The Corsi/Rosenthal Box is based on a 20″ x 20″ box fan. This is because the size perfectly matches with 20″x20″ filters.
Some countries have no box fans. Round fans have been used to build the Corsi/Rosenthal Box.
- 20″ Box Fan – very important that the On button/ Speed Control is on the outer edges of the fan – or on the front where air comes out. You do not want it on the back where air comes in.
Safety note: the box fans have been tested and found to more than up to the task. With that said, as an additional note, it might be good to get one with a fused plug, which the Lasko and Utilitech fans have for sure.