an attic fan’s primary job is exhausting heat out of your attic space. While this is similar to a whole house fan, it does not have the same cooling effect throughout your home. Both systems can help lower your energy use and lower interior temperatures, but a whole house fan has a more immediate impact than an attic fan.

Count on Aire Serv for Reliable Installation

Proper installation of your whole house fan is critical for it to function properly. Poor installation can lead to a noisy fan and less effective cooling—not to mention, higher energy bills. The team at Aire Serv has extensive experience in all areas of home heating and cooling, including whole house fan installation. Contact Aire Serv of Rockwall today for a whole house fan installation estimate.