Outside air supply

Heating · Gas Burners · printed page 118 (PDF page 119)

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Book index entries

Supplies from Outside Outdoor Combustion Air Supplies for Gas Appliances

Text in the illustration

1 sq. inch of opening is required for every 4,000 BTUs
the duct is typically insulated and may have a damper and/or trap to minimize drafts
air duct from outside
damper
outside wall
gas furnace
outside air

Generated explanation

The illustration shows an outdoor combustion-air supply duct beside a gas furnace. The duct passes through the outside wall at a high level and descends to discharge near the floor, with an arrow indicating incoming outside air. A damper is identified in the vertical duct, and an annotation notes that the duct is typically insulated and may have a damper and/or trap to minimize drafts. Another annotation specifies 1 square inch of opening for every 4,000 BTUs. The furnace is shown with adjacent distribution ductwork, exposed gas piping and burners, and a vent connector rising from its top.

Components

gas furnace combustion-air supply duct damper outside wall furnace ductwork vent connector gas supply piping gas burners

Materials

sheet metal concrete