AS 4567 pdf download – Twin wall metal flues—Gas appliances
(a)be a tight fit (metal to metal) when made up in accordance with the manufacturer’sinstructions;
(b)not materially reduce the capacity of the flue piping; and(c)be designed not to retain or leak condensation.
2.3.4 Top plate supports and spacers
A twin wall gas flue intended for installation within a wall cavity with other than zeroclearance shall be provided with top plate supports designed to locate the flue in the wallcavity. Each length of flue shall include integral spacers that will maintain the minimumrequired clearance between the outer casing of the flue and the inner surfaces of walls.Such spacers are to be located so that，when lengths are joined, there will be spacers onboth sides of and directly adjacent to each joint.
2.3.5 Ready attachment
Each part of a gas flue shall be designed for ready attachment of one to the other withoutrequiring alteration，cutting，threading，drilling，welding or similar task by the installer,except that a length of flue pipe may be shortened by cutting if sufficient instructionsand/or parts are available to enable the cut length to comply with these requirements.
2.3.6 Definite relationship between flue parts
Any parts of a flue which bear a definite relationship to any other for proper and safe useshall be arranged and constructed to permit them to be incorporated into the completeassembly only in the correct relationship with each other and without the need for alterationor alignment,or such parts shall be assembled and shipped from the factory as one element.2.3.7Assembly by manufacturers
Each gas flue part (such as a flue pipe section，elbow，coupling,tee etc.) shall becompletely assembled by the manufacturer at the factory.
2.3.8 Spacer strength
All spacers shall have sufficient strength and bearing surface to maintain the requiredclearance between the flue pipe,parts of joists,ceiling and floor material，and the innersurface of walls.
2.3.9 Securing supports
A support assembly intended to be secured by nails or screws shall be arranged so that suchholding means wili be in shear.
2.3.10 Use of screws
Where screws are employed to field-join assemblies,the assemblies shall readily receivescrews without being field-punched or field-drilled and a screw shall not extend into a flueinner conduit. Screws and instructions shall be supplied.
2.3.11 Damage free
An assembly intended to support the flue pipe shall not be damaged，nor shall the securityof its aftachment to the building structure be impaired.
Each length of flue or component shall be clearly and permanently marked and suchmarking shall include the following:
(a) Manufacturer’s name and/or trade mark.
(b) Type or designation.
(c) Certificate of compliance number obtained from a certifying body.
(d) Direction of flow, if applicable.
Markings shall remain legible and durable during normal handling and installation, e.g. to abrasion, humidity and temperature.
Instructions in English shall be available, which shall include:
(a) Type or designation.
(b) Manufacturer’s or agent’s name and address.
(c) Illustrations, directions and information for attaining proper and safe installation of the gas flue components including the details below:
(i) Parts required and the process for installing the gas flue, methods of support,and maintenance of clearances to wall, floor, ceiling, roof, joist construction
and building insulation.
(i) Methods and parts to be employed for maintaining ventilation and air circulation where required.
(ii) Any limitations with respect to installation and use, such as maximum height,the jointing of two or more parts to constitute a safe assembly etc.
(iv) Cutting and joining of lengths (where applicable).
Essential external and internal dimensions.