Area Air Cleaner thoughts-

[David Ruhland]

I definitely have the option to exhaust outside. Heck i can even set the entire dust collector outside as i have a 12 foot lean too on the back side of my shop. I like this idea MUCH better. .ALONG with some better dust collection at the tools..esp the miter saw. what about mounting a cyclone on top of a garden cart i pull behind my lawn tractor outside or better yet.. just letting her fly out the back into my field. There are 400 acres there? I will still work on the air cleaner issue, but i think that getting dust collection at the sources controlled first is the first step.

[David Ruhland]

David, read this before buying anything
Dust Collection Research - Home (billpentz.com).
You are starting down a rabbit hole, lots of different opinions and options out there.
Lot of discussions on here about dust collection.
I started in 1986 with my first dust collector, slowly added, modified, changed it, more changes to come as money allows. (most expensive way to do things)
I use a three-part attack, 1. the air filtration as already discussed, 2. dust collector which basically is a super dust deputy, pull thru filters, 2hp fan and a 3hp fan, 3. rigid shop vac with three different filters pulling thru a dust deputy hooked to a 2" pvc network that all handheld power tools hook to.
Buy the most that you can afford plus half again. Cheaper to buy once then to buy three, four, five times. also, better for your health and family's health to spend the money now. However, anything is better than nothing.
Have fun wood working.
Ron

Ron...

I totally agree with you... can you clarify this? "pull thru filters, 2hp fan and a 3hp fan, 3. rigid shop vac with three different filters pulling thru a dust deputy" I am confused by the "pull through filters, 2 hp and 3 hp fan," and the "three different filters pulling through a dust deputy"

Thank you!
Dave

[Jim Becker]

I definitely have the option to exhaust outside. Heck i can even set the entire dust collector outside as i have a 12 foot lean too on the back side of my shop. I like this idea MUCH better. .ALONG with some better dust collection at the tools..esp the miter saw. what about mounting a cyclone on top of a garden cart i pull behind my lawn tractor outside or better yet.. just letting her fly out the back into my field. There are 400 acres there? I will still work on the air cleaner issue, but i think that getting dust collection at the sources controlled first is the first step.

You will have to carefully consider other implications of exhausing outside, given where you live. You'll not only be putting the dust/chips outside, but you'll also be transporting your heat during the cold months of the year outside.

[Keegan Shields]

When using a cyclone, dust and chips go down into the barrel, not out the exhaust (unless the barrel gets full)

I was initially worried about getting a film of dust outside (I live in the 'burbs) where I exhaust but it has never been an issue.

The DD really does get all of the detectable dust. Do some fines make it out of the exhaust? Probably.

As a side benefit, I don't have to clean a filter and the dust collector's function is greatly improved since there is almost no back pressure on the exhaust.

As I understand it, these types of impellers are very sensitive to exhaust side back pressure. That's why you get such a performance improvement when you switch to a Wynn filter.

For even more performance improvement, eliminate the filter all together (for those with no HVAC).

Those with have HVAC might consider a gate - exhaust internally through a filter during the winter/summer months and exhaust externally with no filter in the spring/fall.

[Ron Selzer]

"I totally agree with you... can you clarify this? "pull thru filters, 2hp fan and a 3hp fan, 3. rigid shop vac with three different filters pulling thru a dust deputy" I am confused by the "pull through filters, 2 hp and 3 hp fan," and the "three different filters pulling through a dust deputy"



David, I got a great deal on craigslist for air filters designed for commercial us that are pull thru. I have approx. 24-30 filters (forget exact number) in a plywood box. Monitor with a Magnehlic. Piping goes to Super Dust Deputy to the plywood box with filters, there is a two hp Grizzly fan pulling from box (original dust collector bought back in 1986) also a three hp Grizzly fan (from 4 bag unit) pulling from the box. This works fairly well as the sawdust collection box is packed tight with a good-sized depression under the Supper Dust Deputy. You have to dig it out, not loose like it was with the three hp only.
The Rigid Vacuum has a paper filter inside then there is a cartridge filter that has another filter over it as I remember it. I have not changed any filters since I set it up about 5 years ago. The dust deputy drops all the dust out based on how clean the Rigid vacuum stays.
Ron

[Scott Winners]

Sorry, late to the party. Pictured is the sort of sensor I am using. I got pretty serious about indoor air quality, mmm, 4-5 years ago. Our last house was within ~300 meters of Wood River Elementary School in Fairbanks AK, you should get about 15 bajillion search engine hits on the air quality in that microclimate.

The main thing is, to me, if you are not measuring your air quality you have no idea if your air filter system is effective.

