I’ve been intrigued for some time by the concept of cooling a home with a whole house fan.
Now that I own a home with no air conditioning, I’ve installed a whole house fan of my own, and I must say I’ve become quite the fan of the product. Pun intended.
There are certain times a year that a whole house fan won’t do you much good, but if you live in a place where the days are warm and the overnight low temperatures drop into the 60s or below at some point in the year, which is true nearly everywhere in North America, your house may very well be a good candidate for a whole house fan, a money-saving, electricity-sparing wonder of an appliance.
Read on to learn how a whole house fan works, how much money a single fan can save you, how to install it yourself, and how to best use it to maximally cool your home for the lowest cost and smallest effort.
We recently bought a 1960s home with no air conditioning (A/C). In northern Michigan, it’s not as uncommon as you might think to have a house without A/C.
Furthermore, the home we purchased has no air ducts or ventilation system of any kind. The heat comes from baseboard units throughout the perimeter of the home, all of which are fed by a boiler. There’s no forced air furnace.
While adding central A/C would be quite costly and complicated given the fact that the basement ceiling is mostly finished and extensive ductwork would have to be installed, we do have other options for air conditioning.
We could put in a few window A/C units, focusing on the bedrooms for a couple hundred dollars apiece. For a few dollars more, we could go for the floor-standing portable models. Note that some of the links on this page are Amazon Associate links. Making a purchase after clicking on a link from this site could result in a commission, supporting our charitable mission.
If we wanted a more permanent A/C solution, we could drop a few thousand dollars for a multi-zone ductless air conditioning system, also known as the “mini split.” I’d probably have to factor in an installation charge, as the setup of such a system may be beyond my DIY capabilities.
As you may have guessed, I opted for none of these.
Instead, I purchased and installed a whole house fan, and we put it to the test during a serious early-June heat wave where the daytime highs reached 90 degrees Fahrenheit and the overnight lows dipped just below 70.
Thus far, I’ve been very impressed. I have no plans to add air conditioning to this home.
The original whole house fan design was a metal box that sat between your ceiling joists that separate your living space from your attic. The metal box contained a fan or two that were situated just above a hole cut in your celing, which was covered by a decorative grille.
The more recent designs, from companies like QA-Deluxe, QuietCool, and Centric Air, have a smaller sheet metal damper box that sits between the joists, a large circular duct of up to about 10 feet in length, and a large round fan that lives in the attic, suspended from the roof joists.
This upgraded design substantially reduces the noise transmitted into the house below, and allows for a single, more powerful fan to be used.
With either setup, the whole house fan’s job is to blow air from your living space into your attic. From there, the air exits your home through a properly ventilated attic via soffit vents, ridge vents, gable vents, and any other roof vents. You should have one square foot of ventilation space for every 500 to 1,000 CFM (cubic feet per minute) that your fan can handle.
Popular whole house fans can push 6,500 cubic feet of air out of your home every minute. A 3,000 square foot home with 9 foot ceilings has, when empty, 27,000 cubic feet. Since your stuff takes up space, all of the hot stale air in the home could be pushed out with such a fan in 4 minutes or less.
What takes all that air’s place? More air, thank goodness! Outside air, that is. Preferrably cooler outside air, which is why you typically only run the fan when the inside air is warmer than you’d like it to be, and the outside air is cooler.
When running, the fan pulls air through any opening to the outside, like any open windows and doors. You should always open a window or two before turning on your whole house fan.
Depending on where you live, a whole house fan will make sense to use at certain times a year. In northern climates, you’ll likely use it all summer long, and perhaps in the late spring and early fall.
If you live in an area where it doesn’t get cool enough at night in the summer to entice you to invite that cool outdoor air in, you might only use it in the spring and fall when the days are warm but the nights are reasonably cool. In the hottest climates, this may only be true in the winter.
Additionally, unlike A/C, a whole house fan can’t do anything about the humidity. When the outside air is thick and sticky, you’re not going to want to fire up your whole house fan.
I’ve used ours thus far in May and June in northern Michigan, and I envision using it every evening to provide acceptable summer comfort daily as long as the next day’s high temperature is forecasted to be in the 70s or above.
QuietCool, one of the popular modern whole house fan manufacturers, has this handy climate zone map of the United States on their site.
In Zone 1 (Hawaii and the tip of Florida), they claim a fan can be used year-round to save up to 75% on A/C related costs, with the exception of 4 to 6 weeks where it is simply too humid.
In Zones 2,3, and 5, they estimate cost savings on A/C to be 50% to 75%. They give Zone 4 a 60% to 75% savings range, and Zones 6 and 7 a 70% to 75% savings estimate on A/C.
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Fans are simple motors with blades attached. They don’t cost much to operate.
