Considering air filtration for my 18'x38' work shop. Any opinions???

[Justin Pfenning]

I'm doing the electrical layout for my shop build out, and I'm considering adding electrical outlets in the ceiling for air filtration units. I've seen the Jet and Rinkon units on sale on Black Friday the last couple years, so I might pick one or 2 up this year. Do these units make a noticeable difference in the shop air quality? Are they a pain to maintain? I was thinking of getting 2 and positioning them centered on the long walls, mounted at ceiling height. I have an Onieda cyclone dust collector to pick up the heavy dust and chips at the machines, the air cleaners would just be for the air borne dust. Is it a worthwhile investment?

[glenn bradley]

The JDS-750 that used to win all the bake offs now seems to be the Rikon 62-1100. I have an older JDS unit and it works great except for the remote control. Numerous reports of failure after a decade or so including mine. I now have it hard wired for the high setting and use an inexpensive remote AC switcher from the BORG. Still works great as I rarely used the lower speed anyway ;-) The point being that this one unit (and volume of exchange) work well in my 30 x 40 shop although I built out the wiring plan for two. I would also recommend running pathway for wireless, audio systems, etc. at this time. I ran two additional conduits for low-voltage applications and used one during the first year of occupancy in the new shop (https://sawmillcreek.org/showthread.php?298253-The-Shop-at-6-Months&highlight=).

[Sam Force]

I have a homemade air filtration unit that works very well. Took an old squirrel cage and boxed it in with 3 filters on 2 sides. Hung it on the ceiling and blow the air into a box in the attic with 2 8 inch flexible vents returning air back to the shop. I vacuum about 1/4 inch of small particles off each side about once a week

[Ron Selzer]

Is it a worthwhile investment?


I have a homebuilt unit with bag filters built into workbench. As long as it is running the wife can come down, walk around, talk to me etc. If not running when I am working, she leaves in a few minutes and has a bad 8-12hrs due to allergies.
I can't really tell any difference. I turn it on when I walk in the shop and turn it off anytime from when I leave to 3 days to a week later. It uses an old furnace fan and is quiet.
Ron

[George Yetka]

They are quiet enough I would wire those outlets to be powered with lights. Thats currently how mine are so I remember to shut it off. I want to rewire the unit to be on all the time so everytime I turn the lights on or off it goes on so I can remember its up there in the first place. Mine is a grizzly but I think a bunch are made in the same factory and painted differently depending. Mine has an equivalent wen and jet model

[Jeff Roltgen]

The Jet AFS1000B has been a great unit for a decade and a half. One minor flaw, it has a capacitor on the main control board that swells and dies, killing the unit. Mine did exactly that, read the notes/instructions about it on the interwebs, and followed replacement instructions with a cheap, easily sourced new capacitor. Back in service and going strong ever since.
Does a very good job by itself, even though I should be running 2 in my newer 42x50 main shop space.
Filters are still available, many different varieties, even the internal "lung" style. Steer towards a brand you can maintain over the years.
Very smart to think this ahead and wire up accordingly.

[Eric D Matson]

I have 2 of the Rikon units in my shop. Its about 850 sq ft. One is powered with a switched plug on the same circuit with the lights. What I don't like about that one is I can't use the timer function. A lot of times, I turn the timer on for a couple hours after I leave. One shuts off with the lights, one shuts off on the timer.

[Alan Lightstone]

Two of the Jet 1000B (or any of the equivalent competitors) oriented opposite each other will work just fine. Skip the Jet 2000. Too loud, and not much higher CFM than the 1000B's.

I'm also a real believer in making a homemade air cleaner with four 20x20x2" MERV 13 or better air filters, a cheapo fan from the home improvement stores, and duct tape. (Lots of posts online, and on SMC showing how). Put it on a timer so it runs 3-4 times a day for 30-45 minutes. It's amazing how that cleans the baseline air in the shop, and is very inexpensive to make. I have one of those that's scheduled to run before I go in the shop in the morning. The air quality when I get inside is great.

