Cheap Box Fan Air Filter Solution


jmaichel
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I thought I would post a couple pictures of my inexpensive box fan air filter. I have been running this fan continuously for about two months now and I am shocked at how much dust it has actually collected. This setup is working better that I thought it would. The only problem is that I already have to buy a new filter and at $20 per filter it's kind of expensive. I think am going to buy two filters and attach them together (duct tape) and then connect them to the fan. I think I will put a lower cost filter with a lower FPR on the outside to collect the big stuff and then the nice filter with 10 FPR close to the fan to collect the fine dust. When the lower FPR filter get clogged I will just replace that instead of having to replace the nicer more expensive filter. 

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post-104-0-01641900-1373341156_thumb.jpg

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I use the central house vacuum system that vents outside to clean the dust off the filters.  Its quick, easy and extends the filter life almost indefinitely.  What doesn't get trapped in the vacuum gets blown outside where it disappears.

 

Mike

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Matthias Wandel (woodgears.ca) has a couple of blog posts up about his shop made dust collection.  He also went through the filters (discovering you shouldn't stand too close to the filter when blowing it out) but also added some felt to the flow as a "prefilter."  I believe there was a loading period, while the felt caked up with sawdust to become a better filter, but I only skimmed the posts.

 

Might help prolong the life of the filter, at any rate.

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I've been running mine for 12+ years and it still works great. Still using the electrostatic filters I purchased 10+ years ago. (They rinse off).

 

http://woodworking.bigelowsite.com/air_filter/index.htm

 

I used a cheap 1500 CFM blower instead of a box fan, but they're about the same price if you can find one at your local HVAC shop.

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  • 1 month later...

Here's my approach to the problem. 

 

post-7964-0-96243700-1376399834_thumb.jp

 

I didn't trust duct tape to hold in the Florida humidity so I built this frame out of scrap hardboard and plywood. The frame is open on the top and has enough space to snugly hold 2 filters against the fan. I have a cheaper outer filter for any coarse stuff, and a higher quality inner filter to catch the fine stuff. 

 

When I need to clean the filters, I can just slide them out and blow them off, or replace them if necessary.

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What do you think the best position is in the shop? Centrally located or where the most dust is created? Do you think pointing the air flow towards the ceiling (if you have high ceilings) might improve its effectiveness since the suction area will be parallel with the dust creation below it?

Think I am going to build one of these in next couple weeks. Maybe something similar to BC's design.

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I can only speak from my experience. I have been told the last thing you want with an air cleaner is, for example, to put it right above your bench, as it draws all the dust right up past your face.

 

I also know from working in the garage, that once the fine stuff gets flying, it's basically everywhere at once, like a fine mist of sawdust. In my shop, this is what I did. I have about 2/3 of the garage, and the remaining third is all of the household stuff. So I have the fan hanging right past the dividing line, from the ceiling and running constantly. Figured in an enclosed environment, it will eventually pull most of the stuff through it if left to run long enough.

 

I'm sure others with much more experience can chime in.

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I've read that you want to avoid a "short circuit", where the filtered air leaving the filter gets sucked right back in.  Many filters are positioned so the filtered air gets blown all the way to the far wall, and the air is sucked in from the other side of the room.  I agree with Bob that the fine dust is spread evenly throughout the air space (except not in the air that's coming out of the filter.

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Here's my approach to the problem. 

 

attachicon.gifFanFilter.jpg

 

I didn't trust duct tape to hold in the Florida humidity so I built this frame out of scrap hardboard and plywood. The frame is open on the top and has enough space to snugly hold 2 filters against the fan. I have a cheaper outer filter for any coarse stuff, and a higher quality inner filter to catch the fine stuff. 

 

When I need to clean the filters, I can just slide them out and blow them off, or replace them if necessary.

 

 

Here's my approach to the problem. 

 

attachicon.gifFanFilter.jpg

 

I didn't trust duct tape to hold in the Florida humidity so I built this frame out of scrap hardboard and plywood. The frame is open on the top and has enough space to snugly hold 2 filters against the fan. I have a cheaper outer filter for any coarse stuff, and a higher quality inner filter to catch the fine stuff. 

 

When I need to clean the filters, I can just slide them out and blow them off, or replace them if necessary.

 

I recently changed the filter and added an extra filter to collect the chunky stuff. I was really thinking about building a box to hold the fan and the filter but when I started thinking about it I realized that the duct tape serves two purposes. First it holds everything together very nicely, ugly as sin but stay together. Secondly, the duct tape provides a very nice seal around the fan and filters, therefore making they system a little more efficient and a more effective. I agree that it should not be right over your bench. Below is a picture of my recent update to it. I added a cheap 4 FPR filter for the chunky stuff and bigger 4" 10 FPR filter for the fine dust that gets through the first filter.  I added a picture of my old filter just to show how much dust it actually collected. I was more effective than I thought it would be. I am thinking about running two of these in my shop. 

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post-104-0-77790100-1377062314_thumb.jpg

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  • 3 weeks later...

My shop is on the middle floor of the barn and I have a box fan hanging in the window of my shop so it exhausts outside. This makes a huge difference to the dust levels in my barn shop. I often set up a second fan in the middle of the room pointing at the first one to try and gather airborn dust and guide it out of the building. I have no idea how effective it is

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