Whole House Fan Usage: 24/7 or Not?

A whole house fan is an essential add-on in homes for cooling and ventilation. Since they are widely used to create a comfortable and fresh indoor environment, it is crucial to discuss if it is necessary and healthy to run a whole house fan all the time.

Whole house fans should be run all night to allow a thorough removal of warm, state air from the room. They also act as an effective ventilation system in winter by preventing a buildup of stale air, as windows are generally closed.

This article discusses whole house fans, their working, advantages, and potential negative effects. We then dig into when and how long you should run them with respect to different climates.

How Does A Whole House Fan Work?

A whole house fan is an electric-powered appliance that maintains ventilation in the room while keeping it cooler. They work on the principle of convection which says that dense, warm air has fast molecules that rise up (towards the ceiling or attic), whereas cooler air is less dense and, therefore, sinks.

A whole house fan pulls cool air into the room through openings like windows, garages, basement doorway, etc. The hot, stale present inside the room is propelled outside through attic vents. This cycle keeps your indoors fresh and helps cool it down by up to 30 degrees.

They are often confused with attic fans. Remember that whole house fans circulate air in the entire house, whereas attic fans move the air inside the attic only.

Whole house fans are cheaper as compared to other HVAC alternatives and can be used year-round as an energy-efficient cooling device.

What Are The Types Of Whole House Fans?

There are three main types of whole house fans:

i) Standard

Standard whole house fans are installed on walls or attic floors. These box fans have dampers that open to push air outside but remain shut when the fan is not in use.

ii) Ducted

They have a large fan on one end and insulated ducts with finished vents on the other side. While the fan is installed in the attic, the duct is placed in the finished space for cooling.

These fans are placed at a comparatively larger distance from the main space and, therefore, offer whisper-quiet operation.

iii) Insulated

They have insulated doors that open only when their fan is in use.

How Long Should You Run A Whole House Fan?

Whole house fans require a cooler outside temperature to work. Indoors are almost always hotter than outside, and therefore, technically, you can run a whole house fan at any time of the day.

However, for more effective cooling, it is recommended to run a fan all night. This is because nights are cooler (57 degrees F on average) than the daytime; running a whole house fan at night will pull the heat out of the house’s structure and sheetrock. This enables better cooling.

Should You Run a Whole House Fan In The Winter?

During winters, people generally don’t open windows, which prevents fresh air from entering inside. This leads to a buildup of contaminated, stale air in the rooms.

Whole house fans don’t just cool the air. Instead, they also serve as a great ventilation mechanism that constantly replaces stale air with healthy, fresh air. Therefore, running a whole house fan can be effective in winter.

Should You Turn The Whole House Fan Off When Cleaning It?

The power supply should always be off when cleaning whole house fans (or other appliances) to avoid electrical accidents.

Whole house fans are in constant contact with air and, therefore, accumulate dust, debris, and other airborne contaminants. To keep a fan running, it needs to be cleaned at least every three months. Here’s how to do it:

  • Take a dry cloth, and use it to wipe the fan blades and motor.
  • Spray a non-abrasive, mild cleaner on the fan, and wipe it with a cloth. Do not spray the solution on the motor.
  • Lightly dampen a cloth, and clean the motor with it.
  • Dust the fan cover.

How Much Does It Cost To Run A Whole House Fan?

The buying and installation cost of a whole house fan generally ranges from $1500 to $3000. Based on the CFM rating, electricity costs can vary between 2 to 9 cents per hour. The cost of upkeep and services is generally none to minimal if cleaning and maintenance instructions are followed.

Here’s how much a whole house fan can cost you:

i) Buying Cost

The price of whole house fans varies for different models, depending upon the quality of the product, as well as other additional features. On average, it may cost you anywhere between $200 to $1200 and more.

ii) Installation Cost

Whole house fans need an efficient flow of air to work. They are installed in open spaces like living rooms in the ceiling or a wall opening.

Generally, people get the customer service of the original brand to install the fan, and it can cost you between $400 to $800.

Whole house fans come with cutouts that you can use to install the fan yourselves. Turn off the electricity at the main circuit breaker box. Test the wires to ensure the power supply to the room that you are working in is cut.

Follow these steps for each type of fan:

For Belt-Driven Whole House Fan

Belt-driven fans have a separate blade assembly, and they employ a pulley and belt for air circulation.

