This product standard specifies the requirements and test methods for dry (designated D) and/or wet (designated W) air flue system chimneys, including terminals in which the products of combustion are conveyed to the atmosphere through clay/ceramic flue liners and combustion air is conveyed to suitable room-sealed appliances through an air duct or an air gap.It also specifies the requirements for marking, manufacturer's instructions, product information and evaluation of conformity.This standard does not apply to structurally independent (free standing or self supporting) system chimneys.An air flue system chimney is made of the following components where a