Maintenance on any of those manufactured units is not a big deal. Just don't forget to clean the reusable filter and replace the outside filters on a scheduled basis.

Just to vicariously spend more of your money, buy a Dylos Air Quality meter (I believe the 1100 Pro model is the one set up for small particles that are the most dangerous to breathe in woodworking) and make it a point to wear a good P100 respirator (lots of good choices since the plague, I use the 3M one) when the air quality in the shop is worse than the usual ambient air readings on your Dylos. That also will make you feel a lot smarter when you see that the air cleaners you bought have done their job. You'll also learn which machines are the worst offenders in your shop for producing airborne particles.

Undoubtedly a worthwhile investment. Your lungs are priceless. Sorry for the tome.

[Justin Pfenning]

I ordered 3 of the Wen 3410's for $105 each (black Friday special) and free shipping. I'm planning to put them in a U pattern to circulate the air through the whole work space.

[Andrew More]

I've seen a number of youtubers test a super cheap box fan + high MERV filter vs professional hanging filters. The more expensive hanging filters add some interesting features like timers, but for just filtering dust the box fan+filter does as well, if not better. You can add the other features via a dedicated circuit with a simple timer for $20-30 from your local electrical supplier.

So if you've got a little time, the hanging filters aren't worth it, IMHO. You're talking about $30-40 and and 15 minutes for a basic setup, vs $160+ and up. If you must provide documentation for some reason, (OSHA?) maybe the professional models are a good idea, for the home gamer there are a lot of other things you could be spending this money on.

[Maurice Mcmurry]

As described by Andrew, I keep 3 cheap box fans, a roll of disposable filter media and clothespins on hand to run in peoples homes when I do an install etc. I often get a "Thanks for doing that" when folks see the dust accumulation.

[Alan Lightstone]

I've seen a number of youtubers test a super cheap box fan + high MERV filter vs professional hanging filters. The more expensive hanging filters add some interesting features like timers, but for just filtering dust the box fan+filter does as well, if not better. You can add the other features via a dedicated circuit with a simple timer for $20-30 from your local electrical supplier.

So if you've got a little time, the hanging filters aren't worth it, IMHO. You're talking about $30-40 and and 15 minutes for a basic setup, vs $160+ and up. If you must provide documentation for some reason, (OSHA?) maybe the professional models are a good idea, for the home gamer there are a lot of other things you could be spending this money on.
I don't think a single cheap box fan with a single high MERV filter is going to do it. And I don't think we're only talking about $30-40 here. The setups we are describing have four 20x20x2" MERV 13 or greater filters (which aren't cheap) and a good high velocity fan. Plus a timer (which is nice). This setup absolutely not $30-40, but will work great. And I measured mine at 814 CFM. Much greater filter surface area, much less resistance to flow, much more efficient filtration.

A Lasko fan with a single 20x20x1" filter does something, but the number of air exchanges per hour is limited by the resistance through the filter and the relatively small filter surface area. If the OP changes out the 1 micron filter on his Wens to something like a MERV 13 or MERV 14, he will do better removing small, more dangerous particles, but will certainly not get 400CFM. I believe David Morse had tested Lasko fans at some point. He probably has real data on their actual CFM. Personally, I wouldn't use as coarse a filter as 1 micro. My $0.02 (actually spent far more on filtration than that).

In my previous testing, my Jet 1000B with a MERV 13 filter on it measured 1119 CFM. Real world testing, not factory optimistic numbers. Here's the link to our long thread regarding air filters: https://sawmillcreek.org/showthread.php?291720-Which-Air-Filtration-is-Better

Justin, do you have a Dylos air quality meter by any chance? If so, we can lead you through testing your setup when installed. It would be very instructive to us all.

And congrats for making that jump into air filtration. Your lungs will thank you some day.

[Andrew More]

I don't think a single cheap box fan with a single high MERV filter is going to do it. And I don't think we're only talking about $30-40 here.
Last time I was in HD they were selling Lasko fans for $20, and then another $10-20 for the MERV 13 filter.


