SBD TANK TYPE HEATERS
SERVICE HANDBOOK
VENTING
Atmospheric, Single, and Multiple Heaters
All SBD water heaters are classified by ANSI as category I
For larger applications, SBD water heaters can be common vented together either in a tapered manifold or constant size manifold. (Follow National Fuel Gas Code requirements for sizing and installation.)
Combined Vents
When vents are combined, the area of the combined vent should be equal to area of the largest 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 chart, 78 sq. inches require 10” diameter vent.
| Area in Square |
| Area in Square |
Vent Size | Inches | Vent Size | 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 SBD 120 are supplied with a 6” to 5” reducer.
•Models SBD 250, 251 and 275 are supplied with a 8” to 6” reducer.
Technical Training Department | 12 |
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