Combustion and Ventilation Air
| Total Input | Unconfined Space (8Ft. Ceiling/Square Feet) | Confined Space (Net Free Area of Louvers) |
| 40,000 | 250 | 100 |
| 60,000 | 375 | 100 |
| 75,000 | 469 | 100 |
| 100,000 | 625 | 100 |
| 120,000 | 750 | 120 |
| 140,000 | 875 | 140 |
| 160,000 | 1000 | 160 |
| 180,000 | 1,125 | 180 |
| 200,000 | 1,250 | 200 |
| 220,000 | 1,375 | 220 |
| 240,000 | 1,500 | 240 |
| 260,000 | 1,625 | 260 |
| 280,000 | 1,750 | 280 |
| 300,000 | 1,875 | 300 |
| 320,000 | 2,000 | 320 |
| 340,000 | 2,125 | 340 |
| 360,000 | 2,250 | 360 |
| 380,000 | 2,375 | 380 |
| 400,000 | 2,500 | 400 |
Total BTU of all Confined Appliances
_____________________________ = Square Feet
20 BTU per cubic foot x ceiling height
Last Modified: July 13, 2026, 2:39 pm EDT