Action Chimneys' comprehensive and specialist knowledge of chimney structure informs our ability to provide homeowners and commercial customers with the very best advice and recommendations. We are committed to providing our customers with an open, transparent and quality service. We listen to our customers and develop our service in response to your specific needs.

The chimney liner serves three main functions

  1. The liner must contain the smoke so that it doesn't leak into the chimney structure. The exhaust gas produced contains water vapor that can condense as it cools. Evidence of leakage of condensed flue gas shows up as dark stains on the sides of brick and stone chimneys.

  2. The liner must be able to withstand the high temperatures resulting from a chimney fire.

  3. The liner must resist attack by acids that are found in wood and coal appliance smoke.

Why upgrade your chimney with a new liner?

There are four main reasons to reline an existing chimney:

  1. Relining may be needed when there is a change of use of the chimney, such as the installation of a smaller, more efficient wood stove, or a fireplace insert into an existing fireplace. To maximize performance and increase efficiency, the flue area should match that of the connected appliance.

  2. Clay liners may fail because of temperature shock caused by a chimney fire, from attack by acids in flue gases, from freeze-thaw cycles in cold climates, or from general deterioration with aging. The most common signs of failure are cracks in clay liners and displacement of broken pieces. Whatever the reason for failure, relining is a good solution for a chimney in which the brick or stone shell is still in good condition but the liner has failed.

  3. Signs of flue gas cooling, such as water condensation, visible staining or rapid creosote formation, are problems that can be corrected by the installation of a new liner, especially one that has insulation around it. Low flue gas temperature results in weak draft, which tends to show up as slow burning, fussy fires that can smoke into the room when the door is opened for loading.

  4. A routine cleaning or special inspection may reveal a safety hazard such as inadequate clearance or combustible material.

Traditional Clay Liners

Traditional clay flue liners have been used extensively in chimney construction since the 1930's, if your house was constructed before 1940, then it is unlikely to have any liner installed inside the chimney stack. In some cases, these liners while perfectly adequate for the time and application, were often crudely assembled by stacking one upon another, with a layer of mortar laid between them. A lime rich sand mix was then packed around the liners, this was the extent of the fitting operation. 


Unscrupulous builders sometimes paid very little attention to proper chimney construction or geometry. This was exacerbated by the fact that it was not possible to inspect the inside of the chimney once completed. As a result, mortar deposits nested inside the liner joint area, which encouraged soot and creosote deposits to gather. A spark could ignite these deposits, starting a chimney fire.

As a consequence of the chimney fire, the clay liners could be damaged through thermal expansion caused by the intense heat generated which results in the cracking of the liners. This allows dangerous gases or flames to reach the inner structure of the house. Modern clay liner design and installation has improved considerably, and clay liners are still widely used in chimney construction, though we rarely use them in our practise.

Ceramic Liners

View a complete installation of a ceramic flue liner.

Rebated high performance ceramic liners are made from composite materials which are fully CE tested and approved. They are fully compatible with the increasingly popular efficient modern appliances as well as meeting the more traditional soot fire requirements. 

Liners are installed with the male spigot pointing downwards. Sealant is applied to the inside of the female socket and any excess projecting into the flue should be wiped off as installation progresses.

Schiedel are the market leaders in ceramic flue development and are the primary brand that we use in installations.

Stainless Steel / Flexiflue liners

A stainless steel chimney liner is a practical solution for when the original clay tile liner was either never installed, or when the tile lining cracks, crumbles and deteriorates over time.  Flexible stainless steel liners come in many sizes and bores. The size or bore will be calculated by our Survey Engineer and will be based on a number of factors such as chimney opening, dimensions of room, and chimney stack height.

Grades of stainless steel liners.

Flexiflue or flexiflue installation by Action Chimneys

Stainless steel is graded using a numbering system which identifies the proportions of nickel and chrome content. The two principle grades used are 316 & 904 grade, the 904 being much more expensive (often twice as much as the 316 grade) but also much more resistant to corrosion.

The main difference between open fires and wood burning stoves is flue gas temperature. An open fire has a very high flue gas temperature, while a stove, which is more efficient has a low flue gas temperature. This low temperature is more likely to result in condensation of the flue gases against the side of the liner (sulphuric acid condenses at 150°C). This condensation is a big problem as acid attack is accelerated massively in the presence of water (which is one of the by-products of combustion).

In an effort to provide the best possible service to our customer base, Action Chimneys recommends the use of 904 grade liners, in fact it is the only grade we stock at present. 

Many of our competitors will argue that 316 grade is more that adequate for your property, and in most cases this is essentially true. Action Chimneys will never place a client in the "most cases" category. We treat your home as if it was our own, and we would only use 904 in our home. Action Chimneys will not compromise on safety.


Furanflex25 chimney liners can provide an ideal solution for your domestic and residential chimney project. Chimneys come in all shapes but many do not follow what could be described as being of traditional design or construction. Traditional lining methods cannot be employed in such circumstances as they cannot provide the optimum size flu for your fireplace.

Furanflex25 has been engineered to mould into the exact cross-sectional shape of your chimney and can be installed in any length or diameter without the need of joints. Once installed it is completely gas tight and resistant to the acidic gases generated during the combustion process.


Action Chimneys are the sole agents and installers of Furanflex25 in the Republic of Ireland. 

More detail on the Furanflex product can be accessed from this link.