13
Vent System Sizing
Refer to the venting tables in the NATIONAL FUEL
GAS CODE, ANSI Z223.1 for details on proper
sizing of the vent system for this furnace. The
furnace is supplied with a three-inch diameter vent
connection. Some models require four inch or five
inch diameter vent pipe. The specification table on
page 2 lists the proper size of vent connector pipe
for each model of furnace. If a vent pipe of more
than three inch diameter is required for the furnace
being installed, the installer must supply a suitable
transition.
Venting into an Existing Chimney
Whenever possible, B-1 metal pipe should be used
for venting. Where use of an existing chimney is
unavoidable, the following rules must be followed:
1. The masonry chimney must be built and
installed in accordance with nationally recog-
nized building codes or standards and must be
lined with approved fire clay tile flue liners or
other approved liner material that will resist cor-
rosion, softening, or cracking from flue gases.
THIS FURNACE IS NOT TO BE VENTED INTO
AN UNLINED MASONRY CHIMNEY.
2. This furnace may be vented into a fire clay tile
lined masonry chimney only if a source of dilu-
tion air is provided, such as by common venting
with a draft hood equipped water heater. If no
such source of dilution air is available, Type B
vent must be used. The existing chimney may
be used as a chase for the Type B vent.
3. The chimney must extend at least three feet
above the highest point where it passes through
a roof of a building and at least two feet higher
than any portion of the building within a hori-
zontal distance of ten feet.
4. The chimney must extend at least five feet
above the highest equipment draft hood or flue
collar.
Inspection of Existing Chimney
1. Before connecting the vent connector to a
chimney, the chimney passageway must be ex-
amined to ascertain that it is clear and free of
obstructions and must be cleaned if previously
used for venting solid or liquid fuel-burning ap-
pliances or fireplaces.
2. Clean-outs must be examined to determine that
they will remain tightly closed when not in use.
3. When inspection reveals that an existing
chimney is not safe for this application, it must
be rebuilt to conform to nationally recognized
standards, lined or relined with a suitable liner,
or replaced with a suitable vent or chimney.
Venting with Metal Pipe
Type B (double wall) vents must extend in a gener-
ally vertical direction with offsets exceeding 45
degrees, except that one horizontal run may be
allowed. Any angle greater than 45 degrees from the
vertical is considered horizontal. The total horizontal
run of a vent, plus any horizontal vent connector,
must not be greater than 75% of the vertical height
of the vent. A Type B vent must terminate at least
five feet in vertical height above the highest con-
nected equipment draft hood or flue collar.
Vent Connection
The furnace is supplied with a three-inch diameter
vent connection at the vent blower. For installations
where the vent passes in front of the blower com-
partment (downflow and some horizontal), a two-foot
long section of three-inch diameter single-wall vent
pipe should be used to extend the vent outside of
the furnace casing. This section of the vent pipe may
be installer supplied, or factory accessory part
number 2802-312P may be used. If a transition to
type B vent is to be done, the transition should be
outside of the furnace casing. If a transition to a
larger size vent pipe is required, the transition
should be outside of the furnace casing
Vent Connector Sizing
A vent connector must be sized properly for the
equipment connected to it. The furnace is supplied
with a three-inch diameter vent connection. Some
models require four inch or five inch diameter vent
pipe. The specification table on page two lists the
proper size of vent connector pipe for each model of
furnace. If a vent pipe of more than three inch
diameter is required for the furnace being installed,
the installer must supply a suitable transition. Use
the vent tables in the NATIONAL FUEL GAS CODE,
ANSI Z223.1 to determine the proper vent connector
size.
The vent connector must be as short as possible
and the furnace should be located as close as
practicable to the chimney or vent.
The horizontal run of a vent connector must not be
more than 75% of the height of the vertical portion of
the chimney or vent above the connector.
A vent connector must not pass through any ceiling,
floor, firewall, or fire partition. A single-wall metal
pipe vent connector must not pass through any
interior wall.