The QC Guys estimate that a modern whole house fan in California at a rate of 16.7 cents per kWh (I pay 14.3 cents per kWh in MI) will cost 6.5 cents per hour on high and 1.8 cents per hour on low.
By comparison, a 40,000 BTU central air conditioning unit will cost 67 cents per hour to operate at that 16.7 cent per kWh rate. The traditional air conditioner costs more than 10 times what it costs to run a whole house fan on high and 37 times as costly as running the fan on the low setting.
The monthly cost of running the whole house fan 8 hours per day is in the range of $5 to $15 a month. You may not need to run it for that length of time, though. I opted for the upgraded remote control that allows the user to set an indoor temperature at which the fan stops blowing.
Compare an average of $10 a month for a whole house fan going 8 hours a day to running central air 8 hours a day, which would add over $150 to the electric bill of an average home. Quietcool’s estimate of 75% savings seems to be an underestimate to me. I’m getting something in the 90% and up range when you run a whole house fan as opposed to A/C.
When you open a few windows and start up the fan, you can generate an impressive “cross breeze” in any room. Just as you feel cooler when sitting in front of a desk fan or beneath a ceiling fan, the airflow generated by your whole house fan will make a room feel cooler than it would at the same temperature in a room with still, stagnant air.
Men only want one thing and it’s to open both windows so we can get a cross-breeze going
— Christina Catherine Martinez (@xtina_catherine) May 3, 2021
With a whole house fan, we can get a magnificent cross-breeze going with only one window!
A whole house fan continually replaces the air inside your home with fresh, outside air, improving your indoor air quality. The Environmental Protection Agency and American Lung Association estimate that the concentration of some pollutants are 2 to 5 times higher indoors as compared to the air outside.
It is important to always have a door or window open when operating a whole house fan. The air has to be pulled from somewhere, and if you have gas appliances with the potential to create carbon monoxide that is normally vented out, you could pull that dangerous air back in.
Whether or not you choose to use a whole house fan, you should have a carbon monoxide detector in your home. If you have a whole house fan, a functioning carbon monoxide detector is a must. I use a plug-in version with battery backup.
An attic can get to be very hot — unbearably hot — especially when the sun beats down directly. Running the whole house fan for just a few minutes can expel the heat from the attic, fully replacing it with air from your living space and the outdoors.
Eliminating that heat sink towards the end of the day can help keep your house cool, especially if the insulation between your ceiling and attic is not what it should be.
Did you burn popcorn in the microwave again? Or leave that pizza in the oven way too long?
Does the Uncle Larry smell linger long after Uncle Larry has left the premises?
Did you help yourself to a second serving of refried beans?
Whatever it is that’s causing that smell, your whole house fan will clear it out in no time fast.
Your whole house fan uses much less electricity than air conditioning, making it a frugal option as we’ve already established. It also uses no coolants, obviously.
If you’re into green living, using a whole house fan is a great option to help lower your carbon footprint.
When we installed our whole house fan late in the spring, our home’s finished basement was pretty darned cold — like 58 degrees cold, even though it was quite warm outside. Not wanting to turn on the heat in the basement since heat rises anyway, I just ran the whole house fan during the daytime with only one window open at the far end of the basement.
The warm outside air rushed through the basement, up the stairs, and into the attic, warming the basement up a good 10 degrees in a matter of minutes!
The manufacturers of whole house fans like to tout the improvement of symptoms in allergy sufferers after installing a whole house fan. The fans are good at expelling dust, dander, volatile organic compounds (VOCs), smoke, and other allergens.
On the other hand, your whole house fan will bring outside air in. If that air is full of pollen, you won’t be doing yourself any favors.
You may be able to have the best of both worlds if you use a whole house fan to bring in fresh air while pairing it with either an indoor air purifier, Pollentec nano screens (which keep out 99.9% of pollutants), or both.
Unlike an air conditioner, using a whole house fan is not a set-it-and-forget-it operation. You must manually open windows before turning it on, closing them in the morning when the outside temperature meets or exceeds the indoor temperature you’ve achieved.
It’s not the heat; it’s the humidity. When the dew point hits the 70s, a whole house fan isn’t going to deliver air that’s any drier. You’d be better off using A/C.
Also, there is an initial cost to purchasing and installing the fan. A legacy ductless design might set you back $650 and modern, high-efficiency fans with ducts and wireless operation can cost $1,000 to $1,800. Add another $400 to $800 if you hire out the installation.
You can spend anywhere from a few hundred dollars for a window model to about $2,000 for a top of the line attic-mount whole house fan. I did a fair amount of research before choosing the fan four our home. I settled on the QA-Deluxe 5500 Energy Efficient Whole House Fan with Insulated Damper plus 2-Speed Remote with Timer & Temp Control.
