I'm tired of waiting for the contractor to come install my chimney. Iv done everything else so far. Removed the old fireplace and chimney. Installed 7100, fresh air, auxiliary air,and have the heat runs planned out. What makes me nervous is once you connect the chimney pipe it cant be undone. A mistake could be costly. I have roughly a 35' run straight up. I dont think it will be to difficult. What is the correct way to start? From the bottom up or the top down? I'm also not sure if the fresh air for the chimney is supposed to be an outside or inside source. Thanks for any help, tips, or things to look out for. Winter will be over soon and I really want to try this guy out.