6
105735
VENT-FREE NATURAL GAS HEATERS
BLUE-FLAME MBN20LB
™
Figure 2 - Ventilation Air from Inside Building
Or
Remove
Door into
Adjoining
Room,
Option 3
Ventilation Grills
Into Adjoining Room,
Option 2
12"
12"
Ventilation
Grills
into Adjoining
Room,
Option 1
AIR FOR
COMBUSTION
AND VENTILATION
Continued
Outlet
Air
Ventilated
Attic
Outlet
Air
Inlet
Air
Inlet Air
Ventilated
Crawl Space
To
Crawl
Space
To Attic
Figure 3 - Ventilation Air from Outdoors
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation
grills or ducts. You must provide two per-
manent 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 NFPA 54/ANS
Z223.1, 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.
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 pro-
vide 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 op-
tion 3, Figure 2). Follow the National Fuel
Gas Code NFPA 54/ANS Z223.1, Section
5.3, Air for Combustion and Ventilation for
required size of ventilation grills or ducts.
WARNING: Rework work-
sheet, adding the space of the
adjoining unconfined space. The
combined spaces must have
enough fresh air to supply all
appliances in both spaces.
