Carrier 58MVP Installation, Start-Up, And Operating Instructions Manual page 15

DUCTS
TO
OUTDOORS
12" MAX
1 SQ IN. VENT
PER 2000 B THROUGH
BTUH*
ROOF
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. 14—Air for Combustion, Ventilation, and Dilution
for Outdoors
but not less than 100 in.
commence within 12" (300 mm) of the ceiling and the
second opening shall commence within 12" (300 mm) of
the floor. The minimum dimension of air openings shall be
at least 3 in. (80 mm). (See Fig. 14.)
c. Combining space on different floor levels. The volumes of
spaces on different floor levels shall be considered as
communicating spaces if connected by one or more perma-
nent openings in doors or floors having free area of at least
2 in. 2 /1,000 Btuh (4,400 mm
all gas appliances.
2. 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
2
free area of at least 1-in.
all gas appliances in the space.
3. In spaces that use the Indoor Combustion Air Method,
infiltration should be adequate to provide air for combustion,
permanent ventilation and dilution of flue gases. However, in
buildings with unusually tight construction, additional air
MUST be provided using the methods described in the
Outdoor Combustion Air Method section.
Unusually tight construction is defined as
Construction with:
a. Walls and ceilings exposed to the outdoors have a continu-
ous, sealed vapor barrier. Openings are gasketed or sealed
and
b. Doors and openable windows are weatherstripped and
1 SQ IN.
PER 4000
BTUH*
D 12"
MAX
F
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
2 (0.06 m 2 ). One opening shall
2 /kW) of total input rating of
/4,000 Btuh of total input rating for
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.
A03174
Fig. 15—Air for Combustion, Ventilation, and Dilution
c. Other openings are caulked or sealed. These include joints
around window and door frames, between sole plates and
floors, between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical and gas lines, etc.
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. mesh. Louvers and grilles must be
constructed so they cannot be closed.
When combustion air ducts are used, they must be of the same
cross sectional area as the free area of the openings to which they
connect. The minimum dimension of ducts must not be less than 3
in. (80mm).
Combination of Indoor and Outdoor Air
1. Indoor openings shall compy with the Indoor Combustion
Air Method below and,
2. Outdoor openings shall be located as required in the Outdoor
Combustion Air Method mentioned previously and,
3. Outdoor openings shall be sized as follows:
a. Calculate the Ratio of all Indoor Space volume divided by
required volume for Indoor Combustion Air Method
below.
b. Outdoor opening size reduction Factor is 1 minus the
Ratio in a. above.
c. Minimum size of Outdoor openings shall be the size
required in Outdoor Combustion Air Method above
15
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
from Indoors
†
12" MAX
A03175