AIR FOR COMBUSTION AND VENTILATION
Continued
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
Into Adjoining
Room,
Option 1
Or
Remove Door into Adjoining Room, Option
3
12"
Ventilation Grills 
Into Adjoining Room,
Option 2
12”
ventilation grills or ducts.
FIGURE 2 - VENTILATION AIR FROM INSIDE BUILDING
WARNING: Rework work- sheet, adding the space of the adjoining unconfined space. The combined spaces must have enough fresh air to supply all appliances in both spaces.
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or ducts. You must provide two permanent 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. 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.
OUTLET AIR
OUTLET
AIR
INLET
AIR 
INLET AIR
VENTILATED
ATTIC
TO ATTIC
TO
CRAWL
SPACE
VENTILATED
CRAWL SPACE
IMPORTANT: Do not provide openings for inlet or outlet air into attic, if attic has a thermostat- controlled power vent. Heated air entering the attic will activate the power vent.
FIGURE 3 - VENTILATION AIR FROM OUTDOORS
5