I recently purchased a us stove 6039 used from a Facebook garage sale site. I'm in the process of going through it and double checking all working components. The question I have is my house has a Chimney already there, it's 6" coming through the wall. Will I be able to reduce that down and hook up to the stove or is there some modification that I'm looking at doing. Previous owner said there was a pellet stove already there with no problems. Tsc associate said I would need to put install new Chimney pipe. Looking for experienced feedback.