DIY Air Cleaner Filter Box with Fan: the Comparetto

My friend Neil Comparetto came up with a very effective, very inexpensive way to clean air for less than $100. It's not fancy, but it works as well or better than many high-end air purifiers and filtration products 'they' are trying to sell you. The important thing is that it's a fan and a filter, which is all you should ask for in an air purifying device- nothing that 'destroys', 'eliminates', or 'sanitizes' using 'electronics', 'UV', or 'plasma'.

[seanile]

I've noticed that a 20x20 filter is the same price as a 20x30 filter. I used 20x30 filters, it made it 10 inches taller and gave me an additional 800 square inches of filter surface. 10x20 per filter x4 sides.

[NB-dzmx]

We used black duct tape, covered all of the cardboard edges with it, and used a black box fan. Looks MUCH better this way!

[CaedenV]

Been a little over a week with a box fan and 20" filter and it is FANtastic! Noisy as hell, so I run it on high for an hour or two in the morning before work, turn it off while I work, then on while I am upstairs for lunch, and then on for a few hours in the evening when the noise level does not matter anymore. This has rocked my world! I have been developing a lot of food sensitivities over the past few years and 2020 was the start of getting that sorted out and finally finding exactly what I am growing allergic to (and oh god... it is everything good! I have lost sooo much weight this last year because I have to avoid all dairy and corn products, ammong other things). Anywho; I was starting to feel a bit better, but still felt tired and zoned out, and just lethargic and not great; Day one with the box fan/filter and I could already notice that my eyes felt less puffy. They didn't feel puffy before, but the feel much easier to open now. After a few days, I noticed I was sleeping better, and feeling more refreshed. More alert for work, and more up for physical activity after work to do projects or play with the kids.

Last friday was the 1 week mark and I just feel like 'me' again. The symptoms had been building so gradually, and were so generalized that I didn't realize I was dealing with a breathing problem. I just assumed that there were still some food issues that needed to be nailed down.

When I get closer to the 2 month mark, then I will pick up a few more of them, and try one of these 4-filter riggs. Also going to try and find a quieter fan with less backwash (ie more air through the filters), and also going to try and put it on a timer so I don't need to remember to run it periodically. I think I have some old christmas timers with the pins you push and pull for on/off times. May be able to use that to have it run for 15 minutes every hour or two to keep things going; and if I can get it to run effectively on low or medium then it may not distract from the work calls.
Also going to look at 20x25" filters. In my area you can often find those cheaper than the 20" square ones. Having the whole thing 5" taller should only make it better, and if they are cheaper then that just makes it awesome.

[firstreviewer]

Not only do these box fan filters work they work very well. I did not build the 4-sided fan filter, but I will now….Here is the proof they work in cleaning the air….A few months ago my wife told me that she was not breathing very well while sleeping. So, I started putting new filters in our duck system more often, but it didn't seem to help her. I then built a box fan filter with a 24-dollar hepa-filter attached. Then not only did my wife sleep better, but our cat, that we had been giving daily allergy medications to for the last 4 years, because it coughed and sneeze, has not sneeze or cough one time in 4 months since we started using these simple filters. Thank goodness no more cat medicine. Give these simple filters a try I think you will be glad you did. I attached my filter to the box fan by using painter’s tape. If you put the filter on the box fan where the air enters the fan you really do not have to use much tape the air stream keeps it in place. Best of luck! FR.

[ebillcoyne]

If you do not seal the bottom, particulates seep through the bottom. For four years I used this and sealed the bottom with another filter and propped up the filters off the floor. Easier on the fan motor too.

[onedecimaleight]

Take the cardboard that the filters come in to display in the store and cut to form for the bottom. Do not leave the bottom open.

[น้ําฝนเปียสง่า-ฝญ]

*Works great with **Fastly.Cool** ! Love all the features offered! Multidirectional, temperature controlled and various speed settings! This is our third of this product!*

[ablackformula]

I just recently built one by screwing then taping an aprilaire 20x20 whole house filter cabinet to a 20x20 box fan. The filter is several inches thick and does a good job!

[QuadroNVS]

I just saw this on DIY filter This Old House. Simple but genius.

[PaulReta]

I suffer from pollen allergy. (Symptoms are sneezing, congestion and runny nose, as well as itching in your nose, eyes and/or the roof of your mouth)
For many years I try every drug available, which improve my condition and I still use them of course. Although, sometimes is not enough. So, if you live in a small apartment as I do you can try this method to filter the air in less than 30 minutes. First turn on your air conditioner in “Dry Mode” (the one with the drop of water symbol), then place a floor fan at maximum speed pointing inside your bathroom, and turn on your shower with hot water. It will create a hot fog inside your bathroom. The contaminated “cool” air will flow inside the bathroom via the fan at floor level, some undesirable particles will get stuck in the damp walls, others in the mist and others will be washed out with the shower rain itself.
Subsequently this hot fog will come out of your bathroom at roof level and your air conditioner will capture this moisture with the rest of the pollen and particles, it will condensate it and be expelled out of your house via its draining system.
Then turn off your shower first, and let de fan and the air conditioner ON until the moisture disappears completely and your bathrooms walls are dried. The time will vary depending your apartment o house dimensions, but you will feel the relief immediately.

[eugenew]

Put a piece of card board on that open end

[zodiacfml]

having it on the floor is great for simplicity but could have better efficiency. having it on floor will only collect particles needlessly which can be picked up during house cleaning (mopping/vacuuming). best to have this around average table height and have the fan point directly to mostly where people are, like that dyson air purifier/fan

[daytopotato]

I love this video and thank you for sharing! I have 1 filter on the back of a fan and I feel like it's problematic. And you mentioned the backpressure which is probably why the fan rattles/shakes a bit when it's on. Buying more filters this evening and will use this box method. Thank you

[thompson]

Does the flow direction matter? I understand that many would want to have a fan blowing out on a cool day, though I am wondering if mount the fan to blow INTO the cube so the fan isn't blowing papers or whatever is hanging out. You could have it at full speed and not cause any air disturbance.

Why do you insist on mounting the suction side to the box? I might have missed it in the video.

[toldt]

TOH just released a video on the Comparetto - 3 months after you. And your video is better. And it doesn't look like Neil approved the TOH video like he did yours. 👍

[tomc]

With a forced hot air system for heating my house, does the constant operation of the fan and filters affect the the air intake of the system?

[randonyearold]

Hi! Informative video! My dad and I have a question since we're looking for something that can fit in our small house. What benefit do the 4 side-grates bring that make this setup better than just a single fan and filter? If you don't mind answering!

[azlannakamoto]

What a great and simple design, i can tell this diy air purifier will give the same performance like big brand would..if you feel like increasing its cadr...no problem just replace the box fan with a stronger one!

[kizunadragon]

use a piece of cardboard for a base and seal it that way all air has to pass though the filter. Also upgrade to Merv 13 2 inch filters. Merv 13 filters catch everything from dust to pet hair to smoke to covid 19. 2 inch filters give more surface area which means the less the fan has to work to pull the air though. The higher the Merv rating the harder it is to pass air through it. You can offset this by getting a deeper filter. Also don't buy a fan with a switch in the back, those are a giant pain for this application.

[c.]

Hi. Question. Does merv13 possibly clean asbestos dust? Im worried about the possibility of asbestos dust in the room, due to a fix to a hairline crack in a wall. The wall is behind the oven, its a very old house. I didnt think of the possibility the plaster might have asbestos until the fix was done. The crack was about 5 feet long. It was opened a bit more and then filled with drywall mud and sanded. I'm worried. And this was done sometime ago. The possibility it contains asbestos is scary