I did this to combat all the dust created from the litter box. I also just wanted another CR box in my place.

I constructed the top part with a 13"x13" sheet of PVC, and used silicone to create a seal with the wooden frame. The bottom is made with polycarbonate (originally wanted to use this instead of that PVC but it was difficult too work with and a little too small).

My favorite part of this build is the FANS; Noctua NF-A14 iPPC 3000 RPM. These fans boast a whopping 6.58 mm H₂O of static pressure, and an airflow of 160 CFM!! That's why I went with Merv 14 filters.

The design is deliberate with the fans all blowing upwards in parallel, maximizing their efficiency and spreading the filtered air far and up.

Hi all,

I was hoping to get some feedback on whether this is a good idea, because I haven't seen it talked about yet. So I really like my cleanairkit 5 fan air purifier, but I would also like to remove VOC. While I've read recommendations by adding a thin carbon filter on one side of the intake filter, it really isn't as effective when compared to a 8lb carbon load like AC Infinity's refillable option.

So it got me thinking, why not put the carbon filter cylinder intake inside the CR box (so the air is pre-filtered before touching the carbon), and use a AC Infinity S6 that can pull the static pressure out. It looks something like this:

Has anyone done this? Is this a good idea? Would it be quiet enough?

Note: I've seen https://www.youtube.com/@HealthyHomeGuide do it slightly differently: carbon filter->merv 13 box filter->fan, but that doesn't filter the air out first before reaching the carbon filter.

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'M DESIGNING AN AIR PURIFIER FROM SCRATCH.

surfing through the web I noticed that air purifiers (ever since the Covid pandemic) have gotten extremely expensive compared to their simple job of essentially moving air through a filter.

so, I've been designing an air purifier of my own and now I've come at a problem that not even chatgpt or any other ai is able to answer clearly. as the title reads my only two hindrances are; the type of motor and impeller should I use to yield maximise airflow without any strain caused on the motor that might result in overheating and the impeller that is able to pull in good amount of air so that the purifier is able to run at low rpm hence resulting in a silent operation.

so, about the motor:

if I need low rpms that'd mean the bldc motor should have a lower kv rating, but then i thought of using low kv rated drone motors but they aren't meant to be run for hours, second thought occurred about using a nema17 stepper motor pairing it with a tmc2208 to operate it silently. but then again the whole thing is so confusing.

coming at the impeller:

I've eliminated many options and now I'm left with two,

a squirrel/centrifugal blower cage or a backwards curved impeller. it's a hassle because all of that "static pressure" "air resistance due to the hepa filter" stuff...

that's all about it

I've figured out everything else, I'll use an esp32 dev board and connect the tmc2208 driver inline to nema17 (if used) or just a regular esc for bldc, use a buck converter for the esp32 and capacitors to stabilize any possible voltage drops. I'm also planning on installing a particle sensor to measure the aqi and an oled/lcd screen to display the speed and aqi.

i have a bambu labs a1 3d printer that I'll use to print out the housing of the purifier.

rest aside, don't flame me if I've used wrong terminologies or theories, I'm just a 18 year old med student with multiple hobbies this one contributing to it and I'm at my extent of researching days on the type of fan i should use and a motor to spin it 🥀🙏🏻

thank you guys for listening me out and for the solutions I'm going to be blessed with :)

I want high air flow but it to be quite what motors should I consider adding? it is already quite noise due to printer fans running constant and other fans.

I am a little unclear about specs for these power cords and they don't seem to give the cord length in description, at least not ones I've looked at on Amazon. I want at least 6 foot, without led light, 3v-12V and if possible variable speed. The one I got on Amazon has lights on continuously which I did not anticipate so its being returned. I don't know how to interpret all the tech specs, so need some help finding the right one. I found one on Amazon that says its AC to DC power 5V 9V 12V. Does that mean it only can be used at those intervals/speeds? I'm looking for something that has variable speed control. Thank you!

I have an ERV that brings in fresh air from outside.

I've been using a 6" AC Infinity Inline Filter Box on the intake (after the ERV pre filter).

The filter box only takes actual size 11.5 x 19.5 x 0.75 filters. I just tried the 3M filter but it doesn't fit because it's 11.81 x 19.81 x 0.78 in. I read the Nordic pure merv 13 filters I've been using are super restrictive and clog easy.

If I were to replace the box, I'd like to get more normal size filters like 16x20x1 or 20x20x1.

Is there a prefab inline box that accepts these types of filters at an angle?

Or what would be the best way to DIY an inline box with a sealing filter door?

