AERCO Esteem O&M Manual - Manual (Page 15)

9
Ventilation and Combustion Air Requirements - Category IV
Methods of Supplying Combustion Air to
a Confined Space - Category IV
I
NDOOR
C
OMBUSTION
A
IR
N
OTICE
The methods listed in this section for ac-
cessing Indoor Combustion Air assume
that the infi ltration rate is adequate and
not less than .40 ACH. For infi ltration
rates less than .40 ACH, reference the
NFPA 54 National Fuel Gas Code for
additional guidance.
Opening Size and Location
Openings used to connect indoor spaces shall
be sized and located in accordance with the
following see Figure 2
• Combining spaces on the same story.
Each opening shall have a minimum free
area of 1 sq. in./1000 Btu/hr of the total
input rating of all gas utilization equip-
ment in the space, but not less than
100 sq. inches. One opening shall com-
mence within 12 inches of the top, and
one opening shall commence within 12
inches of the bottom of the enclosure.
The minimum dimension of air openings
shall be not less than 3 inches.
• Combining spaces in different stories.
The volumes of spaces in different sto-
ries shall be considered as communi-
cating spaces where such spaces are
connected by one or more openings in
doors or floors having a total minimum
free area of 2 sq. in./1000 Btu/hr of total
input rating of all gas utilization equip-
ment.
O
UTDOOR
C
OMBUSTION
A
IR
Isolating the combustion appliance room from
the rest of the building and bringing in uncon-
taminated outside air for combustion and venti-
lation is always preferred.
Opening Size and Location
The minimum dimension of air openings shall
be not less than 3 inches
Openings used to supply combustion and
ventilation air shall be sized and located in
accordance with the following:
One Permanent Opening Method. See Figure
3
One permanent opening, commencing within
12 inches of the top of the enclosure, shall be
provided. The equipment shall have clearances
of at least 1 inch from the sides and 6 inches
from the front of the appliance. The opening
shall directly communicate with the outdoors or
shall communicate through a vertical or hori-
zontal duct to the outdoors or spaces that freely
communicate with the outdoors and shall have
a minimum free area of the following:
Figure 2: :
All Combustion Air from Adjacent Indoor Spaces
Through Indoor Combustion Openings
GF-125