How to Make a DIY Air Filter | Ask This Old House

[@marshacollins9986]

Three months ago I made two of these and began using them in our two story house. There was an immediate noticeable decrease in dust on furniture and floors. Best of all, we realized after a few weeks we no longer wake up at 3 am with sinus/allergy headaches. We are breathing easier. Thank you!

[@freemind3142]

Glad 2 hear that ... allergy sufferers are helpless with dust problems

[@marym1485]

So one fan is enough to cover each floor of the house?

[@denverdanoreno]

Good to know that this system works for you. I've done what many people have done, used one filter on the backside of a box fan, but this one is far out!

[@shantiawilliams3615]

It may even work better if the box is not behind the back of the fan

[@bl8388]

I used one and it helped clean allergens out of the air. Much better! They made me feel foggy and groggy and even kinda boggy. Now I think clearly, and my IQ jumped 50 points! Would be more impressive if my total IQ wasn't 88.

[@Subgunman]

What I have done is add pre filters to catch the larger particles. This way you won't clog the finer filter with the thick stuff. Throw away the cheaper coarser filters more often and conserve the finer filters.

[@benc1927]

I do the same thing except my pre-filters are the washable re-useable ones.

[@one7decimal2eight]

Totally unnecessary. If you're using them in your house they take forever to clog up. Now, maybe if you're using it in a wood shop or if you're in an area with wildfire smoke, sure, add pre filters. Keep in mind the more dense the filter the harder the fan has to work to pull air in.

[@benc1927]

@@one7decimal2eight Not true. I've tried it with and tried it without. You'd be surprised how much the cheap filters will catch. Don't believe me? Just try it out yourself in within a few weeks you'll see.

[@rickfrank7934]

link for your pre filters? do they work with the setup In this video?

[@bobbg9041]

@@one7decimal2eight Also a higher merv ratting can and will freeze your A coil and damage you compressor becuse the A coli froze up. Trust me my old system would build up 4" of ice and tottaly stop the air flow. Making the system work really hard and high electric bills. You should avoid closing off rooms and closing vents you want the air to move without restrictions.

[@glenniz1]

I live in Southern Oregon and during the last ten years we have had the worst fire seasons ever!!! Even with all the windows closed, we still have smoke pollution entering our home. If you have ever had to deal with smoke inhalation over months at a time, you will understand how important this simple invention is...Thank You for this simple, effective, and potentially life saving device!!!

[@petehille5561]

Me too, building one today!

[@stevenlengyel9701]

Yes, same in Southern California the air is horrible, dust like I’ve never seen before.

[@Nunnia222]

Did you build one and how did you like the results? Also fan blowing in or out?

[@chewyslimei289]

​@@Nunnia222 6:57 Air in from the sides and out from the top

[@Ma_Ba]

​@@Nunnia222same question. For a second, he spoke of arrows on filters, but not on fan. Any answer on trial and error? (Wildfire 2.5 particulate indoors because my windows are not airtight.)

[@dosgos]

Put basic foam or cloth outside filters as a prefilter to extend filter life. Prefilter catches larger particles. Clean prefilter from time to time with vacuum cleaner.

[@ekleko1]

I use cheaper lower merv filters, like a 6 or something. I just double them up.

[@ItchyKneeSon]

...and use a pre-filter on your vacuum filter. Then, vacuum your vacuum's pre-filter and filter with a second pre-filtered vacuum. Continue forever. :D

[@digiryde]

​@@ItchyKneeSon So, you get to cursing at the recursive.

[@assassinlexx1993]

I bought washable air filters. They are the best. Just pop it out, hit it with the hose. Next morning dry ready to go. Saved a fortune.

[@nedcramdon1306]

@@ItchyKneeSon Ha, ha, that's about the size of it....... then install a germ zapper laser.

[@bashbroq]

This old house always putting out quality stuff, still one of my favorite shows

[@tnt3692]

A 15 yo boy invented this and put out the info free for everyone

[@skyrocketcoast219]

Northern California: Made one 2 weeks ago, the day our area started to get bad air from big Tamarack Fire 3 hrs away. works perfectly! Did not have any duct tape, used Tvek tape instead. Air filter is placed in front of old glass door in kitchen that goes out to patio.

[@skyrocketcoast219]

Aug3- Usung it now about 3-1/2 weeks: dyi air filter works really really well. Had 5 days bad air&;all ok. put it in daily even when air ok - noticeable difference in using less daily asthma inhaler.

[@freyakitten243]

I'm in Nor Cal as well and with an AQI of over 450 today, I'm thinking I will head to Lowe's tomorrow to make this. Our whole family just finished with having covid and 2 of us have lost our sense of taste and smell so I have no idea if it smells smokey inside, at least this way, I can see the filters getting dirty!

[@BlessedLaymanNC]

Aiming the filter outside is not as good of an idea as it sounds. The fan sucks dirty air in but blows clean air out. When you point the fan outside, it draws more dirty air from outside back into your home. If you put it in a room, it circulates the air and dust. It sucks the dust into the filters and blows clean air in the room. It can leave you with cleaner air in the room than you have outside. That's what you want.

[@johnparis6233]

Do you recommend setting it up where the fan is blowing dusty air OUT of the room through the window? Or blowing fresh air (with the filter) into the room?

[@gone2dmtns]

I'm remodeling a house and this just gave me some ideas on how to setup a filtration system to help keep from contaminating the finished rooms with construction dust and keep the room air a bit healthier.

