You may need to use elbows for your Class A chimney for various reasons. You may want to go around an eave instead of cutting a hole through it with the double wall pipe. Or you may be in the attic and need to avoid a rafter or another obstacle.
The Class A Elbows come in 15 degree or 30 degree kits. A double wall elbow kit has two elbows to make the pipe then turn vertical again. The elbow kit also includes a necessary bracket. Below is a chart that helps you determine the elbows you need for your factory built chimney.
This elbow offset chart is for 5″-8″ Class A chimney pipe.
You cannot have more than 72″ of double wall chimney pipe between the two elbows. If you have more than one section of Class A chimney pipe in between the elbows, a second elbow strap is required. Class A chimney pipe cannot make a 45 degree turn, this means you cannot connect a 15 an a 30 degree elbow together to make a 45 degree. If it is necessary to make a 45 degree turn, you need to find another route for the chimney.