My current air quality monitors are available on Amazon and include a CO2 sensor I trust for about US$75 each. The same maker also has a current unit with just a particle counter in it, and current US EPA conversion to AQI, for about $60. I have not bought the top end model from this maker with the VOC sensor on board as I find the calibration algorhythm suboptimal. I think the formaldehyde/VOC sensing tech this company has chosen has great promise, but I am not satisfied with the LCS (least common squares) calibration method currently in use.

The thing I like about this vendor as pictured below is they tell you what sensors they are using in the device. The Plantower (Plantronics?) S-50 series particle counters are robust and repeatable. They do have a service life expectancy.

Twice (while wearing medical pro grade PPE) I intentionally left the loading door to my woodstove open to run indoor air quality up into the hazardous range, and then tested two different homemade filtration systems for speed and effectiveness. Wife was not home either time. For both events I was running two of the Dylos 1100 Pro side by side, with four of the $60 items as pictured on the same surface. My finding is the PlanS-50 series particle counters are just fine for homeowners, but not laboratory grade gear like the Dylos. Under 6 mcg/m3, if you really want to know how excellent your AQ is, you need a Dylos. Above about 200 mcg/m3 (PM2.5) if you want to know how hazardous your AQ is, you really need a Dylos.

If you just want to know if you have a problem, or don't have a problem, the pictured item (in the $60-$75 range) is perfectly reasonable homeowner grade gear. The older versions of the pictured device (currently about $40 on the big river) use an older/ outdated conversion to move from particle counts in mcg/m3 to AQI.

I personally despise the AQI. The definition (defined in mcg particle per cubic meter) of say "moderate quality air" on the AQI index table is subject to change every time enough bureaucrats get together for enough meetings in enough conference rooms. I try to track all of my data in mcg/m3. Some lifetime PM2.5 exposure is inevitable. The preponderance of current medical evidence indicates less exposure is better. In this regard, PM2.5 is kind of like radiation. You are going to be exposed to some, less is better.

I live in an area with a LOT of wildfire smoke. My home filtration is designed to filter all household air (about 12,000 cuft) when outdoor particles counts are up in the 200s mcg/m3. This is overkill for the small hand tool shop in my attached single car garage. My newest filtration system is currently on my bench under construction. The carcass is nominal 24x24x67 inches. When finished it will have filters on three vertical sides, but plywood all up the back so I can push the unit up against a wall. Motation is via 20" Lasko box fan, about $20.

I like MERV 13 for PM2.5 capture. At team orange home store, that is level 10. At team blue, that would be 3M filtrete 1900 or 2200. I buy the 3M2200s online, they are factory packed in boxes of six filters @ 20x20x1. If you got someone in your house who is getting or has recently gotten chemotherapy, or an organ transplant recipient, going straight to HEPA fltration (MERV level 14-19) I can see that. For baseline healthy household, I find MERV 13 level filtration (with instrumentation) more than adequate and less expensive.

So one pic of the particle counter I like, and one pic of the filter system currently under construction. And bonus pic of a 20" box fan with a MERV13 20x20x1 furnace filter taped to it. I have logged hundreds of temperature measurements on the motor of a box fan pulling through a single filter like this. Pulling through MERV13 with a Lasko I have never found a repeatable 1 degree Fahrenheit difference between fan motor and ambient, but my one datapoint is not going to get you back into a valid homeowners claim. It does work just fine, esp with a particle counter to put an elapsed time on efficacy, but you still have some due diligence ahead of you.

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[David Ruhland]

Thank you for this detailed information. I am working hard to get cleaner air, first by doing a better job collecting it at the source. My shop has living quarters attached and even though i keep the door shut my wife is always complaining about dust. Its work in progress.

[Michael Burnside]

Scott, can you provide a link to the sensor you're using? I have started down the path of writing my own using a few off-the-shelf parts and an Arduino, but for $75 bucks and something you trust, maybe I can use it as a reference. Thanks!

[Jim Becker]

Michael, they look like the one I got from Bangood...there's a thread about them somewhere here. Not my favorite way to buy, but the price was right and the product works well. (metric/celsius only, but it's a "relative" measurement anyway)

[Scott Winners]

Scott, can you provide a link to the sensor you're using? I have started down the path of writing my own using a few off-the-shelf parts and an Arduino, but for $75 bucks and something you trust, maybe I can use it as a reference. Thanks!

Sure.

I found just the sensor here: https://www.amazon.com/DEVMO-Concent...07S5YX84W?th=1

And then three products on one page here*: https://www.amazon.com/HOTKREM-Quali...0&sr=8-21&th=1

* When you select the $43 product on that page you will see the display screen shows 23 mcg/m3 for the PM2.5 count and returns an AQI value (bottom right corner) of "23." That calculated AQI value is using a very old conversion table to get from mcg/m3 to AQI. I believe the particle count in that room really was 23 mcg/m3, and I already think AQI is an exercise in self sustaining bureaucracy. But if you need an up to date AQI calculation so you can talk to your Aunt Marge, on the same product page is a $70 item that uses current EPA conversion table (Aug 2023) and includes a CO2 sensor. The CO2 sensor uses the NDIR (non dispersive infra red) technology that I more or less trust in 2023 as a serious hobbyist.