[@TheZankaloni]

Please tell me more. I’m doing the same. I’m thinking of using pvc pipes for both air input pipes and exhaust pipes. I mean why not?

[@buddhamack1491]

Use a merv 1 filter on the outside of each merv 13 to control larger dust and hair thus prolonging the life of the merv 13

[@coreyg7255]

I did a basic version of this when we were choking with wildfire smoke back in August, worked well and it was pretty obvious how much it was filtering out of the air in the house.. About the only thing I would change here is to run the fan vertically, as it was designed. Laying it horizontal like that is begging for a motor or bushing failure, depending on how that motor is designed to run. Leave it standing like it was meant to be.

[@KenG....]

Yes. Vertical.... couldn't understand why the fan was on top.

[@dougc78]

The fan is on top to increase air flow & filtration. If it was vertical you have less filtration and higher air resistance and higher loads on the motor.

[@coreyg7255]

@@dougc78 How so? Gravity cannot be of much help here. If the bottom of the box was cardboard, and all other sides were filters, you would have the exact same amount of air flow and pressure with the fan sitting in its vertical position, as designed.

[@dougc78]

@@coreyg7255 Very good point!! I completely overlooked the cardboard bottom... Let's just call this one a "Brain Fart"

[@viverra]

According to Camparetto, the HVAC engineer who designed this system, it was designed with a horizontal fan because particles, even microscopic ones, settle due to gravity. That means, first, that the density of contaminants is greater near the floor. A vertical fan pulls contaminants in from the air column on one side of the room, and blows the clean air into the other side of the room. Contaminants already on the downwind side of the room are simply blown further across the room, and they can easily collect in eddies. A horizontal fan pulls the particles in from near the floor, where they are in higher density, and blows the clean air up; the resultant air currents push contaminants from the corners of the room back towards the filter box. It's a more efficient way of cleaning the entire air volume of the room.

[@GS-rw9og]

AS AN ASTHMATIC, THIS INFO IS INVALUABLE AND M AFFORDABLE FOR MY BUDGET AND A WISE DECISION FOR ANY BUDJET, SO GRATEFUL !!!! ,,LOVE THIS CHANNEL,,,THANKYOU FROM MY HEART!!!

[@ajones6784]

This also works with painters tape, which causes much less damage when the unit is disassembled.

[@shelshele]

The glues let out VOC’s

[@pizzawarlord9232]

Surprised no mention about using in wood shop. Been using for years. Gotta change them a lot more often tho

[@rupe53]

Pizza ... have seen similar on both wood shops and auto body shops. There's even commercial versions sold, although more expensive. OTOH, the commercial units are rated to be explosion proof. (chemicals, etc)

[@hathawaydj1]

Indeed. I use only MERV 4s and they help a lot!

[@derrinpickett9948]

I've been using cheap 20x20 air filter taped to a cheap box fan in my work shop for years. I lightly fog the filter with some spray adhesive. Work's great for capturing over spray particals when painting.

[@HolyDrugLord]

@@derrinpickett9948 what level filters are u using? I just bought some merv 10 filters at $25 a piece, but I was thinking of buying the cheaper ones and spraying them and seeing if it works as good as the higher merv filters Do your filters work on smoke when sprayed?

[@mike41062]

Really good idea- i definitely don't have proper ventilation or any dust collection other than a dust pan and brush.

[@bobbliss9607]

I put a wood burning stove in, and regardless of how I manage the air quality, I still get some soot that floats areound. I have the wood stove in our cellar and every time I go down to add wood, of do something in the cellar, I come up with a dry throat, coughing and sneezing. I'ver done everything that I know how to reduce the soot, but with little or no results. Ok, I saw this segment on the DIY air filter... hooky smokes Bullwinkle... this thing REALLY WORKS! I was in the process of ordering a $ 399 deluxe air filter system, but now I not only save a bunch of moola, but , I did this myself. Thanks a bunch guys !!!!

[@MikeTwoPoint0]

I put a merv 8 4" 20x20 on a 20" box fan, it works awesome and doesn't take up so much space.

[@oldtwinsna8347]

Nice to see some current day videos rather than stuff from several years being posted as if it were new.

[@TheDobbermn]

how is it not current day when they are talking about COVID?

[@coryulrich6489]

@@TheDobbermn that's not what he said. He was appreciating that THIS video IS current. Their recent video releases have just been reruns. This is the first genuinely new video they've done in a while.

[@TheDobbermn]

@@coryulrich6489 Yep, as i reread it you are correct.

[@Rearmostbean]

Kinda seems like a terrible idea though. I made one with one filter a while back and there was no airflow. I would have liked to see a demonstration of the airflow here, because it costs $100 to set up. Seems like a lot

[@bobby_greene]

I'm pretty sure this came out a while ago, like last spring

[@70ixlr86]

Clear info on retrofitting a whole home unit. Thank You for making the concerns known. Been using the single filter on box fans for years in the garage. 4 sided is a wonderful idea.

[@bobwadsworth4799]

I wanted to see it in action with some smoke to see how well it draws it in and how well it filters. A follow up maybe This Old House??

[@tmorgan7939]

Yeah. . What the heck ? Nice idea but if it is not powerful enough to pull in pieces you want and need to filter out it's nice but maybe a better idea is to save up for one built with specs to do the job.

[@returntothepath]

@@tmorgan7939 look up Izzy Swans video on a box fan filter vs one sold. You'll be surprised.

