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Twist Lock Chimney System

Twist Lock Chimney System


The Twist Lock insulated chimney system is designed for internal and external use, and comprises of a range of straight lengths and associated fittings and accessories. It is available in three nominal diameters, 125mm (5”), 150mm (6”) and 200mm (8”). The 25 mm insulated annulus ensures minimum heat loss, maximum draught and minimal condensation. It features an inner lining of 316 grade stainless steel and the outer surface is made of grade 304 stainless steel. The 25mm annulus is insulated using ceramic blanket. Components twist-lock together and are secured with a toggled Locking Band included with each piece. The Twist Lock Chimney System has been specifically designed to meet the needs of customers requiring robust and economical insulated double wall pre-fabricated chimney systems. The system has been assessed and certified to EN1856: Part 1. Typical applications include for the exhaust of flue gases from boilers, stoves and heaters. The system is available as standard in a bright annealed stainless steel finish and to order in a matt black painted stainless steel finish. Twist Lock is not recommended for use with condensing appliances.



  • Corrosion Resistant
  • Stainless Steel Construction
  • Range of Sizes 5” to 8”
  • Bright Annealed or Matt Black Stainless Steel Finish
  • Easy to Assemble
  • Adjustable Lengths Available
  • CE Approved
Technical Details:  
Inner Flue Material: 0.55mm 316L Stainless Steel
Outer Flue Material: 0.55mm 304 Stainless Steel
Flue & Fitting Diameters:

5”(125mm), 6”(150mm) & 8”(200mm)

Flue Lengths: 250mm, 500mm & 1000mm
Adjustable Flue Lengths: 305mm - 455mm
Surface Finish: Bright Annealed Stainless Steel
  Matt Black Stainless Steel
Insulation: 25mm Rockwool
Thermal Conductivity: 0.34 W/mK
Reaction to Fire: Euroclass A1
Maximum Temperature: 450°C
Conforms To: EN 1856-1
Approvals: CE Approved


Installation Instructions:


All Components must be installed with the male coupler upwards and the female coupler downwards, engaging over the male. Push the elements together and when seated, rotate the upper section clockwise through about 18°. Complete the jointing process by applying a locking band.


Connecting to the appliance:

An appliance adaptor must always be used to connect the system to appliances with spigot outlets. The inner lining must be fitted inside, but not project below the spigot and can be cut to an appropriate length.


Wall bands are designed to provide lateral stability only. In combination with wall supports, the systems must be laterally braced at intervals not exceeding 2.5 metres.

Wall supports consist of two side plates and a support plate. The support plate have an adjustable barbed male and female couplers on each side of the plate. Always use a wall support immediately above any Tees, because Tees are not load bearing.

Roof Supports are designed to support the chimney on the roof timbers and is provided with adjustable gimbal plates and can be located above or below roof trusses.


The relatively low external casing temperature experienced in normal operation permits installation with only 50mm air gap clearance to combustible materials. Where the Twin- Wall Chimney passes through a combustible floor the appropriate fire stopping components must be used.

Floor & Ceiling Penetrations

A Firestop Plate & Ceiling Support must be used where the system passes through floor and ceiling levels and the chimney needs to be supported over the heating appliance. At higher levels where fire stopping is required without the need to load bear, use a Firestop Plate on each side of the floor penetration. Whatever the configuration, the chimney should be boxed in with material which provide a 50mm clearance to any combustible materials. Joints between chimney sections must not be made within the thickness of the floor.


Rain Caps are for use over oil-fired appliances and may be used where the flue size is 175mm or greater.

H Cowls should only be used over oil fired appliances and usually as a last resort where draught problems occur.