Tar in a chimney or flue is a major problem. Not only does it smell, create a black mess when mixed with rain and potentially soak through walls discolouring decorations but it is a major fire hazard.
Tar will, at some point catch fire, it is a question of when not if. You certainly cannot leave tar in a flue that is to have a flexi liner installed for a stove. The most we have removed is 400kgs from a single domestic chimney!
Tar is created mainly by burning unseasoned logs, slumbering (not burning hot enough) a stove or having an oversized or cold flue. It cannot be removed by the traditional chimney sweeps brush, its like the tar on the road, you can brush it until you are blue in the face, it wont shift.
We use physical removal equipment and, in the worst cases, chemical treatment as well. Although we use extractors to remove dust this is a long and often dirty process and is the only way to get a tar coated chimney back to a state it can be used. As well as being time consuming it can often be an expensive process with cost depending on the severity of the problem.
If you are looking for a solution to a tarred and unusable chimney then we can help.