Interpretation #6989

Section M1403.1 is not applicable to a replacement A/C
unit. The Florida Existing Building Code does note refer
you back to the Residential Code. However, in no case
shall the installation violate the manufacturer's
installation instructions. The requirement for compliance
with FBC-M is Section 301.11 Repair. "... shall be
replaced or repaired in such a manner so as to preserve the
original approval or listing." Beyond the manufacturer's
requirements, the contractor is responsible to review the
installed equipment and its ability to work utilizing the
existing duct system. The use of ductwork that is too small
may prevent proper operation of the new equipment, may
prevent installation in accordance with manufacturer's
requirements (static pressure limitations), or may reduce
the efficiency of the equipment below the minimum Energy
Code stipulations. If any changes to the duct system are
required, then the contractor should make those
corrections. At that point the inspector should review new
work for code compliance.