Twin Wall Insulated Flue System
Our twin wall flue system is constructed of 25mm mineral wool insulation sandwiched between 316 Grade stainless steel 0.40mm thick inner wall & 304 Grade stainless steel 0.40mm thick outer wall. Designed for use with wood, oil, gas and low sulphur coal fuels.
Installation: Simple push fit joint system, with locking band (included)
● Warranty: Full 25 Year Warranty included
● Approvals : HETAS & CE approved
● Available in stainless steel finish (4 in – 8in diameters) and black powder coated twin wall (4 in – 6in diameters)
For installation advice, please visit:
About our Twin Wall
We supply twin wall flue systems manufactured by the German company, Jeremias, who have over 40 years of experience. It's made from layers of 304 outer and 316 inner stainless steel, with mineral wall insulation in the middle.
NB: Sizes refer to the internal diameter of the flue ; Once the external wall is taken into account, the overall diameter is 50mm larger. E.g 5 inch (125mm) flue has an overall external diameter of inches (175mm)
When calculating the length required, 50 mm of each piece will be lost where it connects into the next section. Therefore a 1m length, once connected in the chimney will measure 950mm.
Our flue is designed to give simple push fit installation, each piece seamless integrating with the next, and held in palce with a locking band . Each item of twin wall (length, bend or adaptor) is supplied with one locking band.
Flue must be installed with a minimum clearance of 60mm between the flue and any combustable materials, throughout the entirety of your installation.
No more than four bends or offsets should be used in the twin wall chimney. Multiple bends can severely interfere with the heat flow.
When passing through a roof, building regulations dictate that the flue must be either 600mm above the ridge of the property or 2.3 metres horizontally from any weathered surface.
When connecting to the outlet of the appliance, you must use an adaptor. This is because the insulation within the flue would be exposed directly to the appliance.
When passing through a wall, it is advised to use a solid length of flue rather than have the joints between two sections at the same point as where it passes through the wall.
Our black powder coated twin wall products are fully interchangeable with the stainless steel parts, as the only difference is the surface finish.
A Guide To Twin Wall Flue Components
A quick guide to the most common components.
These come in a range of lengths such as
1000mm, 500mm, 250 mm & 150 mm
These are adjustable lengths, that allow
approx 150 mm of adjustment.
These are used to lock each joint in place.
We supply one band with each section,
but they can be purchased separately if required.
Wall support bracket
Used to fix the chimney to the external wall to provide lateral support
Used to connect your flue to the appliance, at the bottom of the chimney.
(Twin wall flue pipe should never be connected to an appliance without an adaptor)
Bends come in a range of angles , including 30 degrees, 45 degrees & 90 degrees.
Used at the top of the chimney system, to ensure rain doesn't enter.
Twin Wall FAQ
What size twin wall flue do I need?
This will depend on the rating of the appliance and the fuel it burns.
For example, building regulations dictate the following:
● Appliance rating up to 20 kW (smokeless fuels) - Min 125mm diameter.
● Appliance rating up to 30 kW (any fuel) - Min 150 mm diameter.
● Defra exempt stoves - 125 mm diameter
In certain situations it is possible to use 100mm 4 inch twin wall (e.g. garden buildings, boats etc) – please call us for advice on your installation.
When should I use twin wall flue?
It should be used when you don't have any existing chimney stack to connect your appliance to (For example, where you'd normally have a flue liner. It an also be used in situations such as garden buildings & boats.
Can I cut twin wall pipe?
No, you should never cut twin wall flue pipe – you must ensure that you plan your chimney flue accurately and purchase the correct lengths accordingly (remember that 50mm of each section inserts into the next, so a 1000 mm section will actually take up 950 mm of space).