AIR FOR COMBUSTION AND VENTILATION
Continued
WARNING
If the area in which the heater may be operated is smaller than that defined as an unconfined space, provide adequate combus- tion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining unconfined space. When ventilating to an adjoining unconfined space, you must provide two permanent openings: one within 12" of the ceiling and one within 12" of the floor on the wall connecting the two spaces (see options 1 and 2, Figure 2). You can also remove door into adjoining room (see option 3, Figure 2). Follow the National Fuel Gas Code NFPA 54/ANSI Z223.1, Section 5.3, Air for Combustion and Ventilation for required size of ventilation grills or ducts.
WARNING
Rework worksheet, adding the space of the adjoining unconfined space. The combined spaces must have enough fresh air to supply all appliances in both spaces.
Ventilation
Grills
Into Adjoining
12"
Ventilation Grills
Into Adjoining Room,
Room,
Or
Option 2
Option 1
Remove
8
Door into Adjoining Room, Option 
3
12"
Figure 2 - Ventilation Air from Inside Building
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or ducts. You must provide two perma- nent openings: one within 12" of the ceiling and one within 12" of the floor. Connect these items directly to the outdoors or spaces open to the outdoors. These spaces include attics and crawl spaces.
IMPORTANT: Do not provide openings for inlet or outlet air into attic if attic has a 
| Outlet |
| Ventilated | |
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| Attic | ||
| Air |
| ||
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| |
Outlet |
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| |
Air |
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| To Attic | |
To
Crawl
Space
Inlet
Air
Inlet Air |
| Ventilated |
| Crawl Space | |
|
|
Figure 3 - Ventilation Air from Outdoors
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