Confined Space - Carrier weathermaker 8000 Installation, Start-Up, And Operating Instructions Manual

SUPPLY
AIR
INTERIOR
HEATED
SPACE
RETURN AIR
* Minimum opening size is 100 sq in. with
minimum dimensions of 3 in.
†
Minimum of 3 in. when type-B1 vent is used.
Fig. 3—Confined Space: Air for Combustion and
Ventilation from an Unconfined Indoor Space

CONFINED SPACE

A confined space is defined as a space whose volume is less than
50 cu ft per 1000 Btuh of total input ratings of all appliances
installed in that space. A confined space MUST have provisions
for supplying air for combustion, ventilation, and dilution of flue
gases using 1 of the following methods. (See Fig. 3, 4, and Table
2.)
NOTE: In determining free area of an opening, the blocking
effect of louvers, grilles, and screens must be considered. If free
area of louver or grille design is unknown, assume 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.
The size of the openings depends upon whether air comes from
outside of the structure or an unconfined space inside the structure.
1. All air from inside the structure requires 2 openings (for
structures not usually tight):
a. Each opening MUST have at least 1 sq in. of free area per
1000 Btuh of total input for all equipment within the
confined space, but not less than 100 sq in. per opening.
(See Fig. 3 and Table 2.) The minimum dimension of air
openings shall not be less than 3 in.
b. If building is constructed unusually tight, a permanent
opening directly communicating with the outdoors shall be
provided. See item 2 below.
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
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5
DUCTS
TO
OUTDOORS
12 " MAX
1 SQ IN.
A
PER 2000
BTUH *
SUPPLY
AIR
DUCTS
TO
OUTDOORS
1 SQ IN.
B
PER 2000
BTUH *
12 " MAX
RETURN AIR
* Minimum dimensions of 3 in.
NOTE: Use any of the following
combinations of openings:
A & B C & D D & E
Fig. 4—Confined Space: Air for Combustion and
Ventilation from Outdoors
c. If furnace is installed on a raised platform to provide a
return-air plenum, and return air is taken directly from
hallway or space adjacent to furnace, all air for combustion
must come from outdoors.
2. Air from outside the structure requires 1 of the following
methods:
a. If combustion air is taken from outdoors through 2 vertical
ducts, the openings and ducts MUST have at least 1 sq in.
of free area per 4000 Btuh of total input for all equipment
within the confined space. (See Fig. 4 and Table 2.)
b. If combustion air is taken from outdoors through 2 hori-
zontal ducts, the openings and ducts MUST have at least 1
sq in. of free area per 2000 Btuh of total input for all
equipment within the confined space. (See Fig. 4 and Table
2.)
c. If combustion air is taken from outdoors through a single
opening or duct (horizontal or vertical) commencing within
12 in. of the top of the confined space, opening and duct
MUST have at least 1 sq in. of free area per 3000 Btuh of
the total input for all equipment within the confined space
and not less than the sum of the areas of all vent connectors
in the confined space. (See Fig. 4 and Table 2.) Equipment
clearances to the structure shall be at least 1 in. from the
sides and back and 6 in. from the front of the appliances.
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
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