506843-01
Page 14 of 39
Issue 1132
DO NOT
insulate the space between the liner and the
chimney wall with puffed mica or any other loose granular
insulating material.
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 which has been sized according to the
provided venting tables and the vent pipe manufacturer’s
instructions.
IMPORTANT
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
other appliance can be vented into the chimney. The outer
wall of type B1 vent pipe must not be exposed to flue
products. A type B1 vent or masonry chimney liner shall
terminate above the roof surface with a listed cap or a listed
roof assembly according to the terms of their respective
listings and the vent manufacturer’s instructions.
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. 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 flue 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 fireplace chimney flue
is used to vent this appliance, the fireplace opening must be
permanently sealed.
A type B or listed chimney lining system that passes through
an unused masonry chimney flue is not considered to be
exposed to the outdoors.
General Venting Requirements
Vent all furnaces according to these instructions:
1. Vent diameter recommendations and maximum
allowable 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 specified in the provided
venting tables.
3. The minimum vent capacity determined by the sizing
tables must be less than the low fire input rating and the
maximum vent capacity must be greater than the high
fire input rating.
4 .
Single appliance vents
- If the vertical vent or tile lined
chimney has a larger diameter or flow area than the
vent connector, use the
vertical vent diameter
to
determine the
minimum vent capacity
and the
vent
connector diameter
to determine the
maximum vent
capacity
. The flow area of the vertical vent, however,
shall not exceed 7 times the flow area of the listed
appliance categorized vent area, drafthood outlet area
or flue collar area unless designed according to
approved engineering methods.
5.
Multiple appliance vents
- The flow 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 flue collar area unless
designed according to approved engineering methods.
Common Venting Using Tile Lined Interior Masonry Chimney and Combined Vent Connector
NOTE: Refer to provided venting
tables for installations.
NOTE:
The chimney must be properly sized
per provided venting tables or lined with
listed metal lining system.
Figure 17
