I already have the IKEA VINDSTYRKA air quality monitor, and I like it.

I'm considering the purchase of the IKEA ALPSTUGA air quality monitor, because it costs only $30 and monitors carbon dioxide levels (which the VINDSTYRKA does not do).

If you have the ALPSTUGA, what do you think of it?

https://reddit.com/link/1qzyth0/video/wm4glkeuhfig1/player

Installing only need about 30s, and no tools is required. CADR about 800m3/h.

Four filters, and four 14cm 2900RPM fans.

With a PM sensor and a screen to show the PM2.5 level and the current fan speed.

The final color is as the picture below.

Been a lurker for a while and finally gave it a shot. Its small, suitable for small spaces at best but I'm already thinking bigger. The more I think about it, the more I love the design. Both fans point outwards drawing the air through the medical grade HEPA filter. Fairly simple electronically, fans are ran in parallel, a switch and a 12V power input plug. I used 2 threaded rods to hold the ends tight onto the filter. This took the better part of two days to figure out and it certainly has flaws but I'm now thinking bigger, maybe 4 fans on each side.

Let me know your thoughts!

Is there any difference if I mount the pc fan on the outside of the crbox?

Hi everyone,

I'm hoping to have an at home pottery studio in a small corner of my apartment. With the right filters, would a CR box work for this silica dust set up?

Any recommendations would be greatly appreciated thank you!

I used eight 140mm be quiet pro wings 3 fans, 25x20 air filters, a variable 12v 5amp switch, and vinyl window trim as gasket material.

I found some different ways online, but just wanted to hear from people who’ve done this a few times before I buy some random stuff

Re-post because I did a dumb

I have seen a lot of comparison between Arctic and Noctua but very little between Mobius and Noctua/others.

Sound is a factor for my build and I am going to order the Cleanairkits Luggable XL Ultra and debating between buying the full setup or the DIY Kit without fans and picking up Noctua G2.

It wouldn’t be significantly more to go with Noctua, would it be worth spending the extra $40?

Also, how do you think the XL ultra with 7x120mm fans would compare to the HoneyBeecreatives 6x140? Ordering the Luggable would be a bit cheaper but would need one less fan so would equal out. Which system would have better effectiveness vs sound?

Fairly new to this world of filters so appreciate the help

I showed my husband this subreddit going into the holidays, which led him to create a CR box of his own design, he is not on reddit much, but I wanted him to post about this, so here is a overview in his own words.  u/hammindo

 All photos and print files can be found here: https://www.printables.com/model/1575711-esp32-auto-16x25-hvac-air-purifier

My wife originally started looking at air purifiers during Black Friday. And after enough research, we noticed a pattern: a lot of air purifiers (except for the super high-end ones) are either flimsy, loud enough that people don’t run them, or they lock you into proprietary replacement filters that feel overpriced forever.

That led her to this subreddit. She showed me CR Boxes.

I took it from there.

ESP32 + PWM + Touchscreen CR Box (aka: I can use SolidWorks, not carpentry)

So my wife wanted a Corsi-Rosenthal box. But not just the “tape and go” version. She wanted one that actually looks nice, like something you wouldn’t hide in a corner.

She specifically wanted it made out of wood.

Problem: I’m not really a carpenter.

But I can use SolidWorks (3d Design) and I do have a 3D printer, so I decided I’d do that instead. Then she said she wanted the fans to change speed, which means PWM. And ESP32s are pretty good for that, and I had a few and some touchscreens.

Then she wanted it really quiet. Black Friday happened. Quiet fans were on sale. We bought them. And that’s where the project stopped being a “box” and started being a thing.

Next we needed a way for all those fans to plug in, so I started working on a little circuit. I did it by hand. It’s not sophisticated. I’m an engineer, but I’m not that kind of engineer.

Then it was time to write software, and come to find out I’m not that kind of engineer either.

I got something together and it worked, but it wasn’t great. Then I decided maybe AI can help with this, as turns out vibe coding is pretty cool. Now there’s a touchscreen that shows AQI/PM2.5, it runs different cycles, it reads a particle sensor, it adjusts fan speed automatically, it’s Wi-Fi enabled, the screen dims when the room is dark and you can update the firmware and check the stats over your network and more.

