A.O. Smith BL-80 - Outdoor Air Requirements for Confined Spaces; Outdoor Air Through Horizontal Ducts; Outdoor Air Through Vertical Ducts; Air From Other Indoor Spaces

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OUTDOOR AIR THROUGH TWO HORIZONTAL DUCTS
FIGURE 10.
Theconnedspaceshallbeprovidedwithtwopermanenthorizontal
ducts,onecommencingwithin12inches(300mm)ofthetopand
one commencing within 12 inches (300 mm) of the bottom of the
enclosure.Thehorizontalductsshallcommunicatedirectlywiththe
outdoors.SeeFigure10.
Eachductopeningshallhaveaminimumfreeareaof1squareinch
per2,000Btu/hr(1100mm2perkW)oftheaggregateinputratingof
allappliancesinstalledintheenclosure.
Whenductsareused,theyshallbeofthesamecrosssectionalarea
asthefreeareaoftheopeningstowhichtheyconnect.Theminimum
dimensionofrectangularairductsshallbenotlessthan3inches.
OUTDOOR AIR THROUGH TWO VERTICAL DUCTS
The illustrations shown in this section of the manual are a
reference for the openings that provide fresh air into conned
spacesonly.
DO NOT refer to these illustrations for the purpose of vent
installation. See Venting Installation on page 14 for complete
ventinginstallationinstructions.
FIGURE 11.
Theconned space shall be provided with two permanent vertical
ducts,onecommencingwithin12inches(300mm)ofthetopand
one commencing within 12 inches (300 mm) of the bottom of the
enclosure. The vertical ducts shall communicate directly with the
outdoors.SeeFigure11.
Eachductopeningshallhaveaminimumfreeareaof1squareinch
per4,000Btu/hr(550mm2perkW)oftheaggregateinputratingof
allappliancesinstalledintheenclosure.
Whenductsareused,theyshallbeofthesamecrosssectionalarea
asthefreeareaoftheopeningstowhichtheyconnect.Theminimum
dimensionofrectangularairductsshallbenotlessthan3inches.
AIR FROM OTHER INDOOR SPACES
FIGURE 12.
Theconnedspaceshallbeprovidedwithtwopermanentopenings,
one commencing within 12 inches (300 mm) of the top and one
commencingwithin12inches(300mm)ofthebottomoftheenclosure.
SeeFigure12.
Eachopeningshallcommunicatedirectlywithanadditionalroom(s)
ofsufcientvolumesothatthecombinedvolumeofallspacesmeets
thecriteriaforanUnconnedSpace.
Eachopeningshallhaveaminimumfreeareaof1squareinchper
1,000Btu/hr(2200mm2perkW)oftheaggregateinputratingofall
appliancesinstalledintheenclosure.Eachopeningshallnotbeless
than100squareinches(645cm2).
VENTING