1018029-E
.
square inch per 1,000
See Figure
4-A (on page 7).
Each of these openings using vertical ducts shall have a minimum free area of one square inch per 4,000 btu/hr of total input
rating of all gas appliances. See Figures 4-B and 4-C. If horizontal ducts are used, the minimum free area shall be one
square inch per 2,000 of total input rating of all gas appliances.
ceiling. The minimum free area of this opening shall be one square inch per 3,000 btu/hr of the total input rating of all gas
appliances but not less than the sum of the areas of all vent connectors in the space. See Figure 4-D (on page 7).
When calculating the amount of fresh air needed you must include make-up air requirements for the operation of exhaust
Additional information can be found in the latest edition of ANSI Z223.1 (National Fuel Gas Code).
COMBUSTION AND VENTILATION AIR
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