Use the chimney properly
A chimney liner is often part of making the route safe, suitable, and fit for the appliance you want in the room. It is not the glamorous part of the job, but it is an important one.
Customers do not need to become experts in liners. They simply need to know whether the route is likely to work properly.
Talk about the room and the route together
It is usually more useful to discuss the whole installation than to talk about the liner in isolation. The room, the opening, the appliance, and the chimney arrangement all influence the right answer.
If you think a liner may be needed, the showroom or a quick call is the best place to start.