Stoves can be easily self-installed but you need building control approval (which is easily done). You may wish to have your stove installed by a Hetas registered installer in which case you do not need building control approval. more information on stove installation.
When the chimney is very bendy a nose cone can help you get the liner down - however I find that simply using the flex adapter and attaching wires to it and then a rope is usually sufficient.
