5
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
option 1, Figure 3). You can also
remove door into adjoining room (see
option 2, Figure 3). Follow the
National
Fuel Gas Code NFPA 54/ANS Z223.1,
Section 5.3, Air for Combustion and
Ventilation for required size of
ventilation grills or ducts.
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.
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.
UNVENTED (VENT-FREE) FIREBOX
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.
FIGURE 3-Ventilation Air from Inside Building
D1118
FIGURE 4-Ventilation Air from Outdoors
D119
