I bought two of these fans for use as attic gable fans. My two story house has two separate attic spaces, and I wanted to install attic fans to control both high temperatures and humidity in the attics. The recommendations that I found online indicated an air exchange rate of 10 air changes per hour for an attic. The fans specifically listed as attics fans typically are rated at 1400 to 1600 cfm, which was too much fan for my separate attic spaces. Plus, from experience, I knew that the larger CFM fans produce what I consider an unacceptable level of noise. I really dislike listening to the droning hum of a fan. This fan, with its three speeds(825, 710, and 560 cfm), appeared to fit my sizing needs, and I was hopeful that the lesser CFM would also mean less noise. I set the fan in the larger attic space on the medium setting, and the fan in the smaller attic on the low setting. The larger attic has a volume of approximately 2,600 cuft, so the medium setting provides for over 16 air changes per hour. I also purchased a combination temperature/humidity control for each fan (DuoStat Ventatmatic), which so far seems to work with as intended. Although this fan is pricier than some of the other available options, I looked at two criteria that I considered important. 1)The first was noise. I really dislike extraneous noise, so I took the additional step of purchasing some Isolate It sorbothane pads to further minimize the transfer of vibrations from the fan to the house;I used the pads between the fan housing and the plywood that I used to attach the fan to the framed opening of the gable vent. Mounted as such, this fan produces a extremely faint hum.....you have to really listen for it, even when the house is quiet. I have them in the attic over the second floor of my house, and while on the first floor I have to purposely listen for the extremely faint hum of the fan. It is definitely quieter than the sound of a refrigerator. If the TV is on, or other normal household noises are present, you won't hear this fan. In the second floor bedrooms directly under the fan's location, the sound is similar to that produced by my quiet (0.3 sone) bathroom fans. I don't consider that an issue though, as the fans typically operate between noon and 9pm. 2)The second important criteria for me was operating cost. This unit is rated at 1.1 amp on its high setting. I have mine set on the medium and low speeds, so at 120V, I'm looking at about a Kwh per fan per day (based on a run time of 10 hours per day).....or, based on my electricity rates, about ten cents per fan per day. The $6 monthly cost to operate the fans over the summer months will definitely be more than offset by saved air conditioning operation costs. As for issues with the fan's shipment, I ordered mine from Amazon and they came double boxed; the well packed factory box was shipped in a larger Amazon box with additional paper padding. There wasn't any shipping damage, but out of the box, the blades on both fans made contact with the guard cage. The guard cage wasn't out of round; the tolerance between the fan blades and the taper of the guard cage was just too close. I simply took the slightest of pitch out of the fan blades by gently flexing the trailing edge of the each of the blades until they cleared the taper of the guard cage. I can't speak for longevity as the fans were only recently installed, but with their sealed construction, I am hopeful for a long, maintenance free fan life. Lastly, I did not utilize the louvers. With the existing gable vents, there simply wasn't a need for the louvers. I only ordered the fan with the louvers, because for some inexplicable reason, it was cheaper to buy the fan with the louvers than without louvers!
