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All installations and services must be performed by qualified service personnel.
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DUCT SIZES FOR HOMES, QUIET OFFICES, OR SIMILAR INSTALLATIONS
TABLE 2A
Each of the system components (trunk lines, take offs, runs and register and grill-free areas) must be properly sized
and matched together to ensure the necessary air handling capacity of a duct system. A 12" x 8" duct with a 400
CFM capacity for example will not flow 400 CFM if the register(s) to which it connects only flow a total of 200
CFM.
The speed of the blower motor may have to be changed to obtain the proper 55°F to 85°F (35°F to 65°F CHB1-75)
temperature rise for heating when an air conditioning coil is installed. This depends on the static resistance of an
individual duct system and the size of the air conditioner.