The exhaust system

First post on a blog. This is just a cool place to host my junk and ideas whenever.

Today I gained a measure of aromatic privacy by constructing an exhaust system for the window of my dorm room using....
Two of the cheapest LASKO box fans I could find (3 speed, about 18.5"x18.5")
Roll of duct tape
Some scrap cardboard



Just shoving the fans in the window would have been enough to maintain a flow of air from the hallway into my dorm, but I noticed that it was wasteful and there was some backpressure coming back into the room through, over, and between the fans. I measured out a piece of cardboard to fill the space between the glass of the window and the fans and sealed it with duct tape to the top of the fans.

Air moved by a fan moves along a path through the disc traced out by the motion of its blades, so any backpressure is normally free to push back through the plastic grates of the fans around that disc without any competition. This can cause turbulence and hinder the direction of the air flow in the room. To compensate for this, I used duct tape to seal a 1.5" border from the outside edge of each grate, roughly closing off most of the area outside the blades that was vulnerable to backflow.

It's not a perfect system, but it's a vast improvement if you want to keep the smells from your room out of the rest of your dorm building. This might work for people who are cooking bacon, don't use deodorant, or are looking to hide the scent of....ah...incense.

Here's a quick video just to illustrate how this will the air coming IN through your door, not out...