I have on old circa 1970 wood burning stove/ fireplace. These units are excellent at heating my whole whole upstairs. My problem is occasionally smoke emits from the front and I am constantly messing with fire to get it in perfect position so it wont smoke. That being said sometimes it doesnt smoke at all. My damper is wide open & there is no obstruction to the pipe. A friend suggested that the pipe going out the roof may not me long enough and putting another one on may help. Also I cant use the damper at all, it has to wide open or it will smoke. Please take a look at pics. Any advise you can give will help, Thanks.