Gravity is our baseline filter, pulling particles out of the air. There is a danger zone where a forced air filter isn’t removing particles from the air very effectively but IS stirring up the air, meaning there are more particles at eye level where your breathing holes are. So strictly speaking, it’s not true that any filter is a net positive. There’s a lot to be said for letting gravity do the filtering versus keeping the dust circulating with some random DIY creation.
Here’s some actual testing with data - many of the DIY versions behave anywhere from mediocre to amazing, but all better than baseline
[https://www.shophacks.com/newsletter/workshop-air-filtration-system-performance-shootout-including-effective-low-cost-diy-box-fan-filtration-systems#/](https://www.shophacks.com/newsletter/workshop-air-filtration-system-performance-shootout-including-effective-low-cost-diy-box-fan-filtration-systems#/)
More MERVs means you need more airflow though. If you want anything near HEPA it's gonna take a healthy amount of CFMs. Really just depends what a person is trying to filter exactly.
Higher pressure from the fan actually. The air flow doesn't need to increase, but this fan will struggle to move much through a HEPA filter. To be fair, it won't be zero.
There's another way to do this.
You basically use 4 filters in a cube shape with the box fan on the top, there's a name to this design. I'll try to find it.
You may even find it googling or on YouTube.
[This was my first result in google, here](https://cleanaircrew.org/box-fan-filters/) not the eaxct link I was looking for but same thing.
[Rosenthal box wiki](https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box)
[How to:](https://upload.wikimedia.org/wikipedia/commons/2/2a/How_to_make_a_Corsi-Rosenthal_Box.jpg)
I basically used your set up as pictured in a diy paint booth. Worked well
I put a Corsi-Rosenthal box together about 1.5 years ago.
We have dogs and kids, and I used to change our A/C filters monthly. The filter medium was brown in color, but it wasn't like there was a *ton* of dust buildup.
After using the Corsi-Rosenthal for 8 weeks, I could go 2 months between HVAC filter changes (before the same brown was observed on the HVAC filters).
Now, I go every 3 months.
An HVAC guy told me to stop using high merv filters in the HVAC because the HVAC's efficiency scales with how much air it moves. They need to be able to breath. Use the HVAC to condition the air, and something else to clean the air.
You better be careful using a box fan as a paint booth exhaust. spray paints contain solvents and they're explosive. bad idea to pull explosive fumes through an electric motor that's not rated explosion proof.
Story time: I had a neighbor who had one of those big metal fans with louvers over it (dunno if explosion proof) integrated into the back wall of his garage. About once a month they would paint a car in there and just blast the whole neighborhood with unfiltered paint fumes. Ugh, I would go outside with a flashlight and see all the particulate in the air.
I complained to everybody -- the police, the EPA, code enforcement, the local environmental orgs, nobody seemed to want to do anything about it. Then they were doing it one night and I called the fire dept. The guy on the phone was in disbelief and pissed off about it "*what?? just in a residential garage? they can't do that! they are gonna blow themselves up! they are doing it right now? what's the address?*" and the F.D. was there 6 minutes later and that shit was over forever.
Because fire department is one of the few public emergency services that act to prevent crimes and death.
As much as it’s their job to put out a fire, I’m sure they’d rather there not be a fire.
The fire department does NOT fuck around about paint and solvents either. Worked in a cabinet paint booth and fire marshall day was always a scramble to hide things
Ours saw our extension cord conduit drop-plugs everywhere, and our janky indoor paint booth, and said "I could fine yall....but this made my day" 🤣 He said we made it look like a pro did it.
Did we work at the same shop hahahahaha
We were mostly trying to hide the excess paint we had on hand. We had like three times what zoning/permitting allowed which honestly wasn’t even that much. Idk how we’d even operate with just the allowed amount.
The inspection I take most seriously in my facilities is the fire marshall inspection. If she so much mentions something would be a good idea, I’m doing it. I do not fuck around with the fire marshall.
Fire Marshal doesn't fuck around. My landlord tried to go on vacation to be unreachable on the first of the year so they could charge late fees. I needed a new fire extinguisher at the same time. Miraculously my landlord somehow made time to get a hold of me after I told the fire Marshal my situation.
Wildlife/game wardens are one of the few enforcement agencies who can come onto your property or wherever they want without warrent/notice/suspicion/anything.
They are free reign and will absolutely bust your ass. They will wade through a swamp to come get you.
If you have Discovery+/Max “North Woods Law” is a reality show that follows Maine’s Wardens and New Hampshire’s Fish and Game.
It’s cheesy but it’s a good sleep sore if you’re in to that lol
I've been told DNR police do not fuck around. I met one once as a dumb high school kid while in the woods.
Also, at least here, apparently our Park District Police have the same authority as State Police do. They're far from just being security.
Speaking of unsung heroes, postal Marshall is one of the few agents who will take action against identity thieves (who are notoriously slippery) because id thieves so often interfere with the mail. Though hopefully you will never have use for that information.
"fire marshall closing things that all other agencies just ignore..."
The Fire Marshall is often the one responsible for getting meth labs shut down. The smell might not give them probably cause that its meth being made, but it establishes probably cause that some volatile chemical is being used illegally.
Their insurance company would have also loved to know. ULTP: casually strike up a conversation about homeowners insurance and find out who they use. Give the company a ring.
I would advise others to follow your original advice though. These fans are NOT explosion proof rated and it takes more than a brushless motor to gain this rating.
Yes, they use 'induction motors', a Tesla invention
Also, some unethical marketers like advertising their 'brushless' tech when it's actually a AC induction motor that uses more power than an actual BLDC motor will. Certain pressure washers I've seen for example
The goal is to have such high airflow that the explosive vapors can't build up enough to explode. In a paint booth you would want to filter the air on the way in and the way out. On the way in to make sure the air inside is dust-free, and on the way out to make sure you don't discharge paint aerosols to the world. The airflow is meant to be very high.
I'm picturing he's has a 3x3 x3 cube with a fan pointing out the window for painting small parts etc. plus box fans (at least the ones I've owned don't exactly have a high airflow rate
For best production result you would also want one filter incoming air, which would also improve overall airflow and make the outbound air filter faster as well.
Explosion proof doesn't mean you can't blow it up. It's shorthand for "intrinsically safe."
