Chimney Flue Liners

Ultraflex : The ideal solution for wood / log burning & multi fuel stoves

Our flexible chimney liners are the ideal solution for lining an existing chimney stack. With superior protection against carbon monoxide leakage & creosote build up, they also improve the draw of the chimney and efficiency of your appliance or fireplace. Our chimney liner is available to buy in 5 - 8 inch diameters, and suitable for use with multi fuel stoves, wood burning stoves & open fireplaces & comes complete with lifetime warranty and are available to purchase by the metre or as complete flue liner kits.

Our Ultraflex chimney flue liner comes with a lifetime warranty against defects. Valid for as long as you own the property.

(For gas flue liner click here)

Complete Custom Flue KitsComplete Custom Flue Kits
5 inch ultraflex flue liner components5 inch ultraflex flue liner components
6 inch ultraflex flue liner components6 inch ultraflex flue liner components
5 inch ultraflex flue liner components5 inch ultraflex flue liner components
5 inch ultraflex flue liner components5 inch ultraflex flue liner components

Flexible flue liner specifications

Ultraflex Flue Liner is manufactured in the UK, to the highest specifications:

  • Constructed of twin-lined, grade 1 stainless steel with smooth inner & corrugated external layer
  • Corrosion & crush resistant
  • Conforms to grading and testing standards set by Hetas and BSRI.
  • Optimised to expel exhaust gases & fumes (such as carbon monoxide), minimising the build up of tar condensates or creosote.
  • Designation number EN1856-T450-P2-VML-L500-24-G.
  • Complies with British Standards BS-EN1856

Chimney liner comparison : Which liner Do I need ?

Type Construction Suitable Fuel Types Sizes Available Warranty
316/316 316 grade inner / 316 grade outer stainless steel Dry seasoned wood, gas, oil and low sulphur coal 5 inch
6 inch
7 inch
8 inch
904/316 904 grade inner /316 grade outer stainless steel dry seasoned wood, coal, gas, oil, & low sulphur coal 5 inch
6 inch
7 inch
904/904 904 grade inner /904 grade outer stainless steel dry seasoned wood, gas,oil, low sulphur coal, coke, peat and smokeless fuels. 5 inch
6 inch
7 inch
8 inch


When is a flue liner required?

A flue liner is required in the following circumstances:

  1. The chimney stack is prone to leaking smoke & fumes (i.e. failed a smoke test)
  2. Tar/creosote build up is excessive between sweeps
  3. Diameter of the inside of stack is too large for the appliance
  4. Smoke and fumes are not being sufficiently drawn up the chimney
  5. You are installing a new appliance where there is an existing steel liner, and it's age or condition is unknown (typical lifespan of older liners might only be 10 -15 years)
  6. If insulation is needed to improve the operation of the appliance
  7. The stack has irregular internal surfaces, making it prone to bird nesting

What to look for when choosing your chimney flue liners

There are many types on the market for wood burners/DEFRA approved stoves and it can be difficult to know which to choose.

Ultraflex Lifetime warranty

At Flexifluedirect we sell superior Ultraflex solid fuel flexible liners that are manufactured from the highest grade stainless steel. This ensures it will last for many years and we offer a lifetime warranty.

Do make sure that the liner you buy is the right size for your Installation. We stock 5 inch flue liner6 inch flue liner as well as 7 & 8 inch liner.

Chimney liner installation

Chimney Liner Installation

Installation main points

Before installation, ensure your chimney stack is swept and is clear of any debris, as it may interfere with the performance of the liner.

It is essential that the arrows on the side of the flue are facing in the upwardsposition .

The flexi liner cannot be fitted directly to your appliance and must be connected via an adaptor that can be purchased separately.

Once installed, it is important to remember that all such work must be visually inspected as per the UK Building Regulations, Document J .

Do a smoke test to ensure that they are completely smoke-tight.

Detailed installation guides

For more detailed information, see our full flexible liner installation guides


Types of liner : Clay, pumice and concrete liners versus stainless steel

clay, pumice and concrete liner v stainless steel

Solid liners manufactured out of clay, pumice or concrete have the advantage of durability over stainless steel. However, they are difficult and costly to retro-fit into an existing chimney, and are therefore more suitable for new build projects.

Chimney maintenance and cleaning

chimney maintenance

Flues should be swept before winter use, and ideally again at the end of the winter heating season. Sweeping brushes and rods must be used (not chemicals, which may invalidate warranty) and we recommend using a qualified chimney sweep. If possible, perform a smoke test to ensure there are no leaks.

Standard operating temperature is 450°C for solid materials and 250°C for gas and oil; operating in excess of this may damage liners.

Buy with confidence from Flexifluedirect

Secure online purchase

Purchase securely online, with payments handled securely by Worldpay or Paypal. For orders over £125 we offer free next day delivery (to UK mainland addresses)

No quibble returns

We offer a full returns guarantee, whereby you have 14 days to return items for a full refund. There is a 15% restocking charge for returns between 14 -21days, and 25% after 21 days.
Unfortunately we are unable to accept returns on flexible flue as this is cut to your specific size requirements and is therefore classed as a bespoke item.

Need help?

Our technical team is ready and willing to help you find exactly the right chimney liner and parts for your installations. Call us on 01622 711411 (Monday -Friday 9am to 5pm)

Related Pages

What's the difference between 316 and 904 flue liner?

What is the best chimney liner for a wood stove?

How long will a flexible flue liner last?

What size flue liner do I need for a woodburner?

What is the average cost of a chimney liner?

Can I Install my own Liner?

Do I need twin wall flue?

Is it a legal requirement to have a flue liner?

Can you have bends in a wood burner flue?

Do I need to insulate my chimney flue?


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