Neppy's ozone/pm2.5 pollution remediating air filter setup - for pollution sensitive individuals.

neptronix

neptronix

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Not sure if this is interesting to the ES audience, but i figured i'd give it a try.

I live in the Salt Lake City, UT area and we have pretty horrific pollution in the winter and summer. We are not compliant with EPA rules going back all the way to 2012. There's lots of dust, wildfire smoke, refinery pollution, industry, and car traffic that keeps this valley saturated with all sorts of nasty shit. And i can feel it in my sinuses, my brain, and my lungs to a point where it interferes with my ability to work.

I started tackling this shitty air with an expensive filter ( MERV 13+ ) strapped to a 20x20 box fan. This creates an equivalent of a $1000+ air filter setup, because you are passing air through a filter just as large. It's just not as pretty or controllable :). This was actually quite effective in reducing pollen, wildfire smoke, and PM. However, i would still frequently get sick, and i discovered the reason was PM1, VOCs, and gases like ozone.

A month ago while in a mental haze from summer pollution, i spent 2 days researching how to mitigate the super small particles and gases. I learned that Carbon was the key. I decided not to DIY this time and seek out a filter unit with a large carbon filter. The only home-sized unit that uses a lot of filter is the Austin air line.

I bought an austin air healthmate plus jr, rated to handle the size of a bedroom. It has the maximum amount of carbon any filter could possibly have, about 9 pounds of the stuff. I also run a small paper/fiberglass type filter unit in conjunction. In addition to this, i bought a beta version of a Purpleair PA-2 with a VOC sensor added on so that i can benchmark the ozone/PM removing capabilities. I have been truly impressed by the combo.

2020-08-03 12_19_35-Map - PurpleAir - Brave.png

Here is the data from my purpleair setup. That little green circle is where i live. I turned both of my filter units from 50% to maximum right around the time it started creeping up past the yellow, and i'm back in the green and have dodged the usual headache, low energy, coughing fits, etc.

Future plans/improvements

Ultimately i'd like my bedroom to have clean-room grade air, which would require me to buy the larger and more expensive filter unit, but it is a bit too loud. Eliminating my health issues doing the worst of the air pollution season is good enough for me.

The austin air unit is very basic and only has 3 speeds. I am considering replacing the motor drive with a PWM controller whose speed is controlled by a little arduino board that gets information about indoor pollution from a Bosch BME680. Then i never have to dick around with the speed setting, and the sound of the filter's fan would be a nice audible indication of the air quality in my abode. It's quite a bit of work to learn arduino code though and i have more important things to do, so i'll continue fiddling with the knob, lol.

I also did a video of this showing the filter and sensor setup to anyone interested:

[youtube]CD8NiZj_KHQ[/youtube]
 
neptronix said:
The austin air unit is very basic and only has 3 speeds. I am considering replacing the motor drive with a PWM controller
Click to expand...
If it's like every ohter "three speed" motor I've worked on in wall-powered fan systems, then it's an induction motor with multiple windings, and the switch just engages them in different ways.

If so, you'd need to replace the motor itself to use a PWM controller to vary it's speed.

But IIRC you can use something like a VFD to change the frequency and voltage it's driven by, and that would give you "full" speed control.
 
amberwolf said:
If it's like every ohter "three speed" motor I've worked on in wall-powered fan systems, then it's an induction motor with multiple windings, and the switch just engages them in different ways.
Click to expand...

This is most likely the case, especially considering that the motor will not start spinning if you turn the selector knob quickly to position 1 from position 0. I have not pulled it apart to see. But we are not talking about a high tech design here.

The mod will likely require motor replacement and a DC power supply and all sorts of fun stuff if so :/
Automating the 3 speed switching with relays or mosfets would be cheap but create annoying transitions in volume, because the speeds work like this:

Speed 1: 20% power
Speed 2: 40% power
Speed 3: 100% power

amberwolf said:
But IIRC you can use something like a VFD to change the frequency and voltage it's driven by, and that would give you "full" speed control.
Click to expand...

