30 September 2007
I do my casting in the attached garage. I prefer to do this when it is raining as there are so many other things to do when weather is good. My method consists of proping the garage door up about 6” (for cross ventilation), opening the garage window but shielding the area with cardboard, leaving only a square hole about 1 1/2 foot square open at the bottom corner of the window. A 15” dia. household fan is placed in this opening to remove smoke, etc. from casting. This exhaust fan is about 3 1/2 feet below the ceiling. The casting pot is on a workbench below the window about 3 feet to the left of the fan. This has worked OK even in cool weather. However, if you enter the garage the next day, a strong odour of casting remains so it seems that ventilation could be improved.
My next trial involves placing a forced-air furnace fan on a stand at the upper corner of the window. Window shielding is altered to accomodate this and all else remains the same. The furnace fan has a square wooden tunnel extension placed on the fan outlet to reach to the outside of the garage. The opportunity to try this arrangement hasn't occurred but it should give a much improved flow of air (more cfm from the fan)and better removal of smoke, etc. as it draws air across the ceiling area.
If you are trying to move air out of an area, you have to have at least an equal sized opening somewhere else to get good cross ventilation.