All installations and services must be performed by qualified service personnel.
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 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.
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