Installation Instructions (cont'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 rating of all appliances installed in that space. Rooms communicating directly with the space in which the appliances are installed, through openings nor furnished with doors, are considered a part of the unconfined space
In 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 may 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- ing shall have a minimum free area of 1 square inch per 4,000 BTU 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 square inch per 4,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 4.)
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.
a. ALL AIR FROM INSIDE BUILDINGS:
(See Page 9 Figure 1, and Figure 2 below)
The confined space shall be provided with two permanent
openings communicating directly with an additional room(s)
of sufficient volume so that the combined volume of all
spaces meets the criteria for an unconfined space. The total
input of all _as utilization equipment installed in the com- bined space snail 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 gas utilization equipment in the confined space, but not less than 100 square inches. One opening shall commence within
12" of the top and one commencing within 12" of the bot- tom of the enclosure.
ENT
Figure 2 ]
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
commencing within 12" from the bottom of the enclosure.
The openings shall communicate directly, or by ducts, with
the outdoors or spaces (crawl or attic) that freely communi- cate with the outdoors.
Figure 3 ]
3.When communicating with the outdoors through horizontal
ducts, each opening shall have a minimum free area of 1 square inch per 2,000 BTU per hour of total input rating of all equipment in the enclosure. (See Figure 5.)
4
Figure 5 ] | i |
4.When ducts are used, they shall be of the same
5.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 ¼" 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
6.Special Conditions Created by Mechanical Exhausting or
Fireplaces: Operation of exhaust fans, ventilation systems, clothes dryers or fireplaces may create conditions requiring special attention to avoid unsatisfactory operation of installed
10 | gas utilization equipment. |
