Question about Flue System Length and Elbows

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swbco

New Member
Oct 28, 2023
16
Colorado
Hello All,

I'm wondering if there is a formula or rule of thumb for determining how much additional length needs to be added to the flue to compensate for elbows. In other words, how much straight length needs to be added if the flue contains X amount of elbow?

For context, I have approximately 14 feet total, but two feet of that is 30 degree elbow above ceiling. Unfortunately, there is no way to do away with the elbow. The flue was installed at the time the house was built 26 years ago, but we have never had a stove. We are looking at putting in a PE T5 or Super (both easy breathers I'm told). Complicating matters is that we are in southern CO, elevation 5000 feet.

Thanks for your help.
 
The altitude will have a greater effect on draft than the offset. Is the existing flue 6", classA, insulated chimney? If so, you could try connecting the stove with double-walled stove pipe. It may work. If the draft is weak and smoke spillage is noted when temps are below 45º then the chimney may need to be extended by 2-3 feet.