19
FIGURE 13
COMBUSTION AIR FITTING
One permanent opening, located
within 12 inches of the top of the
enclosure, shall be permitted
where the equipment has
clearances of at least 1 inch from
the sides and back and 6 inches
from the front of the appliance.
The opening shall directly
communicate with the outdoors or
communicate through a vertical or
h
orizontal duct to the outdoors or
spaces (crawl or attic) that freely
communicate with the outdoors,
and shall have a minimum free
area of:
a
. 1 square inch for each 3,000
BTUH of the total input rating of all
equipment located in the enclosure
and
B
TUH Free Area Round Pipe
I
nput Each Opening Size
4
5,000 15.00 square inches 4"
6
0,000 16.67 square inches 5"
7
5,000 25.00 square inches 6"
90,000 30.00 square inches 6"
105,000 35.00 square inches 7"
120,000 40.00 square inches 7"
b. Not less than the sum of the
areas of all vent connectors in the
confined space.
If unit is installed where there is an
exhaust fan, sufficient ventilation
must be provided to prevent the
exhaust fan from creating a negative
pressure.
Combustion air openings must not be
restricted in any manner.
CONSULT LOCAL CODES FOR
SPECIAL REQUIREMENTS.
CONNECTION TO
FURNACE
IMPORTANT: When indoor
combustion air is used, the inlet air
o
pening at the furnace must be
protected from accidental blockage.
(See Figure 13).
UPFLOW
DOWNFLOW/HORIZONTAL
2" PVC
D
OUBLE
ELBOW
T
OP
OPTION
E
XHAUST
2" PVC ELBOW
SIDE
OPTION
2
" PVC
DOUBLE
ELBOW*
COMBUSTION AIR
EXHAUST
A
TTACH DOUBLE ELBOW TO INTAKE AIR
C
OLLAR AND SECURE WITH TWO SHEET
M
ETAL SCREWS TO PREVENT ACCIDENTAL
B
LOCKAGE OF INTAKE AIR OPENING.
*NOTE: WHEN FURNACE IS INSTALLED IN A HORIZONTAL POSITION
ONLY ONE 90° ELBOW IS REQUIRED. INSTALL THE ELBOW SO THE
OPEN END IS POINTED DOWNWARD.
A
TTACH DOUBLE ELBOW TO TOP INLET
A
IR OPENING OR 90° ELBOW TO SIDE
I
NLET AIR OPENING TO PREVENT
A
CCIDENTAL BLOCKAGE OF INTAKE
O
PENING. PLUG OPENING NOT USED.
I337
I336
P
REDRILL FOR SCREWS.
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