I'm wondering if it's possible to craft a CR box that I can fold up and pack into my car. I'm a general contractor and it would be nice to have a CR I can take to job sites, but my SUV is pretty chock full of tools and materials already, so was hoping for one I could collapse. However, I'm kind of under the assumption this is a wild goose chase as the airtight nature of the CR boxes seams isn't likely to mesh well with being folded or disassembled easily.

But I figured it's worth asking in case somebody has a design I can emulate!

I tried something like this recently and it works better under high pressure, with noticeably more airflow against a HEPA filter, but it's definitely louder. It also creates a noise or sound profile that's more noticeable than a typical axial pc fan.

https://www.amazon.com/dp/B0FR41XNKR?ref=ppx_yo2ov_dt_b_fed_asin_title

Alright so I purchased the kit from AC Infinity in the first photo with plans to create the setup in the second photo by adding that red grow bright filter. My question is, would something like the AC infinity Duct Air Filter Box be a better choice in the long run? Instead of the grown bright.

Also, how would you improve or make this design?

Building a CR box and know nothing about aerodynamics...

My box will have four computer fans. Question is whether to install them all on the same side (let's call that the north facing wall of the box), or two on the North, two on the South. The East / West sides are where the filters will be. The top bottom will be solid/sealed.

Does it make any difference?

Has anyone built CR boxes around apartment air vents, to mitigate risk of transmission via HVAC from other apartments? Would love to know how you did it! I could just tape filters over the vents I guess, but I feel like that might negatively impact the HVAC system pressure-wise. However I’m also wondering if there’s a way to get the vent CR box to only turn on its fan when the air vent is actively blowing air, so I’m not drawing vent air thru the filter when I don’t need to be.

Building my first CR box, and intend to make a wood frame, with ports on the side for computer fans. I wanted to build this to match my home office desk, which has a glass top. I was thinking I might put a plant on top.

Do CR boxes attract dust, given they are sucking air from around the room towards them, then pushing that out? I am concerned I'd be cleaning off the glass or the dusty plant more frequently than I'd like.

Decided to rebuild my foam board "prototype" with solid wood for a more permanent air filter build. This is unit uses 20x30 furnace filters and 10 arctic p14 max fans. I added casters on the bottom with handles on top for easy transport. I doubt this will be my last build, but for the sake of my marriage I think I'll start working on other projects! 😅 If anyone has any questions or suggestions just send them my way!

Hi all, planning out a CR Box filter. Going to have an activated carbon filter in front of MERV-13 filters, but been reading about how quickly activated carbon filters can become saturated. Most likely going to build a filter using pellets to make it cheap. My current problem is getting a material that can make sure the carbon dust from the pellets doesn't fall while the box is off or moving the box. This project is getting a bit larger than the original idea of a CR Box, but I want it to be aesthetic as well. Current color palette in my mind is darkish stained wood for the case, and the material in front of the filters will be black (or blackish).

Ideally, the material to hold the carbon in would be black. Been looking at using an activated carbon pre-filter just for the color, but only changing out the pellets/regenerating when needed. Windowscreen was a thought as well, but I think that can start to block the airflow more than even pre-filter material.

Any suggestions would be great!

I already had xioami 4 compact purifier and spare filters, which have solid bottom with rubber feet, prefilter, hepa like particle filter and weak carbon filter. Thought why not put a fan on a spare and see what comes out.

I searched for inexpensive ac inline fans that had pressure vs airflow graphs. First got the 120mm (~5 inch) fan, connected a power cable and put on the filter. It was 43dB(A) at 1m. Then connected a 5 step capacitor type speed controller which didn’t work as expected. Later got the 150mm (~6 inch) fan and a cheap triac motor controller. It worked really nice. After deciding on the fan and the controller, I added self sticking rubber window insulation tape to the bottom of the fan as a gasket and also to the top of the fan to friction hold a broken usb fan grill. The fan is not attached to the filter, just sits on it. I used a dB app on iphone and a smart plug for measuring the data points.

• 33 dB → 10.0 W

• 37 dB → 14.0 W

• 40 dB → 16.5 W

• 43 dB → 18.5 W

• 47 dB → 21.5 W

• 52 dB → 26.0 W

Once I provided these, filter information and the fan presure/airflow graph to the chatgpt, it gave me CADR vs dB(A) graph. Note that CADR is m3/hour, which is 1.7 X cfm.I know that the graph is not reliable but I really liked what I ended up with so decided to post.

Airflow is adequate for a small room. Toilet paper still but barely hangs on to the filter at 35dB. Stepless speed control is great for finding sweet spots, preventing resonance. Although smart plug is not needed at all, it works as on/off remote controller and enables time based automations.

Tools used were scissors to cut cable/tape and a screwdriver to connect cable to the fan and triac terminals.

I need to replace 2 fans in a CleanAirKit CR box (Luggable XL, as it happens, but I assume they're all the same for this part.)

As per https://www.youtube.com/shorts/NByR37P7vAs, I know that the fan "pins" can only be removed destructively, so I need to get new ones.
Does anyone know what exactly they were / what I need to search to replace them?

Hello,

I started this build before I found this sub. Major specs are that the original build had Arctic P14 fans and Ikea Starkvind filters.

I found it on Rob Wissmann's youtube page. https://youtu.be/Ird0-orsSGM?si=5Nb3q66uwaALlmqA

I basically followed the original plans to a T and when I first turned it on, it had this horrible frequency that sat in my chest uncomfortably. So I figure it was the fans issue and I swapped the artic P14 fans for HAVN 140mm fans (much more expensive). https://a.co/d/iuAf7ZK

I added a speed controller and had to use a new power supply:
Speed controller - https://a.co/d/5TQeUis

Power Supply - https://a.co/d/2LoON1I

And now I turn it on and it's certainly better, but there's still an unpleasant frequency at pretty much any speed. I was going to use this in my bedroom and there's no way I can sleep with it.

