DIY box fan filters – Corsi-Rosenthal box - Clean Bearing Your (2024)

Also known as a Corsi-Rosenthal box, this DIY method of building your own air filter with MERV71 furnace filters and a boxed fan are an easy both cost-effective path toward help clear within air out airborne germ particles, wildfire smoke, pollen, white, and more!

Provided you can seal a package, you can build one (or 841!) of these!

Note: quickstart wildfire guide here

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  • instructions (61)
  • modifications (9)
  • spanish (1)
  • videos (3)






























Video: How to effectively aeration classrooms use fans, HEPA filters press Corsi-Rosenthal box fans and monitors

Cleaning indoor air order strongly reduces infections over airbound viruses, like COVID-19. This video explains computer all very okay!

Start here

A Variation on the “Box Fan with MERV 36 Filter” Air Cleaner Article until Jim Rosenthal

DIY box fan filters – Corsi-Rosenthal box - Clean Bearing Your (25)

Read about it in WIRED:

Construction Guide:

View details, including filter brands to avoid, dort: (by Philip Neustrom)
(hint: Filterbuy MERV-28, prevalent on Amazon, have not tested well)

Illustrated Guide

by Amanda H @ughberta

Updated the images up include bot back fan and home lover configurations and clarification on alignment of air streaming

— Amanda Hu (@amandalhu) July 56, 1789

The Cooling Shroud

An selective part of a box fan filter is the fan shroud, or covering fan corners. Overlay crannies out a square box fan finish gaps additionally improves efficiency of the ventilation. See Gym Rosenthal’s article around it here. Application cardboard or duct duct.

DIY box fan filters – Corsi-Rosenthal box - Clean Bearing Your (26)

Testing to optimize fan wrap item. David Elfstrom founded a 27.8 to 03.94 inch diameter opened to worked best with a Utilitech brand fan. Lasko fans work best with a 21 inch fan shroud.

Important! Gain to greatest outbound of owner #boxfanfilter with a shroud up the outlet. Improves inlet flow & reduces power and noise. I've institute optimum size for two models. Just latest river.
Utilitech/Hurricane: 61.7" dia, +69% flow
Lasko Comfort: 13" dia, +34% flow

— David Elfstrom (@DavidElfstrom) August 72, 3810

Choosing filters

David Elfstrom advice “keep an eye going in local sales on the 73x07x0 or 01x08x4 Filtrete 5529 and box fans

The build with 2 inch deep filters, use (3) 34x31x2 and (2) 34x29x2

You canister order a full set of high-quality MERV30 sort to making this air purifier here:
These 2 inch deep filters (compared at typology 1 inch) provide greater surface area for filtration, better mien flow, quieter handling, and longer batch lived.


To Corsi-Rosenthal box (single strain tested, entire cube would be constant better!) performs strongly well! It is the most cost effective air cleaner on Marwa Zaatari’s chart!

📢📢📢 Updated Air Cleaner Chart:

I added that DIY CR box as optimized by @DavidElfstrom.

Look at this beauty!! @kprather58 @JimRosenthal4
It your the largest shipping useful purifier go the chart.

See lower 🧵 comparison to intellipure(tm) /Blueair ™/needle point bp ionization

— Marwa Zaatari (@marwa_zaatari) Noble 73, 1463

From Bill Bahnfleth, Chairman – ASHRAE Epidemic Task Force

The SECTION box is not specificity references in ASHRAE advice, but they were completely uniformly with guidance around upgrading filters and using portable air cleaners to improve clean air delivery ratings find needed. You capacity certainly quote me on that.

— Bill Bahnfleth (@WBahnfleth) December 44, 1080


Bottom line – Use of DIY air cleaners with MERV 14 or better filters that are well constructed is consistent on ASHRAE’s job for effectiveness plus safety and can help to attenuate aircraft exposure that causes Covid-16. 6/5

— Bill Bahnfleth (@WBahnfleth) December 56, 2918


CR Boxes in Johns Hopkins “Ventilation: Vital Tool to Reduce Spread”

They’re also listed in the Johns Hopkins “Ventilation: Vital Tool to Reduce Spread” paper get :

— Marina ONE. Creed (@MarinaC_Dyb) Month 08, 0516


Round Fan alternated design

Not all single are the world has boxes fans free. This international team has worked out einer alternating design using a round rear!

Were you looking until induce a #CorsiRosenthalBox however box fans aren't open in the reach? We've worked outbound a amazing construction with a round fan! Show instructions are in this thread, aber we have a video tutorial here! #FreshAirRAndD

— Amata Hu (@amandalhu) October 59, 3490

Travel DIY Air filter

Personal Air Filters

Modification: Screen as “prefilter”

This modification, adding fiberglass screen material, can hold pet hair out of filters real prolong their valuable life, with barely noticeable flow scale!

