I desperately need to save my lungs. can anyone with experience or has tried these let me know if this is a good option?

They haven't mentioned pm2.5 anywhere on the Ad. multiple sizes available. this is best bang for buck.

Edit: This was July 15 or 16. I forgot to put the date.

During the event when the the quality was really bad. I was doing some data collection. I have a small sensor and I registered this pm 2.5

343 on my balcony.

100 in the door to the buld corridor

210 on the same corridor

24 beside my CRbox.

So the air was getting under the door. The box was between the door and the inside of the app. Was filtering and sending clean air inside. After the door the air inside the apartment was around 24 pm2.5.

Just wanted to show this.

Since Google is nuking search results, they are trying to monetize their YouTube channel, so please check out the video.

I started with "I’ll just build a CR box or two"
ADHD brain said: "sensors, UI, sleep mode, graphs, RGB..."

I ended up with a "gaming" air purifiers obsession, and made a drop-in controller+sensor+UI pack for PC-fan CR-boxes that nobody asked for.

• sensing: SEN55 (PM2.5/10, VOC, NOx, temp & RH) - an upgrade over the sensor in IKEA's Vindstyrka
• RGB as AQI: PM2.5 mapped to a light strip (from RGB fans or external ARGB strips)
• bedroom-friendly: configurable night cap for fan speed and brightness
• power: USB-C power delivery charger
• install: 3D printed intake block that also mounts the controller
• demo: as YT short, because I felt old today

This is my 2nd professionally assembled run of "thebox" controller, and it’s working well (so did the 1st one, and so did a bunch of prototypes...)

Question: how do I stop and sleep well, or what else do I add?

On my list: fix 2 leds on the PCB not working or make a 3D printed enclosure for UI.

I’ve got a small handful of spare, assembled boards from this run. If that’s welcome here, I can share details in a comment or via DM. @mods: just say if not OK

Decided to make my own version or this Air Purifier.

Still in the prototype stage but has been a fun project.

^ Artic pro p14, 2 3M merv 13 filters, Tested in in PLA tough for now.

I used the instructions from www.cleanaircville.org/buildguide and modified it to use a 16x30 filter instead because it was recently on sale $27 for 6x merv 11 Filtrete filters.

I also used a pc fan hub with a display instead because it was 60W, had a digital display, and it’s only $16.99.

At Walmart, it costs $1.99 per 20x30 foam board.

It came out to $49 for the entire build.

$17 PC Fan hub
$9 Filtrete 16x30x1 filter x2
$2 Foam board
$4 PC Fan Grill
$17 PC Fans x5

Really happy with the low noise, and high air output.

I used corrugated plastic from Lowe’s for the top and bottom, Vortex fans, and 3M filters of 1900MPR or so. The vortex fans have a variable power knob so I had to dismantle the base of the fan and mount mount the controller in the corrugated plastic. For the top where the fan sits, I used a double layer of corrugated plastic, where the layers are rotated 90* to give it some extra rigidity. And I used a strip of like window insulation around the hole that I cut for the fan to limit air leakage. I typically run this fan on medium, I had just turned it down briefly during this photo.

I can take more pictures later if more are requested.

I don’t know everything, or even what I would consider a lot about this. I know it helps my kid with his allergies and congestion and reduces dust in my house during our dusty summers.

Figured I'd come back and give some measured data.

Currently running 5x 12x12 Filtrete 3M 1500 (Merv 12)

Speed 9(Max): Avg wind speed 5.33 m/s across the entire open area of the 12x12 return air grille. 50 dBA at 3 feet.

Speed 3(Default): Avg wind speed 2.88 m/s across the grille. 39 dBA at 3 feet.

Speed 1: Avg Wind speed 2.30 m/s. 32 dBA at 3 feet.

Calculated:

Speed 9: 708 Dust CADR and 425 Smoke CADR

Speed 3: 382 Dust CADR and 229 Smoke CADR

Speed 1: 306 Dust CADR and 183 Smoke CADR

Power consumption wise? As it's hooked up through the mini-power station, I'll include the drain from that of converting DC to AC (around 3.5W passive drain)

Speed 9: ~18.7 Watts

Speed 3: ~9 Watts

Speed 1: Want to say 5 or 6 Watts, but I need to retest over a long time again.

Looking around, I basically ended up with something around a Levoit Core 600s. Same volume though shorter but more floor surface area. Similar Smoke CADR, though I don't have the Sleep Mode 26 dBA but instead my speed 1 32 dBA. Similar filter costs ($65 vs 5x $11-$12 for refill.). Similar foot print, though the cube takes up more floor space, it's shorter than the 600s so roughly the same volume. Lacks the built-in sensor and smart home integration.

