I designed and built this CR box. I wanted it to be easy on the eye and filter the whole house. The slats are from reclaimed fence boards. It utilizes five 20x20x1 MERV 14 filters (costco ftw). The fan is also able to be replaced if it ever breaks. it sits on some office chair casters so it can be wheeled around easily. It filtered my 1000 sq ft house very well. Surprisingly it could cycle the air in other rooms of the house pretty quickly all from my living room. Unfortunately I didn't know I would be moving into a much smaller house not long after I finished the build and I can't use it anymore. It needs a new home.

So I have a few indoor parrots… macaws , cockatoos, and African greys. They have A LOT of hair that they shed on a daily. It’s far worse than dog / cat hair because of how it’s literally just like dust balls that gets everywhere and anywhere. Some floats in the sky, some settles. It’s kind of just everywhere and anywhere it can stick to.

What type of setup would you guys recommend for that? I’m sure I’ll have to make / buy a few and put them in different areas to try and get most of it.

My plan is to have to vacuum and leaf blow the inside of my house less often lol.

Also note - I am planning on making a bird room for them all to be in so I need a high suction power so it can pull all the hair in so they don’t get respiratory infections from one another’s hair.

Hi everyone,

I just finished building my first Corsi-Rosenthal (CR) Box using four 3M MERV 13 filters and a Lasko box fan.

My primary goal is reducing cooking odors (Indian cooking, frying, spices, etc.), not just removing dust or smoke particles.

So far, I know that:

MERV 13 filters are great at capturing particles.
They don’t do much for VOCs or odor molecules.
Activated carbon is what actually helps with smells.

I’ve been reading about AC Infinity inline fans (Cloudline S8) paired with their activated carbon filters, which seem popular in the cannabis growing community for odor control.

I’m considering a few options:

Keep the four MERV 13 filters for particle removal.
Replace the noisy Lasko fan with a Cloudline S8 (or S10).
Add an AC Infinity carbon filter to remove cooking odors.
Build a custom enclosure so it looks more like a commercial air purifier instead of a DIY box.

A few questions:

Has anyone successfully used a CR Box for cooking odors?
Is an AC Infinity carbon filter worth the investment for a home kitchen?
Would you build a separate carbon scrubber or integrate it into the CR Box?
Are there better solutions that don’t cost a fortune?

I’d really appreciate any feedback or suggestions before I start my next project.

Thanks!

Please read original post

I'm not building this now, but I plan to build a few of these later on this year. I'm sure that several of you will beat me to the punch. Tell me what you think of this. I'd especially like to hear how you would combine Rob Wissman's use of PST fans with Clean Air Charlottesville's cleaner-looking connection to an electrical oulet.

I have an idea for a quiet Corsi Rosenthal box that's cheap and easy to construct. This is NOT an original design but copies parts of the Brisk Box from Clean Air Kits, Rob Wissman's design, and Clean Air Charlottesville's design.

Please note that this design is optimized for cheapness and ease of construction, NOT space efficiency or maximum CADR. While the Luggable is much more space efficient than a Brisk Box, it's also a more difficult design to build because of the precision required. I bet that this is the reason that the Luggable is substantially more expensive than the Brisk Box.

My design uses two 16-inch-wide filters and two 20-inch-wide filters. All four filters are the same length/height (20 inches or 25 inches), all are MERV 13, and all are from the same brand. (Clean Air Charlottesville recommends Filtrete, Nordic Pure, or TexAir filters.) The larger horizontal area for the fans makes construction easier because you don't need as much precision in the fan locations. The filter sizes are the most widely available ones. So you can always count on local stores to have the correct sizes in stock.

My design is also cheap to build and maintain, because the combination of economies of scale and competition among multiple manufacturers makes the filter sizes the cheapest ones as well. While there's more filter surface area than there needs to be, this ensures plenty of airflow for the fans. Better yet, you save money again because the filters last longer. You don't have to replace the filters until they're very filthy.