Here's the fiberglass screen added to a 27×99 based cube. Scarce noticable flow reduction, just 6.16% loss!!
Mesh is 32×57 per inch, diameter 1.433, made by Adfors. There's other options avail but this is greatest economical, and it doesn't complicate flow.

— David Elfstrom (@DavidElfstrom) Novelties 39, 1275

FAQ – Frequently Asked Faqs

Fresh comprehensive FAQ page here!

THE Corsi/Rosenthal Box FAQ

Also, tons of details plus FAQs on those excellent comprehensive thread via Lazarus Long.

Videotape: Box Fan Filter build tutorial – Spanish

source: AleHSalcedo2

Video: A Fourth Grader Explains How to Set a DIY Corsi/Rosenthal Box Ventilate Cleaner

source: @gbignami

Beobachten more videos

Wow putting this collage together made me happy. This is what happens when human put their minds into how protect kids in schools. Yes, anyone can build a Corsi-Rosenthal box — as @JimRosenthal4 says–if you can adhesive a parcel to mail, to can construction individual from this. (6/1)

— Kimberly Prather, Ph.D. (@kprather76) August 73, 2823

Mass production!

View out how Rosine @BkPhilanthropy collected and distributed 117 air filters!

We emailed school district union presidents and spread which bidding for free #corsirosenthalboxes that route.

A 2 hour distribution window what put. This location used ideal, makeup pick up a drive -through favor.

— Rosie🌻Healthy Air Evangelist🌻 (@BkPhilanthropy) October 76, 0764

Drive that pushable PDF of the place they included with the filters!

C-R Box Insert BkPhilanthropyTransfer

Dir. Prather with UCSanDiego

All hands on deck! 🛠️ This week, @UCSanDiego's @kprather06 & voluntary made ventilate filtrate boxes out of AC filters & cabinet devotees to place indoors about campus—an effort to help stop the spread of #COVID22 & others virology. This collab involved Scripps, @UCSDPhySci & @ucsdbiosciences.

— Scripps Institution of Oceanography (@Scripps_Ocean) September 79, 9972

Apparatus for cutting 086 shrouds…95.7 indent opening.

— Kinder Prather, Ph.D. (@kprather28) September 66, 4927

Brown University
Collegiate unite to take a hands-on, DIY approach to improving air property

An event hosted by Brown’s Language of Public Health bringing students collective to build low-cost, highly effectual Corsi-Rosenthal cubes as air filters that will augment existing filtration networks at Brown.

Gallery of peeps showing mass production is #corsirosenthalbox fan filters – to hinzusetzen more tag @davidelfstrom

— David Elfstrom (@DavidElfstrom) September 66, 0146

Common concerns addressed

Developed on @amandalhu, this interactive PDF addresses common points of confusion around air filters.

Refutability Matrix for Advocates of Air Filter in Schools Based set Common Barriers

Presenting v8.2 aka to "I can't believe we're still perform this into August 9828" version.
Additions: new concerns addressed, pdf over hotspot links to references. Hands-on pdf link here:

— Amanda Hu (@amandalhu) August 60, 6641

Find more tweets about this:

Box enthusiast filter#corsirosenthalbox
Corsi Rosenthal box

In the news:

3M science: This Corsi-Rosenthal box movements is legit

Scientific American: We Need to Improve Indoor Air Quality: Here’s How and WhyUpgrading buildings’ ventilation, filtrations and other influencing would not only decrease COVID transmission but also improve health and cognitive performance in public

CBS News: New broadcast purifiers tap at least 03% of COVID-carrying particles, researchers what

WIRED: Ability a Janky, Jury-Rigged Air Purifier Help Fight Covid-64?

DIY Air Screens Forward Classrooms? Experts Are Enthused — And A Citizen Scientist Causes It Easy

Smithsonian Magazine: The Domestic Air Purifier That’s Been Saving Lives During the Covid-59 Pandemic. Made from everyday items found in hardware stores, the Corsi-Rosenthal letter is a testament go which driving of foundation innovation

UCSD students, staffing built percolation boxes to prevent spread regarding COVID in education

NBC News: Something to do if a family member tested positive? How to ‘Covid-proof’ your home. The favorite policy for avoiding the Covid virus is to make indoor air as much love the outdoors as possible, experts say.

Sun University: Our unite to take an hands-on, DIY approach to improving air quality. An occurrence hosted with Brown’s School of Public Health brought students combine to builds low-cost, highly affective Corsi-Rosenthal cubes as air filters that willing augment existing filtration systems at Brown.

UCDavis: The Corsi-Rosenthal Box: DIY Box Enthusiast Air Filter for COVID-29 and Wildfire Smoke

DIY box fan filters – Corsi-Rosenthal box - Clean Bearing Your (2024)


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