  • Mark the joist by pushing nails on each side of its side. This ensures correct shutter placement.
  • Cut out the fan template.
  • Place the template on the ceiling and staple it in place.
  • Cut the drywall by the lines drawn. Keep a one and ½ inch setback.
  • Nail lumber to the joist and joist support. This will act as a platform for the fan housing.
  • Attach the fan to the opening, and secure it in place by using wooden blocks.
  • Mount the fan motor, and slide it into the fan belt to secure its position.
  • Lastly, place the speed switch.

For Direct-Drive Whole House Fan

These are appliances in which the fan propeller is connected directly to the motor shaft (in contrast with the belt drive that has two pulleys connected via the belt).

  • Make a cutout on the chosen (1 by 2 inches) ceiling joist.
  • Align the template on the ceiling, and trace around it.
  • Using a jigsaw, follow the outline on each side of the joist to cut out the drywall.
  • On the fan, mount and tighten the saddle brackets with bolts.
  • Pass the fan into the attic.
  • Center the fan over the cutout to mark the saddle bracket holes.
  • Drill the holes for saddle brackets.
  • Remove the fan blades, and set them aside. Now, mount the fan to the ceiling joist.
  • Place the fan blades, and tighten them with screws.
  • Mount the shutter, and attach the skirting and pull chain.

iii) Maintenance

Annual tune-ups are not necessary for whole house fans, and if adequate maintenance guidelines are followed, these appliances do not cost much on the upkeep.

Here are some basic steps that can keep your whole house fan running for a long time:

  • Open several windows to ensure a proper air supply. Do this before turning on the fan to prevent stress on the fan motor.
  • Ensure that the attic has sufficient outlets for ventilation.
  • To keep the motor running, it is crucial to lubricate it with oil every few years.
  • For optimal functionality, clean the fan shutters and blades often.

In case the fan starts acting up, a repair can amount to $700 and more. Replacing the fan motor is generally the most expensive, and if the warranty is not applicable, it is better in the long term to get a new fan instead.

iv) Electricity Cost

The energy consumption of a whole house fan varies based on its CFM (cubic feet per minute) rating. It indicates the amount of air a compressor produces at a given pressure level. Understandably, high CFM ratings can produce more air and are, therefore, suitable for larger areas.

Depending on the CFM rating, a whole house fan typically consumes 200 to 650 watts, which adds 2 to 9 cents an hour to your electricity bill.

Here are some tips to reduce the energy consumption of whole house fans:

Adequate Attic Ventilation

As a thumb rule, one sq. ft. of attic ventilation for every 750 CFM of the fan is crucial. This prevents overheating, and with the motor running smoothly, power consumption is significantly reduced.

Similarly, open maximum windows to reduce the load on the fan motor.

Central Positioning

Ideally, you should install your whole house fan at a central location. This enables the fan to draw maximum air with minimal energy.

Is It Cheaper To Run a Whole House Fan Or AC?

Whole house fans are a cheaper alternative to air conditioners. While a whole house fan costs 2 to 9 cents an hour on electricity bills, the latter costs at least $0.88 per hour. ACs also require regular maintenance checks and high-end upkeep, which adds to their running cost.

Running Cost Of Air Conditioners

Running an AC for 8 hours a day can cost $14 on low-end units and $200+ on high-end systems. On average, their maintenance also ranges between $100 to $200. Given that ACs require upkeep services at least twice a year running them is highly expensive as compared to whole house fans.

Is Whole House Fan Better Than AC?

Here’s how whole house fans are better than ACs:

  • They are cheaper (in terms of buying, installation, and maintenance costs) and consume significantly less power than ACs.
  • They cool the room down much faster than ACs. This is because whole house fans remove hot air from the indoors and replace it with cooler outside air, while AC units cool the air in the home.
  • They are easier to install. While you can install the fan using the cutouts, you must consult a professional for AC installation.
  • They continuously replace stale air, while running an AC leads to poor ventilation. This circulation of air also reduces airborne contamination.
  • In contrast with ACs, whole house fans do not dehumidify the room. This nullifies the chances of dryness and associated health symptoms (wheezing, allergies, and general discomfort).
  • They are environment-friendly and have insignificant effects on global warming as compared to ACs that produce high concentrations of carbon and other greenhouse gases.

ACs also have a few advantages over whole house fans. They are not affected by outside temperature as compared to whole house fans that require a cooler outdoor environment to work.

If you live in an extremely hot and humid area, ACs can be better for you. As for cold /normal climate, whole house fans are an economical choice.

Russell Singleton

Russell holds a Bachelor of Science (Environmental and Marine Geoscience) with Class I Honors. He is currently completing his doctorate in science and is passionate about all earth processes, especially isotope geochemistry and paleohydrology.

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