I'm installing a flex liner in a masonry chimney on the outside wall of my house. Should I spend the time and money on the insulation kit for this? I do have about 4 feet of flat run and two elbows getting into the chimney. Second and most important, I have a cleanout at the bottom of this masonry chimney now. Is it ok to run the pipe past the T where it comes in the house at down an additional 5 feet to this existing door to make cleaning the chimney easier? I could take the cap off through this door then and clean the mess up very easily.