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MI-Flex Flexible Flue Liners - Durable and Flexible Flue Solution

MI-Flex is a top-tier choice for flexible flue liners, renowned for its durability and flexibility in chimney installations. The MI-Flex range includes options in various diameters to suit different chimney sizes. The high-quality stainless steel construction ensures longevity and resistance to heat and corrosion. Whether you're fitting a new stove or updating an existing fireplace, MI-Flex provides a reliable solution. Discover why MI-Flex is a preferred choice among installers and homeowners for safe and efficient chimney lining.
MI-Flex is a top-tier choice for flexible flue liners, renowned for its durability and flexibility in chimney installations. The MI-Flex range includes options in various diameters to suit different chimney sizes. The high-quality stainless steel construction ensures longevity and resistance to heat and corrosion. Whether you're fitting a new stove or updating an existing fireplace, MI-Flex provides a reliable solution. Discover why MI-Flex is a preferred choice among installers and homeowners for safe and efficient chimney lining.


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The best selling flue liner in the UK. Suitable for gas, oil, and approved solid fuels. Call our advisers on 01670 206 999 if you need any help choosing.

£1.88 £3,657.99
Showing 20 of 397 items
904L Mi-FLEX 150mm x 1m CUT LENGTH

904L Mi-FLEX 150mm x 1m CUT LENGTH

36Z-150-1
£36.99 (including VAT)
In stock
904L Mi-FLEX 150mm x 40m COIL

904L Mi-FLEX 150mm x 40m COIL

36Z-150-40
from £1,928.99 (including VAT)
In stock
904L Mi-FLEX 180mm x 1m CUT LENGTH

904L Mi-FLEX 180mm x 1m CUT LENGTH

36Z-180-1
£83.99 (including VAT)
In stock
904L Mi-FLEX 180mm x 32m COIL

904L Mi-FLEX 180mm x 32m COIL

36Z-180-32
from £3,502.99 (including VAT)
In stock
904L Mi-FLEX 200mm x 1m CUT LENGTH

904L Mi-FLEX 200mm x 1m CUT LENGTH

36Z-200-1
£93.99 (including VAT)
In stock
904L Mi-FLEX 200mm x 30m COIL

904L Mi-FLEX 200mm x 30m COIL

36Z-200-30
from £3,657.99 (including VAT)
In stock
904L Mi-FLEX 250mm x 1m CUT LENGTH

904L Mi-FLEX 250mm x 1m CUT LENGTH

36Z-250-1
£223.99 (including VAT)
In stock
904L Mi-FLEX 300mm x 1m CUT LENGTH

904L Mi-FLEX 300mm x 1m CUT LENGTH

36Z-300-1
from £360.99 (including VAT)
In stock
Triplelock 80m Dia x 1m Z PACK (Liner ONLY)

Triplelock 80m Dia x 1m Z PACK (Liner ONLY)

4Z-80-1
from £10.99 (including VAT)
In stock
Triplelock 80m Dia x 44m Z PACK (Liner ONLY)

Triplelock 80m Dia x 44m Z PACK (Liner ONLY)

4Z-80-44
£471.99 (including VAT)
In stock
Triplelock - Installer Pack B (Clamp, GC1) - Ø 100

Triplelock - Installer Pack B (Clamp, GC1) - Ø 100

34-100-PB
£10.99 (including VAT)
In stock
Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 100

Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 100

34-100-PC
£16.99 (including VAT)
In stock
100mm (4 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

100mm (4 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-100-1
£10.99 (including VAT)
In stock
100mm (4 inch) Flue Liner 316L for Gas and Oil  44m Coil

100mm (4 inch) Flue Liner 316L for Gas and Oil 44m Coil

4Z-100-44
from £486.99 (including VAT)
In stock
Triplelock - Installer Pack B (Clamp, GC1) - Ø 125

Triplelock - Installer Pack B (Clamp, GC1) - Ø 125

34-125-PB
£11.99 (including VAT)
In stock
Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 125

Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 125

34-125-PC
£16.99 (including VAT)
In stock
125mm (5 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

125mm (5 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-125-1
£10.99 (including VAT)
In stock
125mm (5 inch) Flue Liner 316L for Gas and Oil 44m Coil

125mm (5 inch) Flue Liner 316L for Gas and Oil 44m Coil

4Z-125-44
from £486.99 (including VAT)
In stock
Triplelock - Installer Pack B (Clamp, GC1) - Ø 150

Triplelock - Installer Pack B (Clamp, GC1) - Ø 150

34-150-PB
£13.99 (including VAT)
In stock
Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 150

Triplelock - Installer Pack C (Clamp, GC1, Nose Cone) - Ø 150

34-150-PC
£17.99 (including VAT)
In stock
Your MI-Flex Questions Answered

What sizes are available in the MI-Flex range? -

MI-Flex is available in various diameters, including 80mm, 100mm, 125mm, 150mm, 175mm, 200mm, 250mm, and 300mm, catering to a wide range of chimney sizes.

Is MI-Flex suitable for wood-burning stoves? +

Does MI-Flex require professional installation? +

Can MI-Flex be used with gas fires? +

Is MI-Flex suitable for listed buildings? +

What is the warranty period for MI-Flex products? +

Can MI-Flex be used for both residential and commercial applications? +

MI-Flex stands out as a premium option for flexible flue liners in the UK. Its innovative design allows for easy installation, offering flexibility to navigate bends and offsets in chimneys efficiently. Made from high-grade stainless steel, MI-Flex ensures durability and longevity, making it a cost-effective solution in the long run. The smooth inner surface of MI-Flex promotes optimal airflow and prevents the build-up of creosote and debris, enhancing the efficiency and safety of your fireplace or stove. When it comes to quality, durability, and performance, MI-Flex is the go-to choice for chimney lining projects.
Why Buy MI-Flex Products
MI-Flex flexible flue liners are ideal for both residential and commercial properties. They are suitable for use with wood-burning stoves, multi-fuel stoves, gas fires, and oil boilers. MI-Flex offers a versatile solution for various chimney types, including masonry and pre-fabricated chimneys. Whether you're renovating an old property or installing a new heating appliance, MI-Flex provides a reliable and efficient flue lining solution. Its flexibility and durability make it a popular choice among installers and homeowners looking for high-quality chimney components.

Trusted By Trade Professionals

Our MI-Flex products and services are trusted by hundreds of professionals nationwide. We're committed to providing quality and reliability that meets the high standards of our customers.

Dedicated Support

Experience our unparalleled customer service and support when you buy MI-Flex from National Flues. Our team is here to assist you every step of the way, ensuring your needs are met with expertise and care.