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110148-01B
For more information, visit www.desatech.com
For more information, visit www.desatech.com
6
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 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, 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. 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.
AIR FOR COMBUSTION AND VENTILATION
Determining Fresh-Air Flow for Heater Location (Cont.)
Ventilation Air
Figure 4 - Ventilation Air from Outdoors (FPVF33PRA Shown)
Figure 3 - Ventilation Air from Inside Building (FPVF33PRA
Shown)
Outlet
Air
Ventilated
Attic
Outlet
Air
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
Or
Remove
Door into
Adjoining
Room,
Option
3
Ventilation Grills
Into Adjoining Room,
Option 2
Ventilation
Grills
Into Adjoining
Room,
Option 1
12"
12"
WARNING: If the area in which the heater may be
operated is smaller than that defined as an uncon-
fined space or if the building is of unusually tight
construction, provide adequate combustion and ven-
tilation air by one of the methods described in the
National Fuel Gas Code, ANSI Z223.1/NFPA 54 Sec-
tion 5.3
or applicable local codes
.
The space in the example on page 5 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 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 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.