The main heating duct for the house entered the crawlspace by running down the side of the wall directly in front of the stairs. This meant there was a large protrusion into the room in front of the stairs, which just kind of annoyed me because it just seemed in the way, and contributed a bit to the basement feeling smaller. It also annoyed me because it looked to me like it would be easy to run the duct underneath a space in the stairs directly ahead of where it currently ran down the wall — which is exactly what I did.
The process wasn’t overly difficult or expensive. I had two 45-degree angle pieces made up at a local sheet metal shop ($66 with tax). I got a straight piece of vent and some assorted connectors and clamps at Home Depot (~$15). I also ended up buying a jigsaw — but hey, I needed one of those anyways.
Basically, I just removed the old vent that ran down the wall, and then cut the old vent back to line up with one of the joists under the stairs. I then cut out a hole in the plywood under the stairs, and started running the duct. One of the old 90-degree pieces feeds up into the a new 45-degree piece, then a small section runs with the angle of the stairway into the other 45-degree piece, which then completes the run back into the main duct.
Having never worked with duct work before, it definitely was more of a pain than I suspected it would be. There are basically two different types of connectors that connect sections together – an “S” connector that goes along the top and bottom, and a “D” connector that slides over groves on the sides and actually holds the sections together. My connections worked fine mechanically – it is very solid – but not so well with regards to leaks. I had to use a bit of foil tape to tape up the corners to avoid leaks when it was on. The existing vents do not have any tape — they just have very well done connections between duct work. I’m not sure if it is just the experience, or if there is some sort of special tool that helps (perhaps a bit of both..).
Anyways, I’m pretty pleased with the results, and the duct does not protrude from the wall at all now. This means three things: I don’t have a big thing sticking out of the wall unnaturally; I have to do a little bit less drywall work later on; and I now have a place that I can build a bar fridge into the wall (more on that later!).