• Introduction

ThermaFlue is a high quality insulating sleeve for flexible flue liners. Each sleeve is hand manufactured and inspected to exacting standards. The sleeve is stitched with Aramid sewing thread, ideal for high stress applications requiring extreme strength and heat protection. Each length has an overlap collar with a D-G link system that ensures consistent thermal insulation. Adjustable hook and loop fasteners facilitate a taut fit around the flexible flue liner. With additional flame retardant Velcro fastenings.

• Distribution

Thermaflue can be purchased through one of our stockists Flue & Ducting Ltd, IMS-insulation, MI Flues, Oriel Flues (Ireland) and Timber & Tile (NI).

Please email sales@thermaflue.com to find your nearest stockist.

Excellent thermal properties

To purchase Thermaflue

please contact sales@thermaflue.com

Quick and simple to fit

• Application

It is recommended that where chimneys are positioned on external walls, or where the chimney void is particularly large, that the flexible flue liner is insulated. This is to prevent the flue gases from
condensing which is highly corrosive and will result in the liner prematurely failing.

Insulating a flexible flue liner helps maintain flue gas temperature and improve chimney and appliance performance.

• Material Specification and Warranty

The inner wall is a high quality inflammable needled glass fibre that provides excellent mechanical resistance and stability. The outer wall is a moisture repellent non-flammable silicone coated material. ThermaFlue is guaranteed for 10 years.

• Dimensions

ThermaFlue is manufactured in one metre sections and available in two widths. TH5-6 is suitable for 125mm and 150mm diameter liners and TH7-8 for 175mm and 200mm diameter.

• Approval

Thermaflue as been tested to BS EN1856-2:2009 with a designation number of EN 1856-2:2009 Designation T600 N1/P1/P2 D or W Vm(L*****) G. In the case of a chimney fire like the liner it must be replaced. It is capable of withstanding higher temperatures but must be replaced, like the liner itself, after a chimney fire.


Thermaflue insulation sleeves
Final Report 56742/2
To BS EN 1856-2:2009 & test methods of BS EN 1859:2009

10 years product guarantee

• Warranty terms and conditions

Thermaflue™ sleeves are guaranteed for ten years subject to the following conditions:

  • The appliance must be operating normally, set correctly and using only good quality fuels. Check the HETAS website for a list of approved fuels.


  • The guarantee is not valid if refuse or any type of plastic is burnt, or if the appliance is located where any substance containing Chlorine of Florine can be drawn into the air intakes, or where fuel which releases chlorine is burnt.

Installation Guide

• Description

Thermaflue™ insulation sleeves are designed to improve the operation of solid-fuel burners and minimise deposit build up within the flexible flue liner by maintaining a more stable flue draught and temperature.

The sleeves are comprised of two layers of high-temperature insulation material; an external water-resistant, silicone coated woven E-glass cloth and an internal needled fibreglass matting. These are wrapped around the flue liners and secured with buckle fasteners and connected along the length of liner by metal D and G links.

• Specification

Designed and tested to withstand long term operational temperatures of 600°C. Suitable for all gas, oil and solid-fuel burning appliances to which a flexible flue liner can be attached.

• Ordering and Sizing

This product is available in 1 MTR lengths in two sizes; 125 – 150mm (5” – 6”) and 180 – 200mm (7”- 8”).


Thermaflue UK Ltd,
Unit B Herrod Avenue, Off Haigh Avenue,
Whitehill Industrial Estate, Reddish,
Stockport, SK4 1NU

Have a question?

Use the form below or write to us at sales@thermaflue.com to get in touch.

To order call:   0161 480 2994

Stockport, SK4 1NU

Flue & Ducting Ltd
Unit B Herrod Avenue, Off Haigh Avenue,
Whitehill Industrial Estate, Reddish,
Stockport, SK4 1NU