Baby it's cold outside!
Even in the sunny state of California we are seeing temperatures drop to 23 degrees overnight. Some people still rely on good old fashioned wood burning inserts and even open fireplaces to heat their homes. I know that our house goes through a lot of wood in the winter season. Keep in mind that the type of wood you burn has a direct effect on the build up in your chimney, not to mention waxy papers etc. that may be thrown into your fire once it is started. Almond and oak firewood burn pretty hot and clean while pine, citrus woods and duraflame logs can definitely clog up that chimney.