Bryant 355BAV Installation, Start-Up, And Operating Instructions Manual page 24

Ventilated Combustion Air
intake termination in crawl space
Fig. 29 - - Crawlspace Termination
AIR FOR COMBUSTION AND VENTILATION - - Ventilated
Combustion Air Option
Provisions for adequate combustion, ventilation, and dilution air
must be provided in accordance with:
U.S. Installations: Section 9.3 of the National Fuel Gas Code
NFPA 54/ANSI Z223.1- -2009, Air for Combustion and Ventilation
and applicable provisions of the local building codes.
Canadian Installations: Part 7 of the CAN/CSA B149- -1- -05,
Venting Systems and Air Supply for Appliances and all authorities
having jurisdiction.
CAUTION
!
UNIT CORROSION HAZARD
Excessive exposure to contaminated combustion air may
result in safety and performance related problems.
Combustion air must not be taken from inside structure
because that air is frequently contaminated by halogens,
which include fluorides, chlorides, bromides, and iodides.
These elements are found in aerosols, detergents, bleaches,
cleaning solvents, salts, air fresheners, adhesives, paint, and
other household products. Locate combustion- -air inlet as
far as possible from swimming pool and swimming pool
pump house.
3˝ (76 mm)
12˝ (305 mm)
A06496
This furnace requires OUTDOOR AIR for combustion.
WARNING
!
CARBON MONOXIDE POISONING HAZARD
The operation of exhaust fans, kitchen ventilation fans,
clothes dryers, attic exhaust fans or fireplaces could create a
NEGATIVE PRESSURE CONDITION at the furnace.
Make- -up air MUST be provided for the ventilation devices,
in addition to that required by the furnace. Refer to the
Carbon Monoxide Poisoning Hazard warning in the venting
section of these instructions to determine if an adequate
amount of make- -up air is available.
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to supply outdoor air via grilles, louvers or vents
could result in death and/or personal injury. Many homes
require air to be supplied from outdoors for furnace
combustion, ventilation, and dilution of flue gases.
The furnace combustion air supply must be provided in
accordance with this instruction manual.
An attic or crawlspace may be considered a space that freely
communicates with the outdoors provided there are adequate
permanent ventilation openings directly to outdoors having free
2
area of at least 1- -in. /4,000 Btuh of total input rating for all gas
appliances in the space.
NOTE: In determining the free area of an opening, the blocking
effect of the louvers, grilles, and screens must be considered. If the
free area of a louver or grille design is unknown, it may be
assumed that wood louvers have a 20 percent free area, and metal
louvers or grilles have a 60 percent free area. Screens, when used,
must not be smaller than 1/4- -in. (6 mm) mesh. Louvers and grilles
must be constructed so they cannot be closed.
Combustion Air Termination- - Direct Vent / 2- - Pipe
System
Combustion air pipe must terminate outside the structure with the
vent pipe as shown in Fig. 31. Follow the clearance requirements
show in Fig. 34. Refer to Vent Termination section for complete
details on termination options.
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