SBN TANK TYPE COMMERCIAL GAS WATER HEATER
SERVICE HANDBOOK
When vents are combined, the area of the com- bined vent should be equal to area of the largewst single vent, plus 50% of area of all others joining.
EXAMPLE: To combine two 6” vents with an 8” vent, the area of a combined vent should be
one half area of two 6 inch
vents (14 + 14) plus area of 8 inch vent (50) or 78 sq. inches. Referring to char, 78
sq. inches require 10” diam eter vent.
| Vent Size | Area in |
| Area in |
| Square Inches | Vent Size | Square Inches | |
| 5" | 20 | 10" | 79 |
| 6" | 28 | 12" | 113 |
| 7" | 38 | 14" | 154 |
| 8" | 50 | 16" | 201 |
| 9" | 64 | 18" | 254 |
NINE RULES FOR
GOOD VENTS
1.The vent pipe should ALWAYS be the same size as the outlet of the draft diverter or factory supplied vent reducer.
•Model SBN 120 are supplied with a 6” to 5” reducer.
•Models SBD 250, 251 and 275 are supplied with a 8” to 6” reducer.
2. The diameter of a vent pipe should NEVER be reduced, no matter what the circumstances.
Technical Training Department | 13 | ©2003 |
Ashland City, Tennessee
