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6
AIR FOR COMBUSTION AND VENTILATION
Continued
4. Compare the maximum Btu/Hr the space can support with the
actual amount of Btu/Hr used.
________ Btu/Hr (maximum the space can support)
________ Btu/Hr (actual amount of Btu/Hr used)
Example: 63,360 Btu/Hr (maximum the space can support)
79,000 Btu/Hr (actual amount of Btu/Hr used)
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 support.
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 adjoin-
ing room or add ventilation grills between rooms. See Ventilation
Air From Inside Building,
Page 6
.
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 actual Btu/Hr used is less than the maximum Btu/Hr the space
can support, the space is an unconfined space. You will need no ad-
ditional fresh air ventilation.
WARNING: If the area in which the heater may be
operated does not meet the required volume for indoor
combustion air, combustion and ventilation air shall
be provided by one of the methods described in the
National Fuel Gas Code, ANSI Z223.1/NFPA 54, the In-
ternational Fuel Gas Code, 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 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.
Figure 3 - Ventilation Air from Outdoors
Figure 2 - Ventilation Air from Inside Building
Or
Remove
Door into
Adjoining
Room,
Option
3
Ventilation Grills
Into Adjoining Room,
Option 2
Ventilation
Grills
Into Adjoining
Room,
Option 1
12"
12"
Outlet
Air
Ventilated
Attic
Outlet
Air
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
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 out-
doors 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.
