This furnace burns up to 30" logs and can run 8-10 hours on one fueling. We had this plumbed into our ductwork in our home and it kept our over 3000sq ft home comfortable. This model produces up to 130,000 BTU's. Fans automatically turn on/off to prevent circulating cold air. Also has a controllable damper. Comes with 3 pieces of triple wall piping and wood rack. $1000. OBO