Ten years ago my wife and I purchased some property and put a manufactured home on it that we custom ordered with a wood burning fireplace in a very harsh winter weather community and not knowing at the time that the monstrosity we installed may have looked nice, however was not efficient in heating the house more then say 20 feet in front of the it. Now its time to replace with some thing more efficient in heating and I found a manufactured home approved fireplace insert from Northern tool that is more like a wood stove in the sense it sticks out approx. 8 to ten inches from the hearth and should be much better for heating which brings me to my dilemma current fireplace has 8 inch flue and chimney stove insert I would like to purchase has 6 inch flue can I just run 6 inch 24 gage 304L stainless steel chimney pipe right up through my exsisting built in chimney and would it be safe I have attached a picture of the fireplace we had installed and that took up an entire wall I might add....... I also attached and image of the new insert I would like to install