[@benjabhd]

@@tmorgan7939 i made mine like this model 1 week ago and is not worth the 50 i spent in the 4 "7" rated filters. Doesn't work. I works better to put just 1 filter attached in the back of the fan

[@tmorgan7939]

@@benjabhd Thanks . Good luck with the changes you made..

[@indegruv]

Take the idea and improve it 🤑

[@TomTerrific]

I use one good filter 20 x 25 up against a box fan. Simple, but it works great.

[@JJ-dz6oj]

Before you upgrade your HVAC filter I recommend installing a magnehelic pressure gauge. Most systems are rated to run at .5 inches of water max dP (differential pressure), so get a gauge that goes to .5 or 1 inwc. Ideally your system will run at less than .3 inwc with a new filter, but there are more factors at work than the number of pleats or the efficiency of the filter media. If your return is not sized sufficiently it may mean higher face velocity at the filter. Higher face velocity means higher dP, which means the blower works harder to pull air. Installing a gauge will help you figure out the baseline of your system and determine what filter you can use. An added bonus is that you can start replacing filters when the pressure drop, or dP, gets close to .5inwc versus changing every three months. Unfortunately filter companies don’t publish pressure drop on the package.

[@tomfenimore9667]

Great information that most people are absolutely ignorant of. Most systems have undersized returns.

[@bobboscarato1313]

@@tomfenimore9667 Very true. That's one of the reasons systems don't last as long as they should!

[@da_Luv_U]

The air blower will not work harder. It will actually pull less amps. Less airflow due to airflow restriction means less work. Now the evap coil is designed for a certain airflow, that in turn will work less efficiently.

[@JJ-dz6oj]

@@da_Luv_U It depends on the type of system you have (PCS, constant torque, variable speed). Regardless if the blower works harder versus longer, more energy will be consumed to achieve the desired temperature as differential pressure increases.

[@normbograham]

They used this type of "box", to trap cigarette smoke, 30 years ago, from a break room. it worked great. They used 1" thick filters, and FIVE of them, mounted in the ceiling. The guy used a rebar welded frame.

[@laurabowne3409]

Just made this for my pottery studio because silicosis is real! Thank you !

[@starveil101]

Ooph. Totally agree! I wish I wasn't so relaxed about this at my first job out of highschool! I worked PT for 5 years at a franchise pottery studio and naively signed a disclosure about this but can't remember what specific harms it mentioned. No one on staff ever wore masks with the glaze dust or for anything else. Knowledge is definitely power, and so is age/experience 😊👍

[@Twistedf8te88]

Made this myself today using a A black Lasko fan from Walmart some black duct tape and air filters works really well.

[@victorherrera8026]

I do this with one filter put in the back of box fan standing up. Airflow holds it or a little tape to secure. Works great.

[@geronimolopez5070]

I really like the back to back simple conversation style, it helps understand what's really important about the subject

[@Marchautowerks]

I live in a century old house, no hvac steam radiator for heat and put window units in for summer. Definitely want to try this

[@123mjolie]

I'm going to use this in a cabin that I am sanding 20 year old rough sawn wood. And before I can clear coat everything. Thanks this should work great!!

[@Ladyofvirtue247]

This is genius!! I recently purchased 2 reaaaaalllllly expensive air purifiers and the replacement filters are expensive as well just last week, needless to say I will be returning the expensive air purifiers and making two of these! One for my office space one for my home.

[@Tom-bb4zw]

NJ resident here. Just built my first one today- hope it works as advertised!

[@seanile]

Great idea! I improved upon this. Instead of 20x20 filters, I used 20x30. Made it 10 inches taller with an additional 800 inches of filter surface ( 10"x20") additional per filter (x4 sides). I used the cardboard box that the fan came in to cut out the base and taped it up with gorilla tape. Highest merv filter I could find at Home Depot was 10. Thank you for the great idea!

[@laboulesdebleu8335]

Been running essentially the same in middle of my house for 2 or 3 years now, except instead of using cardboard opposite the fan, I taped in a 20x20. My original plan was to modify an inexpensive furniture dolly to set it on, but just taped on 1" cubed blocks of cedar at the 4 corners. Filters last about 14mos, and no issues with fan so far.

[@bobbg9041]

Call around merv 10 isnt that great, you can spray a filter sticker on the filters to catch more. You want mim, merv 13. 15 is even better thats hospital grade merv 16 is clean room purification. Merv 10 is what newer hvac systems use. My filter in my hvac system are 5" thick. Oh look on Amazon. Honeywell or some off brand. They copy Air bear filters . Amazons a good place to look. You can search Google for merv ratings and what each category is for.

[@meganofsherwood3665]

National Allergy Supply (online) tends to be expensive, but I know they carry filters of at least Merv 12

[@bobhekker4060]

Over achiever...lol! Great idea!!

[@DarkStarProGamer]

Simple, yet elegant solution that beats products priced upwards of $500. Thank you!

[@Zincink]

I needed this like 2 years ago. Bought a Whirlpool doctor recommended hepa air filter. My Dad used to use a box fan w a filter for painting in the winter.

[@youfinallyfoundwaldo1364]

As a toxic mold survivor, I gotta say this is amazingly helpful. This is actually something that people with extreme mold sensitivity and reactions does to help keep them from getting sick, disabled, etc... But I’ll be doing this as an ac unit as well in the hot summer since I can’t use my ac system as mold is inside them and would blow mycotoxins all over my home, belongings and myself. Thanks so much!!!!!

