Venting - A.O. Smith BTR 120-400 Service Handbook

VENTING

This section of the Service Handbook is not a complete venting installation instruction. Refer to the Instruction
Manual that came with the water heater; ensure the venting has been installed per all Instruction Manual
requirements. Costs to correct installation errors are not covered under the limited warranty.
The instructions in this section on venting must be followed to avoid choked combustion or recirculation of
flue gases. Such conditions cause sooting or risks of fire and asphyxiation.
Heater must be protected from freezing downdrafts. Remove all soot or other obstructions from the chimney
that will retard a free draft.
Type B venting is recommended with these heaters. For typical venting application refer to Technical Data
Venting in the Instruction Manual. This water heater must be vented in compliance with all local codes, the
current revision of the National Fuel Gas Code (ANSI-Z223.1) and with the Category I Venting Tables.
If any part of the vent system is exposed to ambient temperatures below 40°F it must be insulated to prevent
condensation.
• Do not connect the heater to a common vent or chimney with solid fuel burning equipment. This practice
is prohibited by many local building codes as is the practice of venting gas fired equipment to the duct
work of ventilation systems.
• Where a separate vent connection is not available and the vent pipe from the heater must be connected
to a common vent with an oil burning furnace, the vent pipe should enter the smaller common vent or
chimney at a point above the large vent pipe.
All BTR water heaters are classified by ANSI as category I (non-condensing, negative pressure venting)
appliances. They are approved for Type B venting. 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).
4 Servicing should only be performed by a Qualified Service Technician