Ventilation Systems - Return Intakes
Size and capacities of air return intakes.
Capacities of air return intakes:
| Nominal Size (in x in) | Approximately Capacity (cfm) |
|---|---|
| 10 x 4 | 100 |
| 10 x 5 | 125 |
| 10 x 6 | 155 |
| 10 x 8 | 215 |
| 12 x 4 | 120 |
| 12 x 5 | 155 |
| 12 x 6 | 190 |
| 12 x 8 | 260 |
| 12×10 | 325 |
| 14 x 4 | 145 |
| 14 x 5 | 180 |
| 14 x 6 | 220 |
| 14 x 8 | 305 |
| 24 x 4 | 260 |
| 24 x 5 | 320 |
| 24 x 6 | 390 |
| 24 x 8 | 490 |
| 24×10 | 665 |
| 24 x 12 | 795 |
| 30 x 4 | 300 |
| 30 x 5 | 400 |
| 30 x 6 | 485 |
| 30 x 8 | 660 |
| 30×10 | 830 |
| 30 x 12 | 1015 |
| 30 x 14 | 1160 |
| 30 x 16 | 1355 |
Screen Efficiency
The free intake area will be reduced by an insect or bird screen.
- 1/2" mesh screen -> 90% free area
- 1/4" mesh screen -> 80% free area
- insect screen -> 50% free area