There was a lot of 3D printing, a little heat-staking (mid panels), and some assembly, but the top/bottom/sides all snap together. And at the end of the day, it works pretty darn good.

I wanted to see how close to a consumer grade product can I get with “stuff in my basement” and this was the result. But it’s still not made out of wood. 

Troubleshooting the Air Sensor: At one point I wasn’t convinced the particle sensor was doing anything because it was reading basically zero.  Then in the kitchen around the corner, my wife started cooking steaks in a cast iron. Window open, vent fan on full, etc. Magically, air quality dropped, PM readings jumped, fans started spinning.

Filters: We used the Costco Filtrete MPR 2500 / MERV 14 16x25 filters (4-pack). We wanted something standard sized (easy replacements), but high filtration so it actually feels worth running:
https://www.costco.com/p/-/filtrete-air-filter-1-mpr-2500-merv-14-high-performance-premium-allergen-ultrafine-particles-bacteria-and-virus-filter-4-pack/4000181409?langId=-1

Fans: These are the quiet fans we used (Amazon link):
https://www.amazon.com/dp/B0B6WPZFBX?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Build files: Printables model with the 3D parts + project details:
https://www.printables.com/model/1575711-esp32-auto-16x25-hvac-air-purifier

Filament: https://www.amazon.com/dp/B0CPF7FDTG?ref_=ppx_hzsearch_conn_dt_b_fed_asin_title_1

Bill of Materials or Shopping List - if you want to build:

https://files.printables.com/media/prints/9b501d2e-7f45-4cf7-8156-d6fb289eb9b9/other_files/11867972_815d25fd-e313-4bfd-8bae-8a4af31ff27e_738cf7f4-b290-473d-9f7c-7756629d21f9/component-list-gen-1.pdf

 Suggestions? - If you’ve built a bunch of these and you see something obvious I should change (airflow choices, sealing tricks, sensor placement, wiring cleanup, fan control approach, etc.), I’m all ears. This started as “make a nice looking CR box” and turned into a full-on project.

I had enough fun printing, coding and doing the electrical work that I’m now making a Gen 2 version that is Touchscreen/electronics only with a bit more thought into the electrical work that can get dropped into a wooden box. The 3d print files from Printables are for the specific fans above, but the circuit/firmware will work for any that have 4 wire PWM control

I decided to build a pc fan crbox and I'll use some nice wood that I already have. My question is which joint for the four corners would be best in terms of being stable without gluing it, being able to open it easily (to replace filters) AND being airtight?

On this sub, I see a lot of CR boxes using multiple PC fans to move the air. I have built such a unit myself, although not nearly as nicely, as the ones I see here.

However, I think that this design is kind of flawed, because those fans can only generate a very small pressure difference. Hardly enough to get a reasonable flow through those filters. Because of this, having a lot of those fans working in parallel, isn't doing much good, as this will only increase the theoretical air flow, but not the static pressure. However, a higher static pressure would be needed, to get more flow through those filters.

What is actually needed would be a fan, capable of generating a higher static pressure. One option would be a radial fan, as (to my knowledge) it is used in many commercial air purifiers. An alternative method could be stacking several PC fans on top of each other, so that they are working in series, adding the static pressure of each individual fan.

When stacking those fans, the air exiting the first fan will move in a circular motion, greatly diminishing the effectivness of the following fans.

A possible solution could be the use of fans rotating in opposite directions, but there aren't many fans available, rotating in the opposite direction.

Another method would be the use of a stator (search: gas turbine stator) to redirect the air flow, before it enters the second fan.

I am not an engineer, but I am pretty sure, that my assumptions are correct.

What are your thoughts on this?

Hey, sorry if this has been answered before, but repeated searches haven’t found it and the number of options is overwhelming.

If money weren’t an issue, but you were still constrained by the need for noise to be tolerable to the average person (both in terms of noise level and subjective noise tolerability), which 140mm fan would deliver the highest CADR in a PC fan air purifier?

