Modern, efficient appliances need modern, efficient chimneys. The selection, location and installation of the chimney is at least as important as the type of wood-burning appliance you choose. A properly designed and installed chimney will give many years of reliable service and will allow your appliance to perform properly. An effective chimney is an important part of any successful wood burning system. Many of the reported problems with the performance of wood burning appliances can be traced to chimney deficiencies of various kinds. Knowing how chimneys work is not only necessary in selecting the correct chimney and designing the installation, but is useful in the day-to-day operation of the appliance.
Chimneys operate on the principle that hot air rises because it is less dense than cold air. When a chimney is filled with hot gas, that gas tends to rise because it is less dense than air outside the house. The rising hot gas creates a pressure difference called draft which draws combustion air into the appliance and expels the exhaust gas outside. The hotter the gas compared to the air outside, the stronger the draft.