Chimney size?

[Newbie18]

Are there any guidelines as to the size and height of a chimney? Does it make much difference if there are 2 90 degree elbows in the chimney, as I have it vented out a rear wall as opposed to going straight up. My pan is a 2x4 SS flat bottom on top of a 2x5 insulated arch.

[motowbrowne]

Just guessing here really, but I'm thinking you're gonna want to go with 8" pipe. You could probably get away with 6" though. The longer your stack the more draft you'll get. Rule of thumb is twice the length of your arch, so 10' in your case, but you'll likely need more to overcome your elbows. Ideally you run the stack straight instead of with 90 degree turns, but, all you can do is do the best you can with what ya got.