1000mm Straight Length 175mm (Black) KW Pro

£128.24 Inc VAT

The 1000mm Straight Length pipe is used to create the main run of your chimney system.

Twin wall flue size guide

1. Pipe and elbow diameters

With twin wall flue pipe, the internal and external diameters are different. This is because they have 1 inch of insulation surrounding the inner pipe that makes the outer pipe 2 inches larger than the inner pipe. The diameters referred to always relate to the INTERNAL diameter of the pipes it is this diameter that is important when connecting your flue pipe to a stove.

2. Brackets and finishing plates

Due to the reasons above all brackets and plates that are cut to fit twin wall pipe will actually measure 2 inches more than their stated diameter.

Stated Diameter I = Internal Diamater E = External Diameter Brackets & plate Diameter
100mm (4″) 100mm 150mm 150mm
125mm (5″) 125mm 175mm 175mm
150mm (6″) 150mm 200mm 200mm
175mm (7″) 175mm 225mm 225mm
200mm (8″) 200mm 250mm 250mm

Other useful information regarding twin wall flue systems

  • Your flue system (internal diameter) must never be less than the flue collar diameter on your stove and the stated flue requirements of that stove.
  • You can increase but never decrease the diameter of your flue system.
  • For that reason we do not sell reducers or decreasing components.
  • You should have a maximum of 4 elbows in your system.
  • The maximum angle of a bend permitted is 45 degrees other than coming straight out the back of your stove.
  • You should aim for an overall height of at least 4.5 meters from the top of your stove for the flue to work well.
  • The outlet or terminal of your flue system needs to finish at least 1000mm above your roof or 2,300mm horizontally from your roof, or 600mm above the ridge of your roof, whichever comes first.
  • Need help planning your system? Call us on 01376 315 760 to speak to our HETAS approved team of specialists who can plan your building regulation compliant system with you.

The 1000mm Straight Length pipe is used to create the main run of your chimney system.

The KW Pro system is designed for all solid fuel, wood, coal, gas, oil, and pellet heating appliances. It operates up to 600°C and comes with a 25-year warranty. KW Pro’s 25mm high-density mineral insulation, injected under high pressure, enhances thermal efficiency and ensures reliable flue performance. Its exceptional thermal properties have earned it a G50 classification.

With the largest selection of starting components in the UK, KW Pro allows for aesthetically pleasing transitions from stove to chimney. Each component includes locking bands for support, with standard bands supporting up to 1.9 meters of pipe and structural bands allowing an additional meter.

Available in Stainless and black finishes, for 80mm-200mm internal diameters.

Designation number EN1856-2 T600 N1 W V2 L50040 G50/EN1856-1 T200 P1 W V2 L50040

  • Brand: Kw Pro
  • Finish: Black
  • Distance to Combustibles: 50mm
  • Internal Diameter: 175mm
  • Outer Diameter: 225mm
  • Effective Length: 965mm
  • Grade of Steel: 316 Internal, 304 External
  • Thickness of Steel: 0.40mm
  • Insulation: Compressed Rockwool
  • Temperature Resistance: 600°C
  • Approvals: HETAS/CE
  • Warranty: 25 year(s)

Additional information



Flue Diameter


Flue Parts


To Fit

Twin wall pipe


KW Pro