Midtherm Extension Length 75-350mm Stainless Twin Wall Flue

The Midtherm HTS Twin Wall Flue – Extension Length (75-350mm) offers a durable, fully insulated solution for extending flue systems with adjustable flexibility and secure connections.

  • 5″ or 6″ diameters
  • Stainless steel chrome finish
  • Push fit connection (comes with 1 band)
  • Suitable for solid fuel and gas/ oil

Crafted from high-quality stainless steel, it’s compatible with multiple fuel types, rated for 450°C, and backed by a 20-year warranty for registered installations.

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Estimated Delivery: 3-5 Working Days

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    FREE delivery on orders over £1,000

    Within 100 miles. One-person delivery; receiver unloads unless upgraded.

    • 14 day no-hassle returns
    • Full manufacturer warranty included
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    twin wall stainless adjustable
    Midtherm Extension Length 75-350mm Stainless Twin Wall Flue

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      Delivery, Click & Collect & Returns Information

      Collection Information

      We offer free Click & Collect from our Reading, Berkshire showroom and warehouse at RG7 2PQ.

      Please select “Click & Collect: Berkshire Showroom (RG7 2PQ)” at checkout to reserve your item.

      If the Add to Basket button is not available, please call 0118 970 1717 or email info@bonfire.co.uk to place a Click & Collect order.

      Please do not travel to collect your order until we have confirmed that your goods are ready. We recommend contacting us in advance to confirm stock availability, collection times and loading details.

      Please ensure you arrive in a suitable vehicle for the size and weight of the goods being collected. Our team can assist with loading where safe and practical, but the customer is responsible for securing the goods for transport.

      View our showroom information


      Delivery Information

      Delivery times are usually approximately 2–3 working days, depending on stock availability at the time of order or if stated otherwise. Some products may have longer lead times, especially if they are made to order, supplier stocked or awaiting manufacturer availability.

      Once your order has been placed, we will contact you to confirm the estimated delivery date and advise you of any known delays.

      Delivery costs are calculated at checkout based on your postcode, order value and delivery location.

      Free Delivery Over £1,000

      Free delivery on orders over £1,000 is available within 100 miles of our showroom at RG7 2PQ, unless stated otherwise.

      Unless otherwise agreed in writing, free delivery is a dedicated one person small van / 3m Sprinter-style delivery service.

      This means:

      • the goods are delivered to your address or the nearest safely accessible point;
      • the delivery is made by one driver;
      • the receiver is responsible for safely unloading the goods from the vehicle;
      • the driver may assist where safe and practical, but this cannot be guaranteed;
      • this service does not include tail lift delivery, two-person delivery, white glove delivery, internal placement, unpacking or installation.

      For heavy, fragile or bulky products, please ensure suitable unloading assistance is available at the delivery address.

      If you require help unloading, a tail lift vehicle, two-person delivery, white glove delivery, internal placement or any other special delivery arrangement, please contact us before placing your order or before dispatch so we can provide a bespoke delivery quote.

      Dedicated Delivery Service

      Where possible, we use a dedicated direct delivery service rather than a general pallet network. This helps reduce handling, lowers the risk of damage in transit and gives larger or fragile products the best chance of arriving safely and in one piece.

      However, unless an upgraded delivery service has been quoted and agreed in writing, this remains a one-person delivery service and the receiver is responsible for unloading.

      Tail Lift, White Glove and Bespoke Delivery

      Tail lift, two person and white glove delivery options may be available on request, depending on the product, delivery location and access.

      These are upgraded chargeable services and must be agreed before dispatch.

      Please contact our team on 0118 970 1717 or email info@bonfire.co.uk if you require:

      • tail lift delivery;
      • assistance unloading;
      • delivery onto a driveway or into a garage;
      • white glove delivery;
      • delivery into the property;
      • restricted access delivery;
      • timed delivery;
      • delivery to a building site or commercial address.

