I took the plunge and installed a whole house fan earlier this year. This was our alternative solution to an air conditioning unit that costs quite a bit to install ($3,000) and over the long run will use a lot less electricity each month. Here in Colorado Springs, it really doesn’t get all that hot and simply exchanging the inside air with outside air can make the house feel a whole lot cooler. Granted, it won’t be as cool as an air conditioning unit, but it will make a big difference. The added benefit is, the air in the attic that can reach 140°F will also be expelled.
I’d rate the installation as moderately difficult only because the whole house fan I purchased had a blade diameter of 30 inches. This meant I had to cut a ceiling rafter and re-frame the opening (ceiling rafters are separated by 24 inches on center). This can be a little intimidating to some, but it’s not all that big a deal.
If you purchase a fan with a diameter less than 24 inches, chances are it will fit snugly between the rafters and you won’t have to cut one. However, the smaller fans won’t move nearly as much air and don’t work as well. Some people will lay the larger fans atop the rafters, but this isn’t advisable as it can cause a buffeting sound. The rafter can also obstruct the airflow reducing efficiency.
Before installing the whole house fan, make sure there is enough ventilation in the attic. Air that is being pulled from inside the house must also be pushed out through the attic’s soffit, gable, roof or ridge vents. If there isn’t enough ventilation, you can cause structural issues with the roof, or the fan won’t operate as efficiently as it should. Calculate the square inch opening for the whole house fan, and make sure you have at least that much area in attic vents as well.
Installing the fan in a central location is best. I put mine at the top of my stairs in the center of my house such that it’s about the same distance from each window. If the fan is located in a distant part of the house, it may not efficiently exchange the air throughout the house because it will pull more air through the closer windows. That’s not to say it won’t work, but it won’t work as well.
I chose a belt driven unit because they tend to be quieter than a direct drive unit. Direct drive motors have to spin faster (rpm) than a belt and pulley system. This can create quite a bit of motor noise in addition to vibration noise. The belt will need to be changed, but only after several years of heavy use.
I also installed louvers that open when the fan turns on and automatically close when the fan turns off. They are gravity operated and work nicely. There was a small amount of adjusting that needed to be performed on the spring to help the louvers open when the fan turns on. If you don’t adjust it right, the louvers might not close when the fan turns off, or they may not open all the way when the fan turns on.
The 32 x 32 inch hole in my ceiling made me a bit nervous. I was worried that it would create a horrible cold air draft in the winter, but that doesn’t seem to be the case. The louvers do a pretty good job of stopping the cold air from entering the house. I’m thinking I might purchase the insulation kit that Velcro’s in place, but I’ll wait to see how things are once it really gets cold outside.
I’m very pleased with the whole house fan. I wish I had built up the courage many years earlier, but better late than never. We run it mostly in the evening or at night when the air outside is cooler than the inside. But even if it’s slightly warmer outside than inside, the moving air makes the house a whole lot more comfortable. If we really want a nice breeze to move through just a room or two, we will only open the windows in the rooms we’re in. Although typically, you’d open a bunch of windows just a bit all throughout the house so the whole house cools off.