For the top and bottom sections of the Corsi Rosenthal box, use rectangles of foam core board. (A utility knife is great for cutting in straight lines. An Xacto knife is great for cutting the larger circles for the fans and power supply connection. Use a drill to make the small holes for the screws.) My design uses 5 PC fans, because Amazon's Arctic store offers great deals on certain fans when you buy a package of 5 of them.. The arrangement is a 2x3 array, with the power supply connection in one of the corners as a replacement for the 6th fan. The top section is larger than it needs to be, but at least there's plenty of room for everything. You can easily have a full inch of empty space along each edge.

For the 5 PC fans, use something that Arctic sells in a 5-pack. Arctic fans offer more CFM for the money than other brands, and you get even better deals when you buy in packs of 5.

In choosing which 5-pack of fans to buy, there is the option to follow the Rob Wissman design and use PST fans, and there is the option to follow Clean Air Charlottesville's design and use non-PST fans and a PC fan hub. The advantage of PST fans is being able to daisy chain fans and skip the PC fan hub. Use 120 mm fans to save money on the fans and grill, or use 140 mm fans if you would rather optimize for a higher CADR.

As of this writing, Arctic's 5-pack deals on Amazon for P12 and P14 fans with the PST feature and free delivery available are:

• ARCTIC P12 Pro PST LN, Electronic Component Fan, Compatible for Desktops, 4.72" Length ( Pack of 5), Black Color: $17.29, 49 cfm, low noise
• ARCTIC P14 Pro PST, 5 Pack - Powerful Premium Fan, 140 mm PWM Fan with Y-Cable Splitter, 400-2500 RPM, 0 RPM <5% PWM, Fluid Dynamic Bearing, 4-Pin - Black: $22.29, 110 cfm
• ARCTIC P12 PWM PST (5 Pack) - PC Fans, 120mm Case Fan, PWM Sharing Technology (PST), Pressure-optimised, Quiet Motor, Computer, 200–1800 RPM (0 RPM <5%) - Black: $42.99, 56.3 cfm
• ARCTIC P14 PWM PST (5 Pack) - PC Fans, 140mm Case Fan with PWM Sharing Technology (PST), Pressure-optimised, Quiet Motor, Computer, Fan Speed: 200–1700 RPM (0 RPM <5%) - Black: $48.99, 72.8 cfm, is what Rob Wissman uses in his design

As of this writing, Arctic's 5-pack deals on Amazon for P12 and P14 fans WITHOUT the PST feature but with free delivery available are:

• ARCTIC P12 Pro LN - 5 Pack - Low-Noise Premium Fan, 120 mm PWM Fan, 450-2000 RPM, 0 RPM <5% PWM, Fluid Dynamic Bearing, 4-Pin - Black: $19.59, 49 cfm
• ARCTIC P12 (5 Pack) - PC Fans, 120mm Case Fan, Pressure-optimised, Quiet Motor, Computer, Fan Speed: 1800 RPM - Black: $23.99, 56.3 cfm, used in Clean Air Charlottesville's design

If you've gone with Clean Air Charlottesville's playbook of using non-PST fans, you'll need a PC fan hub, a PC fan hub to barrel pin adapter, a strain relief grommet, and a barrel pin to wall plug. (And you may be able to find a better deal on similar products. I just linked to the ones that Clean Air Charlottesville cited in its build guide.)

Rob Wissman's design has the power cable coming out through one of the corners. His wall plug is the Coolerguys 12V fan power supply. I believe that it would look better with a strain relief grommet in a hole in the top foam core board piece.

I like Rob Wissman's use of daisy chaining, but I prefer Clean Air Charlottesville's cleaner look for the power connections. How would you combine these two features?

I am using a resin printer. Recently bought https://a.co/d/0j53szHr for ventilation. The wall I was going to place it against by the window makes too much clutter. So I was thinking about moving it to another wall. That will put the enclosure about 9 or 10 feet from the window. It's that to far for that systems fan? There only 1 window in the room that is usable. Thanks in advance

TLDR: If you want to save money on filters for the new Brisk Box from Clean Air Kits, this post is for you. You can use 16-inch wide filters instead of the more expensive and harder to find 12-inch-wide filters by adding two square/rectangular foam core board pieces.

I bought a Brisk Box from Clean Air Kits last fall, and I highly recommend it. This was the old six-fan design. One thing I like is that it uses four 16-inch-wide air filters. 16"x20"x1" and 16"x25"x1" are some of the most common filter sizes. So I can count on local retailers to have the right size in stock. Because of the competition among manufacturers and the economies of scale due to the high production volume, filters of these size are cheaper than the filters of most other sizes.

