I'm installing a Brunco wood furnace. The flue comes out the back of the stove. I'm also installing a Metalbestos chimney up the side of the house. Is it better to have the stove pipe come straight out the back of the furnace and through the wall, or come out of the stove with a 90, up a few feet, another 90, and then out through the wall? I would be eliminating 2 90's with the first method, so I thought I would get a little better draft. With the latter method, I may be out of luck if I ever got a different stove and the flue did not match up with the original. Any downside to putting the 90s in before I go out throught the wall?