Installation & Service Manual
1 Determine unit location
Combustion Air Options
CAUTION Under no circumstances should a mechanical room ever be under a negative pressure.
Particular care should be taken when exhaust fans, clothes dryers, compressors, air handling units, etc., take away air from the inlet.
This unit has four combustion air options.
1. Outside Combustion Air, No Ducts
You can direct outside combustion air to this unit using either one or two permanent openings (see FIG.
One Opening
The opening must have a minimum free area of one square inch per 3000 Btu input (7 cm2 per kW). You must locate this opening within 12'' (30 cm) of the top of the enclosure.
Two Openings
The combustion air opening must have a minimum free area of one square inch per 4000 Btu input (5.5cm² per kW). You must locate this opening within 12'' (30cm) of the bottom of the enclosure.
The ventilation air opening must have a minimum free area of one square inch per 4000 Btu input (5.5cm² per kW). You must locate this opening within 12'' (30cm) of the top of the enclosure.
Figure 1-6_Outside combustion air, two openings
Figure 1-5_Outside combustion air single opening
2. Outside Combustion Air, Using Ducts
You can direct outside combustion air to this unit using two air ducts to deliver the air to the boiler room.
Each of the two openings must have a minimum free area of one square inch per 2000 Btu input (11cm² per kW).
Figure 1-7_Outside combustion air, using ducts
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