I just purchased a Lopi answer and am going to put it into my fireplace.The damper readMajestic special 1922 (the year the house was built) it has a 4" opening.Do I have to remove it? Is there a flex pipethat will go thru the opening? A friend just mentioned getting a chimmney linner.I also want to know if single wall pipe is ok to run up the chimmmney.Any advice to safley install my stove and save money would be of great assistance.Thankyou.