[@WisdomAgreements]

Exactly what I'm dealing with now. I'm in low income housing and we have a central ac, been running for 3 days and I already smell the mold. I have my ION fan going, but looking for more options. I have severe heat sensitivity so I need to use the AC.

[@youfinallyfoundwaldo1364]

@@WisdomAgreements I totally get all of that. I’d rather be hot and learn how to cool my home and body down vs get more mold suck and ruin my things again.

[@WisdomAgreements]

I found some green filters at Home Depot. I covered the vents and it traps mold, dust, dust mites, pollen, etc. It's just like this.

[@meganofsherwood3665]

It may be too expensive (cost me my $200 covid support check), but one thing I did was get the AirFree mini incinerator air cleaner, to actually kill rather than just trap mold & mycotoxins. I don't know how much it would help if the problem is in the air conditioner itself, but I know it's helped in my intractably moldy bathroom. I know another thing my doctor did was put me on Milk Thistle Extract for mold toxicity, and it helped me a lot. Best of luck on your healing journey!!

[@scottmiller5975]

I'm not sure why other window fans have become such pieces of garbage kzbin.infoUgkxGjG43--gYqIoT4Xkur2PqCrtbKwTv2h6 but this one definitely is nice. It's quiet, it has buttons for different functions that you generally don't have to keep pressing over and over again like some of the others, and the remote is a nice feature. Still, button simplification could go further to single functions for each and every one, but it's decent enough. It's a very quiet fan, the quietest window fan that I have ever had, and that alone is worth the extra money over the cheaper ones.

[@opiate2L]

Very good discussion. Many people do not understand the problem with restricting air to the AC unit. We're told to change our filter to keep air flowing but then sold a highly restrictive filter. 🤔

[@SadSackGaming]

Thank you for talking about the resistance aspect of this. I always assumed that by putting in a better filter, you would have to be adding work for the system itself and it is nice to know that my brain wasn't off.

[@tjrooger1092]

As an HVAC guy, thank you for telling everyone NOT to go buy a 1 inch merv 13 air filter. Those are home wreckers. Those require very specific system designs, like one filter for every room in the house.

[@charlies.5777]

I read somewhere that a 3M 1500 Filtrete filter has an excellent balance of low restriction and high filtration. Do you agree with this statement??

[@tjrooger1092]

@@charlies.5777 That's impossible to guess at. It depends on you much headroom was designed into your system. You can tell by turning the system on and then dropping in the filter. The more the filter snaps into place, the more of a restriction it is. Another thing you could try is taping some kind of streamer to your supply grills, like yarn or toilet paper or whatever. You'll be able to see how much air flow you're losing. In the end it's your house. Try it and see if you notice the difference either in filtration or how your house feels. Personally, I use Flanders EZ Flow II merv 4 about $1.50 each. Air flow is the key to comfort. It's why you have an HVAC system. To move air of the right temperature to where you want it.

[@charlies.5777]

@@tjrooger1092 Thanks for your advice - I appreciate it. FOR what it's worth, when you're standing under a vent when the HVAC is running, it feels like you're under a hair dryer and If you drop a piece of paper by the air return when it's running, it pulls it Out of the air like a vacuum cleaner. Hopefully that's a good sign, ESPECIALLY since it didn't do that when I had the higher-rated ( RE MERV rating) 3M filter in there.

[@VenturaIT]

@@charlies.5777 We have a 1" MERV 13 in our HVAC from 3M and also one on a box fan. It did not break the HVAC and does an excellent job of removing particles. We can test it with our Dylos 1100 Pro particle counter. Our HVAC is heat only with no continuous fan so we can't use it very often, however. We have 3 expensive HEPA purifiers with carbon as well. I've heard that MERV 16 is too much but not MERV 13. But check with a pro.

[@Acaidia]

Why don't they just make every new system with high merv filters in mind? It seems dumb how you can get a brand new system that can't even handle filters designed a decade ago. With the way things currently are you're left with two choices: Either running a high merv filter that gives you clean air but restricts air flow and damages your system or a lower merv rated filter that allows for good air flow but doesn't clean the air very well. Either way you're forced to settle for less than optimal performance.

[@johnwang9914]

Early in the pandemic, I had envision people setting these up everywhere, hanging from the ceiling in school hallways, over restaurant tables, etc. but of course we hardly saw any of these at all.

[@johnwang9914]

@@613kc You truly have a loose interpretation of what constitutes proof. Have you always deluded yourself...

[@Juangomez9186]

In some schools the air purifier is installed in the air return ducks.

[@johnwang9914]

@@Juangomez9186 Placing more filters in the air return typically requires increasing the power to the centrifugal air pumps due to the higher resistance as HVAC, even home HVAC are designed for the 25% filtration of fibreglass air filters. At the very least, the filter housing would have to hold thicker filters such as 4" or 6" thick MERV-13 to reduce the resistance (the thicker filters have deeper folds hence more surface area for the air to flow through). Then there's also how many times the HVAC are designed to cycle the air in the room in a given period of time. Portable air purifiers would be less expensive than retrofitting the HVAC with better filtration and could offer more directed and more frequent filtration.

[@moorefilmltd]

@@johnwang9914 not always. There’s the iWAVE air scrubber which isn’t a filter. There’s bypass HEPA filters so it’s not fully blocking the duct. Then you have product like the SoliceAir purification systems. Both UVV and UVC lights to combat odors and surface/airborne viruses. Along with their Micropower guard filter which is 1 inch, also ionizes particles,and can filter out particles down to .03 microns in size with air resistance the same as a standard 1” pleated filter. These are usually the systems schools and corporations install.