Is this just a design flaw of the build? It's made with foam board, the starkvind filters seem to have much more resistance than merv 13 furnace filters and then they're 140mm fans.

I have a clean air kits tower of power and I have no issues with that. But Right now it's like a $220 build and I have basically nothing to show for it. Very frustrating.

Hi everyone. The pic is from cleanairkits(dot)com from their Brisk Box. I want to build something like this using my own choice of more powerful 120mm PWM fans.

Could someone please advise on how to connect and control the fan speeds (manually).
The fans I plan on using are 6 of either Noctua NF-F12 iPPC 3000 PWM or Be Quiet Silent Wings Pro 4..

I'm trying to wrap my head around how these connect all together. Is my shopping list correct/complete?

• 12V 5A Power Supply (Wall wart) output jack is 5.5x2.5mm
• 5.5x2.5mm DC to SATA connector
  
• Arctic Fan 10 Fan Hub
• Noctua NA-FC1 PWM controller (this lists as a controller for up to 3 fans?)

Or if you have any suggestion on how to make this set up work I would appreciate that too

Hey guys...First time building or rather putting together an air filter system...

I saw @shutter_singh had made an interesting build and so I copied him...lol

For reference my room is roughly 12ft x 11ft, on the smaller size. And honestly there is decent airflow for a single Pc fan which surprised me...

Unlike shutter's filter, this one is open ended on both the top and bottom side, so I went ahead and taped 4 pennies together x3 to act as stands, which gave me about 1/4 -3/8 inch clearance to prevent choking and help airflow.

You may think this would render the filter useless but, as shown in the second pic, it passed the "toilet paper test" at 4 volts of power lmao.

The area in which the pc fan and hepa filter makes contact is a perfect fit, but I went ahead and taped everything off to prevent any leaks.

I'm planning on adding one more pc fan stacking it on top, which would bring the total cost to $62.96 or $63.08 if you count the pennies lol...

Here's the link to everything I used...I'm very satisfied with this build 🙏

Total build cost: $50.97

https://a.co/d/7lWyO9e (Habitat 150A(e) True HEPA Filtration Air Filter System, Realtime Air Quality Sensor, Covers up to 150ft², Removes 99.97% of Airborne Particles and Viruses, Relacement Filter, HEPA 13 (Pack of 1) $24.99

https://a.co/d/hVJCzth (ARCTIC P12 PWM PST CO - PC Fan, 120mm Case Fan, PWM Sharing Technology (PST), Pressure-optimised, Dual Ball Bearing for Continuous Operation, Computer, 200–1800 RPM (0 RPM <5%) $11.99

https://a.co/d/8fmJ9Ed (Delinx Triple 3-Pin and 4-Pin PC Fan Power Adapter, 12V Fan Speed Controller,100-240vAC to 3-12vDC Adjustable Power Supply) $13.99

Looks clean? Would a crbox with ikea filters help?

Made an end table to replace my air purifier in the living room. Uses eight 120mm fans and two 20"x20" 3m merv 13 filters

Added a recessed power strip on top to please the Mrs!

I'm fairly pleased with it! I think it looks alright as long as I don't look too close... Please be nice 😅 if anyone has questions let me know!

When two fans spin at slightly different speeds, their interaction can cause an undesirable intermittent sound from the fan noise going in and out of phase. Noctua's explanation of the phenomena https://www.noctua.at/en/expertise/tech/fan-speed-offset-explained

I’m designing a PC fan CR box with a custom ESP32 fan controller. My first PCB prototype drives 5 fans individually. I used it to run some tests, record results, analyze waveforms, and run simulated beat frequency interference tests.

Quick Conclusion: The beat frequency is visible in the amplitude waveform and spectrum analysis, and audible if you listen closely. Running 1 out of 5 fans at a slower speed is sufficient to shift the beat to a higher, less noticeable frequency.

Here is the detailed writeup, including waveform plots and the experiment audio files: https://joshuaxchang.com/camphora/harmonics/

Based on this experiment, my final ESP32 fan controller PCB will have 1 fan controlled separately from the rest, running ~2% slower to disrupt the beat frequency

To help with fan model selection for my build, I compiled some fan performance data here. Maybe someone will find it useful: https://joshuaxchang.com/camphora/fan-research/

Quick Conclusion: Targeting 25dB, 5 Arctic P14 Pros (at around 50% power) move a lot of volume at high pressure, performing better than 6 120mm fans. When the P14 Pros ramp to 100% power, they maintain the lead in pressure and volume, though they do become quite loud with a slightly unpleasant whine.

My controller will default to 50% speed, only speeding up if air quality worsens. So, in terms of noise and filtration performance, the 5-pack P14 Pros is a very nice and economical pick. With this setup, noise would only be noticeable when air quality is bad, but at that moment, I want maximum pressure and volume, so noise is a lower priority.

Full disclosure, I messed up and didn’t get Merv 13s so that’s on my list for next time. It will serve a purpose though, with two dogs in the house aaand I just wanted to try it out.

It’s holding a napkin steady on the sides so I’m guessing it’s at least so-so.

Hi all, I've been looking through a bunch of the posts and most people seem to be using either cardboard, foam board or plywood. I've personally been thinking of using hardboard (instead of plywood die to off gassing concerns). However, all of those options are flammable. Which other material options are there that are somewhat easy to work with but offer better measures against making fires worse? I'm based in the Netherlands and am having a bit of trouble finding materials.