FuranFlex® technology – introduction

FuranFlex® chimney liner material and technology developed and produced by Kompozitor Kft. fundamentally differ from any other applications.

FuranFlex® is the only method, by which chimneys of any shape, dimension and length can, without having to demolish any walls be lined with joint-free airtight liner of steel hardness and stainless composite material that is also resistant to flames and heat.

Composite material

Composite is the professionally defined term for thermosetting resin of high hardness with fibre glass reinforcement. The once hardened resin will no longer soften back again and will not melt either. Its structure is similar to that of reinforced concrete. The difference is as much as having concrete instead of resin and steel reinforcement bars instead of fibre glass in place.

The hardness and corrosion-proof characteristic of FuranFlex® made of composite are better that those of steel, whereas it is five times lighter. The two versions of FuranFlex® have the unique feature of fire-resistance. The black material resists to heat up to 500 °C, while the red one up to 1000 °C.

Why do chimneys need to be lined?

At burning fuels, acidic vapour is generated and condensed inside the chimney. In a few years time, it tends to damage concrete, stainless steel, the mortar in between the bricks and also the internal plaster. This process is called chimney corrosion. The slots generated due to corrosion may let carbon-monoxide in the rooms, which can be fatal. In Europe, several hundreds of people die every year due to the defects of chimneys. In most of the countries, providing chimneys with lining is mandatory. The pictures below show the signs of chimney corrosion.

KezdolapAzottTuzfal1 KezdolapAzottSzobafal IMG 1387

Conventional chimney liner tubes


Chimneys have traditionally been lined with either rigid or flexible tubes of stainless steel, ceramic or with internal spreadable plaster.

KezdolapKorrozioHowever, rigid stainless steel tubes can be installed in high chimneys or chimneys of other than a straight construction only with the demolition of walls. At the same time, the flexible, stainless steel tubes are of rather thin wall, therefore they easily corrode and tend to be damaged while being installed. The corrosion guarantee provided for such materials usually does not exceed 10 years.

Ceramic tubes can only be used for lining chimneys of straight construction. They need to be assembled from several shorter sections. Their heat-resistance is excellent and they also resist to acidic effects. However, their sealing is uncertain at the joints and they would let water and acids leak through.

The main advantages FuranFlex® provides the user with

  • no demolition of wall, the residential spaces remain clean during the lining works
  • lining works only take a few hours
  • can be applied with all types of boiler and chimney
  • chimneys up to 100 m height and 120 cm diameter can be lined without joints to be applied
  • its inner surface is smooth and its heat insulating capacity helps boilers operate economically
  • FuranFlex® corrosion-proof guarantee is 25 years
  • FuranFlex® RWV corrosion-proof guarantee is 10 years


FuranFlex® international partners


FF RWV guaranteeIntroduction - Technology - FuranFlex composite liner - FuranFlex chimney lining official website
FuranFlex® liner provides the following unique features

  • any length without a joint
  • follows the branching lines of chimneys
  • takes up the shape of the chimney, the cross section of which can vary from circular, square or oval
  • its shape can be of variable cross sections
  • perfectly gas-compact
  • smooth inner surface, eased smoke gas flow
  • good heat-insulating, increases chimney draft
  • thin wall, does not decrease the dimension of the cross section in the chimney
  • hardness of steel
  • non-combustible
  • heat-resistance by the type: 500 °C (FuranFlex®) and 1000 °C (FuranFlex® RWV)

Examples of possible FuranFlex® installation

  • can be installed with all types of boiler
  • even several liners can be installed in the same chimney
  • can be applied at boilers with open and closed combustion chambers
  • quick repair of storm water ducts in full length
  • best solution for setting up corrosion-proof ventilation duct systems
  • chimney lining up to 100 meters without a joint

transp osszeallitas

Individual chimney duct

transp osszeallitas gyujto

Gravitational collector chimney

transp osszeallitas LAS

Pressed collector chimney

transp osszeallitas RWV

Wood heating chimney

Reputation of FuranFlex®


FuranFlex® liners are exported by Kompozitor Kft. to all countries of Europe as well as to the USA. So far, over 5 million meters of liner have been installed.

FuranFlex® has won several awards including for example Genius Europe Award and the Innovation Trophy in Paris.




The following pages contain everything to be known about the FuranFlex® material, installation technology and provide general information worth considering about chimney lining.