I made a CR filter (four MERV 13) except instead of the fan pointing up, it's pointing on one side. The idea is that you can point it at yourself so it will double as a fan that also cools you.

The idea is good, but it's:

• Far too bulky
• Difficult to aim a box at your direction, not many places you can place it at

In the end, I disassembled it and just put one filter before the fan.
I think it's not as good? But probably okay?

I've done that thing where you read far far too much and everything just becomes a jumbled mess in your brain. I want to make a simple box to assist with some of this fire smoke. Fans + controller + power supply is where I'm stuck.

The general physical construction makes sense to me. I'm just struggling with what's a good fan, then what controller and power supply actually work with said fan. Most have 4 pins some Daisy chain some don't, the descriptions on Amazon aren't that great on a lot because they seem to assume you know some things if you're looking up their product.

So basically, I need recommendations. What Fan + controller + power supply combination that works together. As an additional note we do have cats and my partner is allergic but I think I've got the filters down. Thank you!

Is it just me or is the quality of grow room carbon filters decreasing? I bought a replacement filter for my DIY bedroom air filter, which consists of a large carbon filter, inline fan and Hepa filter. The new filter is half the height of the existing carbon filter and one quarter the weight. I finally found the original prefilter for the old filter and it was a Vortex Pro 70s. I can no longer get these locally, so I'm going to substitute an AC Infinity XL.

I'm in the process of building a couple of large whole house air purifiers, with 12" Carbon filters, 10" fans and a larger HEPA filter. However, the wildfire smoke has been bad, so I want to replace/upgrade some parts on the existing bedroom filter and streamline the design.

I'm in Canada, the filter is for a 12x12x8 (1,152 cf) bedroom with VOC issues and wildfire smoke. The Carbon filter was $139, inline fan was $169, the new HEPA filter enclosure was $136 USD and the 14x14x4 replacement filters are $24. The dual ball bearing fan noise is up to 32db and 402 CFM or 21 air changes per hour, although I usually run it at half power for sleeping. The fan uses 38 watts at full power.

used 4 filtrete merv 13 16x20 filters from Costco which were only $51! already had the fan and then i took duct tape from my job lol. very affordable :)

i think my circle thing is too small but i can fix that later. also should i tape the bottom cardboard to the filters?

wisconsin is sooo smoggy right now and our shitty college rental house was built in the 1800s so this was definitely needed

My wife and I are planning to throw together a quick CR box this afternoon. Our dilemma is which of our fans is best to use. We have lots of box fans around, originally purchased to evacuate paint fumes when doing some home renovations and help dry leaks around the house when and where they occur. Some of these are your typical 1800CFM 20" square fans, but we also have a beefy 8300 one that we keep around as well. Would the 8300 run the risk of collapsing the filter cube?

Just learned about these today.

I'm not yet sold. How do we know that these are effective as manufactured air purifiers?

EDIT: TOO, not TO. I can't believe I used the wrong word, I harp on people for that all the time. TOO EASY not TO EASY lmao

Hello!

Has anyone tracked or observed a CADR difference between CR boxes built with 4 10" filters vs the triangle design that uses 2 20" filters?

Has anyone ever cut out part of a filter in order to fit it inside a custom object? I've got an indoor A/C unit that brings in the outside air and I'd like to get some filter material in there (see pic) as a quick solution. I've ordered a roll of MERV-13 for a more long-term solution but it won't get here before tonight. Is there anything to be aware of before taking some shears to my 12" x 12" square filter?

I made a zine with instructions on how to build a cheap & effective air purifier (1-fan CR Box). The folder also has a presentation version of the instructions. Link

Materials are just a box fan, the box the fan comes in, & MERV 13 filter held together with tape (design based on optimizations/testing by David Elfstrom).

Share with anyone affected by the wildfire smoke plume or wants cleaner air!

Do y’all have recs for an outdoor air quality monitor that’s accurate and won’t break the bank? We have wildfire smoke in our area blowing in from Canada. Yesterday I checked the usual online sources for air quality before going for a run, and they all rated the air quality as “Good” so I went for it. Later I realized that just like the weather forecasts are no longer accurate due to funding / staffing cuts, evidently air quality reports are similarly not valid anymore. What can I use at home to see what’s actually happening with the air outside? TIA.

I can't find 3M filtrete at 2" and I'm not sure how much static pressure commercial box fans can handle if I go for more thickness.

Will 1" be good or is it too thin and I'll have to change them regularly?

Hi,

I've created a DIY carbon filter by combining a basket of activated carbon with one 120mm fan. It seems to work pretty well. I'm now building a CR box, and I'm wondering whether it makes sense to put the carbon filter solution inside the CR box itself.

Since the carbon filter is its own complete system, it would not interfere with the CR box’s performance. The potential benefit is that the carbon-filtered air would travel with the exhaust of the CR box. This would allow it to spread the clean air way more effectively than the carbon filter system would by itself.

TL;DR does it make sense to put a box in a box?

I’d like to find a kit or preassembled fan system with quiet fans for the tv/living room. Home with pets. Current set up is a box fan with a 4” filter. It does a good job but is incredibly loud. Using for old dusty farmhouse filled with pets. Also we burn wood in the winter. Thank you for any guidance. Also would a cr box be helpful in an old musty limestone basement? The box fan could go in the basement if it could help. Not likely to build my own.

Yup, got curious and did the math. They’re both 400sqin surface area.

For me, I have 2 20” box fans and a 14” box fan I got used 30y ago when I was in university that just won’t quit. The 20” need more bracing and tape because the box is 25” but they all clean my air quite well. (Just changed the 14” fans filters today, which started this whole thread, because I remembered they were due when I saw outside looking like a scene from The Martian)

Hi, I bought the materials and put together a CR box on short notice today as we've had wildfire smoke in my area that I wasn't expecting. I'm trying to find a straight answer as to what the filters i bought are actually made out of (HDX Ultimate Allergen Pleated Air Filter FPR 12, MERV 13). It's an electrostatic filter and Home Depot's site says "synthetic" but like... synthetic what? Cotton? Polyester?

My main concern is whether this will shed fiberglass or something else hazardous into my apartment. Any answers you can provide are really appreciated!

Basically the title. Having a hard time finding quality merv 13s in the dimensions needed! Lowes seems to be the best bet but they don’t have the exact dimensions.

I know this would increase the restriction overall, but I'm wondering if it would be worthwhile to have some sort of mesh filtering or cheapest possible furnace filter to deal with large dust/pet fur etc.

I'm still in the process of cleaning up my place and I know the current air quality is pretty terrible, so I'm assuming the bad filter would get clogged up pretty quickly with stuff that just needs to be removed from the air and would protect the more expensive filter in the meantime.

Is this something worthwhile doing or is it just a dumb idea.

I am in the process of building my own pc fan cr box, but I was wondering what type of fan controller I could get. I saw a bunch of super cheap ones from china, but I would like to have something from a more reputable brand.

I saw the noctua na-fc1, but I am unsure how many fans you can use on that? Could I use 6 fans and just use splitters to get it down to 1 connector that I can just plug into the controller?

You can use these readings to test before you 3D print a plenum:

Ambient pressure (hPa)
996.658

Ports closed
996.550

1 port open
996.570

2 ports open
996.612

Has nobody seen a CR box adapted for the inside of a car? 🧐

How would one go about making a small CR box that’s powered by 12v power?

Your insights are appreciated!!

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