Do I Need A Flue Liner?

If you have a standard masonry chimney and wish to install a woodburning or multifuel stove, it is highly advisable to fit a stainless steel flexible flue liner with the stove.

Corinium Flue Systems recommends fitting a flue liner for the following reasons;

• Masonry chimneys, particularly in older properties, are likely to have cracks. Without a liner, any fumes from the stove and creosote formed will leak through cracks in the masonry, possibly exiting in other rooms in your house or in your neighbours'.

• Creosote is a tar like substance that is formed when fumes emitted from the stove cool down as they rise. When these gaseous fumes cool down, any substances contained within the fumes condense and are deposited on the inside of the flue or chimney. A flue liner has a smooth inner skin with less surface area for creosote to be deposited onto, whereas in a masonry chimney it is likely to build up in cracks or crevices. Creosote is highly flammable and is often the cause of chimney fires.

• A flue liner is much narrower than a chimney and is the same diameter from top to bottom. This continuous, consistent pathway will allow the flue gases to exit the chimney much quicker, with less chance of deposits. A flue liner's narrow, consistent diameter also means that it will warm up much quicker than a chimney. This results in an improved draw, making it easier to get a fire burning without lots of smoke back into the stove. A flue liner will retain the heat longer than a chimney after the fire has died out, which means it will be easier to start a new fire the morning after the night before.

• A flue liner is generally more straightforward to sweep. Creosote deposits formed will be harder to remove from a large chimney, especially build ups in cracks or crevices.

A question frequently asked is whether the flue should be insulated - this is done by backfilling the chimney around the flue liner. This is not necessary, but can be beneficial if you have a particularly cold chimney i.e. external, very exposed and very large. Normally the warming of the air in the chimney surrounding the liner during burning is sufficient for insulation.

They are also frequently asked whether a flue liner is necessary to comply with building regulations. It does not state in the building regulations that a flue liner has to be fitted with a stove. However, you must be sure that the chimney is in good working condition and has been sufficiently maintained. The majority of installers and retailers will recommend fitting a flue liner; particularly in older properties, as it is safer and more efficient.

We do not advise asking your installer not to fit a flue liner purely on the basis of cost. Once you have made the one off investment, your stove and flue liner, if properly maintained, will last for years. Most stove and flue manufacturers offer a warranty on their products - for example, Corinium offer a ten year warranty on our flue liner, subject to conditions of use.

HETAS Advise: Chimneys & Lining

What is Chimney Lining?
The function of a chimney is to safely remove the products of combustion from a fireplace or appliance to outside of the building, without causing any danger to the occupants of the house. A chimney works because hot air rises and moves from high to low pressure. Factors such as running the appliance at a very slow rate or cold air leaking into the flue will cool the gases and affect the performance of the chimney. Lining systems are designed to replace the flue in an
existing chimney, with dimensions appropriate to the appliance. Insulation may be added or
integrated into the new flue system to improve the efficiency of the draught. This is a particular requirement for external situations. The Lining method of a chimney and materials vary

Why Line Chimneys?
Chimneys are lined for a number of safety related reasons. The
illustration (right) shows two types of chimney system lining. While new chimneys may require relining, systems that predate 1965 will often require a modern lining solution for the following reasons:
1. The flue may have lost integrity and can leak smoke into rooms or other parts of the building.
2. Condensates or tar can seep through chimney walls causing
staining, inside or outside of the building.
3. Lining with insulation included improves the operation of
appliance and flue (particularity important when the chimney is on an external wall).
4. Defective flue systems may be eroded and rough. This will cause frictional resistance to the flow of the gases resulting in poor updraught.
5. Large flues (over 200mm) particularly ones containing voids may affect appliance performance. Some appliance manufacturers specify smaller flues for efficient operation.

Methods of Chimney Relining and Renovation
Chimneys with existing flues can be relined in several different ways. These
include:
1. Using rigid sections of clay, pumice or refractory liner installed by cutting into the chimney wall or by lowering sections down from the top of the stack and infilling with an insulating material.
2. Insulating concrete, pumped in and around an inflatable former by a
specialist contractor.
3. Stainless steel flexible liner in a continuous length lowered down the chimney.
4. Spray on coating by a specialist contractor.
5. Ceramic coating by a specialist contractor.
The suitability of any of these methods of lining is dependent on each
individual system. You should seek professional advice on what is the most
appropriate solution for your need.

Chimney Faults
Before having a liner installed in your chimney, you should have it swept to remove soot and tar deposits by a professional chimney sweep. For those that already have a chimney lining, a
competent sweep will be able to inspect for the following faults:
1. Liners fitted upside down
2. Out of line or overlapping liner
3. Obstructive ledges hindering updraught
4. Protruding cement at joints
5. Liner removed during previous service work or installation
6. Damage through incorrect sweeping (see “more information” for professional
chimney sweep organisations)
7. Masonry damaging the liner
8. Blocked terminal (cowl or rain cap)
These faults can lead to a number of problems with the operation of a solid fuel appliance. More importantly, faults with chimney lining can pose a risk to the safety of household
occupants and should be rectified immediately.

For more information

The Solid Fuel Association technical and consumer helpline provides helpful advice on any aspect of solid fuel appliance installation and use.
Tel: 0845 601 4406
Web: www.solidfuel.co.uk


 The National Association of Chimney Engineers (NACE) provide a register of competent chimney engineers in the UK and Ireland for a variety of chimney work.
Tel: 0800 0924019
Web: www.nace.org.uk

The Association of Professional and Independent Chimney Sweeps sets standards for, and improve the knowledge and safety of sweeps in the UK.
Tel: 0845 604 4327
Web: www.apics.org.uk



The Guild of Master Chimney Sweeps works to improve standards and professionalism in the UK chimney sweeping industry. They have a directory of Guild approved sweeps on their website.
Web: www.guildofmasterchimneysweeps.co.uk


The National Association of Chimney Sweeps (NACS) promotes high standards for the sweeping,
inspection and maintenance of chimneys. They have a directory of approved sweeps on their website.
Tel: 01785 811732
Web: www.nacs.org.uk

For more information and access to a variety of HETAS advice sheets, visit the HETAS website at www.hetas.co.uk

How Not To Install A Wood Burning Stove

Just a quick video to show the difference it can make using experienced, recommended fitters to install your wood burning stove.

The client had seen the work we had carried out in their next door neighbours house and wanted the same in theirs. They had their builder carry out the work to the fireplace and were going to give us a call regarding installation of the stove. They had other workmen in the house at the time who said they could arrange for the stove to be fitted as they had a friend who fitted them. The client assumed that all fitters would install his appliance to the same standard but soon found this not to be the case.

We were called out to tidy up the installation as the client was not happy with how it had been left........we did this and it was a good job he called us in as the register plate had been made from flammable material and also the stainless flexi liner was installed upside down.....this doesn't sound like a big deal bit it will take your liners life expectancy from 20 years down to a possible 5 due to condensation getting between the two skins causing the liner to corrode prematurely.

In the end the client was delighted but unfortunately had to pay for the installation twice. He had no comeback on the installer as he was a friend of a friend and didn't want to cause upset.............the installer also wasn't HETAS Registered so there was no paperwork or notification given to building control. This would be mostly likely to render his home insurance invalid should he have had a fire caused by the stove.