Bryant 312A Installation, Start-Up, Operating And Service And Maintenance Instructions page 9

DUCTS
TO
OUTDOORS
12" MAX
1 SQ IN.
PER 2000 B
BTUH*
DUCTS
TO
OUTDOORS
1 SQ IN.
PER 2000
A
BTUH*
12" MAX
CIRCULATING AIR DUCTS
*Minimum dimensions of 3 in.
NOTE: Use any of the following
combinations of openings:
A & B C & D D & E
Fig. 7 - - Air for Combustion, Ventilation and Dilution for
Outdoors
The opening shall commence within 12 in. (300 mm) of the
ceiling. Appliances in the space shall have clearances of at least 1
in. (25 mm) from the sides and back and 6 in. (150 mm) from the
front. The opening shall directly communicate with the outdoors
or shall communicate through a vertical or horizontal duct to the
outdoors or spaces (crawl or attic) that freely communicate with
the outdoors.
Indoor Combustion AirE NFPA & AGA Standard and
Known- -Air- -Infiltration Rate Methods
Indoor air is permitted for combustion, ventilation, and dilution,
if the Standard or Known- -Air- -Infiltration Method is used.
WARNING
!
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning 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.
1 SQ IN.
PER 4000
BTUH*
D 12"
MAX
VENT
THROUGH
F
ROOF
1 SQ IN.
PER
4000
BTUH*
1 SQ IN.
PER
4000
BTUH*
E
G
12"
MAX
C
12" MAX
DUCT
1 SQ IN.
TO
PER 4000
OUTDOORS
BTUH*
F & G
A03174
CIRCULATING AIR
DUCTS
INTERIOR
HEATED
SPACE
CIRCULATING AIR DUCTS
* Minimum opening size is 100 sq in. with
minimum dimensions of 3 in.
† Minimum of 3 in . . when type-B1 vent is used.
Fig. 8 - - Air for Combustion, Ventilation, and Dilution from
Indoors
The Standard Method:
1. The space has no less volume than 50 cubic feet per 1,000
Btuh of the maximum input ratings for all gas appliances
installed in the space and
2. The air infiltration rate is not known to be less than 0.40
air changes per hour (ACH).
The Known Air Infiltration Rate Method shall be used, if the
infiltration rate is known to be:
1. Less than 0.40 ACH and
2. Equal to or greater than 0.10 ACH
Infiltration rates greater than 0.60 ACH shall not be used. The
minimum required volume of the space varies with the number of
ACH and shall be determined per Table 3 or Equations 1 and 2.
Determine the minimum required volume for each appliance in
the space and add the volumes together to get the total minimum
required volume for the space.
9
VENT THROUGH ROOF
12" MAX
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
UNCONFINED
SPACE
6" MIN
(FRONT)
†
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MAX
A03175