WIR 2
If the actual Btu/Hr used is less than the max- imum Btu/Hr the space can support, the space is an unconfined space. You will need no addi- tional fresh air ventilation.
WARNING: if the area in which the heater may be operated is smaller than that defined as an unconfined space or if the building is of unusually tight construction, provide adequate combustion and ventilation air by one of the methods described in the National Fuel Gas Code, ANSI Z223.1/NFPA 54 section 5.3 or applicable local codes.
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 open- ings: 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 ??). Follow the National Fuel gas Code, ANSI Z223.1/NFA 54, section air for combustion and ventilation for required size of ventilation grills or ducts.
Fig.2 Ventilation Air from Inside Building
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grilles or ducts. You must provide two permanent open- ings: 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, ANSI Z223.1/NFA 54, section 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 has a
Fig.3 Ventilation Air From Outdoors
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