18-28-803.3 Size.
   The connect shall not be smaller than the size of the flue collar or the size of the outlet of the draft hood supplied by the manufacturer of the appliance except as provided in Section 18-28-804. Where the appliance has more than one flue outlet, and in the absence of the manufacturer's specific instructions, the connector area shall be not less than the combined area of the flue outlets for which it acts as a common connector.