Live data from Hacker News

Build a do-it-yourself home air purifier for about $25

uofmhealth.org

41–50 of 355 posts

Re: Build a do-it-yourself home air purifier for about $25

#41
post #34

I've been running a 3M Filtrete MPR 2800 in my furnace filter. https://www.purpleair.com/ confirms it works. There house averages maybe 60 PM 2.5 vs 200 outside. Don't know how good it is for furnace, but it hardly runs otherwise in Northern CA.

Do you have two air sensors, or do you just have one indoors and compare it with weather data?

Re: Build a do-it-yourself home air purifier for about $25

#42
post #2

Is there an advantage to attaching the filter to the front of the fan so air is blown through it (as shown in the video) versus taping it to the back of the fan so air is sucked through it? Just curious if that would make any difference. It might be easier to get the filter to stay if it's getting sucked to the fan.

probably makes the fan quieter.

Re: Build a do-it-yourself home air purifier for about $25

#43

I been pondering about this solution for months since my air purifier died back early summer. I also have an additional idea to make it more automatic by using a raspberry pi, hooking it up to a powerswitch tail (essentially cutting power to a fan) and have it automatically turn on and off depending on time of day, etc.

Maybe you could even use it in conjunction with something like a laser particulate sensor, to scope how effective it is and track its progress from day to day. Kick it on when it detects a nasty bunch of filth in the air, and kill it once it reaches a set acceptable level.

https://hackaday.com/2018/10/09/hacking-the-zh03b-laser-part...

This one only goes down to one micron though, so it might not be usable for many allergens.

Re: Build a do-it-yourself home air purifier for about $25

#45
post #38

I been pondering about this solution for months since my air purifier died back early summer. I also have an additional idea to make it more automatic by using a raspberry pi, hooking it up to a powerswitch tail (essentially cutting power to a fan) and have it automatically turn on and off depending on time of day, etc.

I have mine on a homekit enabled outlet ($20) for scheduling and presence-based triggers. Unfortunately I haven't found a homekit enabled air quality sensor to pair with it.

Eve room? https://www.evehome.com/en/eve-room

Re: Build a do-it-yourself home air purifier for about $25

#46

I been pondering about this solution for months since my air purifier died back early summer. I also have an additional idea to make it more automatic by using a raspberry pi, hooking it up to a powerswitch tail (essentially cutting power to a fan) and have it automatically turn on and off depending on time of day, etc.

Maybe you could have the input being a air quality sensor or scrape air quality from local government site / sensorup site.

Re: Build a do-it-yourself home air purifier for about $25

#47
Generally there are two classes of objects that you want to filter for.

Particulates and VOC (Volatile Organic Compounds). Think of particulates as specs of dust with varying size and VOC's as random chemical compounds such as spray paint, smoke, oders.

The general go-to clean room/industrial filter stack is Prefilter(F5 Bag)->HEPA->Activated Carbon. The pre-filter catches all the big particulates to prevents clogging the HEPA filter. The HEPA filter catches all of the really small particulates. The activated carbon captures most of the VOC's/oder/smoke.

The official way to monitor when a particulate filter is bad, is to measure the pressure drop across the filter, and compare to manufacture specs. For the carbon filters, you would install a gas sensor measuring whatever chemical your trying to scrub. When there is a spike in that particular gas compound from your sensor. You know the carbon filter is saturated, and should be changed.

It looks like the the filter mentioned in the article video,combines all the filter products into a single product. Nice! If your air handler can manage the increased pressure drops, please buy the most legit filters you can buy. It's literally the cheapest insurance you can buy.

Re: Build a do-it-yourself home air purifier for about $25

#48
post #45
post #38

Earlier quoted context omitted.

I have mine on a homekit enabled outlet ($20) for scheduling and presence-based triggers. Unfortunately I haven't found a homekit enabled air quality sensor to pair with it.

Eve room? https://www.evehome.com/en/eve-room

Thanks! Last I checked they were no longer selling version 1 of this product and hadn't released version 2 yet. This might fit the bill.

Re: Build a do-it-yourself home air purifier for about $25

#50

I was looking up air quality monitors but can't seem to find any on amazon with a calibration certificate that will accurately measure 0.3 micro particles. Am I the only one who thinks this is a great opportunity for a smart product with an app that has the features of a professional air quality monitor and simple UI / UX? If such product exists, does anyone know where I can find it?

Why do you need an accurate measurement for consumer air quality monitoring? I believe even a DIY arduino project with cheap optical dust sensor, like PPD42NS or GP2Y1010AU0F, would be enough.
Post reply on HN