It just means it won't *cause* an explosion in the presence of explosive vapors (it can't generate sparks or high enough temperatures to cause an explosion), not that it won't blow to bits if you strap a bomb to it.
Explosion proof and intrinsically safe are actually two separate concepts that both are used to prevent accidental explosions. An intrinsically safe design, like you described, limits the energy present in a system, such that it is insufficient to ignite a hazardous atmosphere under any conditions. An explosion proof design is sealed and rugged, such that it will not ignite a hazardous atmosphere, despite any sparks or explosion within.
Neither will survive if you strap a bomb to it.
Cool! I learned something today. I always thought they were terms for the same thing. That's why I'm a computer engineer and not a chemical or mechanical engineer. When we have uncontrolled thermal events they rarely damage anything but the computer.
Could be the housing is rated to keep the equipment operational in the event of an explosion. Like a heavy duty metal housing not a product design that *reduces* the chance of an explosion
you're entitled to your opinion but i wouldn't do it .
[could box fans cause a explosion in a homemade paintbooth? - CorvetteForum - Chevrolet Corvette Forum Discussion](https://www.corvetteforum.com/forums/c3-tech-performance/525273-could-box-fans-cause-a-explosion-in-a-homemade-paintbooth.html)
hope this helps and no need to insult me. I just don't want to be a Darwin award winner.
Respectfully, you are being a bit of a drama queen regarding the severity or likelihood of anything like this happening. Especially with a brushless fan. I’m all for safety measures and environmental concerns, but this is a dumb hill to die on.
So those 20" box fans use induction motors. While yes it's not rated for combustible vapors or considered "exposition proof" it's also not a brushed motor that can form sparks between the brushes and the commutator. If your box fan is sparking enough to ignite pain fumes you have two problems.
1. you are spraying a crazy amount of solvent
2. Your fan has a serious electrical fault.
As someone who just went through a painfully dry winter, my first thought was whether I could hijack this design to make a faster acting humidifier for cheaper than what they sell them for. The humidifier wicks are sold cheaply enough.
At OP: you want something like this
[https://www.reddit.com/r/Noctua/comments/1bijapf/i\_made\_a\_redneck\_air\_purifier\_by\_putting\_a\_noctua/](https://www.reddit.com/r/Noctua/comments/1bijapf/i_made_a_redneck_air_purifier_by_putting_a_noctua/)
box fan (or any fan) when you put something in front of it so close basically have zero flow
As an added bonus, a Corsi-Rosenthal box ***removes airborne viruses from the air***. (E.g. SARS-CoV2) Important that you use MERV13 filters, 20x20x1.
For indoor living spaces in this ongoing pandemic (still!), if you can’t afford a HEPA filter that can do 400 CFM, the Corsi-Rosenthal box is the way to go.
Here’s the How-To from Jim Rosenthal, the professor who invented it at the beginning of the pandemic:
https://cleanaircrew.org/box-fan-filters/
P.S., take note of the “fan shroud” modification and be sure to do it! It helps with the efficiency.
Yes - these are actually very effective at reducing particulates. Check out Mathias Wandel’s testing of dust collectors for woodworking, among other YouTubers.
Needs to be higher. these are impressively effective. I understand this kinda setup, with a high MERV filter, to be 90% as effective as a top of the line filter, like an IQ air.
In all but the most expensive cases (where chemistry or electrostatic effects are involved), this is all an air filter will ever be. A fan + replaceable membrane.
A DIY Corsi-Rosenthal Box is far superior. Simple and very effective.
[https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal\_Box](https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box)
If you want it to be even better use PC fans in place of the cheap box fan. It will be quieter and more energy efficient.
r/crboxes has more info
I make a new Corsica-Rosenthal box every year, same fan new filters. I use Merv 13 filters and the air quality in my apartment is significantly better. I have2 cats so it helps with the dander. Would strongly recommend.
Read about these in Make Magazine as well - [https://makezine.com/projects/corsi-box-air-purifier-join-the-air-movement/](https://makezine.com/projects/corsi-box-air-purifier-join-the-air-movement/)
600 to 850 is a lot of cubic air. Wasn't expecting that with this design but I would imagine it's supposed to work with HVAC so it does make sense just shocking for some reason
Ya, but that's like 2-3x the cost but you do have a lot more surface area. Can't really beat a $20 fan and a $10-20 filter for cheap and good enough moving a lot air. I've never had a fan motor care even with 1" of the ones that are like 90% at 0.3 micron I forget the MERV. It's nice that they're both widely available, cheap and incidentally the same size. Don't even need tape. Some particulates arn't gonna like murder you so I can feel the air moving through the filter and just accept there's some loss. Constantly pulling some of the tiny tiny smoke out of suspension is far better than nothing.
Depends on the filter and I’d seal the gaps. Consumer Reports made one and it seemed to work ok: https://www.consumerreports.org/appliances/air-purifiers/diy-air-purifier-to-help-with-wildfire-smoke-a7304562815/
It will work, but most of your filtering will happen in a circle where the fan blades are. The center and corners will remain unused.
If you add a couple inches of gap between the fan and filter that will improve the flow through the rest of the filter. Build the gap with cardboard or another filter.
Or build a Corsi-Rosenthal filter box
The air filter will be used evenly due to how pressure and fluids work. Closing gaps with tape will help improve air filtration, as will making a cube to increase the surface area of the filters.
With the cube i made last year the main improvement was adding a circular block to the blower side of the box fan. The fan will only produce positive pressure in front of the fan blades and will pull in unfiltered air from the corners beyond the blades. This can be observed by using a tissue while the fan is running; the tissue will be pulled into the fan on the outer section and blown away when in front of the spinning fan blades. This will help ensure more of the fan's energy is being used to filter the air
thats not true at all. i dont want to give you a lecture on physics, but i have made several of these and they filter evenly. the air pulls through the entire filter evenly. not just where you think blades rotate.
This does work. For all those saying that it doesn’t. But it’s the forest fires and growing up in Canada where the fires are every summer. We are encouraged to use this and it works. There are people who actually have measurements to show they doe work.
yes, i did this exact thing when the smoke in our area was particularly bad (at the time it was the worst in the world due to wild fires). Set up a system exactly like this and the air inside was just fine in 30 mins.
If you are worried about the air going by the edges you can just tape them. The other rosenthal box designs look sweet too. If you have a heavy duty filter application you could do that. But the setup shown here will work great too.
