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Gas FLEX - High-Quality Flue Liners & Accessories | National Flues

Gas FLEX offers a range of flexible flue liner and installation accessories designed for gas appliances. At National Flues, we provide a comprehensive selection of flue liners in sizes ranging from 80mm to 300mm. These products are suitable for gas and oil applications, ensuring your fireplace operates efficiently and safely. Gas FLEX products are known for their durability and ease of installation, making them a top choice for both homeowners and professionals in the industry.
Gas FLEX offers a range of flexible flue liner and installation accessories designed for gas appliances. At National Flues, we provide a comprehensive selection of flue liners in sizes ranging from 80mm to 300mm. These products are suitable for gas and oil applications, ensuring your fireplace operates efficiently and safely. Gas FLEX products are known for their durability and ease of installation, making them a top choice for both homeowners and professionals in the industry.


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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 £881.99
Showing 20 of 84 items
Triplelock 80m Dia x 1m Z PACK (Liner ONLY)

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

4Z-80-1
£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
150mm (6 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

150mm (6 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-150-1
£15.99 (including VAT)
In stock
Triplelock 150mm Dia x 40m Z PACK (Liner ONLY)

Triplelock 150mm Dia x 40m Z PACK (Liner ONLY)

4Z-150-40
from £835.99 (including VAT)
In stock
175mm (7 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

175mm (7 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-180-1
£19.99 (including VAT)
In stock
Triplelock 180mm Dia x 32m Z PACK (Liner ONLY)

Triplelock 180mm Dia x 32m Z PACK (Liner ONLY)

4Z-180-32
from £843.99 (including VAT)
In stock
200mm (8 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

200mm (8 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-200-1
£22.99 (including VAT)
In stock
200mm (8 inch) Flue Liner 316L for Gas and Oil  30m Coil

200mm (8 inch) Flue Liner 316L for Gas and Oil 30m Coil

4Z-200-30
from £881.99 (including VAT)
In stock
250mm (10 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

250mm (10 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-250-1
£64.99 (including VAT)
In stock
300mm (12 inch) Flue Liner 316L for Gas and Oil  (316L Grade)

300mm (12 inch) Flue Liner 316L for Gas and Oil (316L Grade)

4Z-300-1
from £118.99 (including VAT)
In stock
Your Gas FLEX Questions Answered

What sizes are available for Gas FLEX flue liners? -

Gas FLEX flue liners come in sizes ranging from 80mm (3 inch) to 300mm (12 inch), catering to a wide range of gas appliance installations.

Are Gas FLEX flue liners suitable for gas and oil applications? +

How do Gas FLEX flue liners enhance safety? +

Can homeowners install Gas FLEX flue liners themselves? +

Do Gas FLEX flue liners require regular maintenance? +

Are Gas FLEX flue liners compatible with all gas appliances? +

Can Gas FLEX flue liners improve the efficiency of a fireplace? +

Gas FLEX flue liners are crafted using high-grade materials to meet stringent safety standards. Our range includes liners in various diameters and lengths to suit different installation needs. Whether you're fitting a new fireplace or upgrading an existing system, Gas FLEX products offer a reliable solution. Each flue liner is engineered for optimal performance and longevity, providing a smooth passage for gases to vent out effectively. At National Flues, we not only offer top-quality products but also expert advice to help you select the right components for your project.
Why Buy Gas FLEX Products
Gas FLEX flue liners are essential components for venting gases from gas appliances safely. These liners create a secure passage for combustion byproducts to exit your home, reducing the risk of harmful emissions inside. By using Gas FLEX products, you can ensure proper ventilation for your fireplace or stove, enhancing both efficiency and safety. The flexible design of the liners allows for easier installation, making them ideal for various applications. Whether you're a homeowner or a professional installer, Gas FLEX flue liners provide a durable and reliable solution for your heating system.

Trusted By Trade Professionals

Our Gas 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 Gas 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.

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