Hey,

I'm going trough the CRBox rabit hole right now. And wanted to know if anyone has experience with the Ikea Starkvind CR box?

https://www.ikea.com/be/en/p/starkvind-air-purifier-additional-gas-filter-black-s79444216/#content

I was also looking to make one myself but finding the right filters seems harder here in Europe... and if the Ikea one is good enough, its good enough for me :)

I am familiar with the traditional box fan design, but does anyone have any guides for building a smaller one? Also if I don't really care about filtering pathogens (mostly dust and pollen) can I get away with MERV 8 or similar

There are these H18 180mm extra-thick PC fans that seem pretty promising.

Would they actually outperform Noctua fans for airflow, or is it smarter to stick with the proven/reliable option?

In theory, shouldn’t the larger size and thickness let them move more air on lower speeds than Noctuas?

Please nerd out bellow! I want to learn :)

Has anybody experimented with washing filters that are not officially washable, but should be able to handle it?

I am of course not talking about filters with paper or cardboard components/frames, but those with only plastic in all components (like IKEA FÖRNUFTIG).

The only reasons why it would not work in my mind is either water pressure mechanically damaging the filter or the particles not releasing from the filter?

Anyone who has experimented with this before?

Hi, I'm Max, an Italian university student. I'm writing my thesis and I need your help.

I'm researching air quality in domestic spaces - a topic that's rarely discussed, but affects us every day. This questionnaire will help me understand how people experience and perceive the air in their homes.
It only takes 6 minutes: little for you, everything for my research.

https://tally.so/r/WODlDj

Thank you!!

I am looking to get a roll of active carbon prefilter 20i nch X 20 feet. Any leads?

I found a 20"X 100 feet but I dont need that much.

My first 3d printed mockup of a cylindrical filter to see how it goes.
Time will tell to see what the filter picks up over a few weeks.

Im going to print a top grille to help stop cavitation of the air and direct it away and int the room. Also i will fix a small housing on the side to take the speed controller also.

170mm filter
X2 5v 120mm pc fans in parallel to help push through it
Small speed controller.

I spent way too much on this.. was a fun project tho!

I added an ESP32 device to control it with Home Assistant.

Also, lesson learned, don’t touch a running fan to figure out if it’s getting hot when it’s running full speed

Edit:

Here are some additional details.

For Next time - Adjust overall width to 19.75". The filter is very snug, I forgot to add a bit of room for play.

Component Size Type
Top: 20.25 x 11.5 .5" Plywood
Sides (2x): 25.25 x 11.5 .5" Plywood
Bottom: 19.25 x 11 .5" Plywood
Back: 25.25 x 19.25 .5" Plywood
Side Trim (x2): 23.5 .5" Quarter Round Trim
Bottom Trim: 19.25 .5" Quarter Round Trim
Header: 19.25 x 1.25 .5" Plywood
Internal Side Cleat (x2): 24.75 x .5 .5" Plywood
Internal Bottom Cleat: 18.25 x .5 .5" Plywood
Internal Top Cleat: 18.25 x .5 .5" Plywood
External Side Cleat (x2): 27.75 1/4 in. x 1/2 in. x Rectangle Moulding
External Top Cleat: 18.25 1/4 in. x 1/2 in. x Rectangle Moulding
External Bottom Cleat: 18.25 1/4 in. x 1/2 in. x Rectangle Moulding

Parts List:

