Slightly Different Shop Air Filtration Approach

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Forum topic by MitchG40 posted 01-24-2014 09:18 AM 1095 views 0 times favorited 5 replies Add to Favorites Watch
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3 posts in 1610 days

01-24-2014 09:18 AM

Topic tags/keywords: air filtration diy

Hello all. I am brand new to this site (as a registered member). I’ve seen much discussion about shop air filtration and LOVE some of the DIY units I’ve seen you guys put together. I have an idea for air filtration in my shop and would like your experience based opinions.

So, all of the DIY and store bought air filtration units seem to either hang from the ceiling, mount on a wall, or roll around on casters. I’ve seen quite a few plans that include the use of attic fan type blowers mounted in boxes with an array of fine filters.

Here’s the question, why not use the attic space over my garage shop to house the filtration unit and then duct the return air right back down into the shop? I imagine a system using 2 attic fan blowers that would be enclosed in a box IN THE ATTIC just above the shop with the filters housed behind an unassuming grate (like a common HVAC air return grate found in your home) that is mounted flush to the shop ceiling. Then, using large capacity HVAC ducting (and a short run of it) return the air to the shop in a different location promoting circulation around the shop. The benefit here would be that in low ceiling situations (such as mine) one would not have a large box looming overhead blocking much needed lighting and potentially resulting in a knot on the head here and there.

I understand that a long run of ducting would restrict flow, but in this case I imagine using large, short runs of it. Is there something obvious that I am missing? I haven’t seen ANYONE online discuss this approach.

If I can’t find a good reason from you all NOT to try this approach,... then I will build it and share the results here.

5 replies so far

View Mark Davisson's profile

Mark Davisson

597 posts in 3344 days

#1 posted 01-24-2014 11:48 AM

I can offer no good reason to not do it. Sounds like a plan!

-- I'm selfless because it feels so good!

View DIYaholic's profile


19623 posts in 2701 days

#2 posted 01-24-2014 12:46 PM

I say go for it…..
I have seen one setup that used the space in between ceiling joists, to duct the air, so I think your approach has merit.
The key factor is the strength and CFM capacity of the blower. You want the ability to recirculate the shop air several times per hour. The next consideration is the filtering efficiency of your filter selection. Be sure to use a pre-filter (common furnace filter, to get the bigger stuff), then the highest MERV rated filter you can afford. It is all about getting the super fine (3-5 microns and smaller) particles.

I look forward to seeing what you come up with & how well it performs!

BTW: Welcome to LumberJocks….
A great place to feed your wood working insanity!!!

-- Randy-- I may not be good...but I am slow! If good things come to those who wait.... Why is procrastination a bad thing?

View Bob Kassmeyer's profile

Bob Kassmeyer

223 posts in 2952 days

#3 posted 01-24-2014 12:48 PM

I was thinking it might be a pain to change filters but I guess not any harder then with a hanging unit. The only other thing I could think of is the heating or cooling of the air going through the duct work in the attic. Other then this like Mark said it sounds like a plan.

-- Bob Kassmeyer, Nebraska

View Sandblastguy's profile


42 posts in 2138 days

#4 posted 01-24-2014 12:55 PM

Sounds like a great plan. The only thing is have you considered how this will affect your climate control. Not sure where you are from but the attic space can get very hot or cold and running even a short length of ducting could create a real problem with heating or cooling. You might be better to build an insulated cavity between the rafters and just hand the dust collector in it .

-- Sandblastguy Orangeville On. Creating Art From Nature

View MitchG40's profile


3 posts in 1610 days

#5 posted 01-25-2014 01:32 AM

Thanks for the input guys. I hand’t thought of the climate control issue, but I will be sure to insulate the ducting to minimize this effect. Currently the only climate control I have in the shop is a kerosene heater. I plan to add a NG forced air shop heater soon. Up here in the Pacific Northwest the garage stays cold more days out of the year than hot.

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