A.O. Smith 120 trough 500 - Manual (Page 14)

BTR TANK TYPE HEATERS
SERVICE HANDBOOK
A.O. Smith Water Products Service Handbook
Irving, Texas ©2000 Training Department
13
VENTING
Atmospheric Multiple Heaters
All BTR water heaters are classified by ANSI as category I (non-condensing, negative
pressure venting) appliances. They are approved for type B vent.
For larger applications, BTR 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.)
BTRs may be common vented only with other category I appliances. (See venting
section in the National Fuel Gas Code).
A minimum of ¼” rise
per foot of horizontal
vent is required.
Chimney