Installation InStructions (cont'd)
Combustion Air and Ventilation
for Appliances Located in Unconfined Spaces
Uncon_qned 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 comuiunicatin_ directly with the space in which the appliances are installed, through openings not 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 Comb.ustion Air and Ventilation_ for Appliances Located in Confined Spaces, b.
1.When directly communicating with the outdoolS, 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 Figure4.)
•CHIMNEY O_ _ VENT
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 aggregateinput 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 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 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.
I Figure 4 ]
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.)
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.
I Figure 3 1
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 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
shall be fixed in the open position or interlocked with the
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, clothes dryers or fireplaces may create conditions requiring special attention to avoid unsatisfactory operation of installed
10gas utilization equipment.