I’d consider the QA-Deluxe to be a mid-range fan, but it does have some nice features that the competition QuietCool whole house fans don’t have, at least according to the folks at QA-Deluxe.
QA-Deluxe 5500 & 6500
Competition
The Cadillac of whole house fans is the Centric Air fan. It’s got the highest quality components and a price tag to match. If we were planning on our current home being our forever home, I would have spent the extra $500 or so on a Centric Air model.
A third popular option are the line of fans from QuietCool. They are priced similarly to the QA-Deluxe fans, get similarly positive reviews, and may be a viable alternative. They also make a roof mount whole house fan that can bypass the attic. This might be the best option for a house with a flat roof or cathedral roof.
When shopping for a whole house fan, you’ll find that the cost rises right along with the fan’s CFM, a number that is usually part of the fan’s model number. For example, the QA-Deluxe 3300 model is capable of moving **surprise** 3300 cubic feet of air per minute.
You generally want 2 to 3 CFM per foot of living space.
If you have a smaller home, don’t want to bother dealing with the attic or cutting holes in your ceiling, you can opt for a window version. It won’t clear the heat from the attic, but it will expel your interior air out one window while pulling fresh air in through all the others.
Air King makes a 20″ window whole house fan that moves 3,560 CFM on its high setting, and it currently sells for under $200. Install 2 of these and you should be able to cool a large home nicely. It would not be inappropriate to say that the fan really blows.
Installing my QA-Deluxe fan was not particularly challenging. I was able to get the job done in about 4 or 5 hours as a solo DIY task.
If you do not have a power outlet in your attic, you will also need to install a regular 110v outlet if you’re up to the task or have an electrician add one for you. You’ll likely have numerous power cords running through the attic, so it should not be difficult to find a power source.
Centric Air put together a quality installation video that walks you through the steps.
Tools suggested are as follows:
The first step is identifying a place for the opening in your ceiling. It’s best to use a hallway far from the bedrooms so that air is moved from the bedrooms through most of the house before exiting through the ceiling.
I’d also caution against locating the opening for the fan in a living room. Although the newer models aren’t as loud as the original style, they’re still noticeably audible, and, when on the high setting, could interfere with conversation, television, music, etc…
Once you’ve chosen a place to put it, drill a hole somewhere where you’d like the grill to be. This drywall (or in my case, plaster) will be cut out, so don’t worry about doing damage. The video shows making pilot holes from above, but I made one hole from below first, poked something long through the hole so I would see it in the attic, and then made my pilot holes from above.
Next, you draw the outline of the grille, cut your hole, pass up your fan, duct, and damper box. Head up to the attic with adequate lighting (a headlamp and/or work light will help) and your tools.
You attach the bracket to a roof truss in the attic with a supplied lag bolt plus screws and hang the fan from the bracket. Mine had a spring-snap carabiner pre-attached. Install the damper box brackets on the joists just over the drywall, set the damper box on them, and attach the duct to both the fan and the damper box with self-starting screws.
The last step is to wrap a strap underneath the ducting to support it and put a couple of screws with washers through the strap and into joists on either side.
Plug in the fan and it should automatically communicate with your remote control within a minute. I used adhesive velcro strips to secure mine to the wall next to a light switch by the fan opening.
I highly recommend getting the job done in the morning, and if you can time it right, doing so on a cloudy day. That sun can heat your attic up in a hurry.
In the evening, open windows only in rooms you want to start cooling first. For example, our kids go to bed before we do, so before turning on the fan, I open their bedroom windows exclusively.
After they’ve gone to bed, we open our bedroom windows and perhaps living room and kitchen windows.
If you open a large window or door close to the fan, you won’t be pulling nearly as much air from the far reaches of the house, so save any windows or doors near your fan and its ceiling opening last if you choose to open them at all, which you probably won’t need to do.
If you’ve been pulling in cool air throughout the evening, you clearly want to trap that air in when it starts to warm up outside. If you forget to close up before heading out for the day, you’ll undo all the good you did overnight.
I’ve found that our home will heat up at a rate of 0.5 to 1 degree per hour, depending on the temperature differential and how much sun we’re getting. I wish we had a good shade tree, but at least we have a good amount of thermal mass with plaster rather than drywall throughout the home.
Still, even when we had daytime temperatures in the 90s, the warmest the house got was 80 degrees, and that was in the early evening when the outside temperature was starting to drop into the low 80s. We just opened up the house and fired up the fan at that point for the airflow cooling effect, and by nighttime, the house was reasonably cool again.
If your kitchen or bathroom exhaust fans are inadequate or non-existent, and it’s not crazy hot outside, you can turn your whole house fan on for the time that you’re cooking or showering to evacuate all that moisture, smells, or smoke.
A downside is that it’s going to work much better for the bathroom if the door is open, so be sure to close that shower curtain if you value your privacy.