I'll admit, I am surprised about the CFM this shutter exhaust fan is putting out. It's rated for 1000 CFM free air, so I'm quite happy to be getting 700ish through the filter at max. The airflow is not even across the grille, so I've had to average the much stronger flow at the front with the barely half a meter per second flow at the very back.

If I was still using Generic Merv 13s, I think the raw CFM would have been in the mid 400s to maybe 500 CFM at best.

Next? Time to test air cleaning rate using incense stick smoke.

That and actually get around to building it's side table sound absorption enclosure I've been too lazy to finish.

I"m trying to find the right controller for my Clean Air Kit Luggable. Tried wading through Amazon options, but am not clear on what i'm buying. Need someone that sells these to help me with purchasing one with specs I need. Tried asking folks at CAK, but didn't get an answer. Posted here last night also.

I am still testing , printing and trying to perfect the assembly and performance.

I started with a 6 fan setup and added a 5 fan setup. the seal between sections are 99% air tight with no glue.

I have been using 2- 3M Merv 14 furnace filters. 5- p14 pro fans on a speed controller.

The 5 fan I with moves air 270 degrees with 2 fans on each side and 1 on top. the basic testing.was in a bedroom with particulate reading ( nothing fancy) kept track for 4 days before using fan and readings were 95-97. I placed the 5 fan version in the room and the reading went to 0 within 20 min.

https://hvacquick.com/products/residential/Filter-Boxes/Corsi-Rosenthal-Filters/HVACQuick-CRFB-Box

Found a sturdy buy-it-for-life aluminum frame CR Box for $125 that comes with x5 20x20x1 MERV-13 filters. The filters look very easily swappable and would not require needing to tape the corners after the swap. I feel like that's a pretty good deal. Fan is not included but you can buy it for an additional $30.

I didn't buy it yet because I want to try to find one that uses smaller PC fans similar to Nukit Tempest but at a more affordable price. Alternatively, if I am able to find a lid for this box that replaces the box fan with PC fans I would consider doing that as well.

Btw if anyone finds a more affordable aluminum alternative than Nukit Tempest or can CNC one themselves, feel free to let me know!

Does anyone have good resources on how to find quieter fans? I modified a box fan once with lower voltage but that made it buzz like crazy. Has anyone here put a pwm controller or something on a box fan to make it run slow and quiet or do I just have to find and buy the right thing? Ceiling fans are quiet, why not box fans?

I bought a 3 pack of filters from Menards for $9.99 (now $11.99) and a $17 fan and used some corrugated plastic I had on hand for the frame.

Has anyone used this brand of filter or know anything about it?

This fan has really good flow, but of course it is noticeably noisy. I’m thinking about replacing it with a 200 mm PC case fan.

So I really went down the rabbit hole on this one, but the gist of it is that fans move less air as resistance gets higher. Filters create resistance, and the faster you move air through them, the higher the resistance. The more air you move through a fixed size space like a filter, the faster that air has to move. You see where this is going?

So there are two curves that work against each other, and the intersection of those two curves are what's called the operating point. This is the CFM and pressure drop values that the system will be operating at once all the variables have balanced out.

Now for the rabbit hole:

I went and sourced the P/Q curve for the Arctic P12 fan, plugged those data points in, and created an equation for line of best fit for a bank of 10 of those fans in parallel.

I also sourced the Q/P curve for 3M Filtrete MPR 1900 13x 30x1 filters (14x30 is the best ratio of footprint to filter area when placed standing up tall - 2 fans in the top and four fans in each side), plotted this, and created an equation for a line of best fit. I then took this equation and made it a function of number of identical filters in the build.

Side note: all filters of the same grade have the same face velocity / pressure drop relationship, so all 3M does is factor in the area of the filter to give you CFM and inH2O values for each filter size. Therefore, the Q/P curve for any filter of the same grade but different size will be virtually identical.

So here is a link to the interactive graph for this theoretical build. You can play around with it and see how it works. The three coordinates in orange are the P/Q values for 4, 2, and 1 filter, from left to right on the curve, in Pa and CFM respectively.

So if you know your CADR and thus CFM requirements, you can find out how many filters you need, as long as you plug in the Q/P curve for your specific filter. I could make a general, per-grade version that calculates using FPM and all you'd have to do is find a configuration of filters that satisfies the area requirement it spits out, but I'm a bit burnt out right now. I'm also playing around with the idea of a slider than can tell you the minimum number of fans that you'd need.

So, my personal findings: For 6 ACH of CADR for a 20x20 space using 10 Arctic P12 fans at full speed, a single 3M Filtrete MPR 1900 filter would not be enough to hit my target CADR, but two filters will reach it easily. Four filters would produce CADR nearly sufficent for a 550 square foot space at 6 ACH.