If your house is tight enough that you can hear the flapper plates on the dryer vent rattle when you close a man door, you should probably have at least one CO2 detector in the house.

This product line is not consistently available on the big river website. They come and go. This product line is (reportedly) routinely available from banggood. I have never purchased from banggood, but they do have a reputation for sending many many many emails to customers. The temp/humidity sensor on these provides an output I routinely ignore. Temp/RH is in the ballpark. Temp/RH output is not useless, but it is one chair over from useless to me.

EDIT: For the price, I am satisfied with these units. I have good/high confidence in the particle counts. I have good/high confidence in the CO2 readings on my more recent purchases. I don't give a hoot about AQI. I own an accurate thermometer. I have several consumer grade RH meters from different makers, and when I look at 5 or 6 of them I feel like I have a pretty good idea what the RH in my space probably is, +/- 5%.

[Alan Lightstone]

We discuss this topic on a regular basis, as it's important to us as woodworkers, and human beings who don't want to breathe in all this hazardous dust. Here's a link to a thread that we discussed this topic at length and performed a number of tests and air quality measurements:
https://sawmillcreek.org/showthread....tion-is-Better

Scott, as usual, brings up many important/useful points. There are a number of useful, relatively inexpensive air quality meters that you can purchase. I have a number that I have purchased from Bangood. I also ignore AQI indoors (though I was fascinated by the high readings we got outdoors this past week when amazingly the Canadian wildfires went out to the Atlantic, and circled around and covered Florida. Haze like I've never seen outside, and my Dylos readings were 45x what my ambient usually is, which is off the charts.) That being said, my air filtration systems in my shop worked very effectively in removing that, as well as the MERV 13 filters I routinely place in my house HVAC system.

I'll repeat what I always post about this topic in that my personal approach to this is that I always wear a respirator in my workshop when the small particle count on my Dylos reads over usual ambient level (which is 500 0.5 micron particles). So whatever approach you take, get a particle meter and a good P100 respirator to wear.

I am now fortunate to have Grit Automation air quality sensors which automatically turn on my Jet 2000 and Jet 1000B air filters at designated particle counts, so my shop pretty well always stays at good levels, and when airborne dust is generated, they quickly work to return those levels to acceptable/safe levels.

I built a similar box filter to what Scott is describing, and testing it, it works quite effectively. I would make a few changes, though to Scott's design. I would use 4 20x20x2" MERV filters (or 3 in Scott's case being against the wall and use a more powerful fan than the Lasko. The fan I used is this one: https://www.amazon.com/NewAir-Velocity-Industrial-Settings-WindPro18W/dp/B076RKVBB1
That fan has much higher CFM rating (3000CFM vs 1800, but both are overstated or measured with no filters), and in my testing moves far more air, far greater air exchanges per hour. I put a variable speed fan control http://VIVOSUN Variable Fan Speed Co...ilation System that I plug it into, as well as a timer that turns the fan on for 45 minutes, 3 times a day, so that when I walk into my workshop, the air is already very clean.

Scott's design has about the same surface area of filters, but is physically much larger. He can walk into a home improvement store and buy those filters. I find that the 2" filters need to be ordered online, but that's usually an easy process.

I've also found great success duct taping a MERV13 filter to my Jet air cleaners. This essentially turns their filters into 2" filters and measurably increases their efficiency. You have to be careful. There are diminishing returns here if you cause the fan CFM to decrease significantly due to the larger resistance it is sucking or pushing through, but my measurements showed this was effective.

[Scott Winners]

I also ignore AQI indoors

I'll repeat what I always post about this topic in that my personal approach to this is that I always wear a respirator in my workshop when the small particle count on my Dylos reads over usual ambient level (which is 500 0.5 micron particles). So whatever approach you take, get a particle meter and a good P100 respirator to wear.

I built a similar box filter to what Scott is describing, and testing it, it works quite effectively.

Hi Alan! Where the heck is David in this thread?

You might be able to walk into a box store in the lower 48 and find MERV 13 filters on the shelf. It isn't a thing for me up here, at the northwest corner of the paved roads on North America.

One thing Alan (and David) used to berate me about was filter efficiency, fan speed. I get it now.

At the old place, I had five bedrooms, kids at home, a wood stove running and poor outdoor air quality. It was a 1980 build with multiple moisture/ mold issues. In that scenario it made sense to feed expensive conditioned air to the wood stove for combustion, just to get the air turnovers within the house; and deal with incoming PM2.5 with filtration. This is why I have 2 of the Dylos and 4 of the less expensive particle counters. I was taping them to walls and hanging them from the ceilings to figure out where I needed to look for particles to protect my kids.