The setups we are describing have four 20x20x2" MERV 13 or greater filters (which aren't cheap) and a good high velocity fan. Plus a timer (which is nice). This setup absolutely not $30-40, but will work great.
Fair enough, I probably should have been clearer on what I was describing. So right now that would be ~$100-150, with 4 box fans + 4 MERV 13 filters. What you're describing 4 20" box fans + MERV13 filters is going to have a much much larger area than the normal commerial hanging filter. Even with their deep filtering they're not going to move the same amount of air, or have the same amount of CFM. Lasko rates their box fans at ~1000 CFM. Not sure what the filter is going to do to the air flow, but I doubt it's going to cut it down to 250 CFM.

If you want to save some money you can often get old squirel cage blowers for $25-50 off Craigslist. Once you move to the 4 filters that's probably going to be the better approach, and it will have higher CFM than most hanging filter systems.


In my previous testing, my Jet 1000B with a MERV 13 filter on it measured 1119 CFM.
So you're running a $500 filter? That would buy a LOT of box fans + 20x20x1 filters. Looking at the design for that system, it's basically 1 1/2 of box fan filter area at 30x24. AND you need to buy special filters at a higher price from Jet.

[Alan Lightstone]

Last time I was in HD they were selling Lasko fans for $20, and then another $10-20 for the MERV 13 filter.


Fair enough, I probably should have been clearer on what I was describing. So right now that would be ~$100-150, with 4 box fans + 4 MERV 13 filters. What you're describing 4 20" box fans + MERV13 filters is going to have a much much larger area than the normal commerial hanging filter. Even with their deep filtering they're not going to move the same amount of air, or have the same amount of CFM. Lasko rates their box fans at ~1000 CFM. Not sure what the filter is going to do to the air flow, but I doubt it's going to cut it down to 250 CFM.

If you want to save some money you can often get old squirel cage blowers for $25-50 off Craigslist. Once you move to the 4 filters that's probably going to be the better approach, and it will have higher CFM than most hanging filter systems.


So you're running a $500 filter? That would buy a LOT of box fans + 20x20x1 filters. Looking at the design for that system, it's basically 1 1/2 of box fan filter area at 30x24. AND you need to buy special filters at a higher price from Jet.

Many good points, Andrew. And to some extent we are describing apples vs. oranges. I already had owned the Jet 1000B and bought the Jet 2000 for my workshop. I wasn't terribly pleased with the Dylos particle readings I was getting in the stock configuration (just took too long to get rid of particles, and noisy too). Doing some tests and adding some better quality filters I was able to increase their efficiency markedly, demonstrated with a boatload of testing. I wasn't terribly concerned about the cost of adding the filters. Does it work - very well. Is it $30-40. Not even close.

As far as the homemade box filter, I got involved in this during Covid, I had just retired, and had time on my hands. I first learned about them on an Ask This Old House episode. I refuse to mention the two persons whose names are commonly associated with these filters as they really weren't the first to come up with the idea, but you always hear it called their name's box. Petty peeve on my part.

During the beginnings of Covid, many of these were built, as they are quite effective at air purification for small particles. A group of students at UCSD even mass built a ton of these for classrooms in San Diego. Way to go guys!

But these filters are very effective for woodworkers. They remove large amounts of very small particles that we don't want to breathe very effectively. A Wen, Jet, or whoever's normal box filter with a 1 micron outside filter doesn't do that well. The filter is just too porous. Could you buy a HEPA filter as a replacement for the outside filter? Absolutely. Will it filter small particles better? Of course. But at the cost of reducing the CFM of the setup. Will it's efficiency go down? Good question. Testing would show if it helps or hurts. I found that adding a second MERV13 filter to the outflow of the Jet 1000B made things worse, and I removed it.

But I have added MERV 13 filters to the inlets of my Jet1000B and Jet 2000 and they significantly improve small particle collection. That link showed the test results.

