Corsi–Rosenthal Box Review

Using a simple box fan with four MERV 13 air filters, this high-powered unit might look like a large, Frankensteined monstrosity, but it scored among the absolute best for overall air cleaning performance. It's a surprising and fun option for those who want a cool science project to do with the kiddos or who need a fast fix when air quality suddenly plummets.

Air Cleaning Performance

Because it is, effectively, four huge square air filters duct taped to a standard-issue box fan, the Corsi-Rosenthal Box provides powerful particle removal, cleaning about 97% of large particles (bigger than 2.5 microns, such as dust or respiratory particles) in a short 10 minute timespan. This wowed our testing team, earning this DIY box one of the best scores for pure air cleaning performance, which was weighted as 40% of each unit's overall score.

It took this DIY box a mere 21.5 minutes to clear 99% of all fine particles, with sizes between .5 and 2.5 microns. For reference, most bacteria are 2-3 microns, and wildfire smoke is rated between .4 and 1 micron.

“Cleaning the air in a third of an hour is just a stupendous achievement,” said our lead tester. “If you need air cleaned quickly, there really is no better option than this make-it-yourself contraption.”

Though it's on the noisy side, the Corsi-Rosenthal Box offers superior air cleaning at a fraction of the cost of many other units. We feel that it would be a good option for people who aren't noise sensitive and need a big, powerful purifier for an industrial space, warehouse, or garage. It would also work wonders in a pinch if your local hardware store ran out of air purifiers during a particularly demanding fire season.

Noise

Unfortunately, Air Cleaning Performance is the only place where the Corsi-Rosenthal Box outshone its competitors. In our noise metric, which was weighted as 30% of every product's overall score, it scored among the lowest purifiers, with a staggering 60.8 decibels of measured noise on its highest setting.

In general, an electric toothbrush has an up close decibel rating of 60, and freeway traffic has a decibel level of 70, meaning that the Corsi-Rosenthal Box would be quite loud in an ordinary home or office setting. “Only the low setting is an acceptable sound level for regular use,” notes our lead tester, who checked the ambient noise level of each machine from six feet away.

Though it's easy enough to put together a Corsi-Rosenthal Box in 15-20 minutes, its noise level while whirring away on high is likely too loud for most users' primary needs.

Ease of Use

The no-frills simplicity of the Corsi-Rosenthal Box makes for an air purifier that's light on cost, but also light on extra features and functionality. The only features available on this bad boy will, essentially, be the features that come baked into the box fan you use when you construct it.

Users of the Corsi-Rosenthal Box will need to assemble it themselves, making its ease of setup score significantly lower than its name-brand competitors. It's also incredibly large and bulky, compared to other air purifiers on our list, with its four huge filter panels taking up more space than most people might want in a mellow living room setting.

That being said, one of our testers in California noted that the time-consuming setup might be a feature, not a bug, for some science-minded users with kids at home. “I liked putting it together. It didn't require any tools other than duct tape and scissors, making it about as difficult as a kindergarten science project,” he noted.

Generally, this unit will only have low, medium, and high fan settings for adjusting overall airflow and, thus, cleaning power. “If you want to upgrade it you could also buy a box fan with smart capabilities to allow for scheduling and remote operation,” said our lead tester.

Operating Cost

Sometimes, high performance comes at a cost, as was the case when we hooked up our Corsi-Rosenthal Box to a voltage meter to see how much power it pulled across its different fan speeds. This was certainly not the most efficient model on our list.

There's no reason to beat around the bush; the large and powerful Corsi-Rosenthal Box uses a huge amount of electricity when compared with our other award winners. On its highest setting, it pulled 106 watts. When set to low, it still used 72.2 watts, which is more than most units we tried out on their highest setting. Using the average U.S. electricity cost of $0.17 per kilowatt hour, we estimate that this big box fan filter would cost about $134.18 to run round-the-clock for a full year.

Should You Buy the Corsi-Rosenthal Box?

If you're the kind of shopper who loves a funky little do-it-yourself project or wants a large and powerful air purifier for their garage or warehouse, building a Corsi-Rosenthal Box might be a great solution. Though it's darn noisy, it'll offer excellent particle filtration at a fraction of the cost of a name-brand competitor.

What Other Air Purifier Should You Consider?

Even though it's significantly more expensive up front than this DIY box, the Winix 5510 is another high-powered air purifier that's suitable for large spaces. The same goes for the Alen BreatheSmart 45i, which also offers interchangeable front plates to suit a huge range of home aesthetics.