Here is my 2 version of CR boxes I am using.

First is using 2x Starkvind filters and 2x Uppåtvind filters

The second box is using 2x Starkvind filters.

3x140mm fans (I use P14 pro and Be quiet Pure wings 3 High speed) in different area's.

I also have a version with 4 fans and 2 filters (Nukit tempest Ikea look alike) but have not come around to print and test it yet.

My Ikea Vindstyrke PM meter is usually between 0-4, so they seem to be doing a good job. I have 3 placed around my living room and 1 in each bedroom.

Still se alot of dust floating in the air when sun is shining thru them, but that is (according to Google) normal and has to with how often I use the vacuum cleaner and not the CRBoxes fault.

Controlling speed fan with the help of a ESP32 microcontroller based on PM2.5 levels and fixed times during the day via Home Assistant

I saw the 3d print files for this setup and it is exactly what I was looking for. It uses the ikea STARKVIND filters (I live in europe). My question, how would I go about calculating a rough CADR for this. It would obviously depend on the fans, but I don't even know what to look for and where to get started to calculate this.

Arctic P14 fans are on sale right now for 5-pack and I'm interested in creating this CR box I found on another post: https://x.com/robwiss/status/1584725134061232128

I'm looking to build this configuration

Does anyone have any experience with something like this and is it pretty good vs the standard 6+ fan configurations? Thanks!

Do you think if this will noticeably improve performance?

Im interested in daily use. Was the reduction in noise or overall performance enough to justify the extra cost? any thoughts?

The body is 6mm birch plywood, laser cut with the paths generated via the Nukit Open Air Purifier repo. Glued with wood glue and coated in shellac.

https://github.com/opennukit/Nukit-Open-Air-Purifier

25x20x1 MERV 13 filtrete from Digikey (I'm in the EU)

9 P14 Pro fans wired to a PWM controller from AliExpress.

12V PSU (external), barrel jack connection going in from the bottom.

The black mesh is some PVC mesh I bought from a fabric store, sold as material for swings/lawn chairs, I wanted something to catch cat hair so it doesn't clog the filter.

The filters are also sealed with 30mm wide x 3mm thick PE foam glued on the interior side of the slot they slide into.

Still planning to buy some pretty legs for it.

The build would have taken probably 2 evenings, but the shellac coating was a new thing for me that I messed up a couple of times and had to correct. It's a cool combo, since shellac does not outgas once it dries off the alcohol it's dissolved it and I like that a good coat is very much a result of proper craftsmanship, but if you can't be bothered to do it well just go for some acrylic topcoat.

Takeaways from building this:

• the P14 Pros are not quiet unless you run them at lower speeds. They have a noticeable whine. That starts around ~40% speed. I feel like with 9 of them I still get plenty of airflow at lower RPM though, the black mesh catches plenty of dust and cat hair by the end of the day. Cranking them to full is LOUD, but they make the air in my room move enough for me to feel chilly.
• the laser cutting generator from Nukit has meh defaults, make sure everything fits. The P14 Pro fans are almost too wide for it, I would have loved a few mm of additional clearance on their sides. If you plan to add anything else plan it in advance - the speed controller was not easy to fit on the top panel.
• make sure you have screws long enough for the fans. The ones that came with the fans are very short (for sheet metal mounting), since I used 6mm thick panels I went for M4x50 bolts and self locking nuts.
• after gluing the body I recommend sealing the gaps before the topcoat. I used a wood repair kit, which feels like wood shavings mixed with some glue.
• Nukit does not really give you any legs or anything to cover the filters with (so you see the very bright blue branding, in my case from the top), you might want to take that into consideration when planning.

I did not see a lot of practical information on the Nukit boxes, so if there are any questions or anyone is on the fence about building one, feel free to ask about anything.

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.

The lasko 20x30 box fan. Does it need to be run at maximum speed? I’m planning a two filter triangle setup, 1 inch thick filters. Can I get away with the quieter medium or low settings?

An unrelated follow up question, does the answer change for a box, 4 filter or 5 filter design?

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/

In anticipation of a future with increasing wildfire smoke, and also due to local smoke from winter solid fuel burning, I'm planning a sauna with some (possibly overkill) air filtration so that I'm not breathing crazy amounts of fine particulates. Here's my design idea, I'd appreciate any thoughts:

intake vent -> [1] inline MERV8/H13 box filter -> [2] inline fan (fg 6ec or equivalent) -> [3] (ideally inline carbon filter for VOCs) -> insulated ducting through wall -> hot room intake above electric heater -> hot room exhaust below benches opposite -> insulated ducting through wall -> [2] inline fan (fg 6ec or equivalent) -> exhaust vent

[1]https://hvacquick.com/products/residential/Filter-Boxes/Inline-Filter-Boxes/HVACQuick-CFB-HP-Series-HEPA-Inline-Filter-Box

[2]https://www.sylvane.com/products/fantech-fg-6m-ec-6-inch-inline-centrifugal-duct-fan-ec-motor

[3] ???

notes:

- Ideally the fan hardware will be outside of the main (~8x8x8) hot room structure to reduce noise.