The whole house fan will make quick work of any foul kitchen air, and you may want to consider proximity to the kitchen when choosing a place for your fan.
This isn’t so much a tip as it is a reality. If you can use the fan for 3 to 6 months of the year, saving $100 to $200 a month on air conditioning, you’ll save $2,000 in anywhere from about 2 to 5 years. That’s more than enough to buy a high-end Centric Air whole house fan or a QA-Deluxe fan and pay someone else to do the installation.
After it’s paid for itself, the energy savings will continue to pile up for years to come.
Have you used a whole house fan? Share your experiences in the comment box below!
Whole house fans are still commonly found at our home inspections they come in a few different varieties. While most of them are very old units, many of them are still in working condition. There are also newer versions which we see on occasion as Colorado has a decent climate for a whole house fan system.
This type of powered cooling system became popular in the 1950s. It was a cheaper alternative to an air conditioning unit, had lower maintenance than an evaporative cooler, and worked fairly well in specific parts of the country.
However, the units had their shortcomings as well and fell out of popularity over the years as building science evolved.
In this article, we will quickly cover what a whole house fan is, the positives and negatives of having one, and the ideal scenarios for having one installed today.
A whole house fan is a large fan with a very high CFM (Cubic feet per minute) rating that is typically installed at the top floor of a home in the ceiling. This large fan is used as a type of exhaust fan to move hot air from your home to the exterior.
As heat in your home rises in the warmer months, it tends to build up near the highest floor ceiling as the attic insulation will keep the heat from transferring through to the attic.
When a whole house fan is operated, it would blow the heat build-up in this area into the attic space which is typically vented, and the air would be pushed out.
This would create a negative pressure within the house itself, and pull cooler air from the lower areas of the home.
A common technique used while running a whole house fan is cracking or opening windows on a lower level of the home to pull cooler air upwards.
This is a nice way to cheaply cool a home when the temperatures outside are not too extreme. This is particularly effective in the evenings and mornings.
The main benefits of a whole house fan system are the cost, ease of installation, and maintenance. The cost to install a system is far lower than a traditional central air system. All that is required is the fan assembly itself, and a place to vent it.
A traditional AC system requires a very expensive compressor unit, coolant lines that run through your home, and a duct and blower system. While many homes already have a furnace with ducts, some do not which makes installing a traditional air conditioning system very difficult and expensive. A whole house fan can be a great option in this scenario.
Whole house fans also offer the benefit of basically zero maintenance. The fan is always ready to go and newer units require no winterization.
So for a relatively low cost, you can add a simple cooling system to your house. But what are the drawbacks?
Let’s start with the standard unit you see installed in most homes today.
For starters, the fan is usually very large as it needs to be able to turn over the volume of air in your home in a reasonable amount of time. Because of this, the fans are usually loud. Older fans can be VERY loud. This can be bothersome for some people. We see these older fans very often during our inspections around Denver.
Next, their cooling capacity is limited. Using the natural cooling methods mentioned above can only go so far. Once the ambient air temperature of the exterior air gets above a certain degree, cooling performance drops off significantly. This can go further in homes with basements but in general, whole house fans are really only useful in some climates.
Finally, they can cause a substantial amount of air leakage in the winter months. It’s nice to have a cooling system when it is hot, but how about when it is cold? Having a large hole in your ceiling during the winter months can lead to unwanted air leaks no matter how well you try to seal it.
While this seems like a large list of negatives, there are newer models of whole house fans that try to mitigate the noise and winter problems.
Newer versions of whole house fans move the fan further into the attic and have a flexible duct that runs to a vent in the ceiling. This significantly reduces the noise.
The vent piece that connects to your ceiling also has a motorized insulated damper that will close when the fan is not in use. This reduces the heat transfer in the winter. Although these systems are still not perfect, it is a great improvement from the legacy models.
So how do you know if a whole house fan is right for you? The ideal climate to maximize your whole house fan usage is typically areas with all four seasons and somewhat mild summers, or coastal areas where the summer heat does not reach the 90s often.
The United States is split up into climate zones by the International Energy Conservation Code. Using this code, we can determine which areas of the United States can benefit from a whole house fan.
We would suggest that a whole house fan be used in climate zones 5-7 with some exceptions. Climate zone 4 can be acceptable if you live in a more humid area or coastal area where the temperature extremes are more regulated. A whole house fan will work well in climate zone 7, but if the winters are very cold a whole house fan may do more harm than good.
Of course, this is not an exact science. If you are in doubt, asking a local professional is always recommended.
Hopefully, this article gives you a solid understanding of whole house fans and aids you in your purchasing decision. During our home inspections, we always test and inspect a whole house fan from the interior and the attic to ensure they are in proper working order.
If you are interested in a home inspection in the Colorado Front Range area, learn more here.
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