Outdoor Combustion Air Method; The Standard Method - Carrier N80VSL Instruction Manual

S Spaces having at least 50 cubic feet per 1,000 Btuh
may use the INDOOR COMBUSTION AIR, STAN-
DARD or KNOWN AIR INFILTRATION
METHOD.

Outdoor Combustion Air Method

1. Provide the space with sufficient air for proper combus-
tion, ventilation, and dilution of flue gases using perman-
ent horizontal or vertical duct(s) or opening(s) directly
communicating with the outdoors or spaces that freely
communicate with the outdoors.
2. Fig. 7 illustrates how to provide TWO OUTDOOR
OPENINGS, one inlet and one outlet combustion and
ventilation air opening, to the outdoors.
a. One opening MUST commence within 12 in. (300
mm) of the ceiling and the second opening MUST
commence within 12 in. (300 mm) of the floor.
b. Size openings and ducts per Fig. 7 and Table 1.
c. TWO HORIZONTAL DUCTS require 1 sq. in. (645
sq. mm) of free area per 2,000 Btuh (1,100 mm
of combined input for all gas appliances in the space
per Fig. 7 and Table 1.
d. TWO OPENINGS OR VERTICAL DUCTS require 1
sq. in. (645 sq. mm) of free area per 4,000 Btuh (550
2
mm /kW) for combined input of all gas appliances in
the space per Fig. 7 and Table 1.
3. ONE OUTDOOR OPENING requires:
a. 1 sq. in. (645 sq. mm) of free area per 3,000 Btuh
2
(734 mm /kW) for combined input of all gas appli-
ances in the space per Table 1 and
b. Not less than the sum of the areas of all vent connect-
ors in the space.
CIRCULATING AIR
DUCTS
INTERIOR
HEATED
SPACE
CIRCULATING AIR DUCTS
* Minimum opening size is 100 sq in. (64516 sq. mm)with minimum dimensions
of 3 in. (76 mm)
† Minimum of 3 in. (76 mm) when type-B1 vent is used.
Fig. 8 - - Air for Combustion, Ventilation, and Dilution from
Indoors
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
8
2
/kW)
VENT THROUGH ROOF
12" MAX
(305mm)
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
UNCONFINED
SPACE
6" MIN (152mm)
(FRONT)
Ü
1 SQ IN.
PER 1000
BTUH* IN DOOR
OR WALL
12" MA X (305mm)
A03175
Specifications are subject to change without notice.
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 personal
injury or death.
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.

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 2 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.
Table 2 - - Minimum Space Volumes were determined by using
the following equations from the National Fuel Gas Code ANSI
Z223.1/NFPA 54, 9.3.2.2:
1. For other than fan- -assisted appliances, such as a draft
hood- -equipped water heater:
= 21ft
3
Volume
ACH
Other
2. For fan- -assisted appliances such as this furnace:
= 15ft
3
Volume
ACH
Fan
If: Iother = combined input of all other than fan- -assisted
appliances in Btuh/hr
Ifan = combined input of all fan- -assisted appliances in Btuh/hr
ACH = air changes per hour (ACH shall not exceed 0.60.)
The following requirements apply to the Standard Method and
to the Known Air Infiltration Rate Method.
1. Adjoining rooms can be considered part of a space if:
a. There are no closeable doors between rooms.
b. Combining spaces on same floor level. Each opening
shall have free area of at least 1 in.
2
mm /kW) of the total input rating of all gas appliances
in the space, but not less than 100 in.
opening shall commence within 12 in. (300 mm) of
the ceiling and the second opening shall commence
within 12 in. (300 mm) of the floor. The minimum
I
other
1000 Btu/hr
A04002
I
fan
1000 Btu/hr
A04003
2
/1,000 Btuh (2,000
2 2
(0.06 m ). One
441 01 3700 00