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Twin wall flue system

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If you are installing any kind of new burner, such as a wood-burning stove, gas coal-effect fire, or an oil boiler, you probably need an insulated flue system. So what exactly is an insulated flue system?

In simple English, this means you need a flue pipe (outflow pipe for your smoke) with an extra lining inside. We call this a “double wall flue” or a “twin wall pipe”.
Remember these terms!

If you do not have a brick chimney, then you absolutely have to have one of these for health and safety reasons. You can use a twin wall pipe to make a safe chimney system for the outflow of smoke from your burner. 

You can use a twin wall flue pipe as the flue/ main out pipe if you want your pipe to go through standard walls and through floors and roofs.

Our double-wall flues are suitable for use with wood, coal, gas and oil burners. Our Twin wall flue system is also perfect for biomass boiler installations.

The outside diameter of twin wall flue pipes is 50mm more than the inside diameter. So a 150mm pipe has an outer diameter of 200mm.

Our twin wall flue is a class 1 insulated flue system manufactured in Europe. This double wall flue is suitable for use with wood, coal, gas and oil appliances. Made of stainless steel - the twin wall flue is also perfect for biomass boiler installations.

  • Push fit jointing system - secures using a locking band
  • 30-year warranty
  • 30mm of insulation
  • The internal joint system prevents moisture draw through
  • HETAS listed for use in solid fuel applications


All our pipes are supplied with the necessary locking bands, free of charge.

A twin wall flue pipe is a metal tube (flue) insulated with approx. 25mm of insulation (two layers of stainless steel with insulation between). Stainless and black powder-coated systems are fully interchangeable. All of our black Twin Wall Insulated Flue products are a true MATT black finish.

Insulation is necessary to keep the gases hot. If you were to use a non-insulated flue pipe for the whole of your chimney, then the gases would likely cool too much and start to slow down rather than rise, with this causing the smoke underneath to “dam”. This might cause the smoke below to exit out of the vents in your stove instead of the top of your chimney.

Cooling gases also form condensation, which collects on the inner walls of the flue and runs down into the stove (mixed with soot it is a disgusting brown liquid).

We have a wide selection of Insulated Flue Systems in 5 and 6-inch pipes, including twin-wall insulated flue pipes, cowls, flashing, and bends to ensure you can build a complete twin-wall flue system.

All our double-walled flues are fully approved by HETAS and have the EN-1856-1 test certificate.


We can help you design your flue system!

You can send us a diagram, with dimensions to or click to fill in our free FLUE DESIGN SERVICE FORM. And a member of our trained technical team will send you a complete quote for your twin wall flue system.

For information about the legislation, please see our blog about flue regulations