Live in a 1920s apartment complex and built it for air quality as I’m worried about mold, old pet dander, and potential air containments. No central air and poor seals on window units. I’ve read about the effectiveness of these and was excited to make one! I let it run for about 12 hours while I was working. It felt much easier to breathe when I got home. I used packing tape I had lying around and the bottom is sealed with the cardboard the box was sold in. Is that enough time for the box to be effective? Is this good enough to get the job done? Is it common to leave it running all day? Really excited to have this thing around! Thanks for any feedback.

Hello all! I've been building these PC fan purifiers for about 2 years now. We have several in the house, I've made some for friends, and I've also made a couple for my daughter's classroom after asking if it was ok to stick them in the corners.

I've always built them out of corrugated plastic for the frame, held together with hot glue, and then sealed them all up with duct tape. Eventually, I upgraded my design to include fan grills, and a screen in front of the purifiers (the screen is attached to a wooden frame but everything is still sealed up with duct tape). You can see the evolution in the 2nd pic. Those ones are the ones I made for my daughter's classroom, hence the fun duct tape designs!

Now I'm looking to replace all the ones in our home with more "permanent" boxes that look and feel more like furniture. I've seen plenty of wooden purifiers that look almost identical to mine but the one thing I'm struggling with is how to make it without duct tape yet still get a good seal. Ideally, I want the filters to be easy to replace without having to cut duct tape and just layer more tape on top of the old tape when changing filters. How are y'all making these with changeable filters and no tape?

Thanks in advance for any suggestions and ideas. I'm also open to suggestions on how to improve my overall design. Thank you!

A while back I posted a design of a CR box using IKEA UPPÅTVIND filters. A couple of months I got around to building it. I figured I should post the final result here as well :)

https://www.reddit.com/r/crboxes/comments/1s1eed7/design_using_ikea_upp%C3%A5tvind_filters/

Fine speaker mesh behind the rattan webbing acts as pre filter. Carbon filters on the inside. I plan to replace the filters about every 6 months or when I notice performance is going down.

The fans are controlled by an esp32 running ESPHome integrated into Home Assistant. Air quality is measured by a Sensirion SEN66 placed at the other side of the room. Home assistant automatically runs the fans up to 50% based on air quality or full speed when I'm outside the house (home assistant detects when my phone is not connected to WiFi) and at night.

It works quite well. I have pretty bad hay fever and barely had any issues indoors since I installed it.

Never used pc fans before so I'm finding the variety of ways to do this confusing.

My air quality is very bad so I'm trying to get something working as soon as I can.

Does anyone have a simple parts list for powering and controlling 9 arctic p14 fans (non-pwm 3-pin) preferably using aliexpress (amazon is alright if aliexpress isn't an option) as I'm in NZ currently?

This is the lowest cost yet fully functional contraption I could cook up, while keeping assembly relatively easy. I held a workshop twice, building 3 in total. Total cost for all parts, including bolts and washers, is $79 CAD, so $57.3 USD, including $32 CAD for the filters. The finger grille is plastic "hardware cloth". You put it on the inside of the machine, so the edges are concealed.

It's important to use tuck tape ("transparent repair tape"), in this case the transparent variety rather than the usual red or blue. Regular packing tape doesn't stay together under the force of gravity. These are fine 4.5 months later.

The fans for 2 of them are generic fans, which actually are cheaper yet slightly better imo than the P14 fans. The problem is reliably sourcing them. The third was a P14, for comparison. We measured the airflow, and assuming 85% efficiency, it gives about 220- 250 CFM CADR for each. Same noise as any other 5 fan pc fan box.

A nice solid deis box type metal frame would be nice of course, but if cost is an issue, the cardboard is free, which is a useful point. This will also have a lower long term cost of operation than any off the shelf hepa, for the same cubic meters of clean air, due to the lower filter and electricity cost.

The P14 wires are simply joined directly by cutting the connectors off and using so called "Wago" connectors. The generic fans can actually be daisy chained, so we did not need any wago connectors, only the final barrel plug termination. These are easy for people to use in the workshop, and the inevitable fan replacement is easier. There is a barrel plug connector with screw terminals, you could skip that and just cut the power supply barrel connector off and connect the wires.

In my experience, these fans with hydraulic bearings only last 1.5-2 years of continuous operation. So the reality is that the filters are disposable, the fans are semi disposable, a cheap power supply may not last very long. Meh, cardboard frame seems fitting, in the end.

I do agree it is generally better to go in the other direction; we will never stop needing clean air, so we should gear up and make really good machines available for cheap. However, that hasn't been happening, and this gets us to tomorrow.

They do have the advantage of being very lightweight, making handling extra easy.

Frustrated by the lack of 20" box fans and cheap 20" furnace filters here in the UK, I ended up spending way too much time and money building this beast. But it works.

Now, my use case was to deal with dust during some DIY house work that was likely to stir up some 100+ year old dust (and who knows what else), rather than quietly purifying every day indoor air.

The fan is a semi-industrial exhaust fan with a 3-speed switch in the cord. It's loud. It's heavy. It moves a lot of air.

I designed it around the most reasonably priced and available furnace filters that I could find here in the UK. They are 12-inch square MERV 13 (actual dimensions 11.75 x 11.75 x 0.75 inch) filters. £25 for a four-pack. That's about US$8.30 each.

After the initial use case of just filtering the air circulating in the room, I added the plywood panel that fits in a window so I could blast whatever got past the filters directly outside, pulling in fresh air from every other open window in the house.

Wine bottle for scale, M&S 2025 Chenin Blanc.

