Installation Instructions (cont'd)
Combustion Air and Ventilation for Appliances Located in Unconfined Spaces
Unconfined Spac¢ is a space whosevolume is not less than 50 cubic feet per 1,000 Btu per hour of the aggregate input rating of all appliances instalhd in that space. Roomscommunicating directly with the space in which the appliances are installed, through openings not furnished with doors, are considereda part of the unconfined space
In unconfined spaces in buildings, infiltrationmay be adequate to provide air for combustion, ventilationand dilution of flue gases. However,in buildings of tight construction (for example, weather stripping, heavilyinsulated, caulked, vaporbarrier,etc.), additional air may need to be provided using the methods described in Combustion Air and Ventilation for Appliances Locatedin Confined Spaces,b.
Combustion Air and Ventilation for Appliances Located in Confined Spaces
Confined Spacc is a space whose volume is less than 50 cubic feet per 1,000 Btu per hour of the aggregate input ratingof all appliances installed in that space.
a. ALL AIR FROM INSIDE BUILDINGS:
(SeePage9 Figure1, and Figure2 below)
The confined space shall be provided with two permanent
openings communicating directlywith 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 ratingofafi 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.
1.When direcdycommunicating with the outdoors,each open- ing shall have a minimumflee area of I square inch per 4,000 BTU per hour of total input raring of all equipment in the enclosure. (See Figure3.)
2.When communicatingwith the outdoors through vertical ducts, each opening shall have a minimum free area of 1 sc!uareinch per 4,000 BTU per hour of total input ratingof all equipment in the enclosure.(SeeFigure 4.)
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 endosure. (See Figure5.)
I Figure 2 ]
b. ALL AIR FROM OUTDOORS:
The confined space shall be provided with two permanent openings,one commencing within 12 inches of tee top and one commencing within 12 inches from the bottom of the enclosure. The openings shall communicate directly,or by
ducts, with the outdoorsor spaces (crawl or attic) that freely communicate with the outdoors.
I Figure 3 ]
_i " | Ii f I.... |
4.When ductsare used, they shall be of the same
5.Louversand Grilles: In calculating free area, consideration
shall be given to the blocking effect of louvers, grilles or screensprotecting openings.Screens used shall not be smaller
than ¼ inch mesh. If the _ee area through a desi_ of louver or grille is known, it should be used in calculating the size opening recLuiredto provide the free area specified. If the designand free area is not known, it may be assumed that wood louverswill be
6.Special Conditions Created by Mechanical Exhaustingor Fireplaces:Operation of exhaust fans, ventilation systems, clothes dryersor fireplacesmay create conditions requiring
specialattention to avoid unsatisfactoryoperationof installed gasutilizationequipment.
1o
