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AIR FOR
COMBUSTION
AND
VENTILATION
Continued
Figure 3 - Ventilation Air from Outdoors
Outlet
Air
Ventilated
Attic
Outlet
Air
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
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.
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.