In the new place with no kids, we can hear the flappers on the dryer vent chatter when we operate any of the man doors. Our controlling variable for IAQ (indoor air quality) is usually CO2, so we run the HRV system often enough to keep the indoor CO2 level in the green zone. When I go out to the shop to do actual woodworking, I close the weatherstripped door between living and shop space, turn on the air filter, and leave that door closed until PM2.5 counts get back down to ambient. When I am not actually making particles out there I like to keep that door open so my stored lumber for furniture is acclimating to the inside of the house (temp and RH) for less movement later.

In the new place, if I had a higher volume filtration fan, I could open the door between shop and living spaces sooner without letting a bunch of wood dust into the living space. Alan and David are correct about this. In the new place, the intake filter system on the HRV pretty much delivers zero PM2.5 to the interior while outdoor counts are up to 50 mcg/m3. Above 50 mcg/m3 I start seeing PM2.5 in the living space and have to (choose to) deal with those particles.

In the old place I could get away with one 20x20x1 filter taped to the back of a box fan for the winter months with the wood stove running and change the MERV 13 filter annually. However, spring brings pollen and autumn brings leaf mold. To deal with those, I built a cube with three filters on it, and ran that year round in the old place. On the front, a 20" Lasko pushing cold air from the bedrooms along the floor towards the wood stove. On one side, a plywood blank so the unit could go up against the wall of the hallway. On top, another plywood blank so the cat could sleep up there. On the back, the open side, and the bottom, MERV 13 @ 20x20x1. I did use enough caster height so airflow to the filter on the bottom was not impeded.

The big unit, as pictured above, has a 25x25 inch foot print and should be able to handle full apartment filtration (about 9000 cuft) with outdoor ambients up in the 200-300 mcg/m3 PM2.5 range during wildfire season. It is more filtration than I need for my little hand tool shop, but it should be adequate for the whole home in the worst conditions I anticipate.

I do have a data confound. We have a long haired cat that is 13-14 years old. I pulled a bottle of sriracha out of the fridge the other day, looked at nozzle, turned to my wife and asked, "Do we own anything that does not have cat hair on it?" My finding, n=1, is that lower fan speeds through MERV13 at 20x20x1 give faster (of chronic) PM2.5 capture than higher fan speeds. Your mileage, your data, without a geriatric cat in the home, is going to be different than mine.

In the old place I ran the 3 filter system upstairs with the wood stove and the pollen and the leaf mold more or less year round and changed those three filters annually. I had a 6 filter unit similar to the one pictured here that I ran in the shop and during wild fire season. How often I changed the 6 filters depended soley on how severe wild fire season was that year.

I have zero data about the service life expectancy of 1 v 2 v 4 inch thick filters at MERV 13. Using 20x20x1 filters, regular duct tape, and plain Jane furring strips for box build I am at annual or less than annual filter changes with one inch filters. I don't know what you are up against for IAQ.

[Scott Winners]

The reason I started building my own filter boxes is very simple. I had a bunch of stylish air filters in the house. My particle counts started going up. I needed to buy very expensive custom sized filters as replacements, and I said to myself, I can do better for less. I built the entire cube pictured in the previous post, and bought the filters, for less money than the replacement filters for the swoopy "filtration systems" I replaced. Wife approval factor is certainly important, but everytime I replace these relatively cheap 20x20x1 filters we are saving another $100.

[David Ruhland]

Hi Alan! Where the heck is David in this thread?

.

Im here....Processing all this great information.

[Alan Lightstone]

Im here....Processing all this great information.

I think he's talking about David L Morse, who has been incredibly helpful with his expert opinions / advice in these threads in the past. I've also wondered if he still is around here. I miss his help.

Scott, I wondered about the presence of big box home improvement stores near you after your last post. I actually looked up if Home Depot and Lowes had stores in Fairbanks (impressively they do). I can't imagine the prices for things. Ouch.

One of my major suppliers for HVAC filters has become so absurdly slow in deliveries that I will no longer use them. I got the same message from a friend who used them last year to protect his kids from the wildfires in Reno. Yes, at least near me, and online, you have to get 2" filters online. Might be some other sources here, but never found them.

I also find that I need to change those filters in the workshop yearly (or the last set I replaced after 2 years even though they were clearly working, but probably less efficiently).

I can honestly say I've never thought of building an air filter that the cats can sleep on. My two long haired dogs do work the daylights out of my Roombas, and one is constantly clogging these days. But using them keeps a lot of hair out of the HEPA filter in my bedroom, so well worth it considering the cost in replacing those.