      Access Requirements

      Please tell us before dispatch if there are any access restrictions, including:

      • narrow lanes;
      • steep or gravel driveways;
      • low bridges;
      • parking restrictions;
      • steps;
      • restricted turning space;
      • weight limits;
      • difficult access for vans or lorries.

      The driver will deliver to the nearest safe and accessible point. Due to insurance and health and safety restrictions, drivers are not insured to move goods into your home unless a suitable upgraded delivery service has been agreed in advance.

      Checking Goods on Delivery

      Please check all goods while the driver is present. The driver can usually wait up to 15 minutes.

      If any damage is visible, please mark this clearly on the delivery note and notify us as soon as possible. Any damage must be reported within 48 hours of delivery.

      If you are unavailable on the scheduled delivery date, re-delivery charges may apply.

      We provide delivery within a 200-mile radius of our Reading, Berkshire showroom. For customers outside this radius, products may be available for collection only, or we may be able to quote for a bespoke delivery solution.

      For delivery questions, please call 0118 970 1717 or email info@bonfire.co.uk.

      Learn more about our delivery information


      Returns and Exchange Information

      We offer a 14 day return policy for eligible products if you change your mind or are not satisfied with your purchase.

      Return requests must be made within 14 days of receiving your order. The customer is responsible for return delivery costs unless the goods are faulty or damaged.

      Returned goods must be unused, in their original condition and in their original packaging.

      Non-Returnable and Non-Refundable Items

      The following items cannot be returned or refunded unless faulty:

      • flue systems and chimney components;
      • bespoke items;
      • made-to-order products;
      • special order products;
      • unique or one-off pieces;
      • products that have been installed, used or modified.

      Please order carefully and contact our team before placing your order if you are unsure whether a product is suitable for your application.

      Any damaged items must be reported within 48 hours of delivery to help us resolve the issue promptly. If damage is not reported within this time, we cannot guarantee an exchange or replacement.

      A restocking fee of up to 30% may apply to returned or exchanged items where the goods need to be returned to the manufacturer.

      Learn more about our return and exchange policy

      Extend the capabilities of your flue system with the Midtherm HTS Twin Wall Flue – Extension Length (75-350mm). This precision-engineered component of two pieces offers a seamless extension of 75mm to 350mm when attached to a standard flue length, ensuring flexibility and convenience for your installation needs.

      Key Features:

      • Adjustable Extension: Designed to work with standard lengths, this extension provides a range of flexibility. It can be used on lengths starting from 500mm, with a minimum extension of 260mm when used with a 300mm section.
      • High-Quality Construction: Made from premium 0.5mm stainless steel (316 2b inner and 304 BA outer), it offers durability, corrosion resistance, and a sleek, modern finish.
      • Insulated Performance: Sold fully insulated for optimal safety and efficiency in high-temperature applications.
      • Convenient Installation: Includes a special locking band for secure, consistent connections, making assembly straightforward and reliable.
      • Compatibility: Perfect for use with wood, multifuel, gas, oil, biomass, and pellet systems, offering versatility for various heating applications.

      Performance and Certification:

      • Rated for 450°C operating temperatures with a 4-hour fire rating.
      • CE Certified, manufactured under ISO 9001 quality systems, and HETAS registered for assured performance and safety.

      Durability You Can Trust:
      The Midtherm HTS Twin Wall Flue system comes with a 20-year warranty (available for registered and properly maintained installations), ensuring long-lasting performance and peace of mind.

      Joint Type

      Push fit socket and spigot type joint, to be installed with a locking band in place.

      Note: Images show the extension length paired with a standard flue length for reference.

      Downloads:

      Additional information

      Brand

      Midtherm

      Colour

      Stainless Steel

      Country Of Origin

      United Kingdom

      Flue Diameter

      127mm (5"), 150mm (6")

      Fuel Type

      Gas, Multi Fuel

      Material

      Stainless Steel

      Warranty

      20 Years (if registered)

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