Installation & Operation Manual
1 Determine unit location (continued)
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, page 11. Single openings shall be installed within 12" (30 cm) of the ceiling.
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.
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
| *Outside Air from |
| Inside Air from | Inside Air from | ||||
Model | 2 Openings Directly from | *Outside Air from | 2 Ducts Delivered from | 2 Ducts Delivered from Interior | ||||
Outdoors | 1 Opening Directly | Outdoors | Space | |||||
Number | ||||||||
Top | Bottom | from Outdoors, in2 | Top | Bottom | Top | Bottom | ||
| ||||||||
| Opening, in2 | Opening, in2 |
| Opening, in2 | Opening, in2 | Opening, in2 | Opening, in2 | |
402 | 100 | 100 | 133 | 200 | 200 | 400 | 400 | |
(645 cm2) | (645 cm2) | (858 cm2) | (1291 cm2) | (1291 cm2) | (2581 cm2) | (2581 cm2) | ||
502 | 125 | 125 | 167 | 250 | 250 | 500 | 500 | |
(806 cm2) | (806 cm2) | (1077 cm2) | (1613 cm2) | (1613 cm2) | (3226 cm2) | (3226 cm2) | ||
652 | 163 | 163 | 217 | 325 | 325 | 650 | 650 | |
(1052 cm2) | (1052 cm2) | (1400 cm2) | (2097 cm2) | (2097 cm2) | (4194 cm2) | (4194 cm2) | ||
752 | 188 | 188 | 250 | 375 | 375 | 750 | 750 | |
(1213 cm2) | (1213 cm2) | (1613 cm2) | (2420 cm2) | (2420 cm2) | (4839 cm2) | (4839 cm2) | ||
992 | 248 | 248 | 330 | 495 | 495 | 990 | 990 | |
(1600 cm2) | (1600 cm2) | (2129 cm2) | (3194 cm2) | (3194 cm2) | (6388 cm2) | (6388 cm2) | ||
1262 | 315 | 315 | 420 | 630 | 630 | 1260 | 1260 | |
(2032cm2) | (2032cm2) | (2710 cm2) | (4065 cm2) | (4065 cm2) | (8130 cm2) | (8130 cm2) | ||
1442 | 360 | 360 | 480 | 720 | 720 | 1440 | 1440 | |
(2323cm2) | (2323cm2) | (3097 cm2) | (4646 cm2) | (4646 cm2) | (9291 cm2) | (9291 cm2) | ||
1802 | 450 | 450 | 600 | 900 | 900 | 1800 | 1800 | |
(2903cm2) | (2903cm2) | (3871 cm2) | (5807 cm2) | (5807 cm2) | (11614 cm2) | (11614 cm2) | ||
2072 | 518 | 518 | 690 | 1035 | 1035 | 2070 | 2070 | |
(3342cm2) | (3342cm2) | (4452 cm2) | (6678 cm2) | (6678 cm2) | (13356 cm2) | (13356 cm2) | ||
*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 boiler 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.
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