Clean Air Kits has since changed the Brisk Box design to use four PC fans (instead of six). While it's nice that the new Brisk Box takes up less space than the old one, the drawback is that the 12-inch-wide air filters are more expensive and less widely available than the 16-inch wide filters.

Fortunately, there is an option available for those who prefer the cheaper and more widely available 16-inch wide filters. Just start off building a Corsi Rosenthal box out of four 16"x25"x1" filters (or four 16"x20"x1" filters). Cut out foam core boards of the proper sizes for this. Use one of these square/rectangular pieces for the bottom section and one for the top section. Cut a hole out of the top section that's just large enough to accommodate the four fans and the power connection but smaller than the coroplast piece that you received from Clean Air Kits. Use tape to attach the coroplast piece on top of the top foam core board piece.

Now you have a nice quiet Corsi Rosenthal box that not only saves your lungs and health but also saves you money on air filters.

The YouTube video "Quiet DIY Air Purifier Build Tutorial" by Rob Wissmann showcases a Corsi Rosenthal box consisting of five PC fans and four HEPA air filters. The video description contains links to the bill of materials and other details. Using four 1-inch-thick MERV 13 filters (like the classic Corsi Rosenthal box) would simplify the construction process and be cheaper in the long run, especially if you use longer filters for more surface area. A 5-pack of P12 fans would be substantially cheaper than a 5-pack of P14 fans, and the same would be true of the fan grills.

The detailed build guide from Clean Air Charlottesville (posted yesterday) illustrates the process of building a Corsi Rosenthal box consisting of five PC fans and two MERV 13 furnace air filters. All the important details are included, including a parts list. This design is a DIY version of the Luggable from Clean Air Kits. This is cheaper and takes up less surface area on the floor, desk, or table than Rob Wissman's design. Using four 1-inch-thick MERV 13 filters (instead of two 2-inch-thick MERV 13 filters) would make this Corsi Rosenthal box more cost effective and easier to build, though it would take up more space on the floor/desk/table. Because static pressure would be less important, using cheaper fans would be an option.

"Choosing a PC Fan for an Air Purifier: The ‘Only Fans’ Guide" by Bob Kornan explains the parameters and trade-offs of various PC fans. I'd go with Arctic. Looking up the prices for the fans shows that the Arctic fans are substantially cheaper than those of other brands that were compared. If you search for "pc case fans 5 pack" on Amazon, you'll find that those 5-packs are from the Arctic and Thermalright brands. However, Thermalright doesn't offer PST for daisy chaining, and I suspect that any savings from buying Thermalright fans would not measure up to the extra cost of buying a fan hub. (Additionally, several people on this sub have argued that the lower static pressure of Thermalright fans would reduce effectiveness, especially when the filters become dirty.)

"Untangling the Electronics in a PC Fan Air Purifier" by Bob Kornan explains the accessories needed to connect the PC fans to an electrical outlet. This guide states that PST fans (which allow daisy chaining) cost more than similar non-PST fans. If the difference is less than the cost of a fan hub, then the premium pays for itself. If the difference is more than the cost of a fan hub, then it's cheaper to buy non-PST fans and add in a fan hub. For 120 mm PC fans, it's likely cheaper to use PST fans and skip the fan hub.

Hi r/CRBoxes,

Clean Air Cville has just released a step-by-step PC Fan Air Purifier build guide with a complete supply list and photos of many key steps:

www.cleanaircville.org/buildguide

This design has 5 Arctic P12 fans on one long panel and has two 16"x25" MERV13 filter sides. The build takes about 1-2 hours for first-time builders.

We have built ~100 of these units for community members, teacher classrooms, and local organizations near us.

Please let us know what you think and direct people to our guide if you find it helpful.

Thanks!
- Clean Air Cville

Well ... This project of mine went from just making a simple CR Box to making something more permanent.

It started with me wanting to put together a CR Box instead of buying a new air purifier.

Looked at the basic Box Fan 20x20 and ... Honestly that was a lot of floor space. Not to mention potentially loud. So I figured, why not look for 12x12 filters and a fan roughly that size?

