× National Flues
We Will NOT Be Beaten on Price.
Free Delivery on Orders Over £100
5 Star Reviewed on Trustpilot
Free Flue Design Service Available
Help? 01670 206999 (8am-5pm)

Increasing MI-FLEX Adaptor - Ø 100-Ø 125

National Flues presents the Increasing MI-FLEX Adaptor - Ø 100 to Ø 125, a premium accessory engineered for seamless integration between rigid single-wall flue systems and MI-FLEX flexible flue liners. Crafted from high-quality 316L stainless steel, this adaptor ensures a reliable, gas-tight seal re... More...
Hover to Zoom / Click for Gallery

At a Glance

  • - Seamless transition from a single-wall rigid flue to a flexible MI-FLEX liner
  • - Constructed from durable 316L stainless steel for long-lasting performance
  • - Supports a range of fuels including wood (<20% moisture), oil, gas, and smokeless coal
  • - Withstands high operating temperatures up to 600°C (T600 designation)
  • - HETAS and CE approved to meet Building Regulations Document J
Now only £20.49
Including VAT Buy with confidence. If you find this cheaper within 48 hours of checkout, we'll refund the difference.

 

Payment Options

We Won't Be Beaten On Price

At National Flues, we continuously monitor competitor prices. This ensures that we consistently offer you the best deals on all our products. Here’s how we keep your costs low:

  • Daily Price Matching: Our team adjusts prices to ensure we stay competitive.
  • Bulk Purchasing Power: We sell a lot, so we can negotiate better rates with suppliers, passing the savings directly to you.
  • Operational Efficiency: We have streamlined processes to reduce overhead.

Price Match Guarantee: If you find the same product cheaper within 48 hours, we’ll match it and refund the difference.

Free Delivery Over £100: Orders over £100 are free delivery (call us if delivery is required outside the mainland UK).

“I saved 20% on my purchase compared to other retailers. Exceptional service!” – Jane D.

Have Questions?
Phone: 01670 206999
Email: [email protected]

The Increasing MI-FLEX Adaptor Ø 100 to Ø 125 is a must-have accessory for your MI-FLEX 316 and 904 flexible flue liners. This robust 0.6mm 316 stainless steel adaptor is meticulously crafted to serve as a transitional joint, increasing the diameter from a single-wall connecting flue system to a flexible liner by up to 25mm. Ideal for use with appliances operating at temperatures up to 600°C (T600 designation), it supports wood with less than 20% moisture, smokeless coal, gas, and oil.

Complying with Building Regulations Document J, this adaptor must be used within a fully enclosed masonry chimney. Ensuring a secure, gas-tight seal is critical – fire cement, ceramic rope, tape, or high-temperature sealant is recommended for optimal connection integrity. Regular maintenance is essential, with HETAS registered sweeps recommended for solid fuel applications.

Sweep your chimney at least twice a year for optimal performance and longevity.

SKU: 20-100-MR

Technical Specifications
SKU20-100-MR
Material316L Stainless Steel
Adaptor Diameteru00d8 100 to u00d8 125 mm
Wall Thickness0.6 mm
Operating TemperatureUp to 600u00b0C
Fuel CompatibilityWood (<20% moisture), Oil, Gas, Smokeless Coal
StandardsHETAS / CE Approved
SystemMI-FLEX Accessories MF20
Before installing the Increasing MI-FLEX Adaptor, ensure your flue system is completely enclosed within a masonry chimney, as stipulated by Building Regulations Document J. Begin by properly preparing the surfaces for a gas-tight seal. Use high-temperature sealants such as fire cement, ceramic rope, or tape to secure joints reliably. Avoid using chemical cleaners or mild steel tools on stainless steel components. It is recommended to have the installation checked by a HETAS registered professional to ensure compliance with all safety standards. Regular maintenance, including bi-annual flue sweeps, is essential for ensuring optimal performance and longevity of the system.

This adaptor is specifically designed for use with MI-FLEX 316 and 904 flexible flue liners, ensuring seamless transitions and secure connections.

The adaptor is suitable for use with wood (<20% moisture), smokeless coal, gas, and oil, and can handle temperatures up to 600°C.

Yes, Building Regulations Document J requires that the flexible flue liner and its accessories must be installed within a fully enclosed masonry chimney.

To ensure a gas-tight seal, use fire cement, ceramic rope or tape, or high-temperature sealant during installation.

Can chemical cleaners be used for chimney maintenance?

No, chemical cleaners and mild steel tools should not be used on stainless steel chimneys. Professional chimney sweeps, preferably registered with HETAS, should be engaged for this task.

The Increasing MI-FLEX Adaptor provides a transitional increase of up to 25mm from the single wall flue to the flexible flue liner.
Delivery Information +

We work relentlessly to ensure you get your order fast. Estimated delivery for this product is Thursday, April 3rd. If you need faster stove or fireplace delivery please give us a call. We can often reduce longer lead times if we pay the carrier £25 for express delivery. Visit our Shipping Information page for more information.

Warranty & Returns +

All our products come with warranties. Mi-Flex offers a lifetime guarantee. Returns for damaged items are covered by insurance; non-damaged returns incur return delivery costs.

Price Match Guarantee +

We will match any price like for like. If you find it cheaper within 48 hours, we'll refund the difference.

Read our buyers guide for this Increasing MI-FLEX Adaptor - Ø 100-Ø 125

National Flues Ltd Verdict

The Increasing MI-FLEX Adaptor - Ø 100 to Ø 125 is a top-tier choice for those needing to connect flexible flue liners. Its design ensures seamless connections and top performance across multiple fuel types. Available from National Flues, known for reliable nationwide delivery and competitive pricing for both retail and trade customers, this adaptor is an optimal addition to any setup.

The Increasing MI-FLEX Adaptor is used to connect a single-wall rigid flue system to an MI-FLEX flexible flue liner, ensuring a seamless transition and secure connection.

National Flues is a leading supplier of fireplaces and flues across the UK. We specialise in providing top-quality products with unbeatable prices, reliable nationwide delivery, and excellent customer service, catering to both retail and trade customers.

 

Our Rating Image

Secure your MI-FLEX Adaptor now for a flawless and safe flue connection.

Your recently viewed products:

Multiple Payment Options- including Klarna, Clearpay, Mastercard, Visa and Paypal
Free Design Service