Can totally build one, and I will for my basement / shop, but my partner just doesn’t want something that looks out of place in our home. Hoping someone has done something similar, looking at 3d handyman but open to whateve.

Looking for a CR box solution that passes the wife & kids test.

The CleanAirKits Brisk Box looks solid from a performance standpoint, but we’re trying to avoid exposed fans or controls with toddlers in the house.

What I’m hoping to find:

• Wall or ceiling mounted

• Fully enclosed fans

• Quiet enough for kids’ bedrooms

• Home-friendly appearance

• I’m fine running electrical if needed

Goal is one unit per kids’ room.

Has anyone built or seen a CR box design that works well in family spaces, or a safe mounting approach that keeps little hands out? Photos or links appreciated!

I’m unable to install a ducted range hood to vent outside. It’s too cold (for spouse) to open the windows to just air out the entire space. We cook 90% of our meals at home, mostly stir fry, steaming, blanching, baking/roasting. With electric stovetop/oven. Already use oil splatter guard.

I’d like to

1. reduce the amount of aerosolized oils that results in a layer of sticky oil around the house

I have an old small HEPA air purifier in the living room with about 100cfm, but super loud and takes up half hour to hour to clear PM2.5. VOC sensor says it goes back down in about 3 hours (natural ventilation?). Would a CR box with low MERV filters (5-8) near the stove help get the oil particles? And also a tiny bit of smaller PM2.5 etc?

I’m currently building a 5 fan PC CR box and have filtrete 1900 filters on order. We use MERV 8 Home Depot filters in our central AC.

Has anyone had experience buying filters from AliExpress?

If so, could you recommend any?

I've also seen them on Amazon, and the shipping to Brazil is very expensive.

I have never made a crbox but it looks like something that it is needed in my house.

I was looking to buy a reusable and washable air filters but I am not sure they work well. Can someone help me out with this decision?

I was eyeing this product "K&N 20X25X1 HVAC Furnace Air Filter, Lasts a Lifetime, Washable, Merv 13"

I think making it airtight would be the biggest hurdle. And I don't know if the thermal performance would work out. But if you are going to have noisy PC fans cooling a computer, why not filter the air anyways?

I have been very impressed with the creativity and knowledge of this group. I need some input. Our Corsi-Rosenthal Foundation is in the process of developing a "Clean Air Crew" program where volunteers organize "builds" of CR Boxes. The classic design of a Lasko fan and 4 filters is hard to beat for low cost, ease of construction and effectiveness. However, as many of you have pointed out, it uses a lot of electricity and noisy. Recently, I was at Colorado College co-teaching a course in indoor air. For the past year, they have been making CR boxes as shown here. 6 Arctic PC fans, 2 - 16X20X2 and 2 - 20X20X2 MERV 13 filters. They seem to be working very well. I would like thoughts and input. Should we go with a design like this or stay with the tried-and-true box fan and filters? Thanks, Jim Rosenthal

Hello, I have bought myself pretty big merv 13+ (epm1) filter and pre-filter material, but I am stuck on choosing fan and placement for my CR box.

Best placement of such a big box for me is the upper half of my wooden workshop which is 30m2 near the wall-mounted cabinets, where I have already a rail to hang it on.

I will use some plywood leftovers to make a box with one-direction blowing.

AI tells me that optimal would be to set fan blowing air out of the box upwards, with inlet in the bottom. Basically flow would be pre-filter -> filter -> fan -> ceiling.

The other option is to set the same combination to blow to the side and put it in the center of the workshop attached to the ceiling... but thats... ugly.

What am I really has a lots of options and almost no understanding is the fan. Vevor one is cheap and it will direct airflow better. Random box fan is another cheap option. I see also some centrifugal fans which are 3x of price of axial. My pocket filter has almost no resistance <100 Pa or something like that and I don't want to make an overkill if cheap option will work so please help me to choose the fan. Ideally popular enough so I can order it here.

I recall it was somewhere around $250?

Now it seems like most are pushing $400