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VENTILATION AIR
VENTILATION AIR FROM INSIDE BUILDING
This fresh air would come from an adjoining unconfined space. When venting to an adjoining space,
you must provide two permanent openings: one within 12" of the ceiling and one within 12" of the
floor on the wall connecting the two spaces. (See Options 1 and 2, Figure 7.) You can also remove door
into adjoining room. (See Option 3, Figure 7.)
WAR N I N G
REWORK WORKSHEET, ADDING THE SPACE OF THE ADJOINING UNCONFINED
SPACE. THE COMBINED SPACES MUST HAVE ENOUGH FRESH AIR TO SUPPLY ALL
APPLIANCES IN BOTH SPACES.
NOTE: Each opening shall have a minimum free area of 1 square inch per 1000 BTU’s per hour of the
total input ratings of all gas utilization equipment in the confined space, but not less than 100 square
inches.
Figure 7 Ventilation Air From Inside Building
A. Rework worksheet, adding the space of an adjoining room. If the extra space provides an
unconfined space, remove door to adjoining room or add ventilation grills between rooms. See
“Ventilation Air From Inside Building”, page 21.
B. Vent room directly to the outdoors. See “Ventilation Air From Outdoors”, page 22.
C. Install a lower BTU/Hr heater, if lower BTU/Hr size makes room unconfined.
If the actual BTU/Hr used is less than the maximum BTU/Hr the space can support, the
space is an unconfined space. You will need no additional fresh air ventilation.
WAR N I N G : YOU MUST PROVIDE ADDITIONAL VENTILATION AIR IN A
CONFINED SPACE
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