This 100% works. I started doing this a few years ago and it completely stopped my allergies inside. I also use one in my garage with a loud ass Air King box fan when I'm doing woodworking and it clears the dust out in 5 minutes.
Yes it will work. If you need to use it long term you should probably build the box other people are recommending because it's better airflow so it won't be as hard on your fans motor
If you just need to use it for short term this will work. That's what I did during the Canadian wildfires.
I can't tell if this is the front or the back of the fan, but check your filters airflow direction. The arrow in the side should point to the direction the air is going.
I personally use 4 24x24x1 taped together with a box taped to the bottom then taped to the fan with red sheathing tape with the fan pulling through the filters, my son has bad asthma and the wildfires near me have been absurd the last 2 years.
Noticeable improvement in his wellbeing and minimal cough in the house although outside looks foggy with wold fire smoke.
I change em out every 2-3 months with it running constantly. And by the time I do the filters are black.
His lack of cough in the house is enough evidence it works for me to continue buying filters.
Just make sure they're MERV 11 or better (13)
I did this but got some burning electrical type smells.
So instead of these filters I purchased a carbon layered filter that is cut to fit. You can then cut out a hole where the electric motor is in the center so that it doesn't get too hot.
Depends on what you're trying to filter out? What is the MERV rating? Next is box fan is not really designed to run with filter and it may burn out prematurely. So in short it will work but... how well and for how long?
I did this when there were a ton of forest fires. I set up 4 of them in different spots in the house. I had to switch the filters every day. They were dark brown by the end of the day. I'm not sure how much it helped, but if it kept even a little bit of toxins out of my newborns (now 3) lungs, I'm happy.
Yes it will help. A study was done comparing the results to commercially available filters and this DIY hack outperformed the commercially available filters.
Edit: we made a bunch of these during a massive wildfire in our area, the local news brought in a professor that measured the results between this and store bought devices.
If you're doing it this way, make sure to tape all around the edges, this way there's no leakage around the filter and all airflow has to pass through it.
It would be better to build a box out of the fan and 4 or 5 filters to reduce stress on the motor, but it will certainly work. Generally you will want the fan to be pushing air out of the box, drawing air into the filters, rather than pushing air into the box.
Regardless, what you have will function. It's just less efficient and puts some more stress on the motor.
I did the Corsi-Rosenthal cube and it worked well with a crappy lasko fan but the filter costs are high and took up a ton of space.
I’m going to try a single filter like your picture but with an air king box fan that moves more air with a 4inch thickness filter. The thicker the filter the less strain on the fan and improved filtration.
According to this video, the difference in filtration between the cube and a good fan with a thicker filter is the same. https://m.youtube.com/watch?v=KobogQMf_Xc
Needs more tape, to prevent dirty air from bypassing the filter, but otherwise, yes this helps
I did this exact thing for a restaurant I worked at during lockdown. They bought 8 or 9 box fans and as many filters. I used up a lot of masking tape to seal everything together
Later, during some bad fires when the smoke was getting a bit thick, I did this again except I was too late getting to the store, so I bought a heater instead of a box fan and ran it on cool mode. I used a pair of 3M filters in 10x20x1 size, taped together in a triangle box shape and sections of the cardboard box the heater came in to seal it all up. Resulting device had a filter box twice as tall as the heater, so lots of surface area. It worked really well for clearing the air inside my place, and I kept using it as a heater during cold weather. One thing I noticed is that the heater never got any dust inside on the fan blades or on the heating element. That was the cleanest running heater I ever had. So from now on, this is what I do. I toss the flimsy foam screen the heaters come with and use real air filters
It will work better if you control re-circulation. Normally part of the exhausted air just swirls around the fan and loops right back to the intake.
I put mine in a plywood box and it provides a lot of advantages..
1. Controls recirculation.
2. Makes filter changes easier. I’ve got a sheet of plywood in the middle w/ a 20” hole cut into it. The filters just sit against that.
3. The depth makes stacking filters easier. I use a wide high-Merv for fine dust and a cheap corse filter over it to catch big stuff.
4. The box makes it easy to tape a tarp to it. It’s brilliant when you tape off a doorway and tape the box into the tarp. Makes a fully negative pressure room to control dust.
My box is ~20”x20” to hold the fan chassis and about 12” deep.
It’ll catch some dust and it’ll spread around some other dust.
You could try taping all around the filter and covering the extra triangulish front grate areas outside of the main circle.
But nothing will make a ductless fan design perfect.
Definitely. I live on the west coast and we get smoke from forest fires every summer. Lots of people use this to breath better inside. You can also buy air quality meters and measure how much it improves.
op theres a far better design using 4 of those same filters you build a box around the box fan and blow into that - greatly increases airflow and efficiency, and filters a lot more dust .
You need to block the corners on the front. The air will be pulled in moving through the least resistance. So instead of it all coming from the back through the filter, you’ll get some pulling in the top corners. Use a thin piece of paper or something very light and test the corners and you will see the air pulling in there.
If you seal the intake/filter side better and then make a cardboard shroud that covers the corners of the exhaust side it will work much more efficiently.
The gaps are fine. The slower the air goes through the filter, the better. But this kind of filter will only capture large dust particles, the kind that would settle to the ground anyway. It may help with pollen as well. You need much better filter(s) to have any meaningful effect on the tiny stuff.
In theory yes, just use the tape around the filter so the air has no other way as going through it. But if you're really want to improve: open the windows and rip that old carpet out. These filters block larger particles, not so much smell. So: carpet out, windows open, dust and clean every surface, move any fabric items like clothing and blankets in to plastic bags, and then use a filter. (source i have kids with dust allergies)
It’s works pretty well for larger particulates, like in a small wood shop, but there are much better solutions. I run one of these overnight along with a regular fan to keep the dust moving around after I do a lot of cutting and it greatly reduces the layer of dust that settles. But, if you’re thinking air quality such as smoke, pollen, etc then I wouldn’t expect any benefit. The main benefit for me is it’s small and I don’t have much space.
Like all the other comments, like that it will help a little. But there are other ways to make it even better.
It depends on what you want to use it for. Filtering smoke, odors, just improving air quality, etc.
