Installation manual
www.fmiproducts.com
125685-01B8
AIR FOR COMBUSTION AND VENTILATION
Continued
Figure 3 - Ventilation Air from Outdoors
Outlet
Air
Ventilated
Attic 
Outlet
A
ir
Inlet
Air
Inlet Air
Ventilated 
Crawl Space
To 
Crawl
Space
To Attic
 WARNING: If the area in which 
the heater may be operated does 
not meet the required volume for 
indoor combustion air, combus-
tion and ventilation air shall be 
provided by one of the methods 
described  in  the  National Fuel 
Gas Code, ANSI Z223.1/NFPA 54, 
the International Fuel Gas Code, 
or applicable local codes.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining 
unconned  space.  When  ventilating  to  an 
adjoining unconned 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 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, Air for Combustion and 
Ventilation  for  required  size  of  ventilation 
grills or ducts.
Figure 2 - 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"
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation 
grills or ducts. You must provide two perma-
nent 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, 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 thermo-
stat-controlled power vent. Heated air entering 
the attic will activate the power vent.










