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 aggregateinput rating of all appli- ances installed in that space. Rooms communicating directly witll the space in which tile appliances are installed, through openings not fur- nished 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, heavilyinsulated, caulked,vapor barrier, etc.), additional air may need to be provided using the methods described in Combustion Air and Ventilation for AppliancesLocated in Confined Spaces.
1.When directly communicating with the outdoors, 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 Figm'e 7.)
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 8.)
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 10 Figure 1, and Figure 6 below)
"Ille 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 lbr an unconfined space. "Ille total input of all gas utilization equip- ment installed in the combined space shall be considered in making this determination. Each opening shall have a mininmm flee 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 inches
of the top and one commencing within 12 inches of the bottom of the endosurc.
VENT THROUGH
I Figure 8 ]
3.When communicating with the outdoors through horizontal ducts, each openingshall have a minimum free area of 1 square inch per 2,000 BTU per hour of total input rating of all equip- ment in the enclosure. (See Figure 9.)
Figure 6 ]
b. ALL AIR FROM OUTDOORS: (see Figures
The confined space shall be provided with two permanent openings,
one commencing | within | 12 inches | of the | top and one commencing | |
within 12 inches | from | tile bottom | of the | enclosure. The | openings |
shall communicate | directly, or by ducts, with the outdoors | or spaces | |||
(crawl or attic) that freely communicate with the outdoors.
VENTILATION LOUVERS_ | VENT THROUGH | |
(each end of attic) | ||
2 ROOF | ||
| ||
| VENT TO | |
| OUTDOORS |
Figure 7 ]
VENTILATION LOUVERS
Figure 9]
4.When ducts are used, they shall be of the same
5.Louvers and Grilles: In calculating flee area, consideration shall be given to the blocking effect of louvers, grilles or screens protect- ing openings. Screens used shall not be smaller than ¼ inch mesh. If the flee area through a design of louver or grille is known, it should be used in calculating the size opening required to provide the free area specified. If the design and flee area is not known, it may be assumed that wood louvers 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 atten- tion to avoid unsatisfactory operation of installed gas utilization equipment.
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