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 appli- ances installed in that space. Rooms communicating directly with the space in which the 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, heavily insuhted, 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.
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 a_regate input rating of all appliances
installed in that space.
a. ALL AIR FROM INSIDE BUILDINGS: (See Page 9 Figure 1, and Figure 6 below)
The confined space shall be provided with two permanent open- ings communicating directly with an additional room(s) of suffi- cient volume so that the combined volume of all spaces meets the criteria for an unconfined space. The total input of all gas utiliza- tion equipment installed in the combined 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 inches of the top and one commencing within 12 inches of the bottom of the enclosure.
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b. ALL AIR FROM OUTDOORS: (see Figures
The confined space shall be provided with two permanent open-
ings, one commencing within 12 inches of the top and one com- mencing within 12 inches from the 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.
Figure 7 ]
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 Figure 7.)
2.When communicating with the outdoors through vertical ducts, each opening shall have a minimum flee area of 1 square inch per 4,000 BTU per hour of total input rating of all equipment in the endosure. (See Figure 8.)
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AIR OUTLET
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3.When communicating with the outdoors through horizontal ducts, each opening shall have a minimum flee 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.)
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4.When ducts are used, they shatl 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 protect- ing openings. Screens used shall not be smaller than ¼ inch mesh. If the free 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 free area is not known, it may be assumed that wood louvers will be
and metal louvers and grilles will have
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 avokl unsatisfactory operation of installed gas utilization
equipment.
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