I'm hoping David Morse jumps in, as he had mentioned that he had tested some Lasko fans and knows their flow rates. I found that it was significantly underpowered when I tried one in a 4-box filter setup (which should have less air resistance than a single filter) and replaced it with a higher CFM fan I purchased on Amazon. Works far better.

And yes, $500 would buy a LOT of box fans + 20x20x1 cheap filters. But where are you going to put all of them, and the noise would be deafening. Not a good plan for me, at least.

I'm really hoping that the OP has a Dylos particle meter, as I'd love to see results of his setup. We would all learn a lot.

There is a ShopHacks article and a build from Jay Bates who made a nice filter cart (a little prettier than the duct tape version. He does some testing in his shop comparing those to a number of commercial air filtration system, including the Wen, Powermatic, and a box fan with filter. The worst performing was a box fan with a new MERV12 filter. The Wen 3410 took 107 minutes to clear the air, and a box fan took only 33 minutes. One of his lessons learned is that crappy filters are, well, crappy. Good quality filters matter. And using 4 filters, albeit 4 times more expensive, yields 1/16 as much flow resistance - hence greater CFM and greater efficiency.

490841


Here are those links:
https://www.shophacks.com/airfiltrationsystems.html#/
https://jayscustomcreations.com/2016/05/mobile-air-cleaner-cart/

[Alan Lightstone]

Eureka: I read that old thread, and David had included flow figures that he had measured with the common Lasko fans:

"I've done some testing of the Laskos. They can move about 990 CFM with no filters attached. Putting a filter directly on the back of the fan reduces that, to about 500 CFM for a 2" thick generic MERV 8 and about 240 CFM for a DuPont 9100 (MERV 12). A 3M 1500 (also MERV 12) does much better than the DuPont with 380 CFM."

So as I had mentioned previously, adding a single filter to a typical Lasko 20x20 fan reduces their flow rate markedly. 240CFM with a MERV 12 is not exactly stellar flow. And with a MERV 13 or even higher with a HEPA filter they will go down even further. They are 2" filters that he described.

[Justin Pfenning]

Alan, can you recommend an affordable Dylos particle meter? My shop won't be functional with the air cleaners till after the first of the year, but it would be good to measure the performance of the Wen units. I like the idea of building an inlet box with multiple filters to increase the performance. It also allows me to use a standard off the shelf filter size.

[Alan Lightstone]

Alan, can you recommend an affordable Dylos particle meter? My shop won't be functional with the air cleaners till after the first of the year, but it would be good to measure the performance of the Wen units. I like the idea of building an inlet box with multiple filters to increase the performance. It also allows me to use a standard off the shelf filter size.
Justin:

The one that most woodworkers use is the Dylos 1100Pro model. It's the model setup to measure 0.5 micron particles at its lowest setting. A few years ago there was a group buy here, that many of us used to grab those meters. Not cheap. Worth every cent, for no other reason that you know when you can turn off the air cleaners to save electricity, and stop that loud noise. And three of them running won't be quiet.

I would definitely avoid those cheap Chinese made meters that you find on Amazon or eBay. Really not terribly helpful for us in woodworking. I have one in the shop for kicks, really not useful to me at all.

I'm hoping that this discussion is helping you with your new workshop. Buying 3 air cleaners is great (I have a similar sized shop, FWIW). What I find the Dylos indispensible for is that I always wear my 3M respirator until the small particle count gets down to the ambient level of the shop (500 particles in my case. YMMV.) That way, I'm never breathing air worse than outside. Good chance your air is cleaner than mine, though I've never measured it in Nebraska. I live right on the Gulf of Mexico, so if the wind is coming from the west, there's really no polluting entities within hundreds of miles of me. But still 500 particles is that baseline.

I had a friend buy a Dylos who lived in Reno, Nevada during the forest fires. He saw the readings (the government AQI readings were online also) and was stunned how bad the air was that he, his wife, and his kids were breathing. They moved to Florida.