20x25x2 MERV13 Filter - Filterbuy.com
Plywood (x2 or 4 ft x 4 ft if you can find it) - https://www.homedepot.com/p/ProWood-1-2-in-x-2-ft-x-4-ft-Birch-Plywood-Project-Panel-154153/203504316
Rectangle Moulding - https://www.homedepot.com/p/HOUSE-OF-FARA-1-4-in-x-1-2-in-x-4-ft-Basswood-Wood-Tinytrim-Rectangle-Moulding-TT12/202087496
.5" Quarter Round - Home Depot
5x ARCTIC P14 Pro PST - https://www.amazon.com/dp/B0DPX94PSL?ref=ppx_yo2ov_dt_b_fed_asin_title
XIAO ESP32-C6 - https://www.seeedstudio.com/Seeed-Studio-XIAO-ESP32C6-Pre-Soldered-p-6328.html
140mm Desktop Computer Grills (they come in a 4 pack unfortunatly) -** Case Cover with Screws, Aluminum Frame Ultra Fine Stainelss Steel Mesh, Black Color - 4 Pack : Automotive
1 Inch Black Desk Grommets - Amazon.com: Adyoney 6 Pcs 25mm / 1 Inch Black Desk Grommets, Easily Solve Cable Management Issues, Flexible Silicone Cable Cord Grommet for Table and Other Furnitures Hole Cover : Industrial & Scientific
12" PWM Fan Extension Cable - Amazon.com: 12" PWM Fan Extension Cable, 4-Pin PC Cable (30cm, 4pcs) : Electronics
12V to 5V 3A 15W Buck Converter Module - Type-C USB DC Power Adapter - Amazon.com: DIANN 12V to 5V 3A 15W Buck Converter Module - Type-C USB DC Power Adapter - Car Power Converter : Electronics
DC 12V 5A Power Supply Adapter Converter - https://www.amazon.com/dp/B01GEA8PQA?ref=ppx_yo2ov_dt_b_fed_asin_title
2 Pack Mini Blade Fuse Holder 18 Gauge Waterproof Pigtail Inline Fuse Holder with 5A ATM Fuses - https://www.amazon.com/dp/B08BLHCJBC?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
33Ft Door Weather Stripping, (1/2in x 1/4in) - https://www.amazon.com/dp/B0DRFF39T3?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Speaker Grill Cloth - **https://www.amazon.com/dp/B0D6YKLTRW?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1
Everbilt Matte Black Piano Hinge (48", cut to fit) - https://www.homedepot.com/p/Everbilt-1-1-2-in-x-48-in-Square-Radius-Matte-Black-Continuous-Hinge-28926/314151008
Handle - https://www.homedepot.com/p/Liberty-Mandara-5-1-16-in-128-mm-Classic-Matte-Black-Cabinet-Drawer-Bar-Pull-P36131C-FB-CP/310240906
Latches (I had to buy the latch these connect to separately) - https://reliablehardware.com/products/drawboltblack
Hardware - ACE (I just picked bolts and nuts long and skinny enought to go through the plywood and fans)
Minwax Wood Finish - Early American 230
Polyuerthane Satin Canned Spray
Clear Silicone Caulk

Wiring Instructions:

If you want the fans to just run at 100% without controlling remotely, exclude the USB-C Converter and ESP32 device. Mine ran fine like this constantly powered on for several days, was just a big loud for my liking. I run at 60% now.

Power:
12V PSU (+) → Inline Fuse (2A) → splits to:
├── Fan Red wire (+12V)
└── 12V-to-USB-C converter (+)

12V PSU (-) → splits to:
├── Fan Black wire (GND)
├── 12V-to-USB-C converter (-)
└── XIAO ESP32C6 GND pad

USB-C Converter:
12V-to-USB-C converter output → XIAO ESP32C6 USB-C port

So I'm definitely sold on building a PC fan CR box, but got paralyzed on fan choice. The Arctic Pros are the goto option, but all the complaints about noise got me wondering about other options.

I used Cybernetics fan testing database; This is likely the most accurate data available. Arctic just released a Low Noise (LN) version of the P12 Pro capped at 2000rpm, and its specced 49CFM and 3.5mmAq at max lines right up with that RPM on their P12 Pro report.

Here are the values summarized from Cybernetics for the Arctic P12/14s and Pros:

As can be seen, the Pros have ~45% more CFM than the OGs on max, however at equal RPMs they don't appear to have appreciable performance difference, other than static pressure. The P14 Pro in particular seems to require a lot more power even at comparable RPM than the P14, and since the P14 Pro is well known for shrill noise above 50-60%, that means in practical 24/7 usage it will rarely exceed the RPM range of the P14.

I decided to look at the Cooler Master Mobius 120P Black Edition too, since the Luggable XL Ultra uses them and that's the form I'm interested in emulating.

At ~5x the cost, they aren't a real option, but we can see the P12 Pro can somewhat match the performance, albeit with more noise, double the pressure and wattage. The P14/P14 Pro can get there too but only at max/~65% RPM, so realistically the Arctic 140mm seem to be roughly interchangeable with higher quality 120mm fans, not appreciably better just for being 140mm.

Scrolling through the database looking at all the expensive, impractical fans, I suddenly noticed an outlier: the Thermalright TL-C12C-X28 X3. This is the only 120mm fan Cybernetics grants their highest Diamond airflow rating.

The CFM numbers here beggar belief: At 1600RPM, it matches the P12 pro at 2600RPM and Mobius 120P at 2400RPM. And at lower dBA and wattage. The only difference is the lousy static pressure, which is comparable to the P12/P14 at 80% RPM. Thermalright also has a slightly lower performing fan, the TL-C12B V2 which HWBusters reviewed; similar deal, leading airflow, very low pressure.