[@johnwang9914]

@@moorefilmltd UV-C takes a few seconds to sterilize a virus, just having a light in the duct work isn't going to do a thing if the virus just blows past the light. Now the light may be useful to denature virus that get stuck in a filter but most of those duct UV lights are just scams. They also tend to be UV-A or UV-B lights as UV-C are largely not even visible and both UV-A and UV-B would take hours of exposure to denature the virus. Is the air going to be hanging around that light for hours when the fan is blowing? Besides, how much investment have there been in improving HVAC filtration? Even increasing the filtration to MERV-13 would require boosting the air pump power or fitting a four inch thick low resistance MERV-13 filter. I'm talking about portable units that could be easily deployed and how surprising it is to not at least have had portable units commonly deployed one year into the pandemic.

[@kevinstory872]

i first taped a filter on a 20" filter to a fan 30 years ago and always have had one running on low as i have had allergies all my life. i have shown lots of people to make these and never gave the thought of improving the design. 4 filters might be good for high dust situations I guess I will find out.

[@awfab3517]

These work great! The air filters at the store were never big enough for a small size 1600 sf house. Going to make another but so I can remove the cheap filters fast and leave the expensive ones in longer.

[@edlauren9434]

Working on the house remodeling. Flooring and drywall part generates a lot of dust. Will take this air filtration idea for my work.

[@bobby-c7731]

I use MERV 13 filters in my woodshop. I duct tape one to the back of a fan. I like this system because it will move the air more efficiently. Just have to account for the space.

[@michaelkline9647]

A wodden frame could allow it to be hung from the ceiling. A simple pivoting wood latch would make swapping the filters a breeze.

[@jlbeck777]

@@michaelkline9647 I was thinking the same thing, even with the cube implementation in the video. Could be just the thing I need for my own shop, with a lot more capacity to move air!

[@skyrocketcoast219]

Made 1 using ' Tyvek Tape- light weight tape & lasts ages!! 1st box+ 4 sides 2inch merv 13+ fan lasted 2 -1/2 years. Making new one June2022. And we put a cardboard shroud in top of the fan too. Odd note: the tyvek tape is also used around my outside window screens, if there is a gap.

[@pdufusc]

I've always used one of the low mervs at the entrance of the filter box, to save the hepa filter from the animal hair clogging. My a/c is in a small room with a 2' door. It has a filter in the door, prior to the air entering the a/c unit. I'm considering building a box that will sit just inside the door, with the 20" box fan, to pre-filter the air and take some of the load off of the a/c unit!

[@johnvrabec9747]

I use a modified version of this in a home made spray booth that works great. I have 3 sides of PVC pipe with joints covered with drop cloth type plastic hinged with zip ties and a box fan with a 1"filter over it to control overspray in my garage when spray painting things. I also made a lazy susan that attaches to my B&D workmate to get 360° access when spraying.

[@mikemorm1225]

We manufacture filters so I will try and explain how any system can operate fine on a merv 13 or higher. It has to do with pleat count, think of your air filter in your car. It only works well because there are a lot of pleats stacked next to each other. This enables your engine to pull air through a very small filer with little resistance, if you eliminate half the pleats the car would not run well. The more pleats the lower the pressure drop. A merv 13 filter should have 15 pleats per foot to achieve a pressure drop comparable to a merv 8. Here is the catch you have a media that costs more per square foot, you have to use more of it to make the same filter in a merv 8 hence this filter will cost at least twice as much as a merv 8. Hope this clarifies.

[@JJ-dz6oj]

Do your 4” filters have the same amount of filter media as your 1” filters? I’m trying to decrease the initial dP without sacrificing efficiency. I want to increase the media area by increasing the number of pleats per inch, or keeping the same number of pleats per inch but increasing pleat height. Seems like residential filter manufacturers don’t publish pressure drop and media area, just efficiency.

[@JC.SpdRcr5]

My brother in law put a higher Merv filter (because higher is better right?) in his furnace and it put so much stress on the fan blower motor that it burn it out. The higher the Merv # the harder it is to get air through it. That also made it difficult for the air to travel to their second floor. He was told to follow the recommendations and instructions that come with his furnace when they installed the new one. The person who installed their new system wrote the Merv # on the side of the furnace as well as airflow direction and filter size.

[@AdamDaley1]

Im gonna build one of these and walk around town wearing it :)

[@davem6685]

That’s awesome.

[@haroldofcardboard]

merv :)

[@gus473]

Like Marshmello....? 🤔

[@HeyWatchMeGo]

Actually laughed out loud!

[@robbrownstone]

Wear it as a hat and your personal air space will be 100% covid free... :0

[@offgrid2010]

I just decided a little earlier to look for plans, ideas. You were my 1st stop and you told everything I needed to know!!!

[@1942nn]

Thinking about doing this to filter out dust in my home. No matter how clean I keep it, most surface got dust after a couple days.

[@mrgallbladder]

This thing is gonna look awesome in the middle of my living room!

