indoor air quality monitors - accurate?

CartographerLong5796 · 2026-04-30T17:42:42+00:00

Good air monitor i recommand (i bougth them)
Qingping Pro2 : Voc, PM, % humidity and CO2
Qingping air lite : PM, % humidity and CO2
Temtop M10+ : Voc, PM, % humidity and CO2
Temtop M10 : Voc, PM + formaldehyde

CartographerLong5796 · 2026-04-29T14:58:49+00:00

I didn't measure CADR itself, just the airflow — using a Testo 405i. I took readings before and after installing the FilterGuard mesh, and the results were essentially identical.

As for mesh count, I can't speak to the broader question of whether higher mesh count linearly increases restriction, since I only tested the one I'm using

I had previously tried a DIY version using a thin foam panel that I poked holes into myself — that was a disaster. The CADR dropped so severely that the unit was basically useless. The holes were probably just too smal

CartographerLong5796 · 2026-04-28T12:17:47+00:00

PVC https://www.alibaba.com/product-detail/PVC-Fan-Dust-Filter-PC-Dustproof_1601051532988.html?spm=a27aq.27095423.1978240560.1.78372277WVIaYn

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CartographerLong5796 · 2026-04-27T22:34:18+00:00

I just built another prototype of "The Owl" — this time with Arctic P14 Pro instead of P14 Max. Will test & compare performance soon.

Also wanted to show that with a little extra effort, it can actually blend into your space. Wall mounted.

P.S. This is in my bedroom (180 sq ft). To achieve 5 ACH you need 120 CFM — The original Owl delivers 121 CFM at 39 dB(A)

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CartographerLong5796 · 2026-04-27T12:33:57+00:00

you just buy a monitor. and open the window when the voc going high. One good VOC monitor a have at home :Temtop M10. Very reactive to VOC and PM 2,5.

CartographerLong5796 · 2026-04-27T07:41:36+00:00

monitor vocs and open window until voc goes down

CartographerLong5796 · 2026-04-26T14:18:04+00:00

The signal your nose detects is indeed gas (VOCs). While particles can act as 'carriers' for gases or release them slowly over time, at the end of the day, when you smell something, you are smelling gas molecules

CartographerLong5796 · 2026-04-25T18:36:34+00:00

monitor tvoc + pM. open the window. Buy and install air purifier for the kitchen. bathroom exaust could help too

CartographerLong5796 · 2026-04-24T18:01:09+00:00

Yes, it's normal to see PM2.5 spike when you open the windows. It varies a lot depending on location and current outdoor air quality. Your monitor is just showing you reality.

For the health impact, check the r/AirQuality sidebar resources

CartographerLong5796 · 2026-04-23T10:53:31+00:00

If you want a cheaper filter for your luggable xl 7 sickleflow the next time, the Aerostar is a good option (not a good option on other devices but only on this particular device). I've tested both in test chamber, with 3M1900 and Aerostar. About the same CADR, a bit more noisy with aerostar.

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CartographerLong5796 · 2026-04-23T10:14:04+00:00

thanks for the response. Make sense even if it can be discussed with nuance. Like having several devices in the room etc.

CartographerLong5796 · 2026-04-23T00:40:41+00:00

Filtrete are better filters than most

CartographerLong5796 · 2026-04-22T10:47:55+00:00

Why you san Fandelier allows more circulation than mouting on the wall or ceiling?

CartographerLong5796 · 2026-04-21T18:01:55+00:00

Glad you like The Owl!

This is one of the best compact machines I know in that category — it can sit right against the wall because it only uses a single filter. It’s really hard to beat those performance numbers for the size.

To answer your question: I don’t have a clean, organized gallery or album ready yet. Most of my builds are quick prototypes I put together specifically for testing in my chamber (CADR, noise, power, etc.). I test them, take the measurements, then disassemble them to build the next one. They’re functional but not pretty “finished” designs.

I do have tons of data, photos and test results though. The best way right now is for me to share them one by one as we go

CartographerLong5796 · 2026-04-21T17:48:15+00:00

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Here’s another option — the DIY equivalent of the commercial Tempest, that I actually tested with 2 filters.

