I have a 22 year old 1250 sq ft home with a full basement. I have a fireplace upstairs that I have used for 20 years, glass doors, ambiance only. My home is brick with a full masonary brick chimney with 2 flues. My fireplace uses the larger of the two. In my basement which has poured walls their was an alcove as if to install a fireplace but their was no flue opening? Two years ago I purchased a used appalachian stove insert. got out my ladder tied a rope to a twenty pound sledge hammer and found the flue in the basement by knocking on the concrete and listening, got out the hammer drill and finised the job. I then set my stove in the alcove and fabricated a nice boot for my stove to a 6" stove pipe ran this to the flue and all is well. Now for the questions. Do I need a flue liner? and why? What is a cat stove? My house is heated with a heat pump and I have opened a cold air return in the basement and leave the fan running on the heat pump seems to help. This will heat my house but what can i do to improve on efficiency? First day on this sight as I am staying home watching it snow! Thanks Steve