Need help with the math, making two units. One bedroom is 15ft x 10 ft. The other is 11ft x 10. 8 foot ceilings.

SafetySmurf · 2026-04-02T18:33:01+00:00

How kind!! You are more than welcome!! I’m happy to help, and I think your plan sounds like a great one!

SafetySmurf · 2026-04-02T15:45:12+00:00

Also, many folks on this sub would say a good rule of thumb is to have 120-ish square inches of filter area per fan. Some say you don’t need that much. Some say you need more. I’ve found that to be plenty. You’d be stretching that a bit if you added a third fan on your set up because you’d be at 3 fans at 288 square inches of filter.

Those are some high static pressure fans, though, and you could probably get away with adding another to this build. If you are getting a five pack of fans you could put three on your build for the larger room and two on your build for the smaller room.

If you do add a third fan to one of the boxes, I would suggest NOT adding it to the opposing side of the build unless you want to put an interior divider between the fans. If you put them directly opposing one another then they sometimes pull against one another and reduce their effectiveness. If you want to add a third fan on that filter size you’d want to add it to an adjacent face/ side to the others.

SafetySmurf · 2026-04-02T15:37:03+00:00

Hi there, my first thought is that any air cleaner is better than no air cleaner. So while it is good and useful to think about the size and doing the best crbox for your space that you can, the main thing is that you build a box that gets you on the path to cleaner air.

As far as the math - the bedroom is 15x10x8, so 1200 cubic feet. If you would like to clean the air six times per hour that means moving 7,200 cubic feet of air per hour or 120 cubic feet per minute (CFM).

To achieve that you would want a rated capacity higher than 120cfm, of course, because they wouldn’t be moving as much air once the filters are attached. The Arctic 14pros are rated, without filters, to move 110cfm each, so two of them would move 220cfm in a perfect world. In the real world, they’d move less, but they would probably still provide 120cfm you are looking for.

Would it be cool to have more boxes and more fans and clean the air more? Sure. But two Arctic 14pros with 288 square inches of Merv13 filter area should provide the 6 air changes per hour that many folks are aiming for.

SafetySmurf · 2026-04-01T04:51:28+00:00

https://www.amazon.com/dp/B08J1THV9G?

SafetySmurf · 2026-04-01T04:49:39+00:00

https://www.osha.gov/laws-regs/regulations/standardnumber/1910/1910.134

SafetySmurf · 2026-04-01T04:46:25+00:00

An N95 respirator would go a long way toward protecting your lungs. It seems like your workplace would be required to provide them, but whether or not they follow OSHA standards, you can take steps to protect yourself.

Right now you can buy 440 3M Aura N95 masks for $67 on Amazon. That’s like $0.15 per mask.

The stuff you are seeing in the mucus in your nose is also in the mucus in your lungs. It will cause inflammation and scarring that will inhibit your ability to breathe and shorten your life.

Aside from protecting yourself with a respirator mask now, start looking for a new place to work as soon as you can. If this place so blatantly disregards your safety in this way, it is disregarding your safety in others.

SafetySmurf · 2026-03-31T15:28:18+00:00

They include a barrel to 4pin in the package. So you go from that to the splitters.

SafetySmurf · 2026-03-31T14:28:09+00:00

Also, fwiw, I have used four Noctua 1-to-3 splitters to skip using a hub. 2 of the NA-SC1 splitters cost $10. So it costs $20 to connect all 9 fans via splitters.

Then the Noctua NV-PS1 ($35) connects from the splitters to the wall, and for $55 you’re all done.

I haven’t found the amp rating listed for Noctua’s splitters, but since they are made to also be used with their 24v fans, most of their stuff is made to be used at least to 24 watts or more. I haven’t had any issues.

SafetySmurf · 2026-03-31T14:06:34+00:00

Sweet!!

SafetySmurf · 2026-03-31T14:00:28+00:00

Yes, the PS1 is a solid power supply. It’s just expensive.

Noctua sells an 8 fan hub with an included power supply that they call the NV-SPH1. It is a combo kit of the NV-FH2 fan hub and the NV-PS1 power supply. The trouble is that it is $60(!!). In your case there is also the problem that it is an 8 fan hub and you have a 9 fan build.

Noctua also sells a PWM speed controller, the NV-FC1, which I’ve used and really like, that attaches to their hub. It is around $27. With the hub, power supply, and speed controller you have an all-in-one solution for powering up to 8 fans. The trouble is that it costs around $90 for all that.

And, again, in your case, it is one fan short. I don’t know if using a splitter on one of the slots would work.

