About chimneys - How do they work?
Although there are many chimney types out there, they all work on the same principle – updraft. Some of them have a few small pipes and some of them have large chimney openings.
About the updraft
The term described an airflow that rises from the fireplace, up on the chimney.
The size of the chimney is very important and it must be in accordance with the fireplace and the quantity of smoke it will direct. Because wood smoke particles are larger than sewer gas particles, for example, the chimney needs to have a larger opening. Also, the higher the chimney, the better it will pull the air though the inside. It also needs to have smooth walls, so it’s best to clean the walls of the chimney at least once a year.
On the roof
Another important factor that needs to be met is the distance of the chimney above the roof line. This aspect is important as a wind can cause a draft to get into your house, reversing the flow of the smoke and gases. Assuring a proper construction can make it less prone to downdrafts. It’s also important to clean the chimney liners.