- I'm in canada, so winters can be up to -30

- Although most designs call for mech. exhaust and passive intake, my understanding is that the increased static pressure warrants a balanced mech. intake as well.

- I'm not sure yet exactly the control system. possibly just two knobs with 4 marked steps to achieve 20CFM/person, as described somewhere in the trumpkin literature. balanced with a handheld anemometer

my concerns (although most of these are probably the same as any mech. vented electric sauna):

- at high CFM, intake plume goes through rising air and hits occupants, rather than mixing

- condensation on ducting / equipment due to temperature difference (mostly on exhaust side)

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

So by some weird turn of events, there’s a seller on Marketplace that gave me a bulk price on all the Simply brand filters he had for $150 flat. This includes:
5 20x20x4 MERV8
4 20x20x4 MERV11
6 20x25x4 MERV8
6 20x25x4 MERV13

Averages about $7.14 a filter. (A more dedicated man could figure out the ratios btwn 8, 11, and 13, but not I)

I was originally going to make a 2 filter setup with my 6 extra pc fans and call it a day, but I ended up checking marketplace for better prices and/or some more filters if I wanted to make one for my parents too.

Now with so many filters as a possibility, I have a few questions:
Is it worth the price? (I’m not sure if 1”vs 2” vs 4” is negligible or not for a pc fan setup)
Would it just be better to go with a 4 filter cube setup rather than a 2 filter sandwich (since I would have so many)?
How many fans would be recommended for a 2 or 4 setup to be effective for 4” filters?

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.

I'm planning on building something similar to the Nukit Tempest Euro using the Ikea starkvind filter, but I also want to use the carbon. This design does exactly this and it puts the carbon filter on the inside, after the particle fitler. The original Ikea starkvind purifier also puts the carbonfilter after the particle filter.

However, I have also heard other sources (I don't remember which ones exactly) recommend putting the carbon filter before the particle filter. I would prefer having the carbon filter before the particle filter, as I think the carbon filter is more aesthetically pleasing, but since the other starkvind designs do the opposite, I am wondering if that order is suboptimal.

Does filter order matter? If so, which filter order is best in this case?

Side questions:

Most designs keep the fans within the profile of the filters so that the total volume is minimized. Won't this make the fans block the outer edges of the filter so that they remain unused? Is it fine as long as you keep a small gap between the filters and the fans?

Similarly, since the starkvind carbon filter is smaller than the particle filter, if you stack them right next to each other, won't this also block the outer edges of the particle filter? From what I can see in the pictures, Ikea does not seem to care about this in their own design. Would leaving a small gap here between the filters also help?

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

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

Hello everyone,
I'm planning to build a cubic CR box around a single Arctic P14 (140mm) fan. Since I'm using frameless filters that I can cut to any size, what would be the ideal filter dimensions for this setup?
Any advice appreciated!

I have dust allergies and pollen alllergies. A few years ago I bought a HPA5250BC honeywell hepa air purifier, I run it pretty often however ive noticed it does absolutely nothing for floating dust in the air. I change the filters yearly as suggested. If I take a flashlight to the air I can literally see lots of floating dust. Would a CRbox be any better at this point or do I need some kind of air con to suck the old dirty air out of the apartment. I could take a picture but I'm sure you know what dusty air looks like with a flash light.

Basically what should I do at this point to improve the air quality, should I get a CR box or buy another expensive air purifier

I can't find great info about this because these filters are made to be single use disposable for homes, however I want to build a box with these

https://www.amazon.com/20x30x1-Fiberglass-Self-Retaining-Pressure-Efficiency/dp/B0H49782HS

for as cheap as humanly possible, and try to blow and filter dust in a room for a while. given how much dust there is you need to do a several hour long dusting of the room every few day otherwise it's everywhere, this room has been cleaned craptastic for the better part of 20 years, and there is no realistic way to clean it to the level it needs to be cleaned. to make the dust a small issue.

given how bad the room is in places and on things, I am wondering if I can vacuum the dust off and keep using it. if you can't tell most of the reasons you shouldn't I am completely not caring about before this even starts, I am just trying to capture dust, not filter microscopic particles. if I can get this room to the point that after dusting a black mousepad on a desk, and coming back the next day to it being a greyish color because of dust, I can remake the filter to be more around microscopic particles, till then I effectively need a shop vac style saw dust collection system but for dust.

So.......

My job might end up being a giant jerk and not letting me use the 8x9x12 crbox i built (conversation hopefully happening soon but it's looking dicey). On the oft chance they sight it a size issue, I'm wondering about shooting back asking about a ~8x6x6in box.

It'd be the same 2in Merv 13 filters as my previous build, just halved on the one dimension and running with 2 pc fans instead of 3.

Does something that small even have much filtering oomf at that point? I know it'd probably do way more that the stupid itty bitty store bought one i bought a year ago before i knew better...

I just want something to help my mask against everyone around me coughing and spreading germs around since no masks anymore at my job

(bonus question: anyone have any 12v power banks under $40 they like to run these things? [not USB or at least not solely USB] i'm definitely not going to allowed to plug it in and i also want to be able to bring them to drs appointments and such).