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AIR FOR COMBUSTION
AND VENTILATION
Continued
The space in the above example is a confined space
because the actual Btu/Hr used is more than the maxi-
mum 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 adjoining
room or add ventilation grills between rooms. See
Ventilation Air From Inside Building below.
B. Vent room directly to the outdoors. See Ven-
tilation 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 additional fresh air ventilation.
WARNING: If the area in
which the firebox and gas log
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 un-
confined space. When ventilating to an adjoining
unconfined space, you must provide two perma-
nent 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 4). You
can also remove door into adjoining room (see
option 3, Figure 4). Follow the National Fuel Gas
Code ANSI Z223.1/NFPA 54, Section 5.3, Air for
Combustion and Ventilation for required size of
ventilation grills or ducts.
6
Ventilation
Grills
Into Adjoining
Room,
Option 1
Figure 4 - Ventilation Air from Inside
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. Follow the
National Fuel Gas Code ANSI Z223.1/NFPA 54,
Section 5.3, 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.
Outlet
A ir
Inlet
Air
Figure 5 - Ventilation Air from Outdoors
www.desatech.com
12"
Ventilation Grills
Into Adjoining Room,
Or
Option 2
Remove
Door into
Adjoining
Room,
Option
3
12"
Building
Ventilated
Outlet
Attic
Air
Ventilated
Inlet Air
Crawl Space
To Attic
To
Crawl
Space
107331-01H
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