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. 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 air into attic if attic has a thermostat- controlled power vent. Heated air entering the attic will activate the power unit.
Ventilated Attic
Outlet Air 
Outlet Air | To Attic |
| |
| To Crawl |
| Space |
Inlet Air |
|
Inlet Air | Ventilation |
To Crawl Space |
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