Lochinvar 999 - 750, 399 Combustion Air Options, Outside Combustion Air, No Ducts, One Opening

Installation and Service Manual

Combustion Air Options

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.

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.

FIG. 4 Metal Panel Covering Side Combustion Air Inlet

FIG. 5 Moving Air Filter/Bracket Assembly from Rear of Unit to Side

One Opening

The opening must have a minimum free area of one square inch per 3000 Btu input (7cm2 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 (5.5cm2 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/hr input (5.5cm2 per kW). You must locate this opening within 12" (30cm) of the top of the enclosure.

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