r/crboxes

To anyone who wants to run 120mm fans. I am running 8 120mm fans, each draws .33amp but I kept running into temp issues with the 12v-5amp psu I was using. I swapped to a cheap computer psu from a pc shop and now I get 83amps @ 12v.

- Jump the 24pin connector
- Splice a barrel connector to the 12v line of the molex
- Enjoy up to 125 .33 amp fans with enough amperage left for surge protection ;)

PS. - Always use an excessive amount of electrical tape!

$5 - barrel connector DC plug
$25 - used PSU
$1 - used PSU power cable

I found out that I have contact dermatitis from Walnut and needed to get serious about controlling the dust in my wood shop. The majority of my work is with hand tools so my design goal was to have a small footprint, be very quiet, exhaust the clean air upwards, and have a little style since it will be in my sight. There is a 16" x 25", 2500 MPR-rated filter (apparently good to 0.3 microns) on each side. The LED's are pure baloney but it makes me smile.
Thankfully, it actually works. It will drop the Air Quality Index (AQI) down from 23 to 3 in thirty minutes; and that is while I'm woodworking and generating dust. There is a speed controller, hidden under the sliding door, for the PC fans so that I can control the noise.

i’m looking for a sensor that will measure pm2.5 to use in my bedroom. i use a single hose portable AC unit to keep my room cool in summer and want to be able to monitor air quality. i need something simple, under $50.

so far these are what i’m looking at, i appreciate any insight or suggestions.

https://www.amazon.com/Temtop-Air-Quality-Monitor-S1/dp/B0D69P7XQ5

https://www.ikea.com/us/en/p/alpstuga-air-quality-sensor-smart-70609396/

I was shopping for air purifiers on Amazon last week during the prime sales, and was highly vexed about having bought two Coway Mighty's for $300 that would provide a mere 450 CADR. It wasn't until I was second guessing my purchase, which prompted me to research air purification further, that I learned about CR boxes. I quickly switched gears, stayed up till 3am furiously studying the matter, and figured out parts and plans to assemble multiple CR boxes for half the cost and twice the performance.

Lasko 20" box fan: $25 (Walmart)

(4) Filtrete MPR 1900 20x25x1 filters: $50 (BJ's)

I stood 2 filters upright, and taped the edges together. I then added the remaining filters, one at a time, taping the edges as I went. I cut out small squares of cardboard, and taped them to the top inside corners of the constructed box of filters (to minimize gaps between fan housing and filter perimeter). I placed the fan on top, and turned it on!

I know it's not finished, but I just wanted something quick for the moment, and I'll optimize them over the next few days. I plan to add a shroud, better seal the area where the fan and filters meet, add a fixed bottom panel, and completely black out the units with duct tape and gaffer tape.

I also intend to build a unit with the same fan model and a single Filtrete MPR 1000 20x20x4 filter attached directly to the intake side for discreet and exclusive bathroom space usage - just waiting on the filter to arrive.

Thanks for teaching me about this process, everyone. And for any newcomers, know it's really just that easy.

i was told to post this here as you guys would appreciate it

I became interested in making a CR box for myself simply because there is too much ambient dust floating around in my room. However, I tend to try and save money where I can if possible.

I have these old pc fans that have got to be at least a decade old (barring the small CPU fan), some scrap wood, woodworking tools, and some old power bricks laying around. All I would need is some splitters, an adapter, and filters (probably no grills).

Noise is not a concern nor am I too bothered about maximum efficiency so long as it gets the job done. It doesn’t need a small footprint either as I’ll just plop it in the middle of my room when I want it running. It’s also mainly for dust, so I was debating simply going for MERV 8 or 10 filters as well.

Would these actually work? Or is it simply too much of an efficiency loss/headache and that I should go ahead and spend the money on proper fans and/or filters?

So this isn't a CR box question per se, but since you are my people, I figured I'd ask.

TLDR: I need to figure out a way to hack together filters that will slot into my ERV. The manufacturer's filters are no longer available where I live which is going to make the air-exchanger useless in about 3 months.

Backstory: I bought a Zehnder ComfoAir 200 ERV in 2022.

"Why tho?"

Because its flexible home-run ducting allowed me to retrofit our ancient (and small) Victorian townhouse. Metal duct work was not an option.

However, very (very) few people in Canada use Zehnder and this particular model was already quasi-obsolete when I bought it (but because their new-and-improved designs are large and don't ceiling mount, they didn't fit in our limited space. It was this or nothing).

The problem:

• The proprietary filters come in a plastic casing that slots into the ERV. (This is why I now build all my own purifiers. To hell with the proprietary grift).
• Given that the ComfoAir 200 is not a common model of ERV, there are no knockoff filters on Amazon or even AliExpress. The only alternative suppliers are in Europe (and don't ship to Canada).
• Zehnder's website does sell their filters internationally. A drop-down menu has a plethora of countries they ship to... just not Canada. And the Canadian (high-end, ergo overpriced) supplier I used to rely on no longer stocks these specific filters. I've asked them if I can special order, but I already know the cost is going to make my nose bleed.

The solution:

• Try removing the filter media from the spent filters I have on hand and somehow painstakingly hot-glue pleated Filtrete filter media in their place? Would that even work? Has anyone tried that sort of thing?
• Find someone who could, design me a 3D printable CAD file for these filter casings that might allow me to "sandwich" the middle portion of a (larger) Filtrete 2200 between two 3D printed halves (thereby removing the need to try and re-pleat the entire thing manually every 3 months)?
• Go the real DIY route and somehow make compatible filters out of cardboard (and the aforementioned Filtrete 2200)?

One thing this sub has taught me is that filters are not rocket science. (Whereas proprietary filters are a pain-in-the-ass scam). All you really need is an air-tight chamber in which to place good quality filter media (the more pleats — the larger the filter surface area — the better). Keyword: airtight.

Any ideas would be well received.

I am annoyed, but determined to find a way to jailbreak my air exchanger from the grips of impending obsolescence.

Only thing bought was the fan hubs and the filters. most likely I upcycle most of the material/electronics to a better case but thats a future project

Team Ikea filter and Ikea cardboard !

4 Artic 140mm

6 Ikea filters

>100€

All you need is a hot glue gun really

I built this to take advantage of unused space on top of a 30"x12"x84" bookshelf. This fits just about perfectly, with room on one side for the 12V fan speed controller. The 4 140mm Arctic Pro fans can just barely be shoehorned into the end if stacked and clamped together with fan brackets, with a little hole in the middle to feed the controller cable through. I plan to rotate the box once a month to use all four of the long side filters.

Does anyone know if the Vornado 80x would work well with a MERV 13 filter as a CR box as opposed to say an Air King? I plan on only using one filter (due to space) for my woodworking space

https://www.costco.com/p/-/vornado-box-fan/4000322230?sp=grs&langId=-1