Posted: 25/12/2015 at 14:25
One problem with woodburners is that a chimney liner is often needed in order to keep the smoke hot enough. The hotter the smoke, the better the 'draw' and higher the smoke will rise above the property. If a chimney is considered marginal in this respect, then installers may give the owner an option to save a few pounds by not installing a liner and this may be what has happened in this case. The best liners are 'twin wall' with the inner liner getting much hotter than the outer.
Here's a short article on the subject:
Note the potential issue for the owners concerning carbon monoxide with inadequate chimneys. They are not expensive to have installed.