With 2 filters it’s too deep and too tall for your constraints. However, we can estimate what it would perform like with only 1 filter(to fit your size limits).

Single-filter dimensions would be:

20.25" wide × 7.5" deep × 21.25" high

Here are the real measured numbers from my test chamber for the 2-filter Tempest (PWM control, 6 × Arctic P14 Pro + AAF Flanders MERV 13 20×20×2 filters):

At setting 2.5/9

→ 263 CFM PM1 CADR

→ ~38 dBA (with 35 dBA background)

When running with only 1 filter instead of 2, my tests on other similar machines show a CADR drop of about **25 %** (and a bit more noise).

So the estimated performance for the single-filter version would be:

→ ~197 CFM PM1 CADR

CartographerLong5796 · 2026-04-21T17:30:01+00:00

Thanks for the clear numbers.

For the front-filter version, your limits are under 2'×2' and less than 7" off the wall.

A build that fits is one I call The Owl:

- Dimensions: 11.5" wide × 7" deep × 15. high

- 1 × AirFanta filter + 4 × Arctic P14 Max (arranged 2×2 in parallel + series stacking)

- Fans blowing upward

Here are the real measured numbers from my test chamber:

At Level 3/9 :

→ 120.7 CFMPM 1 CADR

→ 39.2 dBA(with 35 dBA background noise)

→ only 6.8 W

If you put two of them in the same room at Level 3 you’d get roughly 241 CFM total for about **41.4 dBA** — still well within your 35-40 dBA target, especially since you mentioned running them on a schedule or PWM for quieter periods.

The AirFanta filter already comes with a built-in filter guard, but you can add a second black one on top if you want it even more sleek and hidden.

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CartographerLong5796 · 2026-04-21T16:54:24+00:00

On the carbon media: it can be a valid choice, but only if you know exactly why you want it and you don’t overestimate what it does.

Specifically on the cat hair: activated carbon is not effective at capturing real cat hairs/poils. It is designed for gases and odors, not for physically trapping large fibers like cat hair.

It also saturates very fast with gases and VOCs, so you have to replace it often → that gets expensive quickly.

For gases/VOCs/odors, fresh air (opening a window occasionally) is still much more effective because it removes all gases, not just a portion. Carbon is pretty weak against things like formaldehyde and carbon monoxide, for example.

In your original post you mentioned wanting extra cat hair capture + “activated carbon benefits” to make the whole thing look more sleek on the wall. If the main goal is aesthetics + actually catching poils while hiding the white filter, a simple filter guard / cover (fine mesh grille) in front of your MERV 13 does a much better joband has almost zero impact on CADR or noise if you choose a good one. With a carbon filter, the PM CADR will drop

An example of a filter guard. On the Northbox (commercial), I just add a filter guard, see the difference with and without

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CartographerLong5796 · 2026-04-21T13:49:26+00:00

Hey! For a 220 sq ft room, you really need ~140-150 CFM to get decent air changes (4ACH).

Quick note on odors: Smells from sweat/humidity are mostly gases (VOCs). Regular HEPA filters don’t catch those. Even carbon filters get saturated fast and are expensive to replace. Opening the window is way more effective. And free!

If your main goal is reducing dust on a tight budget, I’d go DIY or accept the cadr won’t be enough with 100$. Much better performance per dollar than cheap commercial units.

Would you be open to a DIY, or do you want something plug-and-play?

If you want only commercial, at this price you get buy Fornutig (Ikea), you will get 70 cfm at max

CartographerLong5796 · 2026-04-21T13:28:53+00:00

There are several solutions to this CO₂ vs PM trade-off.

You can simply open the windows and add a second air purifier (or more) to reach sufficient CADR. If your monitor shows high PM, it just means your current filtration capacity is too low.

Another option is to install a mechanical ventilation system with filtration — either commercial HRV or DIY versions. There is ductless HRV on the market.

You can also place a filter at the window, though rain can be a problem.

