Paradise ponders... I started on a long-delayed project yesterday: installing a system to prevent my new office (on the second floor of the shed) from ever going below freezing. Actually, I'll probably set it so that it never goes below about 50°F.
This little heating system will work by blowing warm air from the first floor (which is nicely heated by an in-floor heating system) up into the office, and exhaust cold air from the office back down to the first floor. This will require two registers in my office (one near the ceiling for the warm air to come out of, and one near the floor for the cold air to leave). These will be as far apart as I can arrange.
The first step I'm taking is to mount the “squirrel cage” fan I bought to the ceiling in the first floor. That ceiling is covered with 1/2" OSB, with joists on 14.5" centers. The fan's outlet is rectangular, 4 1/8" x 3 3/4", and the fan weighs about 6 pounds. That means I need sturdy wood to mount it to, and the OSB isn't sturdy enough to satisfy me. So ... I fabricated a mounting plate by cutting a section of Douglas fir 2x12 long enough to cover two joists, with a nice square hole (at right, below) to match the fan outlet. I cut out the hole by drilling four holes inside the part I needed to cut out, then threaded my scroll saw blade through one of these holes. The rest was just straight-forward sawing, with lots of turning the work round-and-round to maneuver the blade both ways along each side so that I ended up with nice square corners.
Today I'm going to drill some holes for mounting screws and wiring, then paint that plate to match my ceiling. Then I'll cut a hole the same size in my ceiling, then mount the plate over it. The next step will be sawing a matching hole in the floor above, which ought to be fun to get exactly right :) The joists are 14" tall (engineered wood), so I'll need to make a 14" long “tunnel” (of 1/2" OSB) between the two holes. After I've got all that done, I can mount the fan to the plate. We'll see how far I get on this today :)