I would imagine that's a bit expensive to implement. A DC based 3 speed motor+controller setup is probably the lowest cost option. But it would require me to completely redo all the electronics and work within austin air's housing.

I'm left wondering if i should create my own air filter from the ground up using a beefy 3 phase motor. It could have a large shroud so that you could stack up to 6 20x20 or 16 x 16 1 inch thick filters, which are common and relatively inexpensive. Adafruit sells a few PM2.5/VOC sensor boards that are cheap enough to have one sensor measuring air quality coming in, and going out. This could be used to accurately figure out:

1) What speed the fan should be operating at.
2) If the filter needs to be changed.
3) How effective of a job the filter is doing.

The speed of the fan would be an audible indicator of the filter's load and efficacy. The unit could simply have an on/off switch and a button that limits the maximum speed for 'quiet mode'. Or tons of little LEDs/a screen that displays data. I'd bet that i could build it for less than $200 and perhaps sell it at a price that's competitive with austin air's small unit. The carbon filters would not last as long but the initial price would be lower and maybe people would appreciate the high tech approach.

The Korean/Chinese built Winix 5500-2 ( $250 ) has this pollution sensing functionality but it's yet another filter unit with a tiny element and an oversized chassis to make it look more impressive than it is.
 
Let's see, I assume you're talking about something like this https://www.amazon.com/Honeywell-True-Allergen-Remover-HPA300/dp/B00BWYO53G/https://www.amazon.com/Honeywell-True-Allergen-Remover-HPA300/dp/B00BWYO53G/ with more serious filters? https://www.amazon.com/Aerostar-16x25x1-MERV-13-Particles/dp/B01CR9JNGS/

Even without modifying it I could probably use one around here. https://www.amazon.com/Material-Purification-Bacteria-Particles-Allergens/dp/B087G5BY6G/
 
Yes, something a lot more hardcore than the HPA300.

Check out the filter on my 'junior' size austin air plus. It's wicked expensive, huge, and also about 9.5lbs. It will last years, so when you're thinking about cost over time, it's actually not THAT expensive.

https://austinair.com/shop/healthmate-plus-junior-filter/

My original box fan air filter was inspired by this video:

[youtube]kH5APw_SLUU[/youtube]

The results are impressive considering that he has huge gaps in the air flow!!
However, his device is measuring particles in the pm2.5 range. I want to handle things like ozone and gases, which are much smaller than that. Hence the shit-tons of carbon.
 
I never considered using a rheostat.
A rheostat is basically a variable resistor, no? it would generate a decent amount of waste heat and must be mechanically controlled. I'd have to have the arduino rotate the knob with a stepper motor or something.

This is the cheapest and easiest solution, but i wonder how much extra energy i am using and how reliable/safe it would be long term being run 24 hours a day for years. I imagine it gets less efficient at lower speeds, which i'd like to be at.

I'd pull the thing apart and see for sure if it's the AC motor i'm suspecting, but i'm relying on the thing right now, darn.
 
I've thought about this a lot and decided to start building my own very high tech unit from the ground up that i plan to commercialize. Because this intends to be a commercial product, i'm gonna shut up about my design for now :mrgreen:

However i can tell you DIYers that a lennox 20 x 20 x 5 carbon pleated MERV 16 filter ( $150 ) duct taped to a box fan ( $20 ) would give you equivalent functionality of what i'm about to build. The filter may be expensive but will last a year if not more. It SHOULD stack up to my $$$ austin air healthmate plus jr. in every category except Ozone/VOC filtration. But it'll be a hell of a lot more effective than anything on the market today for allergens and PM2.5.

I however don't know if an ordinary box fan's motor would overheat while pushing air through such an extremely thick and heavy filter media, so it's up to you to find that out :)
 
If building ya live in has heating and cooling equipment. Why not modify filter housing to hold a 5" thick filter and leave the fan running constantly. Benefit would be less noise in area ya live in.

What you need for a project like this is a guy from Buffalo named George. Tin knocker, sheet metal guy. He was a legend in the world of moving air from one place to another. I would draw pictures and he would build the duct work. Sad to say George died. Diabetes.

