Lennox Merit Series Installation Instructions Manual page 10

Common Venting Using Metal−Lined Masonry Chimney
MAX. LENGTH
−− SEE NOTE 1
BELOW.
5 ft. (1.5 m)
MIN. LENGTH −− AS
minimum
SHORT AS PRACTICAL
VENT CONNECTOR
4 in. (102 mm)
minimum
OTHER
APPLIANCE
NOTE 1 − Refer to the provided venting tables for installations. Refer
to the capacity requirements shown in the provided venting tables.
FIGURE 11
DO NOT insulate the space between the liner and the
chimney wall with puffed mica or any other loose gran-
ular insulating material.
IMPORTANT
SINGLE appliance venting of a fan-assisted furnace
into a tile-lined masonry chimney (interior or outside
wall) is PROHIBITED. The chimney must rst be lined
with either type B1 vent or an insulated single wall
exible vent lining system which has been sized ac-
cording to the provided venting tables and the vent
pipe manufacturer's instructions.
A fan−assisted furnace may be commonly vented into an
existing lined masonry chimney if the following conditions
are met:
The chimney is currently serving at least one drafthood−
equipped appliance;
The vent connectors and chimney are sized according
to the provided venting tables.
If type B1 double-wall vent is used inside a chimney, no oth-
er appliance can be vented into the chimney. The outer wall
of type B1 vent pipe must not be exposed to ue products.
A type B1 vent or masonry chimney liner shall terminate
above the roof surface with a listed cap or a listed roof as-
sembly according to the terms of their respective listings
and the vent manufacturer's instructions.
10
SEALED
EXTERIOR
CHIMNEY WITH
METAL
LINER
FURNACE
PERMANENTLY
SEALED FIREPLACE
OPENING
VENTING
When inspection reveals that an existing chimney is not
safe for the intended purpose, it shall be rebuilt to conform
to nationally recognised standards, lined or relined with
suitable materials, or replaced with a gas vent or chimney
suitable for venting the units. The chimney passageway
must be checked periodically to ensure that it is clear and
free of obstructions.
Do not install a manual damper, barometric draft regulator,
or ue restrictor between the furnace and the chimney.
Never connect a Category I appliance to a chimney that is
servicing a solid−fuel appliance. If a replace chimney ue
is used to vent this appliance, the replace opening must
be permanently sealed.
A type B or listed chimney lining system that passes
through an unused masonry chimney ue is not considered
to be exposed to the outdoors.
General Venting Requirements
Vent all internal furnaces according to these instructions:
1 − Vent diameter recommendations and maximum allow-
able piping runs are found in the provided venting
tables.
2 − In no case should the vent or vent connector diameter
be less than the diameter speci ed in the provided
venting tables.
3 − The minimum vent capacity determined by the sizing
tables must be less than the low re input rating and the
maximum vent capacity must be greater than the high
re input rating.
4 − Single appliance vents − If the vertical vent or tile-lined
chimney has a larger diameter or ow area than the
vent connector , use the vertical vent diameter to de-
termine the minimum vent capacity and the vent
connector diameter to determine the maximum vent
capacity. The ow area of the vertical vent, however,
shall not exceed 7 times the ow area of the listed ap-
pliance categorized vent area, drafthood outlet area or
ue collar area unless designed according to approved
engineering methods.
5 − Multiple appliance vents − The ow area of the largest
section of vertical vent or chimney shall not exceed 7
times the smallest listed appliance categorized vent
area, drafthood outlet area or ue collar area unless de-
signed according to approved engineering methods.