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Improve Efficiency and Safety: The Importance of a Flue Liner

Updated: Oct 20, 2023

Flue liners are an essential part of most log burner installations. Once you have picked your perfect log burner, the flue liner ensures that the stove is performing at its optimum efficiency while keeping you and your family safe. Here at Loxwood Burners Sussex Ltd. we typically use a flexi-liner flue to adapt to any bends in your chimney. In this blog, we will discuss the advantages of having a flue-liner installed and the different types of flue liners available.

Please note: this blog is about flue liners in open chimneys, not twinwall installations.

Row of houses with chimneys

Why do I need a chimney liner?

As many of our customers have previously had an open fire in their home, this is a frequently asked question. A flue liner is a long, flexible metal pipe that is attached to the flue outlet on the log burner up to the base of the pot hanging cowl. It is continuous to ensure that all of the gases released during burning travel directly out of the chimney.

It is important that prior to a stove installation the condition of the chimney is surveyed. If there is any risk that fumes could be leaked into the home during burning there must be a liner. This is for the safety of the household. Chimneys can become damaged over time due to age and use, and as such there may be tar build-up or gaps in the chimney that will affect the updraught. Tar build up can also contribute to the risk of a chimney fire.

Installing a log burner offers a great opportunity to improve the overall safety and efficiency of your chimney by installing a new flue liner. We always recommend having the chimney power-swept, even if it is swept annually, to ensure that any tar build-up is removed before the new liner is installed.

Why do stove manufacturers recommend a flue liner?

Stove liners are not a legal requirement when completing a stove installation, however, they are highly recommended by stove manufacturers and governing bodies such as HETAS. When browsing through manufacturer's brochures or websites, you may notice that either a 5 inch or a 6 inch flue is recommended for each particular stove. Stove manufacturers encourage the installation of a flue liner as it improves the overall efficiency of the stove.

By installing a flue that perfectly matches the flue outlet of the stove you can be sure that all gases are travelling directly out of the chimney. Some chimneys can be as wide as 200mm which, if a log burner is installed without a liner, will reduce the overall performance of the stove due to issues with air draw and drafts. The lack of a flue liner, or an ill-fitting flue liner, will make it more difficult to sustain a continuous burn.

Different types of flue liners

There are a couple of options when it comes to a flexi-liners to help you find the right one for your stove.

As previously noted, most flue liners are either 5 inches in diameter or 6 inches. Usually, the stove manufacturer indicates which diameter is most suited to the stove you are purchasing. Most 5kW stoves have a 5 inch flue outlet. It can increase to 6 inches as the stove output increases.

You will have the choice of either a 316 liner or a 904 liner.

316 liner: the 316 liner is often recommended for wood-only stoves. It is cheaper to purchase and suitable for burning seasoned wood.

904 liner: the 904 liner is often recommended for multi-fuel stoves, or as an upgraded liner for wood-only stoves. Due to its higher grade of stainless steel, it can withstand the heat, chemicals and moisture released when burning smokeless fuel, or when burning fuels continuously overnight. The 904 liner is suitable for burning seasoned wood, smokeless fuel and smokeless coal.


Flue liners are as essential to your stove installation as the stove itself. The combination of a highly efficient stove and a well-fitting flue liner make sure that you get the best burn every time. Not only that, but the liner will keep your family safer as it draws the excess gas directly out of the property and prevents tar build-up on the chimney brickwork.

Houses with chimneys at night

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