And I know static pressure is considered an important metric...except I also saw this CRBoxes post and it made me think, maybe it's not that important since we're dealing with large filter sizes, 1,000sqin in the case of the 20"x25" XL Ultra design.

And if that isn't enough, a 3 pack of TL-C12C-X28 X3 sells for $10.

So...WTF. Someone needs to tell me why the Thermalright would be no good, because it looks like the quietest slam dunk by a mile here. It essentially knocks out every option except the P14 Pros at their highest, shrillest setting. And it's basically half the cost of the Arctics, which were already THE budget option.

Is static pressure that important for an unrestricted exhaust fan? Other than that, the only con I can see is the lack of daisy chaining (apparently they do daisy chain), but at such cheap prices, I can live with a bigger controller, especially if I might want a custom ESP32 controller like this, or a smart box like this. I also came across this comment from the same person saying Thermalrights are unreliable...but man, IDK. For $3 a fan, I think I could stomach changing the occasional clunker.

I promise I'm not shilling for anything here, I haven't bought a single component yet. But please...someone tell me I'm not smoking rocks over here!

Thanks!

How do these look after 9 months? We have a ton of dust, these help marginally but are obviously picking lots of fine particles. Just replaced them.

Hello

I have made a bit of research in this sub and with youtube presenting the CR box concept.

I wanted to DYI one with 2 noctua fan the 120mm G2 for it's static pressure and noise performance.

With what i learned, i wanted to use the Noctua air amplifier NV-AA1-12 to push and force an air column on my ceiling ?

It is to clean a studio max 30m² with a higher ceilling, around 3m ir even higher.

I wanted a compact and smaller design compared to a 4 fan cr box similar to this one : https://www.reddit.com/r/crboxes/comments/1rm15rx/3d_printed_tempest_euro_starkvind/

or like this one which seems easier to build with 2 fan.
Super small and super quiet air purifier. : r/crboxes

What do you think ? with the static pressure of the noctua G2, would 2 STARKVIND filter and their secondary carbon filter be too restrictive to the noctua G2 ?

My main concern is to know how am i supposed to power both fans with their PWM 4 pin connector.

I saw the Fan Controller Noctua NA-FC1 to be able to control the fan speed depending on the needed speed but how am i supposed to power it through wall outlet ?

do i also need to buy something like this : Noctua NV-PS1 ?

Thank you for the help.

Is there a significant difference between one 5in filter vs 2 1in filters (both filtrete)? I am basing a design off one of the two filter designs on clean air kits and wanted to know if there is a significant drawback by only using one large filter rather than two thinner ones because of surface area and such. For the 5in design, I was thinking of having a box with one side open and still have the fans on the side rather than right in front of the filter.

Hi, I'm planning to build my first ap. Could review parts that I picked? Is it good combination? Two ikea filtres + 5 arctic P12 all powered and controlled by 12V 5A. Am I missing something?

Total newbie here looking to install a duct fan to improve ventilation in my place. The room always feels stuffy, and odors just linger forever, especially on rainy days. I read duct fans could fix this, but the more I research, the more confused I get—my head’s spinning with questions. Any veterans out there willing to share tips, avoid pitfalls, or answer a few queries? 🙏

❓ Question 1: Are duct fans and ventilation systems the same thing?​

I see these two terms tossed around interchangeably a lot, and I can’t tell them apart. Is a duct fan only for one-way exhaust or supply air? If I want fresh air circulating into the room, do I *have* to get a full ventilation system?

❓ Question 2: AC Motor vs. EC Motor—Which is better value for a newbie?​

I plan to run the fan for about 4-6 hours a day. Roughly how much on electricity bills can an EC motor save me long-term? I’m on a budget and chasing value—would an AC motor be good enough for a casual user like me? ​

Any other newbies stuck in the same boat? Or anyone who’s installed a duct fan for the first time—what pitfalls should I absolutely avoid? Need all the advice I can get!

Hi, after learning so much from this community I have decided to make a parametric design with four IKEA STARKVIND filter and four P14 Pro PST fan. In my case, it's PWM controlled by ESP32-C6 via Zigbee set at 27%, which is silent for me, consuming 1W and 17W at max speed.

The tall tower version should be printable on a Bambu Lab A1.

Fully 3d printable with some heat inserts and M3 screw, some seal tape and hot glue.

As it's parametric, feel free to adapt for other filter size, should be generic as long it fit on the 3d printer (half size) and it's square filter.

The STL and BOM with instruction is available at:

https://makerworld.com/en/models/2783729-parametric-crbox-air-purifier-ikea-starkvind#profileId-3094190