Installation InstrudionS (C6nt'd)
Combustion Air and Ventilation
for Appliances Located in Unconfined Spaces
Unconfined Space is a space whose volume is not less than 50 cubic feet per 1,000 Btu per hour of the aggregate input ratine:
of all appliances installed in that space.
,partof the unconfined space
m unconfined spaces in buildings, infiltration may be adequate to provide air for combustion, ventilation and dilution of flue
gases. However, in buildings of tight construction (for example, weather stripping, heavily insulated, caulked, vapor barrier, etc.), additional air ma_ need to be provided using the methods described in Combustion Air and Ventilation for Appliances Located in Confined Spaces, b.
1.When directly communicating with the outdoors, each open-
in,shall have a minimum free area of 1 square inch per 4,000 BI u per hour of total input rating of all equipment in the enclosure. (See Figure 3.)
2.When communicating with the outdoors through vertical
ducts, each opening shall have a minimum free area of 1
s_uare inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 4.)
CHIMNEy OR _ VEnT
VEhrrUT_O_ LOU_
(each _ oJ a._: I
Combustion Air and Ventilation for Appliances Located in
Confined Spaces
Confined Space is a space whose volume is less than 50 cubic feet per 1,000 Btu per hour of the aggregate input rating of all
appliances installed in that space. | . | - |
ALL AIR FROM INSIDE BUILDINGS. |
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(See Page 9 Figure 1, and Figure2 below)
The confined space shall be provided with two permanent
oi_enin_s communicating directly with an additional room(s) or suttlcient volume so that the combined volume of all
spaces meets the criteria for an unconfined space. The total input of all gas utilization equipment installed in the com- bined space shall be considered in making this determination.
Each opening shall have a minimum free area of one square inch per 1,000 BTU per hour of the total input rating of all _s utilization equipment in the confined space, but not less an 100 square inches. One opening shall commence within
12" of the top and one commencing within 12" of the bot- tom of the enclosure.
b. ALL AIR FROM OUTDOORS: (see Figures
The confined space shall be provided with two permanent openings, one commencing within 12 of the top and one commenc'ng within 12' from the bottom of the endosure.
The openings shall communicate directly, or by ducts, with
the outdoors or spaces (crawl or attic) that freely communi- care with the outdoors.
Figure 3 ]
AIR OUTLET
WA'tER _ATE_
I_T AIR DUCT
Figure 4 ]
3.When communicating with the outdoors through horizontal
ducts, each opening shall have a minimum free area of 1
_uare inch per 2,000 BTU per hour of total input rating of equipment in the enclosure. (See Figure 5.)
_i_caM_v | on C,AS _Nr |
4.When ducts are used, they shall be of the same
. Louvers and Grilles: In calculating free area, consideration
shall be given to the blocking effect of louvers, grilles or screens protecting openings. Screens used shall not be smaller
than _"mesh. If the free area through a design of louver or grille is known, it should be used in calculating the size open- ing required to provide the free area specified. If the design and free area is not known, it may be assumed that wood lou- vers will be
grilles will have
equipment so that they are opened automatically during equipment operation.
6.Special Conditions Created by Mechanical Exhausting or
Fireplaces: Operation of exhaust fans, ventilation systems, domes dryers or fireplaces may create conditions requiring
special attention to avoid unsatisfactory operation of installed
10gas utilization equipment.