The diameter of Flexible Flue Liner your installation requires is determined in part by the stove you have, the size of its outlet collar and the building regulations but simply put, there are two main factors to consider;
- the minimum internal diameter of any flue system must be 150mm if connected to a non-DEFRA or EcoDesign Ready stove or 125mm if connected to a DEFRA or EcoDesign Ready stove and
- the internal diameter of a flue system can never be less than the diameter of the stove’s outlet collar.
So following these guidelines, for example, if your stove is DEFRA approved you could install a 125mm diameter Flexible Flue Liner but if the outlet collar measures 150mm, then so must the flue.
The length of Flexible Flue Liner required is of course dictated by the height of your existing chimney with extra added on to allow for connecting to the stove and ease of installation. Your chimney can be measured by your chimney sweep prior to ordering with the most commonly sold lengths of liner ranging from 8m-11m. But remember, you can cut liner down to size but you cannot add or extend this product so measure twice and order right first time!