Combustion And Ventilation Air - Desa FVFM27PR Owner's Operation And Installation Manual

AIR FOR COMbUSTION
AND VENTILATION
Continued
Example:
Gas water heater*
Vent-free heater
Total
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: 51,200 Btu/Hr (maximum the
space can support)
73,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in this 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 ad-
ditional 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 Ventila-
tion 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 un-
confined space. You will need no additional fresh
air ventilation.
WARNING: If the area in
which the heater may be oper-
ated 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
108382-01G
40,000
____________Btu/Hr
33,000
+ __________Btu/Hr
73,000
= __________Btu/Hr
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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
Grills Into
Adjoining
Or
Room,
Remove
Option 1
Door into
Adjoining
Room,
Option
3
Figure 2 - Ventilation Air from Inside
Building
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
Air
Outlet
A ir
Inlet
Air
Inlet Air
Figure 3 - Ventilation Air from Outdoors
12"
Ventilation Grills
Into Adjoining Room,
Option 2
12"
Ventilated
Attic
To Attic
To
Crawl
Space
Ventilated
Crawl Space