Commercial Air Filter vs Box Fan with Shop Made Filter Frame
Go_Bills
| Posted in General Discussion on
Are there any advantages to purchasing one of the Commercial Air Filtration Systems that typically hang from the ceiling in a shop verses building a frame to hold HEPA filters against a Box Fan. I understand there will be additional load on the Box Fan by adding the filters but you can buy numerous Box Fans for the cost of one Commercial Air Filtration System.
Thanks for your responses
Replies
I don't see the advantage. You would need to find compatible filters to match up with the fan you purchase , and don't forget the electro static prefilter, design a box to house it all, purchase materials. Most likely you will end up with something much heavier than one you can buy commercially. Don't forget the timer and speed control which is really handy as a remote controlled devise. All this to build something that is actually, in my mind, really reasonably priced. I have a JDS that is no longer in production but it was only a couple hundred dollars when I bought it. It's quite adequate for my shop. I see filter systems that appear similar advertised for not much more than I paid years ago. So
A box fan pretty much operates near zero pressure. The box fan won’t push it thru or even pull it thru the filter. Try a putting a very fine mesh screen over it (much finer than a window screen or a several layers of cloth (think a homemade covid mask, three layers) and practically no air will come out the fan. So if you slap a hepa filter on (way better filtration than cloth) , it will be useless.
I run an $18 box fan with several filters (starting at two of those really loose green mesh filters, than a finer filter and finally a really fine filter. Sorry, don't remember the Merv values off the top of my head). It actually works really well. 20 x 20 filters fit perfectly.
I built it into a bench that has wheels, that holds a couple of less-used power tools on top, with some storage and the box fan filter contraption underneath. I have a heavy duty power strip attached to the bench and can just switch it all off from the end. I left myself a little access to the fan speed knob, as well.
I am thinking about building a new housing to hang from the ceiling. But, I'll just use some scrap and a few eye hooks. I'll have to engineer some form of speed control, I guess.
I'm still waaaaaaay under the price of a commercial unit.
I don't have the electrostatic filter (although I was looking at one on Amazon the other day... I think at the point, it would be cheaper to buy a regular factory made unit).
I think, when it hangs from the ceiling, it'll hang a lot lower as well... But, I have nice, tall ceilings. Not really an issue for me...
No remote... But, I can always grab a cheaper holiday lighting remote for cheap.
I dunno, for my small shop, I'd rather spend the money on other things. But, that's just my particular situation.
Anything you can do to eliminate dust is good, whether it be home made or commercial grade. If there's less dust in the air, it's less dust that you can breathe.
Never used a name brand shop filter but have used the box fan setup for years. As mentioned, it needs airflow to work properly and I have a dedicated smaller fan on the opposite side of my small shop to keep the air moving (an open widow also helps). Both are controlled by a cheap remote and I'm content with the setup. If I think I'm overloading the filtering, I'll either don an N95 or leave the shop and let the fans run.
There is no reason why, at least in principle, that it would not work. You would lose little in trying, save the time. If it fails you still have the fan to use in Summer!
The key issues I can forsee are:
1. Loss of commercial features such as remotes and timers, though you can add both with a $5 sonoff device from ebay.
2. Heavier
3. Likely noisier and less efficient
4. Depending on config may increase air flow and actually raise more particles than it removes.
5. Your insurer may use it as an excuse not to pay out...
As with all DIY projects, you are turning time into money, or in this case, cost savings. I'd do it if I lived somewhere that I needed to heat my shop - except in the dead of winter I just open front and back doors and the air self-cleans.
Lately I have seen recommendations for making what you describe out of a box fan and 4 filters of the same size. Set your filters on edge forming a square. Tape them together. Then lay your fan horizontally on top of the square and seal the edges with tape. Now your fan will draw through 4 filters and blow the filtered air upward. This will reduce resistance and improve flow. Tape a piece of cardboard on the bottom edges of the filters if you need to seal it up. If it works for you, you can make a permanent box of plywood to hold the filters and fan.
Common sense tells me its not going to push much air.
If you can find a squirrel cage fan out of an air handler, that's a much better option.
It would have to be rewired for 110V.
I salvaged an attic exhaust fan when having new shingles and ridge vent installed several years ago. I built a plywood box with slots for two furnace filters. It has worked and held up well.
There have been several low-scale comparisons of effectiveness of box fan + filter vs. commercial air cleaners--and the simple facts are that a reasonably-made DIY box fan air filtration system can be effective, though generally not to the same level as a quality air cleaner. For example, a NYT Wirecutter comparison found that the DIY box fan+filter reduced particulates by more than 85% (compared to upper-90s percent efficiency of quality commercial air cleaners). I recall reading an engineer's similar comparison where the DIY box fan system cleared some 75-80% at PM2.5, with a high-end HEPA air clear getting about 90% of same.
I have a box fan system on one side of my garage shop, and I can assure all that it very clearly pulls air through, and given the frequency with which I change filters, it very obviously filters significant amounts of wood particulates out of the air. I also use dust collection with all power tools, and turn on an industrial-capacity vent fan pushing air out through a roof vent. There's still dust, but it's much, much less than before these measures, obviously.
Is a box fan + filter good enough for your shop? That is, of course, a matter of personal preference; shop usage; work style, type, and volume; and more. But a $20 box fan + 20x20 furnace filter in a reasonably planned and produced DIY frame is clearly better than nothing.
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