AS 4567:2005 pdf – Twin wall metal flues-Gas appliances.
A joint shall—
(a) he a tight fit (metal to metal) when made up in accordance sith the manufacturer’s instructions:
(b) not materially reduce the capacity of the flue piping: and
(c) he 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 zero clearance shall be provided with top plate supports designed to locate the flue in the wall cavity. Each length of flue shall include integral spacers that will maintain the minimum required clearance between the outer casing of the flue and the inner surfaces of walls. Such spacers are to he located so that, when lengths are joined, there will be spacers on both 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 without requiring 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 instructions and/or parts are available to enable the cut length to comply with these requirements.
2.3.6 Definite relationship behseen flue parts
Any parts of a flue which bear a definite relationship to any other for proper and safe use shall be arranged and constructed to permit them to be incorporated into the complete assembly only in the correct relationship with each other and without the need for alteration or alignment, or such parts shall be assembled and shipped from the factory as one element.
2.3.7 Assembh b manufacturers
Each gas flue part (such as a flue pipe section. elbow, coupling, tee etc.) shall be completely assembled by the manufacturer at the factory.
2.3.8 Spacer strength
All spacers shall have sufficient strength and bearing surface to maintain the required clearance between the flue pipe. parts of joists. ceiling and floor material, and the inner surface of walls.
2.3.9 Securing supports
A support assembly intended to he secured by nails or screws shall be arranged so that such holding means will be in shear.
2.3.10 Use of screws
Where screws are employed to field-join assemblies, the assemblies shall readily receive screws without being field-punched or field-drilled and a screw shall not c\tcnd into a flue inner 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 security of its attachment to the building structure be impaired.
AS 4567:2005 pdf – Twin wall metal flues-Gas appliances