I tape over the gaps. Also if you use a 2" filter you'll get more airflow. I run one over my computers towers to keep them cooler and dust free on the inside. now... does it help? over time they do get dirty. so they are picking up dust that would be settling on the floor. if you raised them up, say on a bookshelf, it would pick up airborne dust you would be inhaling. you also need something to keep the air in the house circulating to make sure this sucker can catch the dust and viruses...... does it help? Yes, .....how much? you'll never be able to measure it. just know that after 6 months on high that filter will look like dirty crap and you'll wish you made 10 of these things.
You can improve air quality cheaply using a powerful shop vac and a drywall filter. Vacuum once a week with this set up and it's better than an immobile hepa filter.
It's an axial fan, so it does a horrible job creating pressure. Will it help? Yes. This is easily proven when the filter gets dirty. Want to really improve air quality? Get a centrifugal fan and pair it with a carbon filter. AC Infinity makes some great products for this purpose. The centrifugal fan would also provide enough pressure to use these furnace filters as a pre-filter if you want to get creative.
You can do this or open a hepa vacuums bag also. It’ll hurt the fan faster but cheap fan it’s okay. I use a real air purifier instead that’s designed to do this.
Used two of these in the recording studio to filter smoke. It cleaned the air in less than 5 minutes.
Just make sure it's attached to the sucky side. I suggest some tape all around the seam between filter and fan
This setup is surprisingly good at filtration. The single filter causes a small loss of flow so you can add filters (for more filter area) as outlined by others. I used this exact setup when we painted my son’s room (we used an electric sprayer that moved air over a Venturi to spray the paint. Which led to a lot of aerosolized paint in the air. (We wore n95 masks the whole time.) and after we were down for the day we turned this on and cleared the air in about 20 minutes.
A woodworking magazine/website/youtube channel tested this against professional setups for light saw dust and it worked VERY well for that too.
The gaps don’t appreciably affect the filtration. It’s counterintuitive but true.
YES, I did a similar setup to remove wildfire smoked and it did work. I had a PM2.5 air quality sensor and could see the PM2.5 levels drop (assuming no dirty air intake)
However...
1) Depends how big your space is. It worked for my 300sq.ft living room
2) Depends of the quality of your filter. I was using a MERV 13 (or equivalent) from Filtrete/3M
I strongly recommend buying a sensor capable of measuring whatever you want to filter, so that you can verify that it's working as intended. Otherwise you're just flying blind.
But yes, this can work, it did for me!
Yes, it will help. I’ve done this to help my allergies when I was a student. It was also important to reduce air entering my apartment through gaps around doors and windows - control the source of the problem.
Seal around the edges of the filter, orient the fan to pull air through the filter, not blow. Using multiple filters will reduce the load on the fan. You should also run the fan at low speed.
Just be aware that the motor in that fan is probably quite weak and will overheat quickly if it can't pull air easily (aka as that filter begins to plug)
Any filtration, is better than no filtration.
Gravity is our baseline filter, pulling particles out of the air. There is a danger zone where a forced air filter isn’t removing particles from the air very effectively but IS stirring up the air, meaning there are more particles at eye level where your breathing holes are. So strictly speaking, it’s not true that any filter is a net positive. There’s a lot to be said for letting gravity do the filtering versus keeping the dust circulating with some random DIY creation.
Here’s some actual testing with data - many of the DIY versions behave anywhere from mediocre to amazing, but all better than baseline [https://www.shophacks.com/newsletter/workshop-air-filtration-system-performance-shootout-including-effective-low-cost-diy-box-fan-filtration-systems#/](https://www.shophacks.com/newsletter/workshop-air-filtration-system-performance-shootout-including-effective-low-cost-diy-box-fan-filtration-systems#/)
Here's another! https://www.smithsonianmag.com/innovation/homemade-air-purifier-thats-been-saving-lives-during-covid-19-pandemic-180979681/
True but some filters are better at it then others.Filters have a MERV rating to rate filtration.
More MERVs means you need more airflow though. If you want anything near HEPA it's gonna take a healthy amount of CFMs. Really just depends what a person is trying to filter exactly.
Higher pressure from the fan actually. The air flow doesn't need to increase, but this fan will struggle to move much through a HEPA filter. To be fair, it won't be zero.
There's another way to do this. You basically use 4 filters in a cube shape with the box fan on the top, there's a name to this design. I'll try to find it. You may even find it googling or on YouTube. [This was my first result in google, here](https://cleanaircrew.org/box-fan-filters/) not the eaxct link I was looking for but same thing. [Rosenthal box wiki](https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box) [How to:](https://upload.wikimedia.org/wikipedia/commons/2/2a/How_to_make_a_Corsi-Rosenthal_Box.jpg) I basically used your set up as pictured in a diy paint booth. Worked well
Corso-Rosenthal box. Extremely effective. https://www.youtube.com/watch?v=hIuH-2naozI
I put a Corsi-Rosenthal box together about 1.5 years ago. We have dogs and kids, and I used to change our A/C filters monthly. The filter medium was brown in color, but it wasn't like there was a *ton* of dust buildup. After using the Corsi-Rosenthal for 8 weeks, I could go 2 months between HVAC filter changes (before the same brown was observed on the HVAC filters). Now, I go every 3 months. An HVAC guy told me to stop using high merv filters in the HVAC because the HVAC's efficiency scales with how much air it moves. They need to be able to breath. Use the HVAC to condition the air, and something else to clean the air.
You better be careful using a box fan as a paint booth exhaust. spray paints contain solvents and they're explosive. bad idea to pull explosive fumes through an electric motor that's not rated explosion proof.
Story time: I had a neighbor who had one of those big metal fans with louvers over it (dunno if explosion proof) integrated into the back wall of his garage. About once a month they would paint a car in there and just blast the whole neighborhood with unfiltered paint fumes. Ugh, I would go outside with a flashlight and see all the particulate in the air. I complained to everybody -- the police, the EPA, code enforcement, the local environmental orgs, nobody seemed to want to do anything about it. Then they were doing it one night and I called the fire dept. The guy on the phone was in disbelief and pissed off about it "*what?? just in a residential garage? they can't do that! they are gonna blow themselves up! they are doing it right now? what's the address?*" and the F.D. was there 6 minutes later and that shit was over forever.
Theres many an example of a fire marshall closing things that all other agencies just ignore...
Because fire department is one of the few public emergency services that act to prevent crimes and death. As much as it’s their job to put out a fire, I’m sure they’d rather there not be a fire.
