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 appropriate: - clay/ceramic flue liners; - insulation layer; - outer walls; - mortar for jointing flue liners; - acid resistant mortar or elastomeric sealant for jointing flue liners; - mortar for jointing outer walls; - terminal; - chimney base; - pressure equalising opening; - air duct; - air gap; - cladding; - opening section; - cleaning and inspection door; - distance piece; - reinforcement. The air- flue system chimney covers a combination of compatible chimney components obtained or specified from one manufacturing source, with product responsibility for the whole chimney.