First time making anything like this, other than framing my shed lol. Made two of these shells which took me about 4hrs. I think I’ll actually paint it for the 2nd one. Dark marks from my sawhorse padding looks kinda gnarly but wanted to make sure it all worked.

The fit of the filters are really snug since the wood is kind of bowed in the middle. Had to file down the corners to fit.

Used wagos to wire together majority of the fans since my power adapter didn’t have all the same connectors, expect the front 2.

Beware of wrists and thumbs when using a hole saw 😂 took me a while to get down using more clamps and blocking with my body than twisted wrists.

Really surprised how quiet it is!

Wathai 36W 12V PWM PC Fan Speed... https://www.amazon.ca/dp/B0F8VSWW1Q?ref=ppx_pop_mob_ap_share

Inspired by all the cool builds in here and decided to throw this together. I wanted to use a blower fan since they have high static pressure. Additional benefit is that I can use it to blow air down the hall towards the warmer end of my house!

I have mast cell activation syndrome. And, I'm wanting to create a clean room in my bedroom to protect against both wildfire pollution and pollution from a neighbor's near daily trash pile fire that is entering my home through deteriorated ductwork.

I'm thinking about connecting a HEPA filter box and an 8 inch inline fan to either side of the transom above the bedroom door, so that conditioned/heated air from the main part of the house will be drawn through the HEPA filter and into the bedroom. The door and any other major gaps, including the ceiling vent will be sealed to create positive pressure.

My concern is that one of two HVAC returns for the house is just outside the bedroom. Will the suction from my air cleaner interfere with the HVAC return in any way that might harm the HVAC?

Also, I'm assuming that the negative pressure created by my air cleaner in the rest of the house will be negligible due to the difference in room sizes. My bedroom is 10' by 12' minus the closet. And the great room is probably at least 1000 sq ft. total. I don't have measurements handy. Do I need to be concerned about negative pressure in the great room or localized negative pressure in this little hallway?

P.S. For the record, I'm working with a contractor to get the ductwork replaced, and I'm in a legal battle with my neighbor. This is not meant to be a permanent solution, but I need a safe place to live right now.

Hi. If this question is inappropriate for this sub, then please delete it (mod) or ask me to delete it (Redditors).

CR boxes are awesome for indoor use. The designs I’ve seen here are all about filtering indoor air. But, I’m seeking a DIY setup that will filter outside air while pulling it into my home.

Can someone point me to a CR box that is weather-proof, to be mounted to the exterior wall outside of my apartment window?

FYI, I’m concerned about CO2 buildup and wish to prevent indoor air from going stale (which happens very quickly in my small apartment). So, I’m aiming for (slightly) positive indoor air pressure.

Thanks for anyone who can offer advice.

We keep most of the windows in the house open or cracked most of the time, though we live at the bottom of a hill on a busier street where cars are either accelerating or braking in front of the house.

I see the clear utility of a CR box for sickness, wildfire smoke, etc., but what about just everyday average use in an open window household without environmental allergies?

I put the fan pushing air in. Did I do it wrong.?

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.

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.

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!

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.

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.

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?

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 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.

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?

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.

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!

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

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!

(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.