[@PlazaQueen]

I did this at the start of the pandemic, it's awesome to see someone with a big platform show how its done. This is perfect for a shop to catch dust as well. You can make a wood frame for these filters/fan and even put wheels on it. Makes it super simple to change out and move around! (This would be great for low budget schools fighting virus spread)

[@GS-rw9og]

AWESOME

[@rosskovelman460]

Very cool, although suprised you didnt go into more detail around FPR, which is what many box stores sell in terms of filters. And I believe you said it cost around $70 to make it, where a HEPA filtering unit from Winix can be had for around $90 and the filter will last a year. Definitly right size it for the space. And a HEPA filter will get even more finer materials from the air. Thank you for using the platform to get the word out, its so important.

[@DugB0915]

What if you put one or two of these near your air intake vents in the house? Wouldn't that circulate cleaner air for the full house?

[@jaharileah]

I’m not sure but I saw a video where someone was putting filters in their air vents not sure if thats okay or not. I have no one to ask 😂 and I’m nosey I will watch anything that has to do with someone making something.

[@lesliehatun2044]

Love this 😀 ❤️ 😍 💖 I use Filtrate 1900 filters 20x20 bc it works best. You can see the build-up and the air in the home is fresher than other filters.

[@cbryantbear6498]

Is anyone else thinking “Apollo 13?” 😂😂😂

[@MrStaticstate]

Yes :-) this scene kzbin.info/www/bejne/qKqYZmBjf5mSjLM

[@bluesteel5841]

Lol sure am

[@magreger]

Yes!

[@stivo2663]

Comment of the month award. Congratulations!!!

[@IHaveaPinkBeard]

I am now

[@MillenniumFalcon]

Thank you. This is super helpful and I learned quite a few things. I watch you all on TV but did not know you had a YT channel. Kevin and Ross...you guys are my favorites on the show. Awesome to see you both in action together. Added a subscription to watch more helpful videos as you post them. Rock on TOH!

[@chrisy876]

Great idea! Thanks for the video. I have one with one side of HEPA filter only. It worked real well & resolved my allergy problem when the air was filled with ashes & dusts from the wild fire later last year. It only cost me a few $ for the box fan & the filter. Highly recommended!

[@AllThingsQuixotic]

Where is the best place to set something like this up in the home? Centrally located or close to your air intake for central heating/air system?

[@TrudiTrahanupchanOKRA]

I have standing fans, allergic to diesel, fragrances, laundry soap & my bedroom & bathroom were full of such fumes leaking in from windows and floor boards. I finally managed to seal the leaks on the floor & bedroom window but to detox the rooms I saw a TV report similar & bought Merv11 wrapped it around my stand fans and amazing this removed all the diesel fumes from my bedroom and laundry fumes from my bathroom. I keep them running and I can finally sleep without wearing a gas mask. I have paid a fortune for air filters since 1986 and Merv11 wrapped around a fan is even better than anything I ever had.

[@TedSchoenling]

Been running MERV 13 for years 20x20x1 stock system that was put in in 2012... no problems.

[@tribulation138]

depends on your hp and rpms on motor. its a easy upgrade if your motor is underpowered.

[@TAXMAN1978]

FYA: box fans are not meant for static pressure applications and will suffer CFM drop across a filter. Using 2 in a V shape or 4 as shown will reduce this drop. But, the rated CFM of the fan across the filter won't be achieved. Also, square / non-ducted box fans will wind up sucking in air at the corners from the "outflow" side of the fan, believe it or not. You can tape across the corners on the front/outflow of the fan to minimize this loss; ducted/round fans do not share this issue, but they are harder to fit a fan to. All that said, I've got both a 20" box fan and a 24" round shop fan rigged up with filters and they are great.

[@bobboscarato1313]

You're correct; these jury rigged jobs shown on TV are a real joke!

[@yourekittenme.]

If you built a “frame” of some sort around a round fan, would that stop the “air leak”?

[@todddavis9426]

I have a DIY box fan air filter in my home. Just yesterday, I set one up in my in-laws home. I may try this cube concept.

[@bigredwag]

Honeywell (and knock offs) make a "return filter" . Basically 3" filter retrofit for legacy 1" filter return grille. Merv13, works great with very little change in pressure

[@09ThunderOne]

Wow I had no idea these existed. I'll have to look into this. Genius!

[@spacecoyote6646]

I use a single filter held in place by suction from the fan. I had some weatherstripping laying around so I put it on the fan to improve the seal and decrease Blow by. I have two types of filters at all times. One that will stop pollen for my allergies. And one that will Stop Smog and smoke for when the forest fires get bad. Since I don't have the filter taped to the fan I can use the same fan to ventilate my apartment

[@owentbreen]

You need to tape the filter to the fan or else it won’t be as efficient as possible

[@rupe53]

Wow, shades of Red Green show with making stuff using duct tape!

[@babyloobibovski2947]

Remember: if the girls don’t find you handsome, at least they’ll find you handy

[@davem6685]

@@babyloobibovski2947 you beat me to it!

[@Krazie-Ivan]

I'm a man, but I can change, If I have to, I guess.

[@kmiller5808]

HAROLD!!!!

[@MooseTurder]

Remember I'm pulling for you. We're all in this together.

[@brandonyoung181]

Best option is to use those cheapo filters in the furnace so you don’t restrict your hvac system and then use little filter systems like this in each room. You’ll catch so much junk.

[@AS-we9xi]

Axial fan without a shroud = very little static pressure. Your furnace has a centrifugal blower capable of much higher static pressure and closer to 2000cfm (or more). That box fan isn't going to last 6 months running continuous and is much louder. You will get much better performance throwing a deeper filter in your furnace and running the fan. Also load on a centrifugal pump (fan) decreases with decreasing flow (decreasing mass). You will not "seize up" your blower motor, you will actually decrease the load. Blower motors have taps to adjust the airflow based on the amount of restriction from ductwork and filters. They are designed for this. The only risk is having too high of a delta T (temperature differential) across the heat exchanger, which can cause damage to a furnace if it is extreme or freeze up the coils on an air conditioner. The blower can be adjusted to compensate, as designed.

[@jaimeorr4661]

I came up with this exact filter box, back in 2000ish to filter the exhaust on my 1980s LECO Oxygen/Nitrogen analytical instrument. The walls in my lab where black. I had the only lab with NO hood/air filtration

[@nataliemintz6507]

Made one for my house and one for my mom. So easy!

[@bobboscarato1313]

Take it down NOW!

[@The-Grateful-Hippie]

We use a wood burning stove for supplemental heat. However we often need fans blowing cooler air toward the stove so the living room won't overheat and the heat will travel to the colder areas of the upstairs. I'm thinking to try this filter setup to also help clean the air. We have to change our filters more frequently in the winter months so if I get 6 months out of it awesome 👍.

[@dadgarage7966]

It's a hack, but for esthetics, have the pleats in the same direction. And use aluminum sheet metal tape. And make the bottom a filter as well so it can be oriented in any position.

[@cryptickcryptick2241]

Filter Charger can make the filters better. There is a commercial HVAC product called "filter charger" you can get that will spray on an ordinary furnace filter and make the filter catch more particles. Scientifically, this is basically a wetting agent that does not dry out, so it makes the filter catch more particles because there is little water droplets on it.

[@mgoh1984]

Remove the plastic screen from the back of the box fan before assembling the air filters to reduce resistance.

[@Detroit6V92TA]

My parents have a basic Regal oil furnace and Goodman central AC that's not energy star certified. I upgraded them from merv 5 filters to merv 14, and they have no issues with air resistance. The heat and AC still work fine. Although, I'm sure the more energy efficient HVAC systems would have a more difficult time with air resistance. They bought the least energy efficient Goodman AC model and regal furnace since they just wanted a basic, simple and reliable HVAC system.

[@GP1080HD]

I will be building up this today in my garage and hopefully finish it up in 20 days ... :)

[@Mackandal-]

🤣🤣🤣

[@613kc]

It will cost twice as mush and take 3x as long, guaranteed.

[@georgesenda1952]

I have a question. I have a portable air conditioner in my bedroom but it seems that every air conditioner maker ignores people who have windows that slide right to left & the mounting brackets and hose won't stay in the windows. I live in an apartment where the a/c in the bedroom will keep it tolerable but with the sun beating down on the window and wall, if it gets over 80F the ac wont' work. I even put Reflectix on the windows and in my living room and its not much help. Do you know of any bracket that will fit sideways sliding windows ?

[@maxmillanmaxmillan]

I just use a single filter for my small room. I’ve seen a video that uses 2 filters (think triangular.) This would be suitable for a much larger room.

[@wmpmacm]

I have placed 20x20 filters on the back of my box fans for years. I use from 1900 to 2500. Recently the highest.

[@briancasey7693]

Problem is that the higher MIRV filters can choke up your AC causing freezing of the evaporator, or general lack of flow and poor performance

[@seanof30306]

I did this using the cheap 17.95 Lasko fan from Wal Mart. I also did another one using a single 20 x 20 x 2 filter rubber-banded to another 17.95 Lasko fan for the bedroom. I've been running both 24/7 on Medium. High was too noisy, Low didn't seem to be moving much air. They seem to be working fine at filtering the air, but they've had a huge impact on my electric bills. I've been in this home for nearly 8 years. Every month, the power company sends out an energy audit comparing my electricity usage to similar-sized homes in my area. I have always been significantly below average; almost to energy-efficient, despite the fact that my home was built in 1951. Since beginning to use these air purifiers, my power bills are up 40-50 bucks a month from where they've been for the same months in years past and the energy audits show me significantly above average, no longer below it. I'm thinking I may have made a mistake buying the cheapest 20" box fans I could find, and I'm wondering if there are more energy-efficient 20" box fans available. Can anyone help please?

[@seanof30306]

Anyone?

[@UTeewb]

That can't be right. A box fan is around 100 watts. That's 24kw per a month. At 12 cents a kw, each fan should cost you around $3 a month. Buy a electricity monitor to confirm , but I suspect it's something else. Unless you have 5 of them and your box fans are using around 200 watts then maybe ?

[@cryptickcryptick2241]

I have tested several fans with a Kill-a-watt electric meter, on high the fans draw around 80 watts, low fans draw 50-60 watts. 80 watts by 24 hours a day is 1920 watts. (basically two killowatts). Power at $0.12 per killowatt hour, each fan uses about $0.24 of power a day. That is $7.20 of power per fan per month.

[@xonx209]

I prefer to orient the pleats horizontally so the dust don't fall off as easily when bumped. For more serious odor filtering, get a hydroponics carbon canister and attach a duct fan.

[@robertrampale5015]

I built mine with 20x30x1 filtrete 1900s and added filtrete basics as prefilters. Use it to filter basement. I just removed my prefilter after 16 months. I guess my particles were smaller because the 1900s are very dirty. The basics are only slightly dirty. I am thinking rebuilding with double 1900s so i can just replace the outer set without reconstructing the core four filters.

[@VenturaIT]

And these work nearly as good as an expensive HEPA filter, in fact, my cheap box fan has over 1,000 CFM, and expensive HEPA filters have around 200-300 CFM or less depending on the fan speed. The CFM will go down due to the added resistance of the filters. We have a Dylos 1100 Pro particle counter, so we can test if a filter works, and just one of these on a cheap target box fan removes even fine particles almost as good as an expensive HEPA filter. You can also get a MERV 13 filter made by 3M that can go in your HVAC (it did not break our HVAC but check with a pro before trying it on yours, it's usually the MERV 16 that is too much for HVAC, but check with a pro) we did it and it worked through the whole house. These small box fans only work in one room.

[@barneyrubble4827]

Dc fan motors with controllers are very load sensitive, ask me how I know! Very expensive repair, controller bout $600. Motor bout $1300 w/o labor

[@VenturaIT]

@@barneyrubble4827 Cheap box fan works for me nearly as well down to at least .5 microns. But I also have bought the expensive brand air purifiers too.

[@davesteelss3454]

I just built 5 sided version. On the 6th side I add a rubber sheet with a slit in it. I squeeze my head through the slit and wear it everywhere. Totally portable

[@georgewashington7444]

Ha! And a LONG extension cord.

[@WillN2Go1]

Good stuff. I've got a few different HEPA units, and a very sensitive nose. On my floor furnace I have one HEPA furnace filter like these, on an angle on one side of the furnace (floor furnaces are really great at collecting dust and then spreading it). The filter is attached to the bottom of a dorky plywood box hung on the wall above it. On one side of the box is a small round table fan. Now I have hot filtered air blowing through my house. To replace a $400 Honeywell unit that smells like burning wires, I just wired another HEPA furnace filter to the back of a big circular floor fan. (When it's going it sucks the filter against the back of the fan.) This does about as good a job as the Honeywell junk before it started smelling like burning wires. Both of these completely bootleg set ups worked pretty good during California's bad fires a few months ago.

[@wpw4508]

During the 2018 During Paradise Camp Fire, and last fall's fires in California and Oregon, this (plus N95s if you could get em), were a daily necessity. And this was two years BEFORE Covid. Just get box fan, put a furnace filter behind it (watch the arrows!), and turn it on. The suction will keep the filter in place.

[@tabularasa820]

Also, put one of these near each return air in the house to improve your whole house air quality.

[@phyllisannbonviso6641]

My neighbor's wood burner's smoke comes right into my house all the time, going to try this. Any additional ideas for wood smoke and people who are allergic to the smoke, taking all ideas and thank you in advance.

[@mjb12141963]

I started using a single 20x20x1 in my garage when I work with wood and the door closed because of winter and they clog very fast. I am going to try this idea.

[@SheikhN-bible-syndrome]

I literally do the same thing in my 1 car garage at my apartment lol helps so much when I'm cutting plywood

[@AlympiaPeaceful]

Merv 17-20 is HEPA certified

[@drew520]

Looking forward to showing this to my wife and suggesting putting it in the family room😂. But still a very awesome DIY that probably works better than air purifiers 2x the cost

[@dpof1988]

I expected Richard to comi in with a Cutaway and it just unfold on the floor, then laughter !!! 😂😂😂

[@zodiacfml]

impressively simple and efficient! the video missed the fun part of testing the fan speeds though. another caveat, air purifiers use HEPA filters which I found to be around MERV 17??

[@samuelculper4231]

WHAT SPEED DO YOU RUN THE FAN? And obviously the fan should be pointed upwards in this configuration..

[@felisalpinis7357]

I tried putting a 20" filter directly on the fan. Worked great and lasted through the crisis, but afterwards one of the coils failed on the fan due to overstressing. I decided to use more filters & was referred to this video. Pretty much what I'd envisioned, but I would leave one side open for the fan so that it would rest on its base & blow sideways as it was designed to do. Not sure how having the fan flat will affect the bearings.

[@johnparis6233]

Do you recommend setting it up where the fan is blowing dusty air OUT of the room through the window? Or blowing fresh air (with the filter) into the room?

[@n40tom]

What I have been doing is using a Merv 16 20 by 20 by 5 inch filter that I buy on Amazon for $89 and I only used one taped on the back of the intake side of the box fan. It's a lot easier and it works unbelievably well. Plus it leaves your fan in a stand-up position the way it was designed . Also I now no longer use tape I use a light bungee cord to hold the filter on the fan it is so much easier. Take care and be safe . T

[@WoodUCreate]

So who came up with the solution, Neil Comparetto, or Corsi-Rosenthal box? Haven't wood workers been doing this for many many years too?

[@DR-cm4hi]

Neither came up with the design. It has been in use for decades. It's like someone claiming to have invented putting a rubberband around a deck of cards.

[@ESTREPROD]

Great informative vid. I made the mistake of changing my filter from a merv 4 (original) to a merv 13. Not only did my fan motor seize, the coil almost froze over and mold started forming around the motor and coil. I had to go down to a merv 8. I might try to use a 5 inch filter.

[@unclefreddieDied]

works great... my store didn't carry 2" thick filters so i got 1"..... and didn't have merv ratings. instead had FPR. not sure if has the same scale. 10 was the highest/best one they had. i have it in my basement and like i said before, it works great. what a difference

[@adrianabshire]

I need this for my workshop in my garage! Will be building this today!!!

[@andr441]

Did it work?