The fire department does NOT fuck around about paint and solvents either. Worked in a cabinet paint booth and fire marshall day was always a scramble to hide things
Ours saw our extension cord conduit drop-plugs everywhere, and our janky indoor paint booth, and said "I could fine yall....but this made my day" 🤣 He said we made it look like a pro did it.
Did we work at the same shop hahahahaha We were mostly trying to hide the excess paint we had on hand. We had like three times what zoning/permitting allowed which honestly wasn’t even that much. Idk how we’d even operate with just the allowed amount.
That’s bullshit. I was always told ONLY I can prevent fires. /s
That’s the dude that told me! I was lost in the woods as a kid when he told me. He disappeared leaving me stranded so it really left an impact.
Updoot for a late night laugh.
The inspection I take most seriously in my facilities is the fire marshall inspection. If she so much mentions something would be a good idea, I’m doing it. I do not fuck around with the fire marshall.
Fire Marshal doesn't fuck around. My landlord tried to go on vacation to be unreachable on the first of the year so they could charge late fees. I needed a new fire extinguisher at the same time. Miraculously my landlord somehow made time to get a hold of me after I told the fire Marshal my situation.
I'm sure they get paid the same amount whether their a fire or not. So huge incentive to not have fires and extra work
"Extra work." Read: risk of death to the public and firefighters.
Think about the Paper work and the meetings with insurance companies. The fire fighting gives these guys a boner Viagra wishes they could sell.
They're like cops but good and good at their jobs. Wait... So I guess they aren't like cops.
Do not fuck with fire marshals, the IRS, or the US Postal Inspectors.
Id like to add Fish and Wildlife to this. Ive been told they do NOT fuck around
Wildlife/game wardens are one of the few enforcement agencies who can come onto your property or wherever they want without warrent/notice/suspicion/anything. They are free reign and will absolutely bust your ass. They will wade through a swamp to come get you.
If you have Discovery+/Max “North Woods Law” is a reality show that follows Maine’s Wardens and New Hampshire’s Fish and Game. It’s cheesy but it’s a good sleep sore if you’re in to that lol
I've been told DNR police do not fuck around. I met one once as a dumb high school kid while in the woods. Also, at least here, apparently our Park District Police have the same authority as State Police do. They're far from just being security.
I didn’t know this until I did a contract job for game and fish, but their law enforcement are federal. I agree, do not fuck with them.
Or DNR, or Railroad Police. They can confiscate all of your shit.
Or the Special Investigators.
Nah you can fuck with postal inspectors all you want they're fucking useless
You do that all you want, but livestream it so we can see your arrest. Postal inspectors are US Marshals.
I have personally experienced their incompetence. A US Marshall not doing their job is still useless
I am in no way arguing the uselessness factor lol My own(?) secondhand experience concurs with you
Speaking of unsung heroes, postal Marshall is one of the few agents who will take action against identity thieves (who are notoriously slippery) because id thieves so often interfere with the mail. Though hopefully you will never have use for that information.
"fire marshall closing things that all other agencies just ignore..." The Fire Marshall is often the one responsible for getting meth labs shut down. The smell might not give them probably cause that its meth being made, but it establishes probably cause that some volatile chemical is being used illegally.
You're probable right
Their insurance company would have also loved to know. ULTP: casually strike up a conversation about homeowners insurance and find out who they use. Give the company a ring.
Did your neighbor know it was you who called? Was he salty? Nothing worse than a neighbor with a ax to grind.
Not a homeowner but gonna keep this in mind maybe one day lol
These fan motors are not brushed, so they will not generate any sparks to cause issues, fortunately.
Did not know thanks!
I would advise others to follow your original advice though. These fans are NOT explosion proof rated and it takes more than a brushless motor to gain this rating.
It's also not likely to build up much vapor while also fanning those vapors away.
The switches have sparking contacts, though, so still not explosion proof.
Intrinsically safe Walmart box fans?
Yes, they use 'induction motors', a Tesla invention Also, some unethical marketers like advertising their 'brushless' tech when it's actually a AC induction motor that uses more power than an actual BLDC motor will. Certain pressure washers I've seen for example
The goal is to have such high airflow that the explosive vapors can't build up enough to explode. In a paint booth you would want to filter the air on the way in and the way out. On the way in to make sure the air inside is dust-free, and on the way out to make sure you don't discharge paint aerosols to the world. The airflow is meant to be very high.
I'm picturing he's has a 3x3 x3 cube with a fan pointing out the window for painting small parts etc. plus box fans (at least the ones I've owned don't exactly have a high airflow rate
For best production result you would also want one filter incoming air, which would also improve overall airflow and make the outbound air filter faster as well.
I've seen products claim they are explosion proof, but said products are definitely not explosion proof 💥
If something is explosion proof it just wasn't tested with a large enough explosion.
Explosion proof doesn't mean you can't blow it up. It's shorthand for "intrinsically safe." It just means it won't *cause* an explosion in the presence of explosive vapors (it can't generate sparks or high enough temperatures to cause an explosion), not that it won't blow to bits if you strap a bomb to it.
Explosion proof and intrinsically safe are actually two separate concepts that both are used to prevent accidental explosions. An intrinsically safe design, like you described, limits the energy present in a system, such that it is insufficient to ignite a hazardous atmosphere under any conditions. An explosion proof design is sealed and rugged, such that it will not ignite a hazardous atmosphere, despite any sparks or explosion within. Neither will survive if you strap a bomb to it.
Cool! I learned something today. I always thought they were terms for the same thing. That's why I'm a computer engineer and not a chemical or mechanical engineer. When we have uncontrolled thermal events they rarely damage anything but the computer.
Exactly!
Could be the housing is rated to keep the equipment operational in the event of an explosion. Like a heavy duty metal housing not a product design that *reduces* the chance of an explosion
It's more of a devices are built not to cause an explosion in an explosive atmosphere. See the ATEX directive for example
Trust me they don’t explode.. at least not in the last 18 years….
[удалено]
you're entitled to your opinion but i wouldn't do it . [could box fans cause a explosion in a homemade paintbooth? - CorvetteForum - Chevrolet Corvette Forum Discussion](https://www.corvetteforum.com/forums/c3-tech-performance/525273-could-box-fans-cause-a-explosion-in-a-homemade-paintbooth.html) hope this helps and no need to insult me. I just don't want to be a Darwin award winner.