[Andrew More]

To be honest I've got a DIY model using a used blower from a furnace, which is mounted in the ceiling. There's no drywall in my garage, so I'd just put a row of them in the joists. I've got a ton of room up there I could easy put a dozen if I wanted.

I think you're missing the point of the ShopHacks article. If you look at this list from the same article you'll see that he uses a number of different filters, with varying results. The 3M MERV 13 filter + 20" box fan out performs the WEN and the Powermatic professional air cleaners.

Systems Tested and Time Required To Filter The Air (worst to best)
#13 5+ hours. BASELINE - no dust collection and no air filtration.
#12 2+ hours. 20" box fan with a 20x20x2 off brand "MERV 12" filter (I personally NEVER trust a filter other than 3M or Honeywell unless I could test it using a laser particle counter). I suggest that you use an air quality meter to evaluate the performance of any filter system you use in your workshop and decide for yourself. ​
#11 2+ hours. WEN 3410 Air Filtration System (https://amzn.to/2R6syJZ) (squirrel cage blower, bag filter, prefilter)
#10 65 minutes. 20" box fan with 3M MERV 6 and MERV 11 filters on the inlet
#9 61 minutes. Honeywell 50250-S True HEPA Air Purifier (https://amzn.to/2NDZtn4) (squirrel cage blower, HEPA filter, mesh prefilter)
#8 60 minutes. Shop Hacks Prototype with 4@2-year-old dust caked filters - (2000 CFM axial fan with four 24x24x1 Honeywell FPR10 - MERV 13- filters)
#7 41 minutes. Powermatic PM1200 (https://amzn.to/2TCwtzK) air filtration system (squirrel cage blower, bag filter, prefilter)
#6 35 minutes. 20" box fan drawing fresh air in window and 20" box fan blowing fresh air out the door (no filters)
#5 33 minutes. 20" box fan with 3M 20x25x1 off brand "MERV 13" filter
​#4 29 minutes. Shop Hacks downdraft table - (1200 CFM squirrel cage blower with two 20x25x1 and one 20x25x4 inlet filters and one 14x24x1 outlet filter. Inlet filters: 1" MERV 6?, 4" MERV 12, 1" MERV 13, 1" MERV 8?)
#3 27 minutes. 2000 CFM axial fan with two sets of 3M MERV 6 and MERV 11 filters
#2 15 minutes. Shop Hacks Ultimate DIY Air Filtration System (http://www.shophacks.com/airfiltration) - 2000 (CFM axial fan and five 20x25x1 MERV 13 filters)
#1 0 minutes. Shop Hacks dust collection system, no air filtration


I would definitely avoid those cheap Chinese made meters that you find on Amazon or eBay. Really not terribly helpful for us in woodworking. I have one in the shop for kicks, really not useful to me at all.

How so? I got one off Ebay, and it appears to correctly report down to PM 2.5, same as the Dylos. I don't have another one to check it against (sorta defeats the purpose of buying the cheap one :) is it inaccurate in some way? It definitely seems to respond to more or less dusty conditions in the shop.

[Chris Parks]

How so? I got one off Ebay, and it appears to correctly report down to PM 2.5, same as the Dylos. I don't have another one to check it against (sorta defeats the purpose of buying the cheap one :) is it inaccurate in some way? It definitely seems to respond to more or less dusty conditions in the shop.

I would ask the same question as my experience with the Chinese unit is the same as a lot of others who use it routinely in Oz after the readings of several units was verified by comparison to known accurate instruments.

Back to the topic and question that started this thread, air filters can be regarded as proof of failure of the primary dust collection system because the dsut has not been captured at the machine.

[Andrew More]

I would ask the same question as my experience with the Chinese unit is the same as a lot of others who use it routinely in Oz after the readings of several units was verified by comparison to known accurate instruments.

That's reassuring thank you. I knew mine reacted, but it was unclear how effectively without buying the more expensive meter. I _totally_ expect the more expensive to produce a more objectively accurate reading, but I don't think it's necessary for this purpose.


