# going to build my first air filtration unit. Looking for advice.



## unknowneinstein (Apr 20, 2012)

Shop is 17x20x10. I was looking at the jet air filtration system that's about ~$370 but I saw alot of people just build their own so I'm going to try that route. 

I found 2 fans at lowes I can get. 

http://m.lowes.com/pd/Lasko-20-in-3-Speed-Box-Fan/1114391 this one has a maximum 1710 cfm.

http://m.lowes.com/pd/Utilitech-20-in-3-Speed-High-Velocity-Fan/4755301 and this one has a whopping 6800 cfm. My concern with this is its going to move TOO much air with the filters around it. So I'm leaning towards the first one as that is still plenty cfm.

So I'm going to take the fan out of the cage and build a plywood box around it and put filters on. I've seen that most builds only put one filter on the intake side but most commercially made products use 2 filters, one oneach side. Would two filters with a unit such as above restrict air flow too much? 

Last question is what kinda of rating do I need for air filters. I was thinking like an 11 merv on the intake then a 13 on the exhaust. Should I just use one on the intake and make it 13+? Or is the 2 filter system for beneficial? 

Any advice appreciated.


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## ryan50hrl (Jun 30, 2012)

I have a shop built system where I use 3 stages. The cheapest paper filter I can find in first, so when it fills up with dust I can throw it away and I'm only out 2 bucks....

Then two progressively finer filters to actually clean the air. 

If your using a box fan, I'd try a cheap 2 buck filter on the back, and a better filter on the front.


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## hwebb99 (Nov 27, 2012)

Id use the second fan. With the resistance from the filters the CFM will be way less.


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## FrankC (Aug 24, 2012)

Spend your money on a used squirrel cage furnace fan and go from there.


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## unknowneinstein (Apr 20, 2012)

FrankC said:


> Spend your money on a used squirrel cage furnace fan and go from there.


Doing a quick look I see that those blowers ate like $100 for something that gives you 200cfm. Looked on craiglist didn't find anything yet. Why wouldn't one of those box fans be better or at least equal?


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## BWSmith (Aug 24, 2010)

FrankC has it...spend the money.Clean air sets the stage.Once you get used to not working in a bloomin dust bin...it will all make sense.

I've joked at work...."gotta go home and work in a cabinet/millshop to get some clean air".

Spend the effort to make your shop air CLEAN.


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## shoot summ (Feb 21, 2014)

unknowneinstein said:


> Doing a quick look I see that those blowers ate like $100 for something that gives you 200cfm. Looked on craiglist didn't find anything yet. Why wouldn't one of those box fans be better or at least equal?


Talk to an HVAC Contractor, they take out old units, with good fans in them daily. My buddy hooked me up with a single, and a double blower setup, for free...


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