Homemade Air Filtration System

Photo 1. My solution to cheap clean air in the shop.

Air quality is always an issue for woodworkers, especially if we are working in a basement or when we don’t want to give up the heat in the shop to an open window during those cold winter months. There are plenty of ‘store bought’ systems out there to filter the air, but they can be pricey. So for those of us who would rather spend the money on another router or just like to make ‘stuff’, I have a suggestion (Photo 1).

Photo 2. Just a box and an exhaust fan with a big hole in the bottom.

Build a box, cut a big hole in the bottom and install an exhaust fan in it (Photo 2). Then cover the hole with a couple of disposable furnace filters and cut slots in the bottom of the box to vent the filtered air back into the room (Photo 1).

Photo 3. I used metal-clad wire because of all my shop wiring is exposed.

Note: follow all local building and electrical codes when making, wiring and installing the system (Photo 3).

Photo 4a. The box is mounted between the trusses.

Photo 4b. I wrapped insulation around the box for good measure.

Photo 5. Only the filters and vents protrude into the room.

Now would be a good time to discuss a little air flow math: My fan is rated at 1000 CFM in 1600 sq ft of attic space, (cubic feet per minute) – that is how much air the fan will move in a minute. My shop/garage is 22′ x 22′ x 10′ = 4,840 cubic feet, 484 sq ft. So if my math is right, my fan should exchange the air in my shop in about 4 to 5 minutes. That sounds good to me.

I installed mine between the trusses in the attic, (Photos 4a and 4b) only the filters and vent deflectors protrude into the room (Photo 5). If you don’t have an attic, (or your mate won’t let you cut a hole up into the kitchen floor), just mount the box on the ceiling.

Photo 6a. The box measures 31". x 22". x 12".

Photo 6b. Close up of fan and shroud mounted in the box. I did have to bend the shroud base up on all sides to fit. The sheet metal cuts and bends easily.

My garage trusses are 24″ on center, so I was able to use a 15″. fan. The box measures 31″. x 22″. x 12″. high, (Photo 6a and 6b), and the base that mounts to the ceiling measures 32″. x 27″. I was then able to span the trusses and leave extra room for the vent slots.

Photo 7. I used two 1" furnace filters. When the bottom one gets clogged, I replace it and put the new one on top.

I used 2 filters to get better filtration, (Photo 7). I just replace the bottom one when it gets clogged and put a new one on top.

Photo 8. Notice the low profile in the shop.

Notice the low profile of the finished air filter in my garage. Good luck and breath deeply.

Photos By Author

Jake is a registered member of WWGOA. See more of Jake’s woodwork at his website, Saw Dust by Jake.

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