Back to the topic and question that started this thread, air filters can be regarded as proof of failure of the primary dust collection system because the dsut has not been captured at the machine.
While this is not untrue, I honestly do not know how to overcome some of the basic physics of the situation. The miter saw and table saw both have blades moving in excess of 100 MPH, while a dust collector might hit 40 mph. I just don't see how that situation can be easily fixed, along with the dust that is thrown all over the place with doing open cuts with either tool. (Closed cuts usually move the dust directly towards the collector).

I would agree with you with regards to sanding, which is a far more easier situation to deal with from a capture perspective, and further I believe the dust produced by sanding the most harmful.

[Justin Pfenning]

It appears all the shop built units use various types of box fans, and all the purchased units seem to use squirrel cage fans. Any particular reason for that? Can a purchased unit perform at a higher level with a modification to the inlet filter? I was thinking of making a triangle shaped box to allow 2-4 filters with higher MERV ratings on the inlet side. With the upgraded inlet filters, maybe the inner filter wouldn't be needed anymore resulting in higher cfm.

[Andrew More]

It appears all the shop built units use various types of box fans, and all the purchased units seem to use squirrel cage fans. Any particular reason for that?

It would appear that the squirrel fans are better at producing pressure than the axial fans.
https://www.pelonistechnologies.com/blog/axial-vs.-centrifugal-fans

I've got my setup with squirrel fans because I've got a buddy who's an HVAC tech, but you can usually get them second hand for $25-50, at which point I don't believe there are any material differences between the DIY and commercial shop air filters.

[Monte Milanuk]

Interesting thread. Years ago when I got my Delta 50-760 dust collector off of CL, the seller threw in a Delta air cleaner as well. Never used it (previous shop had super low ceilings, and no good place to put it otherwise), and eventually sold it. Now, in the current shop I have plenty of head room and found myself really wanting something to catch some of the finer airborne dust that escapes the miter saw, router, edge cuts on the TS, etc. that my DC and shopvac don't always catch.

Earlier this year I started looking at various air cleaners, and debated on whether to get something cheap, like the Wen, or something nicer. Any of them would have to be shipped. Somewhat as a lark, I started googling box fan air cleaners, and boy was that interesting. Apparently with COVID quarantines and some of the big fires out west last year, regular people started spazzing out (technical term) about indoor air quality. I was laughing my butt off at the number of videos I found showing how to build a cube of furnace filters, one 20" box fan, and some duct tape.

The really funny part? Apparently folks thought this was something new, and now this design has a name: the Corsi-Rosenthal box (https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box).

[Bruce Wrenn]

I built mine. It has an inner bag filter, with a pleated outer filter. On ceiling, near unit, I have a piece of string hanging down. By looking at string, I can tell when outer filter needs cleaning. Every other year, remove bag filter and using shop vacuum clean inside of it.. My unit is hung on ceiling along long rear wall. It's near where my ventless propane heater is. I mounted a thermostat on ceiling above heater so when heater comes on, so does air filtration unit, circulating heat around the shop.

[Mike Burke]

Good information here. Thanks

I am wanting to upgrade my shop air cleaner setup soon. Currently using a box fan Corsi Rothenthal (sp) filter. Just changed filters so I'm good for a few months.
Considering the following for upgrade

Bill Pent'z inline blower and wynn filter
Jay's custom creations squirrel fan rolling filter
Wood smith magazine also had plans for a inline blower / filter cleaner. (april/may 22) issue I think

My shop dimensions
14x30 basement shop
7' ceilings
hybrid cyclone DC with fixed 5" ducting
Ceiling space is limited so I'm thinking about a rolling filter setup.

Any advice on upgrading my air cleaner setup ?

Thanks

[Bob Borzelleri]

I built this unit some 15 years ago. Don’t recall where I got the plans/materials list, but it was pretty easy to source the components.

It uses a pleated bag and pre-filter.