Air King 20 inch fan
1). There aren't a lot of instructions about installation, and the screws to mount the fan to the window frame are a little short for some types of windows.It does come with a template to help locate the mounting screws. I ended up using 1 1/4 screws. The windows have vinyl frames, and the supplied 3/4 inch would not reach the wooden frame the windows are mounted in. If you mount on the inside of frame, you will generally have to tighten the mounting screws from the outside. That generally means using a small ladder or step ladder outside the house. However once installed the mounting is very robust, and you really can close the window even with the fan in place, so the installation can be permanent. It is probably better to have a helper when you install. The entire assembly is quite large, and it comes in an enormous box.
2). The fan is pretty noisy, it moves a lot more air than a 16 inch and it makes a lot more noise. While it is 3 speeds, there isn't a lot of difference between the speeds or the resultant noise levels. Low is 2510 cfm, medium is 3120 cfm and high is 3560 cfm
3). Construction the mounting parts,the fan, and fan screen are all metal. Much of the 'body' is plastic, but definitely is NOT flimsy.
4). The fan uses a 3 prong plug with a heavy cord, so it is grounded. That is probably safer than the common polarized plug used on smaller fans.
5). Motor is 1/6 horsepower, and is permanently lubricated so it should provide years of trouble free service.It appears to be 'industrial' quality
Verified purchase: YesCondition: Pre-owned