Measuring My Diy Air Purifier

Posted3 months agoActive3 months ago

crescit_eundo

75 points

11 comments

chillphysicsenjoyer.substack.comResearchstory

calmpositive

Debate

20/100

Air PurificationDiyIndoor Air Quality

Key topics

Air Purification

Diy

Indoor Air Quality

The author measures the effectiveness of their DIY air purifier, sparking a discussion on its performance, power consumption, and comparison to commercial products.

Snapshot generated from the HN discussion

Discussion Activity

Light discussion

First comment

18h

Peak period

84-96h

Avg / period

1.8

Comment distribution11 data points

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Based on 11 loaded comments

Key moments

01Story posted
Sep 27, 2025 at 7:07 PM EDT
3 months ago
Step 01
02First comment
Sep 28, 2025 at 1:13 PM EDT
18h after posting
Step 02
03Peak activity
4 comments in 84-96h
Hottest window of the conversation
Step 03
04Latest activity
Oct 2, 2025 at 10:44 AM EDT
3 months ago
Step 04

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Discussion (11 comments)

Showing 11 comments

polishdude20

3 months ago

1 reply

I'd be interested to know the decay rate when neither the window is opened or the air purifier is on.

cptskippy

3 months ago

Not the Op but I have PM 2.5 sensors in my house. There is one next to the stove, another in the main bedroom above the kitchen, another in the office above the main bedroom, and another in the garage.

Here's two samples. One was last night when I cooked pancakes, grits, sausages, and hash browns on a gas stove. The fan came on at 6:35:37.

The other is cooking one fried egg in the morning for breakfast.

https://imgur.com/a/zwBU6wA

Rebelgecko

3 months ago

2 replies

Power consumption (maybe CADR per watt?) is also interesting to measure. From what I've seen, that is the main dimension where homemade purifiers can lag behind dedicated ones. Well, that and aesthetics which is more subjective :)

jerlam

3 months ago

2 replies

The CR-boxes are rather bad in that regard, but the newer generation of PC-fan builds are significantly better than mainstream HEPA purifiers:

https://housefresh.com/cleanairkits-luggable-xl-review/#the-...

BizarroLand

3 months ago

1 reply

For comparison sake, a 20 inch box fan, which many CR filters are made from, consume 60-85 watts depending on their speed, which is 50-100% more electricity.

This could be improved by finding more efficient fans, but if you're going for the cheap $25 fans at your local big-box store, you'll pay more for it over time in electricity costs.

I have one as well, but I live in a geodesic dome home and use it in the largest open portion of my house.

The ceiling at its highest point from the lowest point is 18 feet up, and the open section is about 1/2 of my entire home, so the one 20" fan keeps air circulating and being filtered for an enormous portion of my home.

If you live in a more typical home, the 20 inch box fan CR filter might be overkill.

londons_explore

3 months ago

2 replies

The $2 PC case fan wins on both price, power consumption and quietness, and seems able to filter a roomful of air in an hour or so.

BizarroLand

3 months ago

1 reply

You will spend a bit more buying a few of them, a 12v power adapter, and the shell to tie everything together, but you are correct.

londons_explore

3 months ago

If you buy the cylindrical air filters, you can pop one on a table, pop a case fan on top, and hook it up to a phone charger via a 20 cent Usbc adaptor.

As a bonus, the USB-C PD adaptor has selectable voltage (5, 9, 12v) on little dip switches, and that can be used as a speed control for a 12v fan.

Turn it up to max when cooking, and down to silent again when sleeping.

No need for any fixings or case or anything.

homebrewer

3 months ago

You must have very clean air already if such a puny fan would be able to keep particulate levels within acceptable limits. In winter, my Xiaomi purifier with a quite powerful turbine fan (or whatever those things are called — they're optimized for pushing air through dense filters) is barely able to keep PM2.5 within 5-10 micrograms on max speed (with doors and windows closed). A PC fan would make approximately zero difference, on or off.

odie5533

3 months ago

I have a Luggable and love it! So quiet and yet loads of airflow!

zbrozek

3 months ago

I built around this thing, which I run at 10% throttle and which consumes 6 watts at that level:

https://terra-bloom.com/products/terrabloom-10-inline-duct-f...

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ID: 45400114Type: storyLast synced: 11/20/2025, 1:54:04 PM

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