I have a Buck fireplace insert that was in my house when I bought it 18 years ago. It is located near the center of the house. I burn mostly red oak. I can barely see any smoke from the chimney when I am burning wood and the chimney has been extremely clean when I run a brush through it. The stove puts out more heat than I really need. I have thought about replacing it for two reasons: 1) burn time is not as long as I would like and 2) the fan is really noisy. Reason number 1 is a lot more important to me than reason number 2. If I replace it I will get another fireplace insert. I would like a freestanding stove, but the dimensions of the room the fireplace is in won't really permit that. Is there a modern fireplace insert that would give me significantly longer burn times? Would I have to install a metal chimney liner if I get a new stove? Any opinions welcome.