Sometimes people’s chimneys are fine to use without the installation of a flexible liner.  The chimney will then need to be certified by a certified NACS chimney sweep.  This however is very rare because the main reason for lining a chimney when fitting a stove is to help the draw of the stove.

If you would like to fit a stove without using a twin wall flexible liner you will need the NACS registered chimney sweep to complete an integrity test and leave a certificate of compliance which will allow the use of the log burner for only 1 year as it must be checked at least every 12 months.  This is because chimneys can pass one year and not the next after a solid fuel appliance is installed.  It is not improbable or unlikely that the chimney could start leaking smoke within the few months after the installation as leaking chimneys are a common issue.

A register plate for a stove without a liner would have to have a sweeping hatch built into it so that when the chimney is swept, the chimney sweep can gain access to clean the soot from the top of the register plate.  Soot is un-burnt fuel and is a combustible material; unswept chimneys are the cause of chimney fires.  Why not have a look at our animation on the home page for more information.

We advise customers to install a stove with a liner because it makes the stove draw better and reduces the chance of downdraft issues.

The diameter of a flue pipe is 5” or 6” from the top of the stove.  Stoves without liners can experience problems drawing properly.  This is because the flue gases slow down when the smoke travels out of the flue pipe into a masonry chimney stack due to the chimney stack having a larger volume of space.  This change in pressure affects the speed the flue gases escape, resulting in the stove experiencing smoke spillage through the vents.  This can increase the chances of downdraft issues, especially in windy weather.

Issues that increase a chimney having anti-static down draft issues are:

- Tall buildings around a property
- Nearby trees that are taller than the chimney stack, as these do not allow the wind to travel over building and chimney pots smoothly
- Geographical location, for example, being at the top or bottom of a hill
- Cold flues, as cold air wants to drop, which stops the fire drawing at the beginning, or when a stove is first put on
- External chimneys stacks or tall chimney stacks that have a large section of flue outside facing the elements

By installing a stove with a liner, you have the peace of mind that the liner will have a guarantee of 10 years or 20 years - often lasting longer than this if regularly swept in line with the manufacturer's recommendations.

Ian Gay, one of the local NACS registered chimney sweeps that we recommend who covers Twickenham; Kingston; Richmond and South London, mentions:

“The problem now is that many homes that are approaching 100 years are starting to fail the integrity test, making it very hard to sign off homes that were once considered to be fine always.  I am seeing houses that were built in the 1930’s and 1940’s that are leaking now.  So I find myself not being able to issue a certificate of compliance and recommending that the chimney is lined.  Looking back as little as 10 years ago, it was mainly the Edwardian and Victorian properties and older buildings that you would expect needed to be lined by a chimney lining company.”

We would recommend installing a twin wall flexible liner with all stove installations, as do our stove manufacturers, as it is best to run your stove with one.  If you consider that an open fire puts 25% of its heat into the room and 75% goes up the chimney, where as a stove often has 80% of the heat going into the room and 20% going up the chimney.  This will result in a tar build up in the chimney that a chimney sweeps brushes won’t be able to remove called creosote.  Creosote is the build-up caused when flue gases condense as they go up to the top of the chimney, they are created by cold temperatures at the top of the chimney slowing the warm flue gases down, causing soot deposits to stick to the side of the brick or clay flue.

Our chimney lining experts can help you with types of chimney lining, as well as flexible liner installation we installed insulated twin wall systems and the Eldfast ceramic lining system.  Click Here to see our Eldfast Ceramic Lining animation.