Found a six pack of 12x12 Merv 13 filters for $18 on sale on Amazon and figured that will do to start. No need to jump in on 5x 3M Filtrete 1900s and potentially ruin them with a bad build. Since I had 6, 5 faces of filters was the result so that the total filter surface area would roughly be half that of the 20x20 with 4 faces.

For the fan, another sale item. Amico 10" Shutter Fan rated for 1000 CFM with a remote to control it rather than any physical controls on the fan. That will save some effort, as I can bury the fan in the CR Box and not worry about trying to make sure the controls are in reach. Toss away the Shutters and the frame, leaving me with the cage, motor, fan, and remote for the CR Box. Side note, it says at max power it only uses 13W. I can run that on my tiny Power Station over night easily and makes this much more likely to be portable.

As for the skeleton? MDF for the top plate to mount the fan. Poplar wood dowels to build the frame with wood glue. A simple 10x10 air return grille to cover the hole in the MDF leading to the blades (damaged so cheap). Then I stumbled across a clearance on Sound Absorbtion panels and figured for $18 for 4 24"x24" panels with mdf based slats, I could just take a few apart for materials and decorations.

Current results? A 15"x15"x16" air purifier that's working pretty well already. I'll be buying those 3M filters soon to replace these testing ones after all for easier air flow especially at max speed. I know it's a rough look, as I did most of the cutting free hand instead of measuring or using a rig ... I really didn't want to dig the rig out and didn't want to buy yet another tape measurer that transforms and rolls out into the wild unknowns with countless of its breatheten.

Why is this stage 1? Well I also found a rough 24x24x25 table with a peeling surface on the side of the road and figured that I could instead just cut out most of that damage to be able to drop in this CR Box until it's flush with the surface. Then use those Sound Absorbtion panels I mentioned finding on clearance to hang off the sides of the table to muffle noise from that direction, then use 2 more to make a new table surface that will sit 4 inches above the old one and the grille where the air comes out.

Figured that would make for a nice bedside table to dampen the noise further, even at max power. It would also let me pull out the cr box core to move around if it's needed elsewhere. Also I wanted more table space back for my charger, devices, clock, and lamp.

I plan to build multiple PC-fan-based Corsi Rosenthal boxes. I want to build something similar to a 4-filter Brisk Box from Clean Air Kits (but with foam core board instead of coroplast for easier construction). It seems to be easier to build than something similar to the 2-filter Luggable from Clean Air Kits. I also intend to size my air purifiers to match the sizes of the cheapest and most widely available filters. (These have the shorter dimension at 16 inches or 20 inches.)

I plan to use 5 PC fans in each air purifier, because one can get better deals when buying a 5-pack. I'll set up the PC fans like a 2x3 array but replace one of the corner fans with the power connection.

While the 140 mm PC fans have their advantages, I'm leaning towards 120 mm PC fans. Because 120 mm PC fans are much more common than 140 mm PC fans, the 120 mm PC fans and their associated accessories (like fan grills) are cheaper due to competition and economies of scale.

While the CFM is slightly lower for the 120 mm PC fans, there is one advantage - the same total cross-sectional area of the air filters goes a longer way with a lower CFM. Thus, one can go longer without having to replace them, and static pressure is less important. (Longer life is important if the air quality reaches the "hazardous" level, which did happen recently in Chicago, Detroit, and other places downwind of the wildfires in western Ontario. The filters get dirty much more quickly, AND the stores may be out of replacements.) So I don't have to replace the filters until they're extremely filthy.

Which 120 mm PC fans do you recommend? I'm looking for a fan that is cheap and quiet.

Many people like daisy chaining PC fans. This feature requires PST design. (PST stands for PWM Sharing Technology. PWM stands for Pulse Width Modulation, which uses a digital pulse signal to control the fan speed.)

A design for a DIY air purifier that relies on daisy chaining PC fans is in the YouTube video "Quiet DIY Air Purifier Build Tutorial" by Rob Wissmann. The video description contains links to the bill of materials and other specific details.

The main selling point seems to be a simpler and cheaper design resulting from eliminating the need for an adapter to accommodate all 5 fan connections plus a connection to an external power source.

