Yet another DIY air filtration system
For my first post as a member of Sawmill Creek I wanted to share my solution for a homemade shop air filtration system. I benefited from all the descriptions of other DIY filtration systems described in this forum, but came up with a design that worked better for my situation. With a low ceiling in my basement shop, I wanted to avoid hanging an air cleaner from the ceiling. I've read that floor standing versions tend to be less efficient, plus they take up precious floor space. Instead, I decided to install the blower in the utility room next to the shop and run a duct to the filters in the ceiling at the center of the shop.
The following photos will help explain:
1. Dirty Air Intake.jpg
Picture 1: The dusty air intake is located in the ceiling over my table saw. It’s made from MDF to fit in a standard 2’ x 2’ suspended ceiling grid space and contains the filters.
2. Sub Micron Filters.jpg
Picture 2: This shows the 20" x 20" washable pre-filter and the sub-micron filter. They can be accessed by removing two wing nuts and pulling off the end piece.
3. Intake Duct.jpg
Picture 3: The filtered air flows through a 16' long x 8" round sheet metal duct running between the joists above the suspended ceiling. This picture shows the section within utility room leading to the blower.
4. Blower Enclosure.jpg
Picture 4: Air is drawn through the duct by the fan which is enclosed in an MDF box attached to the wall separating the two rooms.
5. Fan Exposed.jpg
Picture 5: The enclosure end panel has been removed to expose the squirrel cage blower.
6. Controls.jpg
Picture 6: With these controls, I can select the blower speed and set a timer to turn off the blower automatically.
7. Clean Air Return.jpg
Picture 7: The blower returns the filtered air back to the shop through this 14” x 14” wall register. I put a piece of cheap furnace filter behind the register to diffuse the air stream and absorb a bit of blower noise.
Despite the greater static pressure produced by the length of duct, the ¾ HP direct drive blower produces substantial air flow even at the low fan speed setting. With fresh filters, the blower draws just 5 amps at 115 volts. I was hoping that locating the blower outside the shop would also reduce the noise level, but if there’s any benefit on that score, it’s minimal. Most of the noise emanates from the wall register, and since the register is located across the room from where I usually work, the noise level is not as bad as it could be. I do have to turn up the radio volume a bit when the filter is running.
As to the cost:
Discarded Blower .......................$0
MDF (4’x 8’x ¾”) .......................$28
Ducts ..................................$54
Super Flow washable filter (20” x 20”) .$29
3M 1900 Filtrete electrostatic filter ..$18
Mechanical timer (6-hour) ..............$24
SP3T switch (HP rated) .................$12
Miscellaneous ..........................$5
--------------------------------------------
Total $170
I haven’t had the system long enough yet to determine its effectiveness. I’m hoping that the sub-micron filters will last a year. The manufacturer recommends replacement every 3 months when used as a furnace filter, but that assumes no pre filtering.
I’m please with the result so far. Any comments or questions are welcome.
Clark
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