17
COMBUSTION AND VENTILATION AIR (cont.)
A. 1 Square inch for each 3,000 BTUH of the total input
rating of all equipment located in the enclosure
and
B. Not less than the sum of the areas of all vent connectors
in the conned space.
If the unit is installed where there is an exhaust fan, sufcient
ventilation must be provided to prevent the exhaust fan from
creating negative pressure.
AIR INTAKE PIPE CONNECTION
A double-elbow may be installed to top inlet air opening,
BUT IS NOT REQUIRED. This will help to prevent accidental
blockage of the intake opening. Reference Figure 13 for
proper elbow diameter.
NOTE: Inlet is specifically designed to prevent material from
being pulled into furnace. If elbows are not used, the intake
opening must be kept clean and free of debris.
Combustion Air
COMBUSTION AIR REQUIREMENTS: CONFINED AND
UNCONFINED SPACES
*$6
:$7(5
+($7(5
)851$&(
237,21$/64,1&+3(5%78+,1/(7$,5
*$%/(
9(17
9(17,/$7('
$77,&*$%/(25
62)),79(176
287/(7$,5
,1$77,&
0867%(
$%29(
,168/$7,21
64,1&+3(5
%78+,1/(7$,5
´0$;
64,1&+3(5
%78+
287/(7$,5
FIGURE 7
AIR FROM AT TIC/CRAWL SPACE
67$
ST-A1227-02
FIGURE 11
NON-DIRECT VENT
AIR FROM ATTIC
OR CRAWL
SPACE
VENT PENETRATIONS
for non direct vent furnaces
air from attic/crawl space
*$6
:$7(5
+($7(5
)851$&(
´
0$;
INLET AIR 1 SQ. INCH
PER 2000 BTUH
OUTLET AIR 1 SQ. INCH
PER 2000 BTUH
OUTLET AIR
1 SQ. INCH PER
4000 BTUH
INLET AIR
1 SQ. INCH PER
4000 BTUH
FIGURE 8
OUTSIDE AIR USING A HORIZONTAL INLET & OUTLET
67$
ST-A1227-03
FIGURE 12
NON-DIRECT VENT
OUTSIDE AIR
USING A
HORIZONTAL
DUCT
VENT PENETRATIONS
for non direct vent furnaces
air from attic/crawl space
ATTACH OPTIONAL DOUBLE ELBOW TO TOP INLET AIR
OPENING TO PREVENT ACCIDENTAL BLOCKAGE OF
INTAKE OPENING. THIS IS NOT A REQUIREMENT. (SEE
PREVIOUS PAGE.) SINGLE ELBOW IS ALLOWED BUT
MAY NOT PREVENT DEBRIS FROM BEING DROPPED
INTO THE FURNACE.
GROUND OR
SHELF SURFACE
6” MIN.
6” MINIMUM
CLEARANCE
PVC
DOUBLE
ELBOW
#8 SCREWS
METAL FLUE
PIPE ONLY
EXHAUST
#8 SCREWS
FIGURE 13
COMBUSTION AIR FITTING – NON-ATTIC COMBUSTION AIR PULL
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