1
Determine unit location
(continued)
11
Installation & Operation Manual
Figure 1-5_
Outside Combustion Air Through Ducts
4. Outside Combustion Air - Using Direct Venting
With this option, you can connect combustion air vent piping
directly to the unit. See the information under Direct Venting
starting on page 26 for specific information regarding this
option.
All dimensions are based on net free area in square inches.
Metal louvers or screens reduce the free area of a combustion air
opening a minimum of approximately 25%. Check with louver
manufacturers for exact net free area of louvers. Where two
openings are provided, one must be within 12" (30 cm) of the
ceiling and one must be within 12" (30 cm) of the floor of the
equipment room. Each opening must have a minimum net free
area as specified in TABLE 1C, this page. Single openings shall
be installed within 12" (30 cm) of the ceiling.
⚠
CAUTION
The combustion air supply must be
completely free of any flammable vapors
that may ignite or chemical fumes which
may be corrosive to the appliance. Common
corrosive chemical fumes which must be
avoided are fluorocarbons and other
halogenated compounds, most commonly
present as refrigerants or solvents, such as
Freon, trichlorethylene, perchlorethylene,
chlorine, etc. These chemicals, when
burned, form acids which quickly attack
the heat exchanger finned tubes, headers,
flue collectors, and the vent system. The
result is improper combustion and a non-
warrantable, premature unit failure.
TABLE - 1C
MINIMUM RECOMMENDED COMBUSTION
AIR SUPPLY TO EQUIPMENT ROOM
Model
Number
*Outside Air from
2 Openings Directly from
Outdoors
*Outside Air from
1 Opening Directly
from Outdoors, in
2
Inside Air from
2 Ducts Delivered from
Outdoors
Inside Air from
2 Ducts Delivered from
Interior Space
Top
Opening, in
2
Bottom
Opening, in
2
Top
Opening, in
2
Bottom
Opening, in
2
Top
Opening, in
2
Bottom
Opening, in
2
502
125
(806 cm
2
)
125
(806 cm
2
)
167
(1077 cm
2
)
250
(1613 cm
2
)
250
(1613 cm
2
)
500
(3226 cm
2
)
500
(3226 cm
2
)
652
163
(1052 cm
2
)
163
(1052 cm
2
)
217
(1400 cm
2
)
325
(2097 cm
2
)
325
(2097 cm
2
)
650
(4194 cm
2
)
650
(4194 cm
2
)
752
188
(1213 cm
2
)
188
(1213 cm
2
)
250
(1613 cm
2
)
375
(2420 cm
2
)
375
(2420 cm
2
)
750
(4839 cm
2
)
750
(4839 cm
2
)
992
248
(1600 cm
2
)
248
(1600 cm
2
)
330
(2129 cm
2
)
495
(3194 cm
2
)
495
(3194 cm
2
)
990
(6388 cm
2
)
990
(6388 cm
2
)
1262
315
(2032cm
2
)
315
(2032cm
2
)
420
(2710 cm
2
)
630
(4065 cm
2
)
630
(4065 cm
2
)
1260
(8130 cm
2
)
1260
(8130 cm
2
)
1442
360
(2323cm
2
)
360
(2323cm
2
)
480
(3097 cm
2
)
720
(4646 cm
2
)
720
(4646 cm
2
)
1440
(9291 cm
2
)
1440
(9291 cm
2
)
1802
450
(2903cm
2
)
450
(2903cm
2
)
600
(3871 cm
2
)
900
(5807 cm
2
)
900
(5807 cm
2
)
1800
(11614 cm
2
)
1800
(11614 cm
2
)
2072
518
(3342cm
2
)
518
(3342cm
2
)
690
(4452 cm
2
)
1035
(6678 cm
2
)
1035
(6678 cm
2
)
2070
(13356 cm
2
)
2070
(13356 cm
2
)
*Outside air openings shall directly communicate with the outdoors. When combustion air is drawn from the outside through a
duct, the net free area of each of the two openings must have twice (2 times) the free area required for Outside Air/2 Openings. The
above requirements are for the pool heater only; additional gas fired appliances in the equipment room will require an increase in
the net free area to supply adequate combustion air for all appliances.
