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Venting Using a Masonry Chimney
The following additional requirements apply when a lined
masonry chimney is used to vent a G24−200 furnace:
Masonry chimneys used to vent Category I central fur-
naces must be either tile-lined or lined with a listed metal
lining system or dedicated gas vent. Unlined masonry
chimneys are prohibited. See figures 9 and 10 for common
venting.
A Category I appliance must never be connected to a chim-
ney that is servicing a solid−fuel appliance. If a fireplace
chimney flue is used to vent this appliance, the fireplace
opening must be permanently sealed.
A fan−assisted furnace may be commonly vented into an
existing lined masonry chimney if the following conditions
are met:
1 − The chimney is currently serving at least one drafthood
equipped appliance.
2 − The vent connectors and chimney are sized according
to the provided venting tables for the USA, and the ap-
propriate venting tables in the standards of CSA
B149.1 of the Natural Gas and Propane Installation
Code in Canada.
IMPORTANT
SINGLE appliance venting of a fan-assisted furnace
into a tile-lined masonry chimney (interior or outside
wall) is PROHIBITED. The chimney must first be lined
with either type B1 vent or an insulated single wall
flexible vent lining system, sized according to the
provided venting tables.
A type B1 vent or masonry chimney liner shall terminate above
the roof surface with a listed cap or a listed roof assembly ac-
cording to the terms of their respective listings and the vent
manufacturer’s instructions.
Do not install a manual damper, barometric draft regula-
tor, or flue restrictor between the furnace and the chimney.
If type B1 double-wall vent is used inside a chimney, no oth-
er appliance can be vented into the chimney. Outer wall of
type B1 vent pipe must not be exposed to flue products.
Insulation for the flexible vent pipe must be an encapsu-
lated fiberglass sleeve recommended by the flexible vent
pipe manufacturer. See figure 9.
The space between the liner and the chimney wall
should NOT be insulated with puffed mica or any other
loose granular insulating material.
If B1 vent or an insulated flexible vent pipe cannot be used
as liners, the chimney must be rebuilt to accommodate one
of these methods or some alternate approved method
must be found to vent the appliance.
When inspection reveals that an existing chimney is not
safe for the intended purpose, it shall be rebuilt to conform
to nationally recognized standards, lined or relined with
suitable materials or replaced with a gas vent or chimney
suitable for venting G24−200 units. The chimney passage-
way must be checked periodically to ensure that it is clear
and free of obstructions.
COMMON VENTING USING METAL−LINED MASONRY CHIMNEY
5 FT.
(1.5m)
MIN.
MIN. LENGTH − AS SHORT
AS PRACTICAL
MAX. LENGTH − SEE
NOTE 1 BELOW.
SEALED
PERMANENTLY
SEALED FIRE-
PLACE OPENING
EXTERIOR CHIMNEY WITH
B1" VENT OR INSULATED
FLEXIBLE VENT PIPE
G24−200
JOIN HEAT
SECTIONS
WITH A ’TEE−Y’
NOTE 1 − Refer to the provided venting tables
for installations in the USA and the venting
tables in CSA−B149.1 for installations Canada.
NOTE 2 − Either single-walled or double-walled
vent connector may be used. Refer to the ca-
pacity requirements shown in the provided
venting tables for installations in USA and the
venting tables in current CSA−B149.1 for
installations in Canada.
VENT
CONNECTOR
SEE NOTE 2
FIGURE 9
