Thread: researching room air filter - Corsi-Rosenthal box- replacin Merv 13- MPR 1800 or 1900

In theory 2 x MPR1000s in series should be equal to or slightly better than one MPR1900.

Just be aware that a conventional room air filter ie used for a domestic dwelling has limited filtration surface area and so will clog more rapidly in a wood work environment.
The small fans used in these filter systems also means that even light clogging will seriously reduce airflow in a workshop so the filters will need more regular cleaning.

Assuming you are trying to clean the air after the garage door has been closed then, yes, a room air cleaner will help.

Pollen is easy to capture. Most grains are in the 10 to 100 micron range with the smallest known AFAIK being 2.5 to 5 micron. So what you really need to look at in filter specs the the E3 (3 -10 micron) performance. So the MPR1000 at 88% will do just as well as the MERV 13 at 90%, perhaps even better when you factor in actual airflow.

For a room air cleaner it's the product of flow and efficiency that counts. There's an industry spec that calls this CADR or Clean Air Delivery Rate. That determines how quickly particles are removed from the space.

I did some testing last year on various filters on a cheap box fan. As an illustration of the tradeoff between filter efficiency and flow restriction I found that at E3 particle sizes a cheap 2" thick generic MERV 8 had the same performance as a much costlier 3M MPR1500. At E1 sizes (smoke) the MERV 8 is nearly useless while the MPR1500 is reasonably effective.

There was a discussion on another forum about reducing the number of filters on the box you referenced. I didn't test that exactly (the purpose of my testing was to find out what could be done easily by anyone in an emergency situation) but I do have some data I can extrapolate:
More Filters 2.jpg
From which it appears that four filters may be a bit of overkill and, to me at least, more than two isn't really justified.

Darn $150+ just for the filters.

Filtrete Healthy Living Ultimate Allergen Reduction AC Furnace Air Filter, MPR 1900, 20 x 20 x 1-Inches, 2-Pack

Good stuff costs money.

Originally Posted by barrysumpter

Darn $150+ just for the filters.

Filtrete Healthy Living Ultimate Allergen Reduction AC Furnace Air Filter, MPR 1900, 20 x 20 x 1-Inches, 2-Pack

Barry, let me say again - for a room air cleaner the MPR1000 will be very close in performance to the MPR1900. The more expensive filter will clean the air a bit faster but both can clean to as low a particle count as you like.

Also, when filters cost about the same as cheap fans it makes sense to buy two fans and two filters. That combination will do better than multiple filters on one fan, at least for the set that I based that graph on.