Minimum Permanent Free Opening, Square Inches
for Masonry Built Fireplaces
Chimney Height (Feet) | 18” Log Set | 24” Log Set |
| Minimum Opening (Square Inches) | |
|
|
|
6 | 49.2 | 56.6 |
|
|
|
8 | 45.5 | 52.4 |
|
|
|
10 | 41.7 | 48.2 |
|
|
|
15 | 37.7 | 43.2 |
|
|
|
20 | 34.3 | 39.8 |
|
|
|
30 | 31.2 | 35.9 |
|
|
|
Table 1
Minimum Permanent Free Opening, Square Inches
for Factory Built Fireplaces
Chimney Height (Feet) | 18” Log Set | 24” Log Set |
| Minimum Opening (Square Inches) | |
|
|
|
10 | 35.3 | 44.2 |
|
|
|
15 | 26.4 | 32.2 |
|
|
|
20 | 22.1 | 26.4 |
|
|
|
25 | 18.1 | 22.9 |
|
|
|
30 | 17.3 | 20.4 |
|
|
|
35 | 15.9 | 18.9 |
|
|
|
40 | 15.2 | 18.1 |
|
|
|
Table 2
3