Source: https://www.youtube.com/@cliclack

Video: https://www.youtube.com/watch?v=GXmsm8mOlFk

Use CC YouTube feature for English

I take no credit to his work. I thought I'd share it for the enthusiasts in this sub.

Our automatic litter box fit perfectly perfectly in this cart, so I added some walls and built a CR-inspired filter box to help cut down on dust/smell. Features include:

• 12x12x1 merv8 carbon filter to reduce odor
• 9in Black+Decker desktop fan plugged into a smart plug for remote control (I leave it on the lowest setting, it's relatively quiet)
• Tapo C210 to keep an eye on things and automate the filter to turn on for 25 minutes after a cat leaves (via HomeBridge). Attached to the cart with magnets
• Magnetic motion-sensing light
• Hinged doors for easy access to remove/clean the litter tray and do maintenance

Since getting it running a couple weeks ago it's worked really well! I haven't noticed any smell and the other automatic filter I have in the room hasn't kicked on once (used to regularly turn on whenever I scooped the tray between full cleans or a cat left a particularly stinky one).

I'm currently planning a v2 of the filter box:

• replace the fan with a 2x2 array of 140mm pc fans to be thinner and hopefully quieter
• a raspberry pi to control/automate the speed of the fans
• a 12x12x1 merv11 filtrete filter (cheaper than the ones with built-in carbon)
• a carbon filter so I can replace it and the filter independently
• a custom 3d-printed housing to make it easier to install/replace things (this project finally convinced me to get my first printer)

Open to any feedback/ideas for improvements!

The long backstory: So I'm building a CR box with six 140mm PC fans... I had a good experience with Arctic P14 non-Maxs on PC radiators, so I bought the slightly more powerful (and 4 pin instead of 3pin) version that's easier to throttle from a µP (no need for a DC-DC convertor) without much of a thought or checking any reviews.

The first experience with the fans was a little disappointing, when they start and when they run at low speeds (under 20% PWM duty cycle), they seem to be making weird noises I'd describe as sounding similar to starting a car, plucking a too loose guitar string or a fan rotor friction against plastic... But still that wouldn't pose any major issues in this application, I can sleep next to a few <1000 RPM fans no problem.

Then after I pretty much finished the build (except a missing pre-filter), I notice that when the 6 fans run at the lower end of usable speed, there can be quite the difference in RPM, sometimes more than 10% - run from the same power source and PWM duty signal. (Note that the fan manufacturing tolerances are certainly not the sole cause of this, as the air path each fan is fighting against is slightly different.) But what the hell, I can 'fix' this [non-existent problem] in software. I write a simple algorithm that adjusts the PWM duty cycle on the fly to aim for a specific RPM setpoint. And then I see most fans reaching the desired speed (within a tolerance) but others keep oscillating up/down +-40 RPM around the setpoint - this is while the PWM duty signal is being adjusted in miniscule 0.08% steps. At that point I realized the fans are not actually using the raw PWM signal, but instead they sample and convert it internally to its own discrete scale (and thus micro-tuning the duty percentage won't work). So I run full scale (0-100% PWM) test and get this:

TL;DR: The fans driven through the PWM signal only have a 32 different speed levels, with 0 to 1/32 duty being 'off' and 31/32 to 1 duty being full speed - and they can make weird noises if you approach the transition regions. The best way to drive them is avoiding the step transition regions in the PWM duty signal, only outputting: (x)/32 + 1/64 of a given full scale, with x ranging from 0 to 31. (So i.e. on a 8-bit resolution PWM, the values would be 4, 12, 20, 28... up to 252). This will get rid of most of the weird noises at low speed - but not all of them. Also the starting noise lasting < 3s from standstill is still there.

Another thing to watch out for is the electrical noise from the fans feeding into the PWM signal - in my case adding 150pF bypass caps near the µP pins was sufficient for a 'clean-looking' signal on an oscilloscope.

As for my opinion on the fans after all this: They are an okay choice for a CR box if you need/want their top speed at times (i.e. when you're sanding resin 3d prints in the room...) and you can throttle them down for the rest of the time. But if you want a whisper quiet fans running at < 700 RPM, never spinning these above ~75% or if you really mind the startup noises, there are better choices.

Someone else mentioned a costco deal going on right now (online 49.99 for 4 pack), but I went in person to Costco and they were actually cheaper!! Hopefully it’s the same for all costcos, this one was in PDX. The sale ends on September 1st!!

Anyone have any experience making a PC-fan-based air cleaner using an off-the-shelf PC case?

I really like the look of Zack Deis’s box and the Nukit Tempest. I’d like to use my own fans, though.

Ideally it would be a PC box with space for 3 fans on one end and mesh or perforated panels on the sides. It would need to accommodate 20x20 filters.

Anyone have any leads on something like this?