Your new flue liner carries a 10 year manufacturers conditional warranty against perforation and splitting. The installation has been carried out to exceed the specification to ensure problem free continued use.
For the warranty to be valid, your appliance must be swept at least twice a year and a certificate of sweeping received on each occasion. These should be retained to avoid any complications in the unlikely event of a claim being made, and should be passed on to any new owners. The warranty covers replacement cost only and excludes the cost of removal of old and installation of replacement.
In any instance, please contact Steven Kay in writing at the above address.
Why sweep so often?
Your new flexi liner is constructed from a twin-wall stainless steel strip that is specially folded to produce a strong, resilient, air tight but flexible tube that is resistant to high temperatures, but with a smooth bore on the interior to prevent build up of combustion residues, soot and tar.
Soot is very hydroscopic, attracting and absorbing moisture. The residue from burning wood collects on the inside of the liner during use, and in its original state is easy to sweep from the liner. If however, it is left in the flue, it will absorb moisture from the atmosphere and condensation and eventually become a wet, tar like substance. Under very wet conditions this will then start to slide and drip down the flue. When the fire is next used, or if there is a spell of warm dry weather, the moisture in the tar will be evaporated, and the tar will return to a solid state with a smooth, shiny surface, no air gaps and 'glued' firmly to the side of the flue. No amount of sweeping will dislodge this from the flueway, and it is very flammable. This has effectively reduced the diameter of the flue, and constant repeating of the process will continue to restrict the airway further. As the flue narrows, so sweeping becomes more difficult and more strain is put upon the liner, eventually to the point where the liner could split in an effort to open the flueway. It also becomes a considerable fire risk.
Soot from burning coal and coal derived products is less likely to become tar like, but will absorb
moisture in a similar fashion, however the damp soot this creates is far more caustic than wood soot
and if not swept regularly, will start to eat away at the steel of the liner, continuously weakening
it. Again, upon sweeping, the weakened liner has the potential to split.
Some fuels (these mainly being re-formed fossil fuel products) will also dry out after being damp to form a cement like residue, which again is difficult to remove and restricts the flue. These fuels can also have a high Sulphur content that if left in the flue becomes very caustic and will attack the fabric of the liner. For more information got to Flue Liners on this site.
As with all solid fuel burning appliances, failure to regularly sweep the chimney can result in a chimney fire, the occurrence of which in a flexi lined flue would almost certainly destroy the liner.