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Removal of Existing Furnaces from Common Vent
Systems
When an existing Category I furnace is removed or replaced, the
original venting system may no longer be sized to properly vent
the remaining attached appliances. An improperly sized Category
I venting system could cause the formation of condensate in the
furnace and vent, leakage of condensate and combustion
products, spillage of combustion products into the living space,
etc.
AIR FOR COMBUSTION AND VENTILATION
FURNACE RELIABILITY HAZARD
Failure to follow this caution could result in premature
component failure.
This furnace can be vented as either a direct vent (2--pipe)
furnace or as an optional ventilated combustion air
application. A direct vent system shall be installed in
accordance with the direct vent (2-- pipe) procedures in the
Combustion Air and Vent Pipe Systems section within this
supplemental instruction. For optional ventilated
combustion air applications, refer to the ventilated
combustion air option procedures in the s ame section.
Application of this furnace should be indoors with special
attention given to vent sizing and material, gas input rate,
air temperature rise, unit leveling, and unit sizing.
CAUTION
!
Combustion--Air and Vent Pipe Systems
For additional venting information contact www.Bryant.com.
General
Vent system or vent connectors of other appliances may need to
be resized. For any other appliances when resizing vent systems
or vent connectors, system or connector must be sized to
approach minimum size as determined using appropriate table
found in the NFGC or CAN/CSA--B149.1--05.
The 355CAV furnaces can be vented as either a direct vent
furnace or as an optional ventilated combustion air application. A
direct vent system shall be installed in accordance with the direct
vent (2 --pipe) procedures in the following Combustion Air and
Vent Pipe Systems section. For optional ventilated combustion air
applications, refer to the ventilated combustion air option
procedures in the same section. Common venting prohibited.
Direct Vent / 2--Pipe
System
In a direct --vent (2--pipe) system, all air for combustion is taken
directly from outdoor atmosphere, and all flue products are
discharged to outdoor atmosphere. Combustion--air and vent
pipes must terminate together in the same atmospheric pressure
zone, either through the roof or a sidewall (roof termination
preferred). A factory accessory vent termination kit MUST be
used in a direct vent (2--pipe) system. See Fig. 34 for required
clearances.
Ventilated Combustion Air Option
Materials
In a ventilated combustion air option, the vent terminates and
discharges the flue products directly to the outdoors similar to a
direct vent system. See Fig. 35 for required clearances. All air for
combustion is piped directly to the furnace from a space that is
well ventilated with outdoor air (such as an attic or crawl space)
and the space is well isolated from the living space or garage.
Materials
Combustion--air and vent pipe, fittings, primers, and solvents
must conform to American National Standards Institute (ANSI)
standards and American Society for Testing and Materials
(ASTM) standards. See Table 5 for approved materials for use in
the U.S.A.
FIRE AND EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
Solvent cements are combustible. Keep away from heat,
sparks, and open flame. Use only in well ventilated areas.
Avoid breathing in vapor or allowing contact with skin or
eyes.
!
WARNING
In Canada, construct all combustion--air and vent pipes for this
unit of CSA or ULC listed schedule--40 PVC, PVC --DWV or
ABSDWV pipe and pipe cement. SDR pipe is NOT approved in
Canada.
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in personal
injury, death, or property damage.
All combustion--air and vent pipes must be airtight and
watertight. Pipes must also terminate exactly as shown in
Fig. 36 for direct vent (2--pipe) system or Fig. 37 for
ventilated combustion air option.
!
WARNING
An abandoned masonry chimney may be used as a raceway for
properly insulated and supported combustion--air (when
applicable) and vent pipes. Each furnace must have its own set of
combustion --air and vent pipes and be terminated individually, as
shown in Fig. 36 for Direct Vent (2--Pipe) system or Fig. 37 for
ventilated combustion air option.
A furnace shall not be connected to a chimney flue serving a
separate appliance designed to burn solid fuel.
Other gas appliances with their own venting system may also use
the abandoned chimney as a raceway providing it is permitted by
local code, the current edition of the National Fuel Gas Code and
the vent or liner manufacturer’s installation instructions. Care
must be taken to prevent the exhaust gases from one appliance
from contaminating the combustion air of other gas appliances.
Do not take combustion air from inside the chimney when using
the Ventilated Combustion Air option.
UNIT MAY NOT OPERATE HAZARD
Failure to follow this caution may result in intermittent unit
operation.
When vent pipe is exposed to temperatures below freezing,
such as when it passes through an unheated space or when a
chimney is used as a raceway, pipe must be insulated as
shown in Table 6 with Armaflex--type insulation.
CAUTION
!
Furnace combustion air and vent pipe connections are sized for
2-- in. pipe. Any pipe size change should be made outside furnace
casing in vertical pipe. The transition has to be made as close to
the furnace as reasonably possible. (See Fig. 38.)
355CAV