Lochinvar 399 - Manual (Page 9)

Installation and
Service Manual
9
FIG. 4 Metal Panel Covering Side Combustion Air Inlet
FIG. 5 Moving Air Filter/Bracket Assembly from Rear of
Unit to Side
Combustion Air Options
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.
One Opening
The opening must have a minimum free area of one square
inch per 3000 Btu input (7cm
2 per kW). You must locate this
opening within 12" (30cm) of the top of the enclosure.
FIG. 6 Outside Combustion Air - Single Opening
Two Openings
The combustion air opening must have a minimum free area of
one square inch per 4000 Btu/hr input (5.5cm
2 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/hr input (5.5cm
2 per kW). You
must locate this opening within 12" (30cm) of the top of the
enclosure.
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CAUTION: Under no circumstances
should the mechanical room ever be under a
negative pressure. Particular care should be
taken where exhaust fans, attic fans, clothes
dryers, compressors, air handling units, etc.,
may take away air from the unit.