9
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills or duct. You
must provide two permanent openings: one within 12 inches
of the ceiling and one within 12 inches 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/ANS Z223.1.
Air for Combustion and Ventilation for required size
of ventilation grills or ducts.
Ventilation Air From Inside Building
This fresh air would come from adjoining unconfined space.
When ventilating to an adjoining unconfined space, you must
provide two permanent openings: one within 12 inches of the
wall connecting the two spaces (see options 1 and 2,
Fig. 2). You can also remove door into adjoining room (see
option 3, Fig. 2). Follow the National Fuel Gas Code NFPA 54/
ANS Z223.1. 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. 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.
Fig. 2 - Ventilation Air from Inside Building
Fig. 3 - Ventilation Air from Outdoors