www.usaprocom.com
200067-01A
8
VENTILATION AIR
AIR FOR COMBUSTION AND VENTILATION
Outlet
Air
Ventilated
Attic
Outlet
Air
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
Figure 2 - Ventilation Air from Inside
Building
Figure 3 - Ventilation Air from Outdoors
Or
Remove
Door into
Adjoining
Room,
Option
3
Ventilation Grills
Into Adjoining Room,
Option 2
Ventilation
Grills Into
Adjoining
Room,
Option 1
12"
12"
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 options
1 and 2, Figure 2). You can also remove door
into adjoining room (see option 3, Figure 2).
Follow the
National Fuel Gas Code, ANSI
Z223.1/NFPA 54, 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 perma-
nent 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, ANSI Z223.1/NFPA 54, 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.
The space in the above example is a confined
space because the actual Btu/Hr used is more
than the maximum Btu/Hr the space can sup-
port. You must provide additional fresh air.
Your options are as follows:
A. Rework worksheet, adding the space
of an adjoining room. If the extra space
provides an unconfined space, remove
door to adjoining room or add ventilation
grills between rooms. See
Ventilation Air
From Inside Building.
B. Vent room directly to the outdoors. See
Ventilation Air From Outdoors
.
C. Install a lower Btu/Hr heater, if lower Btu/
Hr size makes room unconfined. If the ac-
tual Btu/Hr used is less than the maximum
Btu/Hr the space can support,
the space
is an unconfined space. You will need no
additional fresh air ventilation.
WARNING: If the area in which
the heater may be operated does
not meet the required volume for
indoor combustion air, combus-
tion and ventilation air shall be
provided by one of the methods
described in the National Fuel
Gas Code, ANSI Z223.1/NFPA
54, the International Fuel Gas
Code, or applicable local codes.
