EQUIPMENT IN CONFINED SPACE
ALL AIR FROM INSIDE
CHIMNEY
OR GAS
VENT
G24−200
FURNACE
OPENINGS
(To Adjacent
Room)
NOTE−Each opening shall have a free area of at least one square inch (645 mm2) per 1,000 Btu (.29 kW) per hour of the total input rat- ing of all equipment in the enclosure, but not less than 100 square inches (64516 mm2).
FIGURE 1
When ducts are used, they shall be of the same cross−sec- tional area as the free area of the openings to which they connect. The minimum dimension of rectangular air ducts shall be no less than 3 inches (75 mm). In calculating free area, the blocking effect of louvers, grilles, or screens must be considered. If the design and free area of protec- tive covering is not known for calculating the size opening required, it may be assumed that wood louvers will have 20 to 25 percent free area and metal louvers and grilles will have 60 to 75 percent free area. Louvers and grilles must be fixed in the open position or interlocked with the equipment so that they are opened automatically during equipment operation.
EQUIPMENT IN CONFINED SPACE ALL AIR FROM OUTSIDE (Inlet Air from Crawl Space and Outlet Air to Ventilated Attic)
CHIMNEY OR
GAS VENT
VENTILATION LOUVERS
(Each end of attic)
G24−200 | OUTLET | |
AIR | ||
FURNACE | ||
|
VENTILATION
LOUVERS
(For unheated crawl space)
INLET
AIR
NOTE−The inlet and outlet air openings shall each have a free area of at least one square inch (645 mm2) per 4,000 Btu (1.17 kW) per hour of the total input rating of all equipment in the enclosure.
FIGURE 2
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