Owner's Manual

www.desatech.com
111244-01G8
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: 35,840 Btu/Hr (maximum the space
can support)
40,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the above example is a conned 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 adjoin-
ing room. If the extra space provides an unconned
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 Ventila-
tion Air From Outdoors.
C. Install a lower Btu/Hr replace, if lower Btu/Hr
size makes room unconned.
If the actual Btu/Hr used is less than the maximum Btu/Hr
the space can support, the space is an unconned space.
You will need no additional fresh air ventilation.
WARNING: If the area in
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    
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
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
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This fresh air would come from an adjoining un-
conned space. When ventilating to an adjoining
unconned space, you must provide two permanent
openings: one within 12" of the ceiling and one within
12" of the oor on the wall connecting the two spaces
(see options 1 and 2, Figure 5). You can also remove
door into adjoining room (see option 3, Figure 5). Fol-
low 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.

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 oor. 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
Air
Ventilated
Attic
Outlet
A
ir
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
Figure 5 - 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"
Figure 6 - Ventilation Air from Outdoors