1.All air from inside the building as in Figure 9: The confined space shall be provided with two perma- nent openings communicating directly with an addi- tional room(s) of sufficient volume so that the com- bined 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. Refer to Table 3, for minimum open areas required.
2.All air from outdoors as in Figure 10: The confined space shall be provided with two permanent open- ings, one commencing within 12 inches of the top and one commencing within 12 inches of the bot- tom of the enclosure. The openings shall communi- cate directly, or by ducts, with the outdoors or spaces (crawl or attic) that freely communicate with the outdoors. Refer to Table 3, for minimum open areas required.
3.The following types of installations will require use of OUTDOOR AIR for combustion, due to chemical expo- sures:
*Commercial buildings
*Buildings with indoor pools
*Furnaces installed in commercial laundry rooms
*Furnaces installed in hobby or craft rooms
*Furnaces installed near chemical storage areas. Exposure to the following substances in the combus- tion air supply will also require OUTDOOR AIR for combustion:
*Permanent wave solutions
*Chlorinated waxes and cleaners
*Chlorine based swimming pool chemicals
*Water softening chemicals
*Deicing salts or chemicals
*Carbon Tetrachloride
*Halogen type refrigerants
*Cleaning solvents (such as perchloroethylene)
*Printing inks, paint removers, varnish, etc.
*Hydrochloric acid
*Cements and glues
*Antistatic fabric softeners for clothes dryers
*Masonry acid washing materials
TABLE 2
MINIMUM AREA IN SQUARE FEET FOR
UNCONFINED SPACE INSTALLATIONS
FURNACE MAXIMUM | WITH 8 FOOT CEILING |
MINIMUM AREA IN SQUARE FEET | |
BTUH / INPUT RATING | OF UNCONFINED SPACE |
| |
|
|
40,000 | 250 |
60,000 | 375 |
80,000 | 500 |
100,000 | 625 |
120,000 | 750 |
140,000 | 875 |
Installer’s Guide
TABLE 3
MINIMUM FREE AREA IN SQUARE INCHES
EACH OPENING (FURNACE ONLY)
Furnace |
| Air From Outside | ||
Maximum | Air From |
|
| |
Vertical | Horizontal | |||
BTUH/INPUT | Inside | |||
Rating |
| Duct | Duct | |
40,000 | 100 | 10 | 20 | |
60,000 | 100 | 15 | 30 | |
80,000 | 100 | 20 | 40 | |
100,000 | 100 | 25 | 50 | |
120,000 | 120 | 30 | 60 | |
140,000 | 140 | 35 | 70 | |
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9 |