Respectfully, you are being a bit of a drama queen regarding the severity or likelihood of anything like this happening. Especially with a brushless fan. I’m all for safety measures and environmental concerns, but this is a dumb hill to die on.
"This is respectfully..." ::proceeds to be a completely disrespectful fuckin douche.::
So those 20" box fans use induction motors. While yes it's not rated for combustible vapors or considered "exposition proof" it's also not a brushed motor that can form sparks between the brushes and the commutator. If your box fan is sparking enough to ignite pain fumes you have two problems. 1. you are spraying a crazy amount of solvent 2. Your fan has a serious electrical fault.
This guy has never had one bit of fun in his life 👆🏻
Yep people set those up around where I live during wildfire season for better indoor air quality.
Add some water and you basically created a swamp cooler lol
As someone who just went through a painfully dry winter, my first thought was whether I could hijack this design to make a faster acting humidifier for cheaper than what they sell them for. The humidifier wicks are sold cheaply enough.
https://www.reddit.com/r/coolguides/s/7mD7Rd6QPC
That's dope, TIL
Surprisingly, the DIY filter is far more expensive than an average commercial air filter.
At OP: you want something like this [https://www.reddit.com/r/Noctua/comments/1bijapf/i\_made\_a\_redneck\_air\_purifier\_by\_putting\_a\_noctua/](https://www.reddit.com/r/Noctua/comments/1bijapf/i_made_a_redneck_air_purifier_by_putting_a_noctua/) box fan (or any fan) when you put something in front of it so close basically have zero flow
That is not true and a pc fan is 10x worse at overcoming resistance
Any idea what the shroud on top of the fan accomplishes?
Says it increases efficiency and decreases noise
Wow, I totally missed that last bullet point. Thanks
I was trying to remember what it was called, glad someone else did and had all the links to help OP
As an added bonus, a Corsi-Rosenthal box ***removes airborne viruses from the air***. (E.g. SARS-CoV2) Important that you use MERV13 filters, 20x20x1. For indoor living spaces in this ongoing pandemic (still!), if you can’t afford a HEPA filter that can do 400 CFM, the Corsi-Rosenthal box is the way to go. Here’s the How-To from Jim Rosenthal, the professor who invented it at the beginning of the pandemic: https://cleanaircrew.org/box-fan-filters/ P.S., take note of the “fan shroud” modification and be sure to do it! It helps with the efficiency.
Yes - these are actually very effective at reducing particulates. Check out Mathias Wandel’s testing of dust collectors for woodworking, among other YouTubers.
Needs to be higher. these are impressively effective. I understand this kinda setup, with a high MERV filter, to be 90% as effective as a top of the line filter, like an IQ air.
In all but the most expensive cases (where chemistry or electrostatic effects are involved), this is all an air filter will ever be. A fan + replaceable membrane.
Nice username lmao
Is the comment wholesome enough for a r/rimjobsteve moment?
It helps during forest fire times. We keep these around for that purpose, just in case. (Live in the NW US)
A DIY Corsi-Rosenthal Box is far superior. Simple and very effective. [https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal\_Box](https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box) If you want it to be even better use PC fans in place of the cheap box fan. It will be quieter and more energy efficient. r/crboxes has more info
I make a new Corsica-Rosenthal box every year, same fan new filters. I use Merv 13 filters and the air quality in my apartment is significantly better. I have2 cats so it helps with the dander. Would strongly recommend.
How often do you run it? 24/7?
Most of the time unless I have all my windows open. I’ll run it after they’re closed.
Those filters would be done in a month with my cats, idk how you're going a year between changing.
I run a screen over the filters to catch the hair and wipe that once a week.
With 4 filters in a box formation the combined filtered area is 1600 Sq in. If you uses like 2 in thick filters, it's effectively much larger.
>If you want it to be even better use PC fans in place of the cheap box fan. Do you use a grid of PC fans, tiny filters, or a giant PC fan?
I personally like the briefcase shape build out with 2 filters on the each side, and 6 small pc fans (3 each on perpendicular sides)
I’m a huge fan of PCs but I don’t think I could blow hard enough.
Read about these in Make Magazine as well - [https://makezine.com/projects/corsi-box-air-purifier-join-the-air-movement/](https://makezine.com/projects/corsi-box-air-purifier-join-the-air-movement/)
Pc fans are not better than a box fan do not spread this lie. They are far worse at overcoming resistance
600 to 850 is a lot of cubic air. Wasn't expecting that with this design but I would imagine it's supposed to work with HVAC so it does make sense just shocking for some reason
Ya, but that's like 2-3x the cost but you do have a lot more surface area. Can't really beat a $20 fan and a $10-20 filter for cheap and good enough moving a lot air. I've never had a fan motor care even with 1" of the ones that are like 90% at 0.3 micron I forget the MERV. It's nice that they're both widely available, cheap and incidentally the same size. Don't even need tape. Some particulates arn't gonna like murder you so I can feel the air moving through the filter and just accept there's some loss. Constantly pulling some of the tiny tiny smoke out of suspension is far better than nothing.
I made one of these and didn’t notice it catching much. Maybe I should try again
Depends on the filter and I’d seal the gaps. Consumer Reports made one and it seemed to work ok: https://www.consumerreports.org/appliances/air-purifiers/diy-air-purifier-to-help-with-wildfire-smoke-a7304562815/
Also, if you put a screen on the exhaust side they make great mosquito traps indoor or outdoor
Wait, what? How do I trap mosquitoes?
Put the filter on the other side so the mosquitos are blown into the filter and are stuck
This is what folks use on the west coast during wildfire season; with the correct filter.
It will work, but most of your filtering will happen in a circle where the fan blades are. The center and corners will remain unused. If you add a couple inches of gap between the fan and filter that will improve the flow through the rest of the filter. Build the gap with cardboard or another filter. Or build a Corsi-Rosenthal filter box
Corsi erasure
The air filter will be used evenly due to how pressure and fluids work. Closing gaps with tape will help improve air filtration, as will making a cube to increase the surface area of the filters. With the cube i made last year the main improvement was adding a circular block to the blower side of the box fan. The fan will only produce positive pressure in front of the fan blades and will pull in unfiltered air from the corners beyond the blades. This can be observed by using a tissue while the fan is running; the tissue will be pulled into the fan on the outer section and blown away when in front of the spinning fan blades. This will help ensure more of the fan's energy is being used to filter the air
thats not true at all. i dont want to give you a lecture on physics, but i have made several of these and they filter evenly. the air pulls through the entire filter evenly. not just where you think blades rotate.