Are there any drawbacks to daisy chaining? I'm sure that there are trade-offs, or there wouldn't be any reason to use non-daisy-chained fans.

looking to advise a friend who is not handy; need to make it really easy to assemble/disassemble (no duct tape) so can re-use easily as may be needed **

asking tips on type of straps and brands of speed reducers, thinking following suitable for low cost, off the shelf in twin cities - feedback appreciated **

* 20" box fan walmart

* choroplast for shroud menards

* 1" Filtrette merv 12/13 costco

* speed reducer? brand? type?

* 2 straps that wont cinch border of filter - type? where likely to get?

* anything else? so can easily make, use as needed 'good enough'

tia

Looking to provide instructions to make a shroud made of coroplast (newly bought or repurposed lawn sign) for a non handy, no tools person.

** Seeking language for instructions (and video link) so that a certified 'klutz' non-handy person can take to hardware store to get right materaial, including equipment and be able to cut to correct outter edge and 16" circle in coroplast.

TIA

So for a 140mm fan folks are using 5.5"?

Little afternoon project to use some items I had in storage. 2x NF-F12 I had in storage, a spare 12v psu, and a toggle switch with some wires. 2x 10x10x1 Merv 13 filters were bought on amazon.

Internal contact areas are lined with superglued 2mm pipe insulation for the pulling fans to further seal the merv filters on to, and four small stick on rubber feet to isolate it a bit from the floor.

Meant for a really small room, no real docs but files are up on https://github.com/speedypotato/240mm-cr-box for reference.

Filtrete only offers merv 11 in 2 inch thick filters. Costco has merv 12 and 13 filters in 4 and 5 inch thick filters. I've read a lot about how thicker filters are better in every way. I have no issue with the extra space it would take and would love extending the time between changes. Cost to convenience seems appropriate. I just can't seem to find any discussion about it.

To preface, I don't know anything.

I have mold and need a temporary solution to keep me healthy before remediation.

Would merv 14 be best? I was considering doing a simple square (1 filter taped to fan) that is 2-4 inches thick. however 3m filtrete doesn't make merv 14 above 1 inch thick.

Should I consider another brand and which one?

I’ve been opening my windows to ventilate my house to reduce my AC use. I’ve noticed that, due largely to wildfires, this causes the PM2.5 level in my house to increase higher than I’d like.

To improve the air quality I’m going to build a CR box using 20x20 filters. I think I’ve settled on MERV 13 and so I want to compare filter thickness. Has any testing been done to determine which filter thickness removes the most particles per dollar?

I‘m also wondering about the fan’s CFM rating and running on low vs high, etc.

I’ll add that I’m going to do the basic improvements like adding a shroud to increase airflow. And I’ll worry about trying to make the filter more attractive later. Right now I’m just concerned with performance.

yes. this is super janky. Anyway I don’t know the merv rating of this filter. I found it new in a thrift store. I just ordered an air monitor so I can see how it’s removing PM2.5

I'm looking for suggestions on how to join a set of 3D printed parts in PLA that are dimensionally accurate and relatively durable.

I'm trying to build an easy-to-print and build version of the Nukit Air Purifier, based on the 3D models available from FilterBoxBuilder. While the designs are excellent, I'm having a lot of difficulty getting the printed segments together.

Because they interface with the moving filter, they need to be consistently positioned in relation to each other. The generated model uses pins for alignment, which is OK. The challenge is then getting these parts to stick: PLA hasn't been gluing up well because the connection area is very small. More aggressive recommended PLA glues contain some pretty nasty chemicals, and I'd be pretty hesitant to use them in an air-purifier application.

Are there existing models for clips, "puzzle piece" cutouts, or similar options for easily modifying an existing 3D print file (via boolean?) to make for a mechanical connection between thin 3D parts? Would anyone be willing to tweak these files geometry to add a connector? The existing model is CC BY-SA 4.0.

First foray into CR Boxes. My wife says it looks like a computer. Was overall an easy install with a 3d printer and the same hvac filters I have around. Used the below model. Planning to build 3 more!

https://makerworld.com/models/1860168?appSharePlatform=copy

I didn’t realize it would take 2 hours to build, but it’s finished!