Twin wall

Twin Wall
The full range of twin wall flue systems are available with airgap or insulated annulus varying in size (25mm - 100mm). Although relatively low external skin temperatures can be obtained, through selection of the correct annulus thickness, dependant on the flue gas temperature a minimum 50mm clearance must be maintained from the outer skin to all combustible materials.

Installation instructions
All component parts of the selected flue system are connected with the female end uppermost. Jointing integrity is achieved by simply pushing the two sections together and is secured by means of a clamp band which locates into the inner swages on the outer casing.

In a vertical application it is essential that components are installed with male spigot down against the flow of gases. This is to allow condensates, if any, to remain within the flue.
It is recommended that a bead of silicones as sealant be applied between joints on installation.

Twin Wall Components

Straight Lengths
Straight lengths are available as standard in 150mm, 300mm, 420mm, 570mm, 760mm, 875mm and 1210mm lengths, with exception to 100mm diameter pipe which has a maximum effective length of 875mm. These are all the installed effective lengths. We also manufacture any fixed length between the standard lengths to your specification.

Adjustable lengths
The adjustable length fits on to the female end of our straight lengths of flue. thus becoming telescopic to give the exact length of pipe required. When the adjustable length is in position it is then fixed by means of a clamp band which is supplied.

Clamp bands
Fixed to the outer skin at each joint to lock the components in position. Clamp bands are 100mm wide for all diameters.

Stepped adapter
Used when a change in diameter is required over a minimum length.

Reducer/Increaser
This component also changes the diameter of the flue but with a steadier transition to limit resistance.

Appliance adapters
Designed to adapt to any spigot or flange. Manufactured to your requirements.

Elbows
Elbows are used when a change of direction is required within the flue run.
Two elbows can be used to make an offset, by incorporating various straight lengths and adjustable lengths. Offsets can be tailor made to suit your requirements. It should always be remembered that elbows are not loadbearing. All dimensions relate to 25mm annulus flue. Dimensions for other annulus sizes are available on request.

Tees
(Non-standard tees are available to order)

90° Tees
The 90° Tee is used at the base of a vertical rise. A drain Tee cap or clean outdoor can be supplied for inspection or cleaning. This equal tee can be supplied with a reduced branch on request. 90° Tees can be manufactured with a booted joint so as to reduce resistance around the transition.

135° Tees
The 135° Tee is also used at the base of a rise but given the added advantage of a swept entry to reduce resistance to the flow of flue gases. This equal tee can be supplied with a reduced branch and at any angle.

Drain Tee Cap
These caps are positioned to close off the unused opening on the underside of the base tee. The cap is manufactured with a threaded end drain for which pipework can be attached to dispose of any condensate build up which could have occurred. The caps can be easily removed for cleaning access.

Clean-Out door
These doors are fixed at the end/s of the header system to enable cleaning and inspection.

Terminals and external fittings

Rain Cap Terminal
Provides a weather protected vent to atmosphere.

Top Stub Terminal
Provides an unrestricted vent to atmosphere. Also supplied to order with a reduced diameter outlet to increase exhaust velocity.

Universal Terminal
Designed for use with atmospheric gas burning appliances with a restricted outlet to prevent bird access. For sizes 100mm to 350mm maximum

Double Inverted Rain Cap
Designed for use on induced draught systems to prevent back pressure within the flue

Flat/angled flashing
Suitable on flat or slate roofs. Roof pitch must be specified.

Storm Collar
Fitted above the flashing to prevent water entering between the outer skin of the flue and the flashing.