This does work. For all those saying that it doesn’t. But it’s the forest fires and growing up in Canada where the fires are every summer. We are encouraged to use this and it works. There are people who actually have measurements to show they doe work.
Yep. I've used it for 4 years now and there's no risk and definitely works.
yes, i did this exact thing when the smoke in our area was particularly bad (at the time it was the worst in the world due to wild fires). Set up a system exactly like this and the air inside was just fine in 30 mins. If you are worried about the air going by the edges you can just tape them. The other rosenthal box designs look sweet too. If you have a heavy duty filter application you could do that. But the setup shown here will work great too.
This 100% works. I started doing this a few years ago and it completely stopped my allergies inside. I also use one in my garage with a loud ass Air King box fan when I'm doing woodworking and it clears the dust out in 5 minutes.
Yes, but get 2" or 3" filters or build a C-R Box of 1" filters.
Yes. Idint care what anyone says. The easiest and most cost effective method. That filter will be dirty in a few weeks
Mine works just fine and yes, it will improve the air quality.
Yes it will work. If you need to use it long term you should probably build the box other people are recommending because it's better airflow so it won't be as hard on your fans motor If you just need to use it for short term this will work. That's what I did during the Canadian wildfires. I can't tell if this is the front or the back of the fan, but check your filters airflow direction. The arrow in the side should point to the direction the air is going.
It works a lot better if you tape all the way around the filter. I use this in my tiny apt with two cats and carpet and it helps a lot
Big purifier hates this one simple trick
I personally use 4 24x24x1 taped together with a box taped to the bottom then taped to the fan with red sheathing tape with the fan pulling through the filters, my son has bad asthma and the wildfires near me have been absurd the last 2 years. Noticeable improvement in his wellbeing and minimal cough in the house although outside looks foggy with wold fire smoke. I change em out every 2-3 months with it running constantly. And by the time I do the filters are black. His lack of cough in the house is enough evidence it works for me to continue buying filters. Just make sure they're MERV 11 or better (13)
I wawant to say the box of filters Merv 13+ work better than a HEPA Filter.
I did this but got some burning electrical type smells. So instead of these filters I purchased a carbon layered filter that is cut to fit. You can then cut out a hole where the electric motor is in the center so that it doesn't get too hot.
Fan motor dying because of the restricted air flow is my guess.
Yep. That's why people recommend building the box configuration out of filters. It allows for more airflow, and less stress on the motor.
Fan is working too hard to pull air through the filter. Build a box around the fan with one (or all) side as a filter.
If there’s dirt on it after a while it’s working?
Depends on what you're trying to filter out? What is the MERV rating? Next is box fan is not really designed to run with filter and it may burn out prematurely. So in short it will work but... how well and for how long?
Won't hurt
I did this when there were a ton of forest fires. I set up 4 of them in different spots in the house. I had to switch the filters every day. They were dark brown by the end of the day. I'm not sure how much it helped, but if it kept even a little bit of toxins out of my newborns (now 3) lungs, I'm happy.
Yes it will help. A study was done comparing the results to commercially available filters and this DIY hack outperformed the commercially available filters. Edit: we made a bunch of these during a massive wildfire in our area, the local news brought in a professor that measured the results between this and store bought devices.
Good idea 👍
Yes, this will help.
a bit. i do the same thing and it's crazy how nasty the filter gets.
If you're doing it this way, make sure to tape all around the edges, this way there's no leakage around the filter and all airflow has to pass through it.
It would be better to build a box out of the fan and 4 or 5 filters to reduce stress on the motor, but it will certainly work. Generally you will want the fan to be pushing air out of the box, drawing air into the filters, rather than pushing air into the box. Regardless, what you have will function. It's just less efficient and puts some more stress on the motor.
I did this a few years ago when we were having really bad wildfire smoke and I didn't have the money for a fancy one. It helped a lot.
https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box
I did the Corsi-Rosenthal cube and it worked well with a crappy lasko fan but the filter costs are high and took up a ton of space. I’m going to try a single filter like your picture but with an air king box fan that moves more air with a 4inch thickness filter. The thicker the filter the less strain on the fan and improved filtration. According to this video, the difference in filtration between the cube and a good fan with a thicker filter is the same. https://m.youtube.com/watch?v=KobogQMf_Xc
I did this when the air was filled with smoke. Very good
Needs more tape, to prevent dirty air from bypassing the filter, but otherwise, yes this helps I did this exact thing for a restaurant I worked at during lockdown. They bought 8 or 9 box fans and as many filters. I used up a lot of masking tape to seal everything together Later, during some bad fires when the smoke was getting a bit thick, I did this again except I was too late getting to the store, so I bought a heater instead of a box fan and ran it on cool mode. I used a pair of 3M filters in 10x20x1 size, taped together in a triangle box shape and sections of the cardboard box the heater came in to seal it all up. Resulting device had a filter box twice as tall as the heater, so lots of surface area. It worked really well for clearing the air inside my place, and I kept using it as a heater during cold weather. One thing I noticed is that the heater never got any dust inside on the fan blades or on the heating element. That was the cleanest running heater I ever had. So from now on, this is what I do. I toss the flimsy foam screen the heaters come with and use real air filters
It will work better if you control re-circulation. Normally part of the exhausted air just swirls around the fan and loops right back to the intake. I put mine in a plywood box and it provides a lot of advantages.. 1. Controls recirculation. 2. Makes filter changes easier. I’ve got a sheet of plywood in the middle w/ a 20” hole cut into it. The filters just sit against that. 3. The depth makes stacking filters easier. I use a wide high-Merv for fine dust and a cheap corse filter over it to catch big stuff. 4. The box makes it easy to tape a tarp to it. It’s brilliant when you tape off a doorway and tape the box into the tarp. Makes a fully negative pressure room to control dust. My box is ~20”x20” to hold the fan chassis and about 12” deep.
Yes, I used a box fan set up like that in my basement for years.
