Occasionally, we all need to evacuate exhaust gas/ paint fumes/ welding smoke/ beer- induced methane/ whatever from our workspace. Here's a setup I've used for years that works well, takes no space and costs almost nothing. It'll change the air in the room quickly, and pulls a nice breeze in through the windows in hot weather. I started by making a metal frame. Folded up some 18 gauge pieces 24" long or so, mitred and welded the corners to make a stepped frame with a ceiling flange, that'll hold a standard 20 x 20" furnace filter. Cut a flat door from 14 gauge, mounted it on piano hinge, fastened it closed with an accessory latch, foam rubber weatherstrip to seal it. Framed an opening between two trusses overhead, covered the sides of the trusses and built a box to form a tunnel from the ceiling opening to the soffit. Mounted a squirrel cage fan from an old oil furnace in the tunnel, a bulkhead with an opening for the fan outlet separates the inlet from the outlet. Cut a hole in the soffit outside, mounted a louvered AC vent in the hole. The vent also has a flat steel door with hinges and latches to seal it in the winter when not in use. (It needs a repaint) To change the air in the garage, open the inside hatch (a pole with a hook helps), turn the fan on at the switch on the wall. Having to go outside to open the outside hatch is a bit of a pain in the winter, I leave it open in the summer. It's simpler than my description sounds. I hope the pics make it clear.
I've used two of these blowers in a garage project in Houston, using gable vents on the outside and a sliding plywood cover inside, but with a twist! I made them blow in, this is south Texas, after all. Just a note, a reflective barrier and plenty on insulation go a long way toward making your work space comfortable.
The Jalopy Journal
