DUCT SYSTEM DESIGN CONSIDERATIONS

™ Double plenums should not exceed 48 ft in total length. ™ Keep branch run starting collars 24 in. from the end caps. ™ Never locate a takeoff in the end cap. Reducing plenum system The reducing plenum duct system (see Figure 4) can be used when the physical size or layout of the struc-ture calls for greater distances than the length con- ................
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