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

uofmhealth.org

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

#131

Post by hinkley »

peferron wrote: post #130

Important tip: if you set up an air purifier in your home, make sure to plug all drafts around your house: windows, doors, etc. Even a DIY purifier with small airflow can make your indoor air excellent if given enough time to do so and no leaks to fight against. If you want to get some fresh air in your home, do not leave a window half-open all day long—instead, open all your windows at once to cycle the air as fast…

Also open your windows when you vaccuum. Send most of the dust outside instead of just what gets caught in the filter.

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

#133

Post by giardini »

Similar items are commercially available:

"The Fan Buddy is an electrostatic washable fan filter that attracts and captures airborne dust, pollen, dust-mite debris, lint, mold spores and pet dander. It will also help reduce smoke and smog. This Fan Buddy fits on most 20 in. box fans... "

https://www.homedepot.com/p/Fan-Buddy-20-in-x-20-in-x-1-in-W...

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

#134

Post by sgc »

electic wrote: post #110
benbojangles wrote: post #85

I built my own air purifier in 2016, living in London, I was living in a basement and was having breathing problems due to mould. My landlady was gaslighting me at the time, so I built the air purifier. It worked for a while but mould spores cling to the paper filter and eventually grow into the filter material. I think Dyson uses glass fiber filter to stop this problem. My filter helped a lot, but eventually I had s…

Woah, this is pretty scary. Thank you for sharing. How did you know it was mold that was in the air? Is there some sort of test kit that you can buy to test for this. Mold is pretty hard to detect because you can't really see it because it typically hides between the walls. Any advice appreciated.

By the time it is a health issue, it is usually visible. There is some air passage from within the walls to the living space, but not nearly as much impact as the visible mold on walls, furniture, etc. Sauce: Get paid to test sometimes.

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

#135

Post by jjeaff »

core-questions wrote: post #36
wbrasky wrote: post #35

Earlier quoted context omitted.

instead of a raspberry pi and all that entails, might I suggest a simple outlet timer

Good time of year to buy them, too, what with the christmas lights and all that. $5 ballpark.

I have seen the mechanical style ones at the dollar store. I wouldn't set my watch by it, but would be fine for this purpose.

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

#136

Post by sgc »

akeck wrote: post #89

Note that restricting airflow on a radial fan can cause the motor to heat up. Make sure you get a 20-inch fan with a fuse. To reduce heat, increase air flow by making a box with three filters and by using 2 inch deep filters. Also, when I built my three filter "box" last fall, I was able to order a set of three MERV-13 20x20x2 filters directly from Nordic Pure for less than what they cost on Amazon. Finally, to make…

I agree with placing the filters on the pull side, since that is what all hvac units do and what the filters are designed for. To be effective, you are also corrected that a deeper pleated filter with more surface area is the only way to go. But I am unconvinced the motor will heat up. Certainly there will be less air so if it is air cooled it will heat up from that, but at the same time, a fan in a partial vacuum uses less energy and should heat up less. Just slap a meter on it and you will see the draw can be significantly lower, since it is doing less work.

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

#138

Post by LeoPanthera »

HillaryBriss wrote: post #108
LeoPanthera wrote: post #57

Huh! I independently "invented" this myself a couple of days ago when the Camp Fire blanketed the bay area in smoke. I got a 20x20 filter and some duct tape from Home Depot and a box fan from Target. (After discovering that Home Depot only sells fans in the summer.) I don't think I was the only one, though. HD was doing a brisk trade in 20x20 filters, and I think I bought the last box fan at any Target in the entire…

nice job. can you say anything about the difference it makes?

I can tell you that it doesn't smell of smoke in the house anymore.

I still have a sore throat, but I also have to go outside a lot, so maybe that's not surprising.

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

#139

Post by sgc »

Kadin wrote: post #121
Dave_Rosenthal wrote: post #60

I spent the weekend researching, implementing, etc. air filtration as one of those affected by the CA fires. It was worth it! The first step for me was getting a device to measure particles in the air. The air quality index (AQI) is an aggregate score that is made up of contributions from several harmful components. Of these, the quantity (weight/volume) of small particles ( Directly measuring PM2.5 is very hard, req…

Did you put the filter on the intake or outflow side of the fan? I have built one of these (20x20 furnace filter on a box fan) and always put the filter on the intake side of the fan. However it seems like people are placing the filters on the outflow side of the fan instead, for reasons that are not clear. Since it seems like you did some measurements, do you have any idea whether it's preferable to have the filter…

when you place it on the intake, it is sucked against whatever you are using to stop it pulling into the fan, if it is on the outtake, it can bubble out on the edges and the air can escape rather than pass through the filter. Intake is the only correct solution for these homemade devices without a metal diaphram.

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

#140

Post by giardini »

smmnyc wrote: 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.

FWIW if you tape the filter to the back then the fan doesn't get dirty as quickly. [Every now and then you should clean the accumulated dust off a fan.]

BTW you need not cover the entire area of the fan with filter material. So, for instance, if your fan's breaker is shutting the motor down b/c of the load of the filter, you can slide the filter up to cover less of the fan with the filter, reducing the load on the fan motor. While not all air passing through the fan will be filtered, over time most air will eventually pass through the filter and the room will be cleared of particulates.

Similarly, it is not necessary that the filter be the same shape or size as the fan, since with each pass at least part of the airstream is cleaned. Eventually all the air in a room will pass through the filter area.

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