Two or more listed and labeled appliances connected to a common natural draft venting system shall comply with the following requirements:
1. Appliances that are connected to common venting systems shall be located on the same floor of the dwelling.
Exception: Engineered systems as provided for in Section G2427.
2. Inlets to common venting systems shall be offset such that no portion of an inlet is opposite another inlet.
3. Connectors serving appliances operating under a natural draft shall not be connected to any portion of a mechanical draft system operating under positive pressure.