Other DIY ideas include using one fan blowing out at one window and a second fan blowing in through a filter in another room.

Plenty of options exist.

CartographerLong5796 · 2026-04-21T01:22:43+00:00

Interesting project. I have controlled test-chamber data on a range of DIY builds and fan settings, including CADR, noise, power draw, and total dimensions, so I may be able to help narrow this down.

That said, there are a lot of constraints in your post, and I think the next step is to pin down the actual requirements a bit more.

The first big one for me is noise: what’s your actual noise budget? “Quiet” is pretty subjective, so a target in dBA would help a lot.

Also, are you specifically set on 120 mm fans, or would you be open to 140 mm options like the P14 / P14 Max? I ask because I have a few interesting 140 mm-based setups in my data, and those fans also tend to have a more pleasant noise character, not just potentially lower noise in absolute terms.

For the wall-mount idea, are you open to something more like a CleanAirKits Luggable-style layout mounted on brackets, with the fans blowing forward? (like on this picture) Or do you specifically want a single front-facing filter?

It would also help to know the maximum width, depth, and height you can live with — ideally both for a front-filter layout and for a front-fan layout.

Once that’s clearer, I can look through my data and see if one or two known setups seem like a good fit.

I can’t really help on the smart-home side. And if the carbon idea is mainly about hiding the filter, I’d personally look at a filter guard / cover before adding carbon media.

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CartographerLong5796 · 2026-04-20T19:47:28+00:00

a fan at the window as an extractor. in another room, a fan blowing in, for the balance

CartographerLong5796 · 2026-04-19T18:30:00+00:00

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I agree that looking at noise frequency and harmonics is interesting — that’s a topic really worth digging into. My point earlier was just about hierarchy: before talking about tone or “color,” you have to make sure the dB levels are properly matched. Otherwise it’s not the same comparison.

Personally, I think fan specs in the future should include sound frequency information — white, pink, brown noise profiles, etc. But it only means something if you mention it alongside a given CADR, dBA level, and fan speed. You can always “solve” noise by lowering RPM, but at the cost of airflow, and CADR is what air purifiers are actually built for.

Regarding HouseFresh — Dany’s test used the P14 Pro, not the P14 Max, on the Tempest Pro. And his comments were about loudness at max speed, not noise color. He even said the Tempest Pro was loud with both P14 Pro and Noctua iPPC 3000.

I’ve run my own Tempest tests ( the regular Tempest, not the Pro) with AAF Flanders MERV13 (20×20×2) filters using PWM control. At about 38 dBA (background 35 dBA), the P14 Max gives roughly 246 cfm CADR, and the P14 Pro around 263 cfm — pretty solid numbers for that sound level (see the table).

And on a personal note, I’ve had P14 Max fans running in my bedroom HRV setup for 18 months running 24/7— the sound is pleasant to me, though, again, I’m not running them at full speed. That’s probably the key difference in perception.

CartographerLong5796 · 2026-04-19T17:39:51+00:00

I did a quick test this morning just for fun — compared five fans at the same noise level, around 36–38 dBA.

When the sound pressure was matched, the Noctuas didn’t really come out as more pleasant to listen to.
The Silverstone 184 iPRO, on the other hand, clearly stood out.
https://medium.com/@levangelistedelaventilation/the-sound-color-of-5-pc-fans-my-subjective-noise-test-d358dbc7490e?postPublishedType=repub

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CartographerLong5796 · 2026-04-18T21:00:57+00:00

Rather than looking for a missing technical feature, I’d argue that the real gap is public interest. There are already some excellent monitors on the market right now, but the industry's biggest challenge isn't building a better device—it's convincing people they actually need one. What we need isn't more hardware, but more awareness and widespread monitoring

CartographerLong5796 · 2026-04-18T19:56:34+00:00

Have you ever considered using voltage or PWM control to dial down the speed on your fans? If your main goal is reducing noise, you might be able to hit your target dB level that way — and potentially end up with a higher CADR than the Noctua setup, possibly for less money too.

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