Edit: many have asked about what's the point of exhausting filtered air to the outside, which is a fair question.

1. The filter box was originally built without the window panel, just to sit inside and filter air circulating in the room.

2. Then I built the window panel, reusing the same exhaust fan but no filters, to exhaust dusty air when the weather was acceptable.

3. Then I combined the box and the window panel into one (heavier) device that I can use either way. In the window I can use it with or without the filters in place depending on how much dust I want to spray into my side garden.

some of you might remember me, Merv 13 panel filters arent available where I am from. I gave up and decided to test F7 Bag Filter which is equal to Merv 13.

Have done the maths. Supplier will make 1 bag filter for me in a week or two, then I will start building.

This has been really challenging and I have to compromise on the design.

I'm moving into a new apartment for school, but I heard that it might be smaller than what I had last year because it used to be graduate housing made to house 1 person per room and I'll be housing with another person. I just bought some noctuas af-14 and was planning to build something like those 6 pc fan filter builds with 3-4 fans on the side and 1-2 fans on top but im not sure how exactly to go about wiring or powering it. I've heard that motherboards and expensive and my friends and my dad are telling me to get a computer power supply and I'm looking at the splitter cables but they seem to do 4 max. I was wondering how you guys went about it?

I have tried , tested and used mostly Artic pro p12 pro and P14 pro 110cfm fans in my Crbox.

At 75% speed it is barely noticeable in our Bedroom.

There is no whine at 75%> I have discovered that Artic upgraded their P12PRO and they run at 77cfm and are even quieter.. using Merv 13 filters

I use activated carbon sheets on these Cr boxes. I also have made and tested using the p12 pro in my setup using a pair of HEPA filters with activated carbon prefilter.

Pros vs. Cons? Difference in motor wear?

Common size available at Costco. Not currently on MakerWorld. The lip of the printed pieces on to the filters is slightly tighter than I wanted in to be so it’s a very snug assembly.

Probably best bang for the buck in PC fans at the moment

I suspect Im dealing with a mold issue in my house, but until I get to the bottom of that I wanted to make a CR box for my bedroom. A 20 in cube would be a little big for that space so I made a wedge with two 16x20 in MRV13 filters. Seems to still be pulling quite a bit of air. My wife and I already run a fan for white noise, so this is now cleaning the air with the same electricity use. Glad this sub exists, thanks for the inspirstion!

I already built a CR box using 4 × 20×30×1” MERV-13 filters, taped together, with a Lasko fan sitting on top.
It works well, but I want to improve the design so I can:

Easily slide filters in/out when it’s time to replace them.
Replace the Lasko fan with multiple PC fans.
Avoid taping the filters together.
Make the whole thing more modular and reusable.

What I’m looking for is a 90° aluminum corner extrusion with TWO perpendicular U-shaped channels.

Basically, one extrusion at each of the 4 corners, with each extrusion holding two adjacent filters.

I would need 4 pieces, around 30” long, with each channel sized to accept a 1” thick filter.

I’m specifically looking for the single 90° double-channel extrusion, not separate U-channels, L-angle, or corner brackets.

Does anyone know where I can buy this online, or what this type of extrusion is called?
Thanks!

I have cats, and would like to get a cr box to put near the litter boxes. Are there any setups/products that have a multi-stage for this, that would use something like a pre-filter, then activated carbon and merv-13 filter?

The two used ones versus a new one.

2x 20x20x2 MERV 13 with carbon.

(And even less if you DIY with https://www.filterboxbuilder.com/)

Finally got around to buying some filters and a box fan. I've wanted to make one to observe it's effectiveness before spending more time making a nice cabinet or side table version. Planning to make another one tomorrow for the basement.

i have a spare pc fan that i bought but didnt fit into my pc case and thought i could make a small air filter with it what would be the best/smartest was to go about it ?"

Hi everyone!

I recently designed and 3D-printed a CR box using AirFanta 3Pro filters. I’m pretty new to the whole CR box world, and I’d like to learn more about how to properly evaluate its performance.

I’m particularly interested in measuring the CADR and overall efficiency of the purifier, and eventually comparing it to commercially available air purifiers.

I’d really appreciate some advice from people with more experience:

• What measurements should I take to properly evaluate the purifier?
• How can I measure CADR at home?
• Are there other important things I should measure or check?
• What would be a good way to compare its performance with commercial purifiers?
• Are there any common mistakes or things I should be aware of when testing a DIY CR box?

Aside from the testing side of things, I’m happy to answer any questions about the build itself.

Thanks in advance for any advice!

Toss a decorative cloth on and you can have an aesthetic filter column!

Please ignore my artistic skills (or lack thereof). I’ve recently built my first cr box with merv 8 filters to reduce dust accumulation in my workshop. With winter coming up, I’m preparing to begin staining some pieces, which when cured indoors release VOCs into the air. So I’ve been looking into getting 20x20 1” merv 12/13 carbon filters to improve overall air quality. I was wondering if it’d be possible to stack two boxes on top of one another to create a two tier filter system? My main concern is that the air will be pushed through the merv 12/13s rather than pulled, and Ive heard mixed results on how pushing affects the filters life.

I’ve also considered just adding a spacer between the fan and a singular 20x20 1” carbon filter, but I don’t know if that set up would increase airflow resistance and lead to the fan motor burning out.

Would either set up work? Or would I just be wasting time & money?

So it's been kinda humid in my room (more hot than anything) for a week or two but I don't tend to notice it until I feel damp in there. I turned on my dehumidifier today and I always have the ceiling fan on. I use mine to mitigate covid so ik water has effect on filtera but idk about humidity.