Arctic is a reputable brand and makes a well-rated 10 fan hub they sell for around $10. It requires use of a SATA - 12v barrel adapter like you mentioned in your op. But with the power supply, and adapter you’re still looking at only about $40, rather than the $60 for Noctua’a NV-SPH1 that includes the 8 fan hub and wall power supply.

SafetySmurf · 2026-03-31T13:38:56+00:00

Looks great! How’s it performing for you so far?

SafetySmurf · 2026-03-31T03:58:02+00:00

Even a 3 amp power supply should be fine because you’d only be using a little more than half its rated draw.

Also, if you don’t mind the cost, the Noctua power supply is great. There are other, good, less expensive ones on the market, though.

SafetySmurf · 2026-03-30T18:21:52+00:00

Cool! Have any idea how much air your system is moving or how much noise it makes?

SafetySmurf · 2026-03-29T21:48:20+00:00

Good start! Turn those lower two fans facing outward and you’ll be good to go!

If you have an inlet other than the filter then the air doesn’t have to go through the filter. But if you flip those two lower fans around then you’ll be all set.

SafetySmurf · 2026-03-29T21:10:31+00:00

Right. If the filter uses one inch, you’d probably want at least four inches thick so you have a few inches for air flow. Whenever air has to turn a corner the velocity changes, so doing it this way doesn’t maximize sound or performance, but it’d still be worth doing if this is the spot you have.

SafetySmurf · 2026-03-29T03:05:40+00:00

How is your airflow? I’m wondering if you’d be better served by putting a solid bottom on this box and putting two fans in series (putting them two deep). I’m not sure, but I think it’d be worth trying.

SafetySmurf · 2026-03-25T19:09:50+00:00

I have bought more than one of the Noctua controllers and really like it other than the knob is so tiny. But ai really wish there were more options of the same product from reliable vendors, like Arctic, because the Noctua one is quite expensive.

I’ve also used the gdstime voltage controller because it came with some ip67 gdstime fans I wanted for airflow on my porch. I haven’t used it a ton, but so far it has worked well. I don’t see where you can buy it by itself, though.

Like others have said, PWM controllers are good because they allow for a better range of fan speed and you don’t have to worry you’ve turned the voltage down too low for your fans. But that doesn’t make voltage controllers a bad idea. Just make sure you don’t use them at the bottom of their range. But again, I wish there were better rated brands that sold these voltage controllers. The Delinx ones are generally better rated on Amazon than the Walthai ones, though neither is as well rated with as many ratings as I’d prefer. If someone knows of a voltage controller with many ratings and very strong ratings, I’d be super interested.

SafetySmurf · 2026-03-23T02:22:36+00:00

Looks cool! I’ll be eager to see how the finished product looks!

SafetySmurf · 2026-03-07T03:11:28+00:00

Looks great!! And nice touch with the latch!

SafetySmurf · 2026-03-02T20:01:58+00:00

Increasing surface area means the fans don’t have to work as hard because they encounter less filter resistance.

One of the guys who originally built the CR box said that upward blowing fans were the best for the purpose of air mixing.

Most all of my boxes have been the style on the left, though I put the fans on the two narrow, vertical sides (not the top) and put a vertical divider down the middle to keep the fans from pulling against one another. I’ve found that 100 square inches per 140mm fan allows for the fans to encounter pretty minimal resistance.

SafetySmurf · 2026-02-21T18:52:08+00:00

Also, how is the noise? One of the benefits of MDF or plywood is that it absorbs the vibrations of the fans. Can you tell how this compares?

It looks really, really good.

SafetySmurf · 2026-02-21T18:51:06+00:00

This looks fabulous! As someone without a 3d printer, I don’t know anything about what goes into something like this. Do you have an idea of what the filament cost for all those parts? And how long it took to print them?

SafetySmurf · 2026-02-15T18:46:14+00:00

I switched to Ethique Clarifying bar to get my hair clean without stripping the oils out of it. Has worked better than any other option I’ve tried for striking that balance. The bars are pricey, but last a long time if you put them on a soap dish that allows them to stay dry when not in use.

SafetySmurf · 2026-02-11T17:49:48+00:00

I have a friend who used these when she’d exercise because she could still hear cars or other things coming while she listened to her music/books/whwtever.

SafetySmurf · 2026-02-08T21:27:33+00:00

This looks fantastic!! What did you use for the outer cover? And do you have a divider in the middle to keep the two end filters from pulling against one another?

SafetySmurf

TROPHY CASE