Factory-Built Chimney Venting
A. Factory-built chimney
NOTE: All vent pipe run outside shall be constructed of factory-
built chimney sections.
The vent system of the furnace must be self-supporting and must not apply any weight load to the combustion blower.
Combustion Air Sources
There are 2 sources for combustion air:
1. From outside the building (Direct Vent)
2. From inside the building (Nondirect Vent)
Please read the information provided here about Vertical and
Horizontal Venting, then find and follow the instructions for your
Extend the vent connector into the chimney so that it is flush
with the inside of the flue liner. Seal the joint between the pipe
and the liner.
Masonry chimneys serving fireplaces cannot be used for
venting purposes unless the fireplace opening is permanently
A vent connector serving this appliance must not be
connected into any portion of mechanical draft systems
operating under positive pressure.
The vent pipe must not be connected to a chimney flue
serving a solid fuel appliance.
A manual damper, barometric draft regulator, or flue restrictor
must not be installed between the furnace and the chimney.
Where local experience indicates that condensate may be a
problem, the vent shall be constructed to keep condensation
from entering the combustion blower. Provision shall be
made to drain off the condensate.
All unused chimney openings should be closed.
Multistory venting is allowed as permitted by the National
Fuel Gas Code or local codes.
Install all vents in accordance with the vent manufacturer's
instructions. For unlisted material, install in accordance with
the National Fuel Gas Code.
Vent terminals must be installed in accordance with the vent
terminals listing or in accordance with the National Fuel Gas
Code, ANSI Z223.1/NFPA 54 (latest edition), and local codes.
Determine Vent Pipe Direction
A vertical vent should extend through the roof a minimum of 24"
(61 cm) and not be obstructed a minimum of 10 ft (3 m) in any
The vent terminal location shall comply with the National Fuel
Gas Code (ANSI Z223.1) or local requirements. For informational
purposes, the side wall terminal vent clearances are shown in the
Sidewall Vent Terminal Clearances tables.