Elite chimney sweep Maesteg and Porthcawl. Beware birds nests in your chimneys. Here is a link to a nest I removed last week from a chimney in Southerndown. Extremely large and very dangerous if the owners had tried to light the fire
https://www.youtube.com/watch?v=KMuPY0lkyFc&feature=em-upload_owner Check this out.
If you are worried about the risks of Carbon Monoxide Poisoning, you need to look at this video and the following article.
Hope this helps you.
Carbon Monoxide Article
