Connectors should be used to connect an appliance and equipment to the vertical chimney or vent, except were the chimney or vent is attached directly to the appliance. The vent connector should be as short as practical, and the appliance should be located as close as practical to the chimney or vent.

Most fuel-gas appliance manufacturers require the installation of a sediment trap. Sediment traps prevent debris from entering the gas controls and causing hazardous malfunctions.

Individual, branch and circuit vents are permitted to terminate with a connection to an individual or branch-type air-admittance valve. Stack vents and vent stacks should be permitted to terminate to stack-type air-admittance valves. Access should be provided to all air-admittance valves. The air-admittance valve should be rated according to the size of the vent to which it is connected. www.nachi.org

PEX Plastic Tubing

PEX is polyethylene cross-linked plastic tubing. The cross-linked structure prevents the pipe from rupturing over a wide range of temperatures and pressures. PEX is resistant to solvents and cannot be joined by solvent cementing. PEX is flexible and can be bent. PEX can be hot-bent with a hot-air gun. The minimum hot-bending radius is 2½ times the outside diameter. PEX can be cold-bent, too (at room temperature) to a minimum radius of 6 times the outside diameter.