Some things that George taught me. Always easier to pull air rather then push it.

Quiet is one of the most important parts of this science. Rubber bushings and George loved this black sound deadener fluffy sheets that he would spot weld to the inside of the sheet metal. Would make a nice coffin liner.

No box fan silly. George liked squirrel cage fans. Quiet is the type you want. I was in a welding shop on a hot summer day. Big overhead door was open and I thought it was windy outside. Then I saw squirrel cage blower sitting on the floor. Big blower from a old furnace. The old ones had a fan belt and quiet greasy oiled bearings. It was so quiet I did not notice it. It made a amazing amount of wind.

https://www.grainger.com/ is a fun place to look at fans.
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Click to expand...
Must be weekend thing?

Wondering of any better fan shops? George would know.
 
I did actually modify my building's AC to accept two filters lately and i'm having amazing results in my bedroom, which has another two standalone filters.

Check this out. My house is the green bubble with '20' on it. In the middle of extreme fire season :mrgreen:

2020-08-21 12_59_21-Map - PurpleAir.png

Basically, the thicker the material, and the more material you have, the better. This is why my standalone unit will have a shit-ton of filter media. And the housing would be designed as such that you could hook it up to the intake of your apartment vent if you need to.

Squirrel cage fans are a way i want to go with the design. The question is finding one large enough to handle the airflow.
The first prototype will have just a propeller system since it's easy to get going. Then i will design the electronic control system. Then, a better fan.

I agree with your buddy George about pulling air through a filter vs pushing through it. And using dampening materials on sheet metal. :)
 
The cost of the filters will most likely be your biggest expense. I know the ones I buy off of Amazon for my wife's unit are pricey. What do you envision the electronic controls doing? Are you going to control fan speed according to pollution levels? That might take a tricky sensor. Or maybe sensors to check if the filters are clogged? (they filter best right before they plug up and cut the air flow).

Squirrel cage fans have the most 'chooch' but are loud at high speeds. A large standard fan at a lower speed might be quieter and move more air per db. They tend to be bigger though and need a good shroud.

In my shop I have a old squirrel cage fan off of a single wide trailer's furnace that I use to vent the air through the roof when I'm spraying lacquer or power sanding exotic woods. It's about the right size and works well. I called around to heating repair outfits and asked if they had any old take-offs that they would sell for cheap. I think it has a 1/4 or 1/3 hp motor and is a bit loud but sucks well.
 
They are expensive, but the lost productivity i get when i'm in a deep sinus infection or headache spell is a lot more expensive. The math works out. :mrgreen:

I never buy OEM filters. Always overpriced AF. Merv 11-13 filtretes are used in everything i run, except the austin air filter, of course. If i cannot find one in the right size, it cut it up with metal shears and seal the cut sides. An OEM filter for my small portable air filter is $29 but is only 11 x 11. I buy a 25 x 20 Merv 12 filtrete for $25 and cut it up and make 3 filters out of it which are actually higher quality than OEM :)

I don't want to detail my speed control system in public, sorry, but i know it will work and will accurately tell you when to change the filter and also control the speed appropriately so the filter unit isn't just sitting there huffing dust and dirtying itself while making noise :mrgreen:
 
A few years back I set up an ice plant for a guy and had trouble with crappy water plugging up the water filters. We used pressure differential to figure out wnen to change out the filters.

In my shop I run a 4 hp dust control vacuum system hooked up to my stationary power tools. Before I changed over to venting directly outside, I ran the return air through a home made cyclone and a big diesel truck airfilter similar to the Austin filters. If memory serves I bought mine from Wynn enviro filters. Good company.
 
Just an update on my air filter journey.

[youtube]KhksNe5Irac[/youtube]

[youtube]CD8NiZj_KHQ[/youtube]

I'm still relying on the expensive austin air filter primarily until i build my own version of the box fan that includes a carbon filter. The austin air filter is about to last 1 year here in Utah.. most filters are gone in 2 months or less. It was as impressive as promised.

Still sinus infection free for 2 years concurrently.
The austin air unit is a game changer for both allergy and pollution mitigation.
 
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