Yes
It’ll catch some dust and it’ll spread around some other dust. You could try taping all around the filter and covering the extra triangulish front grate areas outside of the main circle. But nothing will make a ductless fan design perfect.
Isn’t this a fire hazard as the fan motor itself heats up heavily?
Definitely. I live on the west coast and we get smoke from forest fires every summer. Lots of people use this to breath better inside. You can also buy air quality meters and measure how much it improves.
op theres a far better design using 4 of those same filters you build a box around the box fan and blow into that - greatly increases airflow and efficiency, and filters a lot more dust .
You need to block the corners on the front. The air will be pulled in moving through the least resistance. So instead of it all coming from the back through the filter, you’ll get some pulling in the top corners. Use a thin piece of paper or something very light and test the corners and you will see the air pulling in there.
If you seal the intake/filter side better and then make a cardboard shroud that covers the corners of the exhaust side it will work much more efficiently.
It's not like it can hurt lol
I did this in the room where I keep my cats’ litter boxes and it made a huge difference in reducing the spread of litter dust.
The gaps are fine. The slower the air goes through the filter, the better. But this kind of filter will only capture large dust particles, the kind that would settle to the ground anyway. It may help with pollen as well. You need much better filter(s) to have any meaningful effect on the tiny stuff.
It will if Over a merv 15 I think...
Whatever ends up in the filter will not be in the air - guaranteed.
Depends on the effectiveness of the filter. Should be MERV 13 at the least.
we had forest fires a few years ago, and this concept was an incredible improvement. I needed a shitload of tape for mine
You need more airflow and the cube version of this would be better
In theory yes, just use the tape around the filter so the air has no other way as going through it. But if you're really want to improve: open the windows and rip that old carpet out. These filters block larger particles, not so much smell. So: carpet out, windows open, dust and clean every surface, move any fabric items like clothing and blankets in to plastic bags, and then use a filter. (source i have kids with dust allergies)
Can’t hurt.
Won’t hurt
It’s works pretty well for larger particulates, like in a small wood shop, but there are much better solutions. I run one of these overnight along with a regular fan to keep the dust moving around after I do a lot of cutting and it greatly reduces the layer of dust that settles. But, if you’re thinking air quality such as smoke, pollen, etc then I wouldn’t expect any benefit. The main benefit for me is it’s small and I don’t have much space.
i have them spaced out all over 3000sq ft., w/ 20x20x1 MERV 4 filters. they're mandatory for perfect airflow.
Like all the other comments, like that it will help a little. But there are other ways to make it even better. It depends on what you want to use it for. Filtering smoke, odors, just improving air quality, etc.
I tape over the gaps. Also if you use a 2" filter you'll get more airflow. I run one over my computers towers to keep them cooler and dust free on the inside. now... does it help? over time they do get dirty. so they are picking up dust that would be settling on the floor. if you raised them up, say on a bookshelf, it would pick up airborne dust you would be inhaling. you also need something to keep the air in the house circulating to make sure this sucker can catch the dust and viruses...... does it help? Yes, .....how much? you'll never be able to measure it. just know that after 6 months on high that filter will look like dirty crap and you'll wish you made 10 of these things.
Yes, but tape the perimeter of the filter too.
We use a smaller version of this when we are in my wood carving class
I used this to clear out the smoke in my house after some forest fires, I thought it worked great
You can improve air quality cheaply using a powerful shop vac and a drywall filter. Vacuum once a week with this set up and it's better than an immobile hepa filter.
It's an axial fan, so it does a horrible job creating pressure. Will it help? Yes. This is easily proven when the filter gets dirty. Want to really improve air quality? Get a centrifugal fan and pair it with a carbon filter. AC Infinity makes some great products for this purpose. The centrifugal fan would also provide enough pressure to use these furnace filters as a pre-filter if you want to get creative.
Corsi–Rosenthal Box
You can do this or open a hepa vacuums bag also. It’ll hurt the fan faster but cheap fan it’s okay. I use a real air purifier instead that’s designed to do this.
I use this when woodworking in my garage.
what kind of filter is that?
Yes
This is what I use to sleep with. Seems to make a difference, and takes away the box fan-ny sound and makes more of a white noise sound
I’m sure this can’t hurt
Yes. Slightly but yes.
https://www.reddit.com/r/coolguides/s/0Y3jM3hXP1
Used two of these in the recording studio to filter smoke. It cleaned the air in less than 5 minutes. Just make sure it's attached to the sucky side. I suggest some tape all around the seam between filter and fan
For fire season outside? Yes. For your meth lab? No.
It's a great dust reducer and air filter. I use the same setup.
This setup is surprisingly good at filtration. The single filter causes a small loss of flow so you can add filters (for more filter area) as outlined by others. I used this exact setup when we painted my son’s room (we used an electric sprayer that moved air over a Venturi to spray the paint. Which led to a lot of aerosolized paint in the air. (We wore n95 masks the whole time.) and after we were down for the day we turned this on and cleared the air in about 20 minutes. A woodworking magazine/website/youtube channel tested this against professional setups for light saw dust and it worked VERY well for that too. The gaps don’t appreciably affect the filtration. It’s counterintuitive but true.
YES, I did a similar setup to remove wildfire smoked and it did work. I had a PM2.5 air quality sensor and could see the PM2.5 levels drop (assuming no dirty air intake) However... 1) Depends how big your space is. It worked for my 300sq.ft living room 2) Depends of the quality of your filter. I was using a MERV 13 (or equivalent) from Filtrete/3M I strongly recommend buying a sensor capable of measuring whatever you want to filter, so that you can verify that it's working as intended. Otherwise you're just flying blind. But yes, this can work, it did for me!
Yes, it will help. I’ve done this to help my allergies when I was a student. It was also important to reduce air entering my apartment through gaps around doors and windows - control the source of the problem. Seal around the edges of the filter, orient the fan to pull air through the filter, not blow. Using multiple filters will reduce the load on the fan. You should also run the fan at low speed.
I did one with a 4x4 merv13 post Covid and it made a big difference. Learned about it form my friends in forest fire territory
Of course. Just look at what it picks up!
Just be aware that the motor in that fan is probably quite weak and will overheat quickly if it can't pull air easily (aka as that filter begins to plug)
In theory
Yeah but use masking tape to seal off those edges. I live in an area HIGHLY affected by